Section 7 Flashcards

Question

A 35-year-old man is diagnosed with acute hydrocephalus due to tuberculous meningitis, and antitubercular therapy is started. He is admitted to the neurosurgery intensive care unit following external ventricular drain (EVD) placement from Kocher point and is showing clinical improvement. During the second day of admission, the patient inadvertently pulls out his EVD drain. The treating clinician immediately places a new EVD from the same point. There is clear egress of cerebrospinal fluid (CSF) in the EVD bag. What is the most appropriate next step in management? 1. Repeat CT head to ensure proper EVD placement 2. Send CSF for culture and sensitivity 3. Plan for ventriculoperitoneal (VP) shunting 4. Plan for endoscopic third ventriculostomy (ETV)

Answer 1

**2. Send CSF for culture and sensitivity** ## Footnote * The accidental removal of an external ventricular drain (EVD) has a reported incidence of only 0.4 %. It is a serious adverse event with high risks for intraventricular bleeding and ventriculitis. * The incidence of ventriculostomy-related infection ranges from 0-30%. However, the mortality from ventriculitis has been reported to be as high as 40%. * It is critical to send the cerebrospinal fluid (CSF) for culture, initiate broad-spectrum antibiotic coverage, and modify the antibiotics based on the culture and sensitivity results. * CSF diversion procedures such as VP shunting and endoscopic third ventriculostomy (ETV) should be performed only after ruling out microbiological evidence of ventriculitis in this patient.

Answer 2

**2. Decompression and posterior fusion** ## Footnote * The above-mentioned scenario reveals significant cervical spondylosis at two levels of the cervical spine. * Decompression with posterior fusion is the ideal treatment of choice for this patient. * Flexion and extension radiographs are required to assess the instability and correctable deformity. * Decompression and laminectomy without fusion lead to poor results.

Answer 3

**1. Alzheimer disease** ## Footnote * The pathogenesis of Alzheimer dementia includes the formation of plaques of amyloid protein within the brain known as cerebral amyloid angiopathy (CAA), which is also a risk factor for lobar intracerebral hemorrhage (ICH). * CAA is due to the deposition of beta-amyloid protein in cerebral cortical blood vessels (rarely in the basal ganglia and brainstem), seen most commonly in the population above 55 years of age. * The apolipoprotein E (ApoE) genotype is thought to impact the pathophysiology of CAA but is not a sensitive test to diagnose the disease. CAA increases the risk of lobar ICH significantly, and imaging often reveals hemorrhages of varying ages, which may be seen as heterogeneously attenuating lesions. * Low cholesterol, when associated with hypercoagulable states or hypertension, can be a risk factor for ICH.

Answer 4

**2. Lower extremity motor deficit** ## Footnote * While even severe pain may be expected to improve with multimodal nonoperative treatment, the presence of motor deficits is less amenable to conservative management. * As motor deficits resulting from direct nerve root compression by a lumbosacral disc injury may result in permanent weakness and the resulting disability, surgery should be considered as an early treatment option when evaluating a patient with lumbosacral disc injury and associated focal weakness. * Without formal adherence to nonoperative treatment such as oral NSAIDs, physical therapy and epidural injections, the duration of symptoms alone is not an indication to proceed with surgery prolonged pain does not have the potential for permanent disability seen with motor deficits. * In the absence of motor deficits, physical impairment is not an indication to proceed with surgical intervention initially when managing lumbosacral disc injuries. Nonoperative treatment such as oral NSAIDs, physical therapy, and epidural injections should be trialed with the expectation that they may improve functional status.

Answer 5

**4. Open surgery** ## Footnote * Early operative treatment is recommended to provide the best possibility for the brain to expand and produce a normal configuration of the skull. Surgery goals are to remove the bony ridge of the metopic suture, advance both orbits and the frontal bones, achieve a rounder forehead contour, and prevent the psychosocial impact and neurodevelopmental delay. * Operative treatment can be endoscopic or open. This child is already one year of age. Endoscopic technique is best used before 3 to 4 months of age due to the skull's pliability. Thus, open surgery is recommended. * In those cases where cranial reconstruction is required, a bifrontal craniotomy is performed to reconstruct the anterior cranial vault, including the lateral portions of the sphenoid wings to allow brain expansion. * If the deformity is minimal or there is only a bony ridge without hypotelorism, a more conservative approach can be used; however, the child should be followed for a minimum of 12 months of age to assess and corroborate adequate cranial growth. Clinical evaluations and family discussions regarding neuropsychological development are engaged. A head helmet is used on the patient on the fifth postoperative day after endoscopic surgery. It is used for the next 10–12 months to directed cranial growth by allowing cranial expansion in recessed areas of the skull.

Answer 6

**1. SNAP amplitudes are normal, CMAP amplitudes normal, and abnormal spontaneous potentials on needle EMG** ## Footnote * The majority of the patients have normal sensory and mother nerve conduction studies. However, needle EMG is possible in cases with radiculopathy but not essential during a spinal stenosis study. If there is a significant narrowing of the vertebral formanina and root compressions in the acute setting, you may find fibrillations and positive sharp waves at different levels bilaterally. * In a patient with spinal stenosis, motor nerve conduction studies and amplitudes are usually normal. Distal latencies should also be normal as the distal aspect of the nerve is not disturbed. However, if the disease has progressed to the point where axonal damage has occurred, you will see a decrease in amplitude of the CMAP on nerve conduction studies. * In a patient with spinal stenosis, sensory nerve conduction studies and amplitudes are usually normal. This occurs because the sensory fibers travel through the dorsal root ganglion, which is located outside the spinal canal. * For the needle EMG portion of the exam, it is essential to test multiple paraspinal levels bilaterally and multiple myotomes in both extremities. In spinal stenosis, often, there are findings of bilateral multilevel nerve root involvement, if there is root involvement.

Answer 7

**1. Steppage gait** ## Footnote * Steppage gait produces an initial contact with toes (foot drop). The heel is unable to strike first. * Steppage gait is caused by ankle dorsiflexion weakness. A herniated disc at L4-L5 will compress the L5 root and create radiculopathy affecting the muscles and producing dorsiflexion of the ankle. * Treatment for steppage gait is hinged or posterior leaf spring ankle-foot-orthosis (AFO) and electrical stimulator. Sometimes surgery can reverse foot drop. * Waddling gait or toe walking is caused by proximal muscle weakness.

Answer 8

**1. Reassurance** ## Footnote * Three ossification centers develop in the immature atlas one for the anterior ring and one for each posterior neural arch. These ossification centers appear at one year of age. * The connection between anterior and posterior arches is composed of neurocentral synchondrosis, which fuses at 7 years of age. The posterior arch usually closes by three years of age. * The pattern of cervical fractures in children younger than 10 years is much different from older children and adults. * Most of the cervical spine fractures in young children occur between occiput and C2 due to large head size and relative hypermobility.

Answer 9

**4. Staphylococcus aureus** ## Footnote * The condition described is a Pott's puffy tumor which is osteomyelitis of the anterior table of the frontal sinus with a subperiosteal abscess. It is a complication of frontal sinusitis that is most commonly seen in young adults due to a more extensive network of diploic veins. The rapid diagnosis for fast treatment of this condition is crucial for optimal outcome and decreases the risk of development of complications such as intracranial extension via erosion of the posterior table of the frontal sinus. Studies have demonstrated that the best strategy for the management of Pott puffy tumors is the combination of medical and surgical treatment to prevent further complications and improve morbidity and mortality. * Once the patient arrives and diagnosis is suspected, the patient should be admitted and started on broad-spectrum IV antibiotic, IV hydration, analgesia, and rapid coordination for imaging studies. A moth-eaten pattern of bone destruction is characteristic on imaging. * Broad-spectrum IV antibiotics should be started as soon as the diagnosis is suspected. Coverage should be provided for the most common pathogens, including gram-positive and anaerobes. It is important to choose antibiotics that have adequate blood-brain barrier penetration for central nervous system coverage. Choices include penicillin or vancomycin, 3rd generation cephalosporin, and metronidazole. Once the culture has a final result, guide antibiotic therapy for that specific pathogen. * While many Pott puffy tumors are polymicrobial, the most common single species are Staphylococcus aureus.

Answer 10

**4. Modic changes type I or type II** ## Footnote * Based on this patient's history and exam findings, a basivertebral nerve ablation procedure is indicated, and MRI diagnostic studies usually reveal Modic Type I and/or Modic type II changes. These are related to vertebral endplate changes with inflammation, edema, disruption, and/or fissuring, as well as fibrovascular bone marrow changes and fatty bone marrow replacement. * Basivertebral nerve (BVN) ablation targets neurotomy (nerve destruction via radiofrequency ablation) of the BVN, which is responsible for carrying nociceptive input from damaged vertebral endplates, often seen in MRI as Modic changes type I and type II. * BVN ablation is clinically indicated to treat chronic axial low back/vertebral pain refractory to six months of conservative treatment in the setting of Modic changes (type I and type II). Modic changes are seen on MRI as fibrovascular bone marrow changes (hypointensive signal for Modic type I changes); and fatty bone marrow replacement (hyperintensive signal for Modic type II changes). * Pedicle destruction, compression fracture, and spondylolisthesis are not structural pathologies treated by BVN neurotomy.

Answer 11

**3. Pulmonary function testing** ## Footnote * Pulmonary dysfunction can include both obstructive and restrictive pulmonary changes. * Physical examination should include a thorough inspection of symmetry, spinal alignment, flexibility, and work of breathing. * Studies have shown a relationship between increased Cobb angle and poor performance on pulmonary function testing. * Dizziness in this scenario may be secondary to comprised respiratory status. Therefore pulmonary causes should be ruled out before a neurology referral.

Answer 12

**2. Rubrospinal tract** ## Footnote * The description is typical of an abnormal flexion response equivalent to a motor score of 3. * The rubrospinal tract is responsible for mediating flexion of upper limbs and extension of the lower limbs. * The flexion of upper limbs indicates the location of the traumatic insult to be above the anatomic location of the rubrospinal tract. * The vestibulospinal tract mediates the extension of both upper and lower limbs. The corticospinal tract governs voluntary motor functioning.

Answer 13

**4. Lateral cervical plain film radiograph in maximum flexion and extension** ## Footnote * The patient has C1-C2 instability, also called atlantoaxial instability. Lateral flexion-extension views are a dynamic study that shows the degree of displacement between vertebrae in the sagittal plane. * Increased motion at the C1-C2 level can lead to vertebral artery occlusion, ischemia of the brainstem and posterior fossa structures, resulting in seizures, syncope, vertigo, visual disturbances and even sudden death after minor trauma. * Surgery is usually indicated in patients who have more than 5 mm of translation in flexion and extension X-rays. * Open mouth anteroposterior cervical X-Ray is not the proper incidence to detect anteroposterior C1-C2 instability. It reflects mediolateral instability, and spinal cord compression is less probable to occur under these circumstances. As with CT, MRI does not reflect the degree of instability between two vertebrae.

Answer 14

**1. Conservative treatment with observation** ## Footnote * Most cerebrospinal fluid leaks from cribriform plate fracture resolve spontaneously. * While conservative treatment is usually the best choice, the patient warrants observation to ensure resolution. * Conservative treatment is preferred for patients who present with a GCS > 8 without other significant intracranial pathology. * If the cerebrospinal fluid leak persists for greater than 7 days, surgery should be considered due to an increased risk of morbidity and mortality.

Answer 15

**4. Perform needle electromyography** ## Footnote * Electromyography (EMG) is most useful after a two week to three-week delay to permit denervation changes to occur in the affected muscles. In a complete neurapraxia lesion, needle EMG will show no motor unit action potentials (MUAPs) under voluntary control, but fibrillations are not present. In complete lesions, the appearance of fibrillations and positive sharp waves is time and length-dependent; they do not appear for a number of days after the injury. In proximal muscles, they appear after 10 days to 14 days and in distal muscles after 3 weeks to 4 weeks. The presence of MUAPs by EMG examination indicates that reinnervation is occurring. * The EMG is more sensitive than the physical examination for detecting early reinnervation, so the return of MUAPs on needle examination in the muscle closest to the injury site is typically the first evidence of reservation. * Neurotmesis is the complete disruption of the nerve and nerve sheath. Recovery is unlikely without surgical intervention as the nerve axons will unlikely grow. For optimal nerve regeneration, nerve stumps must be precisely aligned without tension and repaired atraumatically with minimal tissue damage and a minimal number of sutures. * Blunt transection repairs are usually delayed for 3 weeks to 4 weeks, at which point the nonconducting fibrotic segment of both stumps is appreciable and can be adequately resected before repair. Physical therapy can assist with some improvement of wrist function using compensatory techniques, stretching, and orthotics.

Answer 16

**2. Amantadine** ## Footnote * The sign and symptoms in this patient are suggestive of phantom pain. Treatment should be started when patients have phantom pain and a positive lidocaine trial. * A patient with phantom pain and a positive ketamine trial should begin taking amantadine. * Pharmacological techniques often are used in conjunction with other treatment options. Doses of pain medications needed often decrease when combined with other techniques but rarely are completely discontinued. * Tricyclic antidepressants and sodium channel blockers often are used to relieve chronic pain and in an attempt to reduce phantom pains. Opioids, ketamine, calcitonin, and lidocaine may relieve pain.

Answer 17

**4. T1-T2** ## Footnote * This patient is demonstrating signs of a chronic disc herniation with a gradual development of symptoms without an inciting event. * Her neurologic examination is suggestive of T1 radiculopathy. * T1 radiculopathy will have normal upper extremity reflexes. * T1 radiculopathy will demonstrate diminished sensation at the medial forearm and a decreased strength of the finger abductors.

Answer 18

**1. MRI whole neuroaxis, surgical resection and radiographic surveillance** ## Footnote * The radiographic and histological features are suggestive of pilocytic astrocytoma—particularly the long bipolar cellular process, cystic component, and nodular mural. * These tumors are low grade and curative on surgical resection. Radiotherapy and chemotherapy are not routinely used. * Children with posterior fossa tumors require whole neuroaxis imaging to assess for drop-metastasis. * Patients with posterior fossa tumors often present with obstructive hydrocephalus. Symptoms include headache, nausea and vomiting, blurred vision, and papilloedema.

Answer 19

**1. Surgical excision** ## Footnote * The patient is having an intramedullary tumor. * The radiological features are suggestive of ependymoma. Ependymomas often are located centrally within the spinal cord leading to symmetric expansion, occupy the whole width of the cord, and enhance diffusely with a well-defined border. * Gross total resection is the treatment modality for ependymoma. * Astrocytomas tend to be positioned more eccentrically, can be non-enhancing or have an enhancing nodule or large satellite cysts, and usually, do not have a well-defined border.

Answer 20

**2. Subluxation of the atlas relative to the axis** ## Footnote * The Sharp-Purser test has to be carried out with extreme caution. It determines the subluxation of the atlas relative to the axis. * The examiner places one hand contacting the patient's forehead, while the thumb of the other hand stabilizes the spinal process of the axis. The patient is then instructed to slowly flex the cervical spine, during the movement, the examiner presses in the opposite direction with the palm on the forehead. The test is considered positive if the examiner feels posterior sliding of the head along with patient pain. * If the transverse ligament is responsible for maintaining the position of the odontoid process relative to C1 is affected, C1 will perform an anterior translation (subluxation) with respect to C2 during flexion. * The muscles of the cervical spine ensure stability and mobility of the head.

Answer 21

**3. Simian virus 40** ## Footnote * Choroid plexus papilloma is most commonly in a lateral ventricle in children and in the 4th ventricle in adults. * In children, it can cause hydrocephalus. * Studies have shown that Simian virus (SV) 40 has an association with the occurrence of choroid plexus tumors. * BK virus and John Cunningham (JC) viruses have also been implicated.

Answer 22

**3. Plain CT scan of the head with CT angiogram** ## Footnote * The patient has a penetrating head injury. * The nail is stuck to the pterion and hence there is a chance of injury to the main blood vessels at the skull base. The pterion is the region where the frontal, parietal, temporal, and sphenoid bones join together. It is located on the side of the skull just behind the temple. * Hence this patient needs an angiogram along with a CT scan head. * MRI is contraindicated in this patient due to the presence of a metallic foreign body.

Answer 23

**2. Keraunoparalysis** ## Footnote * A lightning injury should be suspected in this patient, even in the absence of a definite history of lightning exposure. * The rash is characteristic of Lichtenberg figures, which are pathognomonic for these injuries. * Keraunoparalysis is a well-known phenomenon in victims of a lightning strike. It causes transient vasospasm, which can result in pulseless and paralyzed extremity. * A stroke and intracranial hemorrhage should be considered in patients with altered mental status. However, in this case, it would not adequately explain the physical examination findings.

Answer 24

**2. A 55-year old female with refractory intracranial hypertension after a motor vehicle collision with significant long-bone fractures** ## Footnote * Severe dehydration is a contraindication to mannitol as mannitol is a diuretic. * Mannitol is FDA approved to treat increased intracranial pressure, increased intraocular pressure which is not responsive to other treatments, the oliguric phase of acute renal failure and to help increase diuresis of toxic materials. * Anuria is a contraindication to mannitol as mannitol is a diuretic and the patient must be able to produce urine for it to work. * Severe heart failure and significant electrolyte abnormalities are contraindications to mannitol as will increase the circulating plasma volume by increasing the intravascular water content and can worsen heart failure and electrolyte abnormalities.

Answer 25

**4. Extensor hallucis longus** ## Footnote * Isthmic spondylolisthesis is most common in an adolescent at L5/S1 level; hence most commonly affected root is L5 (exiting under L5 pedicle), which supplies extensor hallucis longus and hip abductors. On examination, one can expect reduced power of big toe extension. * L5 nerve root supplies extensor hallucis longus; hence this patient would present with weakness of great toe extension. * Grading of lumbosacral spondylolisthesis is described in the Meyerding classification. Grade 4 correlates with 75% to 100% of the vertebral body forward slip and is likely to cause neurological symptoms. * Different nerve roots supply quadriceps, tibialis anterior, tibialis posterior, and gastrocnemius.

Answer 26

**2. Right-sided otic capsule disrupting fracture with sensorineural hearing loss** ## Footnote * The patient likely has an otic capsule disrupting fracture, given the mechanism and immediate facial nerve palsy. * Commonly they pass through the jugular foramen, internal auditory canal, and foramen lacerum. * Cerebrospinal fluid (CSF) can leak (4-8 times as likely), and the patient can consequently have meningitis. * Sensorineural hearing loss (7-25 times as likely) can also occur.

Answer 27

**1. Prothrombin complex concentrate** ## Footnote * Warfarin greatly worsens the bleeding associated with a head injury. * One of the first priorities is to reverse the effects of the patient's anticoagulation rapidly. * The best medication to immediately start to reverse the warfarin is prothrombin complex concentrate. * Fresh frozen plasma can also be given, but prothrombin complex concentrate is preferred.

Answer 28

**3. Between the galea aponeurotica and the periosteum** ## Footnote * Local flaps in the face are typically elevated in the subdermal plane, with the exception of the scalp and nasal flaps. Scalp flaps are typically elevated in the subgaleal plane, and nasal flaps are often raised in the submuscular plane. * The scalp does not stretch as much as the skin of other body regions; therefore, longer back-cuts and larger flaps are often required to close comparatively small defects in this area. * Incisions in the galea aponeurotica, known as galeotomies, are often employed to permit greater degrees of tissue advancement in the scalp. * The length of the back cut for a rotation flap will often be four to eight times the diameter of the defect. Rotating tissue beyond 90 degrees is advisable because this will minimize the standing cutaneous deformity that occurs, even though rotating beyond 90 degrees will not result in additional decreases in wound closure tension.

Answer 29

**1. Cervical spine films and CT of the head** ## Footnote * Airway, breathing, and circulation have been established. * The diving accident followed by prolonged submersion often involves cervical spine injuries. * ECG should be done as there may be prolonged QT but should wait until the patient is no longer hypothermic. * Other injuries should be diligently sought.

Answer 30

**4. Corpus callosotomy** ## Footnote * The patient is exhibiting typical clinical features of an alien hand syndrome following the epilepsy surgery. * The alien hand syndrome is a variant of a disconnection syndrome seen in some cohort of patients undergoing epilepsy procedures. * The main factor predisposing to such complications in the patient is the corpus callosotomy, one of the components of the disconnection procedures during the epilepsy surgery. * The superficial hemosiderosis predisposes to hydrocephalus in the patient. The suprasylvian block may risk the occurrence of hemiparesis the patient owing to the damage to the corticospinal tract.

Answer 31

**2. Rebleeding** ## Footnote * The major cause of mortality in patients with ruptured aneurysmal bleed is rebleeding of the aneurysm. * The mortality in cases of re-rupture of an aneurysm is as high as 90%. * The placement of external ventricular drain and egress of cerebral spinal fluid can reduce the tamponade effect from the hematoma onto the aneurysmal dome. This can paradoxically lead to the re-rupture of the aneurysm. * Vasospasm leads to new clinical deficits but seldom leads to acute malignant intracranial hypertension. The onset of pneumocephalus in cases of acute hydrocephalus is minimal.

Answer 32

**3. Spinal drain placement** ## Footnote * The longer the stent-graft placed, the higher the risk of spinal ischemia. This is because the increased length of the stent covers more branches from the aorta to the anterior spinal cord. * Spinal drain placement allows real-time decompression and management of spinal edema if spinal ischemia occurs postoperatively. * If neurologically changes occur, such as decreased sensation or motor control of the lower extremities, the spinal drain will be opened, allowing for CSF removal and decompression of the edematous spinal cord. A right thoracostomy would not be useful in this scenario. Lumbar puncture is unlikely to provide a significant decrease in spinal pressure. * A left pleural effusion caused by free hemorrhage may be seen with aortic transection.

Answer 33

**3. Contrast MRI spine** ## Footnote * Contrast MRI reportedly has 100 percent sensitivity, specificity, and accuracy in differentiating recurrent disc from that of the postoperative scar. * Scar enhances almost immediately after injection, due to the vascularity of this scar. The recurrent disc shows a slow enhancement over the first 45 minutes of contrast administration and is characteristically always less than that of the adjacent scar. * Plain MRI was shown to have 100% sensitivity but only 71% specificity, and 89% accuracy in differentiating the same. * CT discography is an invasive procedure. Myelography is neither sensitive nor specific in the evaluation of the same.

Answer 34

**2. Adamantinomatous craniopharyngioma** ## Footnote * There are two histologic subtypes of craniopharyngiomas: adamantinomatous and papillary. * Adamantinomatous craniopharyngioma is primarily seen in pediatric cases but can be seen in adults as well. They have solid and cystic parts. The solid part is characterized by dense nodules and trabeculae of squamous epithelium bordered by a palisade of columnar epithelium, sometimes referred to as a "picket fence." The cystic part has a yellow-brown, cholesterol- rich fluid. * Papillary craniopharyngioma is commonly seen in adults. They are mostly solid without calcification. They are characterized as well-differentiated squamous epithelium lacking surface maturation, with occasional goblet cells and ciliated epithelium * Mild hyperprolactinemia is due to the large size of the sellar mass resulting in the "stalk effect."

Answer 35

**2. ESR** ## Footnote * The Kambin approach approaches the epidural space inferior to the exiting spinal nerve. The intervertebral disc anteriorly bounds it, and thus advancing the needle too far forward can result in penetration of the disc. * An elevated ESR and CRP is the most sensitive laboratory value to diagnose discitis. WBC may or may not be elevated so it is not the best answer. * Injection of contrast and a safety view in the anterior-posterior plane would show the location of the needle tip in the disc. The severe back pain is an indication that the disc likely has developed a discitis infection. * Major procedure-related complications and drug-related systemic effects of ESI requiring hospitalization including spine infection, hematoma, and sepsis are very rare. Though the incidence of permanent neurological complications from epidural steroid injections is rare, great care is taken to avoid critical vascular and neurological structures in the vicinity of the needle during injection.

Answer 36

**1. Age greater than 60 years** ## Footnote * Patients aged greater than 60 years is the most significant risk factor for a major perioperative complication during adult spinal deformity correction, while obesity is the most predictive of a poorer patient-reported outcome after correction of adult spinal deformity. * Back pain is the most common complaint associated with adult spinal deformity. * Adult spinal deformity can cause sagittal or coronal imbalances that can result in postural deficits and decreased function. * A history of tobacco use and obesity has not been found to have an association with the development of major complications.

Answer 37

**1. Ragged red fibers on muscle biopsy** ## Footnote * The patient has Kearns Sayre syndrome (KSS). * Muscle biopsy is the diagnostic test of this pathology and shows ragged red fibers, similar to other mitochondrial myopathies. * The main abnormality of macular OCT will be the loss of retinal pigmental epithelium. The inner retinal thickness will be preserved. * While abnormalities of the brain white matter are frequently seen in patients with KSS, this is a non-specific finding and can not be used to confirm the diagnosis. Patients with KSS do have diffuse retinopathy on electroretinograms, but this is not a confirmatory diagnostic test.

Answer 38

**4. Compression of the posterior cerebral artery due to transtentorial herniation** ## Footnote * This infarct is within the distribution of the posterior cerebral artery. * Transtentorial herniation can cause compression of the posterior cerebral artery against the tentorium cerebelli. * This causes ischemia in the inferior parietal and occipital region. When bilateral, this can cause cortical blindness. If unilateral, it may present with hemianopia. * The superior cerebellar artery supplies the cerebellum, and a thrombus in the basilar would cause ischemia within the posterior fossa.

Answer 39

**4. Tractography** ## Footnote * The fractional anisotropy and the apparent diffusion coefficient MR sequences have now enabled us for from studying the tractography pattern of the nerve. They are now an integral armamentarium for assessing peripheral nerve injuries. * The fractional anisotropy in particular studies the axonal density and the pattern of Brownian diffusion of water along the nerve fibers. It, therefore, allows the earliest anatomic assessment of the integrity of the nerve. * It allows for the visual inspection of any abrupt cut off of the fiber tracts, or comparative analysis regarding any wasting of the fascicles in comparison to that of the healthy counterpart. * The changes in the electrophysiological studies are only appreciable after the Wallerian degeneration is completed. The wasting in terms of the cross-sectional area of the fascicles from the ultrasound is also possible after a few weeks of injury.

Answer 40

**4. Optic nerve sheath diameter assessment by ocular ultrasound** ## Footnote * The increase in intracranial pressure dissipates CSF into the distensible walls of the optic nerve, thereby leading to an increment in optic nerve sheath diameter. * The sequential assessment of the optic nerve sheath diameter (ONSD) by ocular ultrasound is a reliable and economical bedside modality for assessing changes in intracranial pressure. * The sequential assessment of ONSD has diagnostic as well as prognostic implications in managing patients with severe head injuries. * Repeat CT and MRI scans impose significant risks and hazards during the repeated transfer of unstable patients to the radiology department. Though external ventricular drain placement is the gold standard in monitoring intracranial pressure, it has a significant risk of infections and displacement. Moreover, it is very difficult to tap the ventricle in this patient, with a high risk of failure.

Answer 41

**2. Muscle stiffness** ## Footnote * The clinical vignette describes an anterior gray horn disease, likely amyotrophic lateral sclerosis. * The anterior gray column of the spinal cord contains cell bodies of motor neurons. Hence, muscle stiffness is often the first presenting complaint of diseases of the anterior gray horn. * Diseases of the anterior gray horn of the spinal cord include amyotrophic lateral sclerosis, spinal and bulbar muscular atrophy, Charcot–Marie–Tooth disease, progressive muscular atrophy, all spinal muscular atrophies, and poliomyelitis. * Anterior gray horn diseases do not affect sensory or cranial nerve function.

Answer 42

**2. Ketamine** ## Footnote * Ketamine causes a dissociative state and amnesia. * The drug also can increase heart rate and blood pressure. * The increased blood flow due to high blood pressure means that the drug should not be used in patients with intracranial pressure elevation. * Ketamine does not depress respiration and is an effective analgesic agent.

Answer 43

**2. A disc protrusion less than 3–4 mm** ## Footnote * IDET is indicated for disc-related chronic low back pain for a select subgroup of patients with non-radicular chronic low back pain who fail to respond to conservative treatment; ideally for annular tears or disc protrusions less than 3–4 mm. * The goal of thermal disc treatment is to damage the nerve fibers, shrink collagen, and stiffen the disc tissue. This might seal any small tears of the annulus fibrosus. * IDET is indicated for small disc bulges and well-hydrated disc (less than 50% height loss of intervertebral disc space). * Large protrusions may precede a nucleus pulposus herniation and neural root compression. This is unlikely to improve with IDET.

Answer 44

**2. Lamotrigine** ## Footnote * Evidence suggests lamotrigine is the most effective anticonvulsant in the treatment of central post-stroke pain such as in thalamic pain syndrome. * Lamotrigine is second-line after the use of tricyclic antidepressants (TCAs) in the thalamic pain syndrome. * Lamotrigine reduces neuron hyper-excitability in the case of centralized pain seen in thalamic stroke pain. * One randomized controlled trial, comparing lamotrigine to amitriptyline, found lamotrigine moderately useful in the treatment of post-stroke pain. Pain relief was seen in 44% of patients.

Answer 45

**3. Synostosis of the left lambdoid suture** ## Footnote * The clinical diagnosis is more in favor of synostotic posterior plagiocephaly. * Synostotic posterior plagiocephaly is due to the synostosis of the lambdoid suture. * Nonsyndromic craniosynostosis is commonly sporadic. * In deformational plagiocephaly, a CT scan can be normal.

Answer 46

**3. Hemiballismus** ## Footnote * Hemiballismus is characterized by involuntary, violent, wide amplitude flinging of the extremities. * Damage to the subthalamic nucleus is a cause of hemiballismus. * Hemiballismus is a rare condition and can occur after stroke or trauma and in patients with amyotrophic lateral sclerosis (ALS). * The subthalamic nucleus is located dorsally to the substantia nigra, ventrally to the thalamus, and medial to the internal capsule.

Answer 47

**3. Dorsal root ganglion stimulation** ## Footnote * The patient's clinical presentation meets the Budapest criteria for CRPS. * A negative straight leg raise test and no disc herniation on the MRI-lumbar spine make lumbar radiculopathy less likely. Moreover, EMG/NCS did not show any evidence of lumbar radiculopathy. Therefore a lumbar epidural steroid injection, as well as discectomy, would not be indicated. * He has trialed conservative treatments including oral neuropathic medications, physical therapy including graded motor imagery and mirror therapy as well as cognitive behavior therapy. The lumbar sympathetic nerve block was diagnostic but didn't provide any sustained pain relief. Therefore the next step in management would be the consideration of neuromodulation. * Both spinal cord stimulation and dorsal root ganglion stimulation are effective for the management of complex regional pain syndrome. But the ACCURATE multicenter study in 2017 found that for complex regional pain syndrome, dorsal root ganglion stimulation was more effective than spinal cord stimulation.

Answer 48

**1. Nerve injury by traction from the Halo vest immobilizer** ## Footnote * To answer this question correctly, One must first be able to diagnose this patient's condition, then understand the mechanism by which the halo vest immobilizer causes injury to the nerve involved. Anytime a patient reports seeing "double," this refers to diplopia. * On physical exam, the patient cannot abduct his right eye; this means his lateral rectus muscle is not working or has lost innervation. The abducens nerve innervates the lateral rectus muscle. Injury to the abducens nerve can occur from traction between the cranium and torso through the HVI. More common in pediatric patients (18 years old). * Treatment includes observation and release of traction, most resolve spontaneously. * The supratrochlear nerve can be damaged from an anterior pin placed medial to the "safe zone" however, a patient would have paresthesias and sensation loss over the medial forehead/eyelid and nose bridge. The supraorbital nerve can be damaged when an anterior pin is placed medial to the "safe zone" and note lateral to it. Also, patients with a supraorbital nerve injury will not have diplopia and loss of lateral gaze. Therefore, this answer choice is inaccurate.

Answer 49

**3. Fifth nerve only** ## Footnote * The lumbar nerves are the five spinal nerves emerging from the lumbar vertebrae. * A posterolateral herniation of the intervertebral disk at L4-L5 level affects the fifth lumbar nerves. * The majority of disc herniations occur at L4-L5 and the second most common site is C5-C6, C6-C7. * The patient will have radicular pain down the leg on one side. Straight leg testing may be positive. An MRI can be done to confirm the degree of stenosis and nerve compression.

Answer 50

**3. Bone insonation** ## Footnote * Magnetic resonance-guided focused ultrasound therapy is the recent advances in managing epilepsy, which is noninvasive as well as free of any radiation hazards. * However, the skull bone hinders the acoustic window needed for the proper delivery of the acoustic beam to ablate the target tissues thermally. * The bone skull, therefore, connotes the need for a higher dose of the ultrasound beam for the therapy (local heating). * The beam aberration and the local heating is secondary to the high dose of the beam required for the acoustic window secondary to the skull bone.

Answer 51

**2. Thalamus** ## Footnote * The thalamus is associated with memory loss in Wernicke- Korsakoff syndrome. * When a patient presents with confusion and persistent memory and learning deficits, one should suspect the presence of Wernicke-Korsakoff Syndrome. This syndrome usually presents with a clinical triad consisting of altered mental status (i.e., confusion or dementia), nystagmus or ophthalmoplegia, and ataxia. Unfortunately less than one-third of patients present with this clinical triad. To better understand this disorder, one should think of Wernicke encephalopathy and Wernicke-Korsakoff syndrome as two separate syndromes. Wernicke encephalopathy is characterized by an acute confusional state and often reversible clinical features while Wernicke-Korsakoff syndrome has persistent but often irreversible clinical features, including dementia and gait abnormalities. * The cause of Wernicke-Korsakoff Syndrome is a deficiency of thiamine or vitamin B1. Individuals with poor nutrition for any reason are at risk for this disorder. The most common social factor associated with Wernicke-Korsakoff Syndrome is chronic alcohol abuse which leads to decreased absorption and utilization of thiamine. However, it is important to note that there are nonalcoholic causes of thiamine deficiency which can also produce Wernicke-Korsakoff Syndrome. These include malnutrition, starvation, schizophrenia, anorexia nervosa, prisoners of war, and terminal malignancies. In the past, baby formula which was deficient in thiamine led to Wernicke- Korsakoff syndrome. Wernicke-Korsakoff Syndrome also can develop during the first trimester of pregnancy in women with hyperemesis gravidarum. Other common causes are bariatric surgery and malignancies of the gastrointestinal tract. * The diagnosis of Wernicke-Korsakoff Syndrome is made by the history and clinical findings that are supplemented with lab studies showing thiamine deficiency. The aim of treatment is to prevent the disorder from getting worse. One should maintain a high level of suspicion for thiamine deficiency to avoid precipitation of severe symptoms of Wernicke-Korsakoff syndrome. Prophylactic thiamine administration is relatively safe and should be started even if the diagnosis has not been confirmed.

Answer 52

**1. Granuloma of the catheter tip** ## Footnote * Catheter granuloma, also called catheter-associated inflammatory mass, is a noninfectious inflammatory process around the tip of the catheter, which is formed a long time after placement. * While this complication is generally asymptomatic, it can induce a decrease in the therapeutic effect of intrathecal analgesia and symptoms due to spinal cord compression. * When possible, lumbar access below the medulla is preferred to avoid neural compression. * Catheter migration can cause a loss of therapeutic activity. An infection manifests as meningitis or meningoencephalitis. Hematoma presents with symptoms similar to granuloma, but the trend is less progressive, and the differential diagnosis requires neuroimaging.

Answer 53

**3. Cerebral salt wasting syndrome** ## Footnote * Hyponatremia is a frequent electrolyte imbalance seen in patients who had neurological insults like head injury, SAH, or who had intra-cranial surgery. The two most common causes of hyponatremia in these patients are the syndrome of inappropriate antidiuretic hormone (SIADH) and cerebral salt wasting syndrome (CSW). * SIADH and cerebral salt wasting syndrome can be differentiated based on the volume status of the patient and urine sodium excretion. The normal urine sodium value is around 20 mEq/L. For the 24-hour urine test, the norm ranges from 40 to 220 mEq/L per day. * Cerebral salt-wasting syndrome is characterized by hyponatremia, volume contraction, and urine sodium concentrations inappropriately high for the given level of serum sodium. SIADH is characterized by inappropriate secretion of ADH, which causes water retention in the body and dilutional hyponatremia in a clinically euvolemic or hypervolemic patient. * Hyponatremia associated with SIADH is due to renal retention of free water (rather than excess loss of sodium by the kidney). So, the quantity of sodium collected over the 24-hour period and CVP should be relatively normal in SIADH patients, but in CSW, the quantity of sodium excreted over the 24-hour period will be higher, and CVP will be lower than normal.

Answer 54

**2. Pituitary** ## Footnote * Cushing disease, unlike Cushing syndrome, refers to one specific cause, a pituitary adenoma. * Due to the overproduction of adrenocorticotropic hormone (ACTH), these tumors cause a variety of endocrine and psychiatric disturbances. * Diagnostic tests used are salivary and blood serum cortisol, 24- hour urinary free cortisol, dexamethasone suppression test, and bilateral inferior petrosal sinus sampling. Multiple tests should be used. * First-line treatment is surgical resection of the ACTH-secreting pituitary adenoma. Pituitary radiation or bilateral adrenalectomy may be needed for postoperative persisting hypercortisolemia.

Answer 55

**4. Urine output** ## Footnote * Mannitol is a diuretic administered to reduce cerebral edema. * Closely monitoring a patient's input and output while on mannitol is essential. Failure for urine output to increase after administration of mannitol should prompt cessation of mannitol and evaluation for possible renal or genitourinary issues. * When giving mannitol, it is essential to monitor cardiac function as the fluid shifts can precipitate heart failure. * Additional electrolytes, including sodium, potassium, and osmolality, all require monitoring. The clinician should stop mannitol if significant electrolyte abnormalities develop or the osmolality reaches 320 mOsm or higher.

Answer 56

**3. Medulloblastoma** ## Footnote * The patient's age, imaging results, and anatomical location, as well as the extension to the fourth ventricle, all are more suggestive of medulloblastoma. * Ependymomas are the second most likely posterior fossa lesions in this age group. * Medulloblastomas tend to show a more homogeneous enhancement while ependymomas usually appear heterogeneous, due to internal cysts, calcifications, and hemorrhage. * Treatment for medulloblastomas is initially maximum surgical removal of the lesion, the addition of radiation and chemotherapy aims to increase disease-free survival.

Answer 57

**1. Frontal lobe predominant** ## Footnote * Oligodendrogliomas are well-differentiated, slow-growing but diffusely infiltrating cortical/subcortical tumors most commonly found in the frontal lobe. They are generally low-grade WHO grade II neoplasms with favorable treatment response when compared to other gliomas. * Patients with oligodendroglioma most often present with non- specific symptoms such as headache. Seizures may also occur. * Oligodenrogliomas are complex masses which may contain calcification, hemorrhage, cysts, and proteinaceous material. They are often cortically based and demonstrate gyral expansion. Peritumoral edema and hemorrhage are less common, and contrast enhancement is variable but typically mild. MRI offers a better characterization of the tumor margins and infiltration than CT. * Surgery is the mainstay of treatment, although adjuvant radiation and chemotherapy may be considered in the treatment of oligodendrogliomas. More favorable outcome is correlated with younger age, frontal location, lack of enhancement, complete resection, and radiation therapy after partial resection.

Answer 58

**3. External ventricular drain placement** ## Footnote * The first step in the management of a subarachnoid hemorrhage (SAH) is to stabilize the patient and to get an emergent neurosurgical evaluation. Patients presenting with a decreased GCS may require intubation for airway protection. Blood pressure, pulse, respiratory rate, and GCS must frequently be monitored. Pain control and antiemetics are often required for symptom control. * An external ventricular drain (EVD) may be indicated if the patient has a poor clinical grade on admission (decreased consciousness), acute neurological deterioration, or progressive ventricular enlargement on CT. This EVD may be used to remove CSF or blood that can cause increased intracranial pressure. * Modified Fischer scale grade 4 SAH denotes "thick, focal, or diffuse SAH with intraventricular hemorrhage." * Although 85% of the cases are caused by a ruptured saccular aneurysm, head trauma causes some cases of SAH.

Answer 59

**2. Neurorrhaphy and connection to the lingual nerve** ## Footnote * Medial and lateral antebrachial nerves can be harvested with the flap to possibly achieve a sensate skin flap. * While sensation can be achieved, the taste is unlikely to be achieved even with the harvest of the lateral and medial antebrachial nerves. * The flap must be elevated in a subdermal plane so as to not violate and sacrifice lateral and medial antebrachial nerves. * A unique aspect of this tissue transfer is the ability to achieve a sensate skin flap through reliable donor anatomy

Answer 60

**4. Posterior decompression with an interbody fusion of L4-L5** ## Footnote * The locked facet joint is a type of facet joint dislocation that results from jumping of the inferior articular process anterior to the superior articular process of the vertebra below and becomes locked in the position. * Anatomically, lumbar facet joints are arranged in the sagittal plane weak for hyperflexion yet strong for rotation. Hyperflexion with some amount of distraction is the most frequent mechanism of facet dislocation in the lumbar spine. * In the case of neurological weakness and lumbar facet dislocation, urgent surgical decompression is warranted. After decompression, the spine must be fused at the affected levels. * The majority of dislocations involving the lumbar spine occur at the thoracolumbar junction, with decreasing frequency at the lower lumbar levels.

Answer 61

**4. Request for electroencephalogram (EEG) and head MRI to look for a mass lesion or epileptiform focus** ## Footnote * The patient most likely has occipital epilepsy. Gastaut-type is a late-onset form in the teenage years. * Gastaut-type occipital epilepsy is classically described to have visual changes, tonic, clonic, or tonic-clonic movements consistent with a seizure and subsequent severe headache. * Occipital sharps may be seen on EEG recordings. * Medications used for migraines are inappropriate in this case. The patient should be treated for epilepsy.

Answer 62

**3. Dural arteriovenous fistula** ## Footnote * Dural arteriovenous malformation (DAVF) can be a late complication following cortical venous sinus thrombosis. The process is initiated by activating the hypoxia-induced proliferation of vascular endothelial growth factors (VEGF). * DAVF results from neoangiogenesis aimed at forming collaterals to bypass the thrombosed segment, in cases of failed recanalization, following sinus thrombosis. * DAVF recruits vascular supply from both the dural as well as cortical vessels. Its rupture thereby leads to both lobar as well as tentorial bleeds. * Sagittal sinus thrombosis leads to bilateral high frontoparietal territory bleed, following high pressure within the draining cortical veins. The intracranial hypotension leads to characteristic sagging of the major sinuses.

Answer 63

**1. Cloverleaf skull** ## Footnote * The child is having Pfeiffer syndrome (PS). * The clinical features of PS type II are cloverleaf skull (Kleeblattschadel type craniosynostosis) which is usually associated with hydrocephalus, maxillary hypoplasia with resultant proptosis, a “beak-shaped” nose, inferiorly displaced ears and ankylosis of elbow joints. * The clinical findings in patients with PS type III are like those present in PS type II, except for the cloverleaf skull deformity. * Additional features in type III PS include short anterior cranial fossa base, natal teeth, proptosis and various visceral abnormalities (hydronephrosis, pelvic kidneys, and hypoplastic gallbladder).

Answer 64

**4. Severe disc height loss** ## Footnote * Lumbar disc degeneration with more than 50% disc height loss is a contraindication for intradiscal electrothermal therapy (IDET). * Disc degeneration means that nucleus pulposus and annulus fibrosus become rigid. Patients usually experience constant pain due to severe loss of disc height, and this condition is unlikely to improve with intradiscal electrothermal therapy (IDET). * When disc height is lost, nerve impingement, bone, and joint inflammation, and resultant pain can occur. Therefore IDET may not allow improvement in this situation. * Disc height loss may contribute to spinal stenosis and spinal instability. IDET is not recommended for patients with this condition.

Answer 65

**1. Shunt x-ray series** ## Footnote * Congenital obstructive hydrocephalus is associated with a high risk for the development of shunt complications, most commonly the shunt obstruction that characteristically presents with headache, nausea, and vomiting, and lethargy. * Shunt series consisting of radiographs of the shunt components obtained in at least 2 planes is the imaging method of choice in the initial work-up of patients with suspected ventriculoperitoneal shunt obstruction. * Low-dose non-contrast CT is an imaging option used as an alternative to the shunt series for evaluating shunt function. However, contrast-enhanced CT is not used for this purpose. * Phase-contrast MRI is an imaging method used for the qualitative and quantitative evaluation of cerebrospinal fluid flow. Still, it is not used in the evaluation of suspected ventriculoperitoneal shunt failure. Radionuclide shunt study is a technique that can be used in the evaluation of the ventriculoperitoneal shunt malfunction, but not as the first-line.

Answer 66

**4. Immediate closed reduction with cervical traction** ## Footnote * The patient presents with a deteriorating neurologic exam in the presence of a bilateral C5-6 facet dislocation, indicating that there is an acute spinal cord injury either from the initial trauma or secondarily from local inflammation or hemorrhage causing compression. Obtaining a baseline physical exam at the time of presentation is imperative; this will be used to determine if the patient's neurological status is improving or worsening in subsequent exams. * Because the patient is alert, cooperative, and sober, the next step in management is an emergent closed reduction with cranial traction while the patient is awake. An ASIA Impairment Scale of E is a normal exam. An ASIA Impairment Scale of C shows preserved motor function below the neurological level, but with more than half of key muscles below the neurological level showing weakness but with a muscle grade less than 3. Therefore the exam is worsening. * Immediate closed reduction is performed in the awake and cooperative patient with a unilateral or bilateral facet dislocation with or without neurological deficits. This is performed by inserting cranial tongs with axial traction by adding weights from 50-100 lbs with a component of cervical flexion and rotation to aid in reduction. Serial neurological exams and plain lateral radiographs after the addition of each weight. If the neurological exam worsens, remove all weight, and emergent MRI must be performed. Always obtain MRI after reduction in order to determine the best approach for surgical stabilization. * Because of this rapid decline in motor function, you do not want to wait to obtain an MRI as this could lead to worsening of his neurologic status and potentially permanent damage. However, following closed reduction, an MRI should be obtained to evaluate for a disc herniation, as this will determine the surgical approach for decompression and stabilization. Monitoring with the administration of steroids is improper as the patient's decline is likely from the compression/injury of the spinal cord and must be reduced in order to decompress the spine. Also, steroids have not shown many benefits in outcomes, and large doses have been associated with significant postoperative complications.

Answer 67

**1. Surgery with C1-C2 or occipito-cervical fixation** ## Footnote * According to the rule of Spence, the total overhang of C1 lateral masses over C2 should not be more than 7mm. If they are more than 7mm, this indicates an unstable C1 fracture. * A fusion procedure is the best available option for unstable C1 fractures. * Fusion can be performed by either an anterior or posterior approach. * Either C1-C2 fixation or occipito-cervical fusion can be performed depending on the patient's anatomy.

Answer 68

**3. Functional magnetic resonance imaging (MRI) of the brain with blood oxygenation level development (BOLD) imaging** ## Footnote * Patients with post-traumatic epilepsy often will have demonstrable abnormalities on MRI, such as encephalomalacia and gliosis. Corresponding lesions with EEG abnormalities are diagnostic of an epileptogenic focus. * Patients with lesions adjacent to regions of the eloquent neocortex require functional imaging to determine the laterality and location of the language centers within the brain. This allows the surgeon to try and spare as much of these regions as possible if cortical resection is required. * Contrast administration is only useful if there are suspected vascular lesions or abnormalities associated with the destruction of the blood-brain barrier. In patients with clearly demonstrable abnormalities following traumatic brain injury, contrast administration adds little to their diagnostic workup. * Single-photon emission computed tomography (SPECT) imaging can help improve the localization of a seizure focus within the brain but is only used as a supplementary imaging modality. It is used in combination with structural imaging from either CT or MRI.

Answer 69

**4. Pseudomonas aeruginosa** ## Footnote * Etiologic causes of brain abscess are often polymicrobial. * Gram-positive bacteria and anaerobes are common causes. * Gram-negative bacteria such as Pseudomonas aeruginosa are seldom implicated. * Brain abscess is a focal area of necrosis with a surrounding membrane within the brain parenchyma, usually resulting from an infectious process or rarely from a traumatic process. A brain abscess can originate from infections in the head and neck, lung, heart, skin, pelvis, and abdomen. Facial trauma, even from neurosurgical procedures, can result in necrotic tissue, and brain abscesses have been reported afterward. Metal fragments or other foreign bodies left in the brain parenchyma can also serve as a nidus for infection. The most frequent microbial pathogens isolated from a brain abscess are Staphylococcus and Streptococcus. Among this class of bacteria, Staphylococcus aureus and Viridian streptococci are the commonest.

Answer 70

**2. Motor cortex stimulation** ## Footnote * Motor cortex stimulation can be used to help treat facial pain associated with central post-stroke pain (thalamic pain syndrome). * Motor cortex stimulation is effective in two-thirds of patients with central post-stroke pain. * Of patients who had relief with motor cortex stimulation, at least 40% of pain relief was achieved. * Motor cortex stimulation is an effective treatment method for both thalamic pain syndrome and central post-stroke pain syndromes outside of the thalamus.

Answer 71

**2. Initiate anticonvulsant therapy** ## Footnote * Traumatic aneurysms may result from either penetrating head trauma or closed head trauma. Aneurysms following penetrating injury occur most often in teenage boys following a cranial cerebral gunshot wound. Aneurysms resulting from closed head trauma can occur either from injuries to the skull base or convexity. Injuries involving the skull base frequently can cause aneurysms originating from the petrous, cavernous, or supraclinoid carotid arteries. As with aneurysms resulting from penetrating trauma, these are more likely to occur in teenage boys. Injuries to the convexity can involve the distal component of the anterior cerebral artery because of the falcine edge. Distal cortical aneurysms are usually associated with an associated skull fracture. A penetrating injury would have been ruled out by the admission exam and CT. * The initiation of anticonvulsants would be appropriate as it is uncertain at this point whether the seizure results from the contusion or subarachnoid hemorrhage (SAH). An intravenous administration of levetiracetam 20 mg/kg would be one consideration. A postictal exam is requisite to determine if the decline in the child's Glasgow coma scale requires intracranial pressure monitoring. * Additional imaging would be appropriate to rule out a potential rupture of a traumatic intracranial aneurysm. Imaging preference regarding MR-angiography versus CT-angiography (CTA) is usually institution-specific. CTA will often provide a better image, though at the expense of additional radiation to the child. * Four-vessel angiography is the gold standard diagnostically and requisite in not only ruling in a traumatic aneurysm, but also in assisting the surgeon in determining the appropriate surgical, medical, and/or interventional treatment.

Answer 72

**3. Cerebral angiography** ## Footnote * The patient has features of a carotid-cavernous fistula (CCF) on the right side. * There is likely to be an abnormal communication between the internal carotid artery and the cavernous sinus. * This patient needs an angiogram to identify the site and size of abnormal communication. * CCF can be mistaken for an orbital apex syndrome or even stroke.

Answer 73

**3. Stop the intrathecal opioid therapy and assess for the regression of the lesion** ## Footnote * The patient most likely has developed intrathecal catheter tip granuloma formation seen as the intradural mass, causing the neurological deterioration in the patient. * Catheter tip granuloma develops following activation of the protein kinase leading to monocyte migration surrounding the catheter tip at the arachnoid layer. This is visualized as the enhancing intradural lesion at the tip of the catheter. * The high dose of intrathecal opioid is postulated for the pathogenesis of the formation of catheter tip granuloma. Therefore, the lowest possible dose of opioids needs to be prescribed in the patient. The first step in the management is to stop opioid therapy and assess the spontaneous regression of the lesion. * Abscess formation leads to high-grade fever with chills and rigors. The surgery in cases of catheter tip granuloma is only indicated in cases of persistent and worsening neurological deficits in the patient or cases with a diagnostic dilemma.

Answer 74

**3. Hypodense bilateral fluid collections in the subdural space** ## Footnote * Acute bleeds are hyperdense, but chronic subdural hematomas are hypodense. * 20% to 30% of patients present without a history of trauma. * Symptoms include headache, mental status changes, focal signs, and seizures, but some patients are asymptomatic. * Observation may be reasonable for asymptomatic patients with small hematomas, but surgical evacuation is needed for large or symptomatic chronic hematomas. Hypodense bilateral fluid collections in the subdural space are usually seen in the CT scan.

Answer 75

**2. Lumbar spinal stenosis** ## Footnote * The patient has neurogenic claudication, or increased pain with walking or standing. * This is often secondary to spinal stenosis. * Spinal stenosis can be severe, with paralysis and incontinence, or totally asymptomatic. * Lumbar disc disease is usually worse with sitting.

Answer 76

**3. Complete surgical resection with no other treatment modality** ## Footnote * The patient has a pilocytic astrocytoma. These are curative on complete surgical resection alone. * Radiotherapy may have a role if some aspects of the tumor are not resectable. * Pilocytic astrocytoma is classified by the World Health Organization (WHO) as grade I gliomas. They are usually cystic with a mural nodule, although some can be solid with little to no cystic component. * There is no role for chemotherapy.