neurosurgery 2 Flashcards

Question

A 42-year-old female was recently diagnosed with spontaneous intracranial hypotension. All of the following are frequently associated with this problem EXCEPT? A. The headaches often resemble a post-lumbar puncture headache B. MRI scans with contrast may reveal enhancement of the dura over the cerebral and cerebellar convexities C. Spontaneous improvement is rarely seen, since CSF leaks are often identified adjacent to nerve roots D. Spinal fluid may reveal elevated protein and pleocytosis E. Analgesics containing caffeine may be helpful

Answer 1

C. Spontaneous improvement is rarely seen, since CSF leaks are often identified adjacent to nerve roots The headaches of spontaneous intracranial hypotension often resemble post-lumbar puncture headaches. Headaches are usually worse in the upright position and are generally relieved when the patient is lying down. The diagnosis is established by lumbar puncture, which reveals low opening pressure or dry tap. It is not uncommon to have elevated protein and pleocytosis. It is postulated that this syndrome results from leakage of GSF to the outside neuraxis, often around nerve roots. MR cisternography is often capable of demonstrating the leak. Jugular compression will elevate intracranial pressure but usually makes the headache worse, suggesting that low pressure may not be the only factor responsible for the headaches. MRI scans often reveal dural enhancement over the cerebral and cerebellar convexities, tentorium, and falx, which usually resolves with resolution of the symptoms. Treatment should be conservative, since there is often spontaneous improvement. Analgesics containing caffeine and adequate hydration seem to help. In some cases an epidural patch may be required; surgical closure of the fistula is rarely required

Answer 2

D. A 1-cm cavernoma of the right caudate nucleus that previously hemorrhaged A long history of radiosurgical treatment for arteriovenous malformations exists. The best responses are often obtained for lesions with volumes less than 4 cm3 . Multiple metastatic lesions are also amenable to this treatment modality, as are recurrent gliomas located in a variety of locations including the brainstem, thalamus, or other eloquent areas. There is, however, controversy about the radiosurgical treatment of cavernomas. While disease control has been documented, some authors are concerned with the potential of treatment-related complications such as recurrent hemorrhage after radiosurgery

Answer 3

D. Hippocampectomy Prefrontal lobectomy, cingulotomy, ventrolateral cordotomy, and periaqueductal gray stimulation may interrupt pain pathways or the response to painful stimuli. Hippocampectomy does not interrupt these pathways but may decrease the severity of complex partial seizures

Answer 4

A. Thalamic stimulation Traumatic injury to the brainstem including the superior cerebellar peduncles and their connections can result in severe tremor that may be delayed by weeks to months following the brain injury. In some cases, improvement or resolution occurs spontaneously, so some authors have recommended a period of observation before considering surgery. The largest published series for secondary tremors is among patients with multiple sclerosis, although a growing body of information is now available for patients with posttraumatic tremors. With posttraumatic tremors, thalamic stimulation (Vim) may be considered for those who are refractory to medical management, although results have been mixed. Thalamotomy is another treatment option for this group of patients, although postoperative dysarthria or worsening pre-existing dysarthria is an especially troubling complication in some of these studies

Answer 5

E. Hypercoagulable state Profound hypothermia during circulatory arrest can result in various physiologic effects including increasing blood viscosity, metabolic acidosis (underperfused tissue), hyperglycemia (secondary to hypoinsulinemia), decreased corticosteroid secretion, complement-mediated pneumonitis, renal failure (due to transient decrease in glomerular filtration rate, hemolysis, and blood product reactions), hepatic failure, and hypothermia-induced coagulopathy (due to platelet dysfunction and slowing of the enzymatic clotting cascade)

Answer 6

B. Cervical bruit The most common physical manifestation of extracranial carotid artery disease is a cervical bruit. The degree of stenosis necessary to produce a bruit has been reported to be as low as 25%, but in various studies its presence has been found to indicate a significant level (\> 50%) of stenosis on angiography in at least 70% of patients. False-positive rates of 10 to 40% and false-negative rates of 30 to 70% have been reported for cervical bruits. The Framingham Study found that the risk of stroke and TIAs in patients with bruits was two to three times the risk for patients without bruits. Such patients were also about 2.5 times more likely to have a heart attack and 1.9 times more likely to die during the study period

Answer 7

B. Neurocysticercosis

Answer 8

E. Seizure

Answer 9

E. Taenia solium Neurocysticercosis (NGG) is the most common parasitic infection of the central nervous system (CNS) worldwide. Humans are the definitive host for the adult tapeworm Taenia solium, which thrives in the small intestine without consequence. Fecal shedding of eggs usually leads to ingestion of eggs in contaminated water or food by an intermediate host, typically humans or pig. Once inside the intestine, the eggs are released and produce primary larvae that enter the circulatory system. Hematogenous spread to muscular, ocular, and neural tissue then occurs. Once inside the brain, the primary larvae develop into secondary larvae, the cysticerci. Clinical manifestations of the neural form of the disease are varied and nonspecific. This pleomorphism is related to the number, size, and topography of the lesions. Parenchymal disease (as in this case) is most common and presents with seizures in 50 to 80% of patients. Treatment typically includes antiepileptics, albendazole, or praziquantel, as well as a short course of steroids to reduce the inflammatory reaction during antihelminthic treatment. Niclosamide may be given orally to treat adult tapeworms in the Gl tract. Fluconazole is an antifungal and not used to treat this disease process. The colonization of the ventricular system often presents with rapid clinical deterioration due to increased intracranial pressure from obstructive hydrocephalus. There is still controversy about the best treatment for this form of the disease, but most authors advocate either a trial of antihelminthic medication, endoscopic cyst resection, or microsurgery. Subarachnoid disease is usually more difficult to manage because the cysts are usually multiple, attain larger sizes, and produce severe basal meningitis, but antihelminthic medications are typically first-line therapy for this form of the disease. From the many tests performed, current data indicate that enzyme-linked immunosorbent assay (ELISA) and electroimmunotransfer blot (EITB) tests are the most effective laboratory tests for diagnosis. Peripheral white blood cells, ova and parasites in stool, and eosinophilia are inconsistent and unreliable markers of disease. This patient also harbored a fourth ventricular cyst and obstructive hydrocephalus, which accounts for the rounded third ventricle

Answer 10

B. Vein of Galen aneurysm A neonate suffering high-output cardiac failure, hyperdynamic precordium, dilated cervical and cranial veins, and arteries with a "machine-like" bruit heard over the head and neck is most likely harboring a vein of Galen aneurysm. Vascular tumors, CC fistula, blue rubber bleb nevus syndrome, and sinus pericranii do not typically present with this constellation of problems. Although transcranial ultrasonography is an excellent way to diagnose these lesions, the "gold standard" is cerebral angiography. In infants, a transarterial and transvenous route to eliminate the high-flow shunt is often employed. This technique may not lead to complete obliteration but often converts highoutput cardiac failure to a persistent fistula. In an older child or adult, the treatment is frequently gradual and entails graded elimination of the shunt with endovascular surgery, usually via a transarterial route

Answer 11

E. Pronator quadratus The deep branch of the radial nerve passes through a slit in the supinator muscle (arcade of Frohse) to the posterior forearm. After passing this slit, the nerve is called the posterior interosseous nerve and supplies the supinator, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, abductor pollicis longus, extensors pollicis longus and brevis, and extensor indicis muscles. The anterior interosseous nerve, a branch of the median nerve, supplies the pronator quadratus

Answer 12

E. All of the above The ability to create irregularly shaped radiosurgical volumes is important to achieve conformal irradiation of target tissue, as all tumors or lesions are rarely perfect spheres. The following techniques can be used to create an irregularly shaped plan during radiosurgery. First, combine multiple isocenters of irradiation in different planes. For example, a series of 4-mm isocentors of irradiation is often used to tailor radiation to the porus acusticus for schwannomas. Second, individual isocenters can be weighted variably to change their relative shape. Finally, individual radiation beams can be blocked to restrict dose away from critical structures, such as the optic chiasm

Answer 13

C. Interruption of the sympathetic chain located on the anterior surface of the longus colli muscles A rare complication after anterior cervical procedures is the development of a Horner's syndrome (anhidrosis, miosis, ptosis) from interruption of the sympathetic chain located on the anterior surface of the longus colli muscle. The thoracic duct enters the subclavian vein on the left and is particularly vulnerable to injury during left-sided anterior cervical procedures

Answer 14

C. Thoracic duct A rare complication after anterior cervical procedures is the development of a Horner's syndrome (anhidrosis, miosis, ptosis) from interruption of the sympathetic chain located on the anterior surface of the longus colli muscle. The thoracic duct enters the subclavian vein on the left and is particularly vulnerable to injury during left-sided anterior cervical procedures

Answer 15

D. L4-5 Degenerative spondylolisthesis is most common in women at the L4-5 level, but may also be seen at the L3-4 level. Because this often occurs with sacralization of L5 in many patients, the facet degeneration may be explained as a hypermobility syndrome

Answer 16

A. Transarticular screw fixation and fusion if the lateral atlantal masses are intact with good-quality bone Irreducible pathologic conditions affecting the cervicomedullary junction in patients with rheumatoid arthritis frequently require an anterior cervical procedure to remove the offending pathology (frequently pannus formation), followed by dorsal fixation and fusion. Reducible atlantoaxial dislocation is best managed by a posterior fusion and fixation procedure. Usually transarticular screw fixation is desirable if the bone quality is good and the lateral masses of the atlas are intact: but if this is not the case, placement of a rectangle of bone between the posterior arch of C2 and CI followed by wiring may be an option. This, however, has been associated with higher failure rates in some studies. These patients often required further reinforcement with cervical immobilization techniques such as halo placement. Dorsal occipitocervical fusion is almost always required for patients with rheumatoid cranial settling and in those following rheumatoid pannus resection. Transoral odontectomy with or without posterior fusion is not required for this patient since there was a reducible lesion. Laminectomy alone would likely further destabilize this patient, while halo placement without fusion would run a very high risk of failure

Answer 17

E. Osteoblasts for bone healing The ideal bone graft provides the following elements for successful healing: osteoconductive matrix, osteoinductive factors, viable osteogenic cells, and structural support. Only fresh autografts contribute viable osteogenic cells to the developing fusion. Processed allografts frequently have no living cellular elements and are mainly derived from the tissues of the recipient bed

Answer 18

E. None of the above Although traumatic brain injury (TBI) has been shown to result in increases of calcium flux into cells with subsequent cell injury, no clinical benefit has been observed in clinical trials attempting to attenuate this response in patients with TBI. A subset of patients with subarachnoid hemorrhage, however, did show a benefit. Calcium may enter cells via ion channels influenced by excitatory amino acids (glutamate, aspartate). Unfortunately clinical trials to antagonize these receptors have been discouraging in TBI

Answer 19

E. Motor cortex stimulation Surgical therapies including cerebellar stimulation, dorsal column stimulation, peripheral denervation, thalamotomy, and pallidotomy have been used in the past to treat various forms of dystonia. Although the thalamus has been the primary target for years, more recently many surgeons are targeting the globus pallidus with good results. Medications such as anticholinergics, muscle relaxants, and benzodiazepines are of limited use to patients. Botulism toxin is a safe and effective therapy for many focal dystonias but has not proven effective for patients with segmental dystonia, hemidystonia, or generalized dystonia

Answer 20

A. Arcuate fasciculotomy The surgical management of psychiatric disease can be helpful for select patients with treatment-refractory major affective disorders, obsessive-compulsive disorder, and chronic anxiety states. Surgical interventions have included anterior capsulotomy, limbic leukotomy, subcaudate tractotomy, and anterior cingulotomy but not arcuate fasciculotomy

Answer 21

A.Arcuate eminence The superior semicircular canal projects into the floor of the middle cranial fossa as the arcuate eminence

Answer 22

D. Hypoglossal nerve

Answer 23

B. Greater petrosal nerve injury

Answer 24

B. Additional exposure through Kawase's quadrilateral Structures often visible on the middle fossa floor during subtemporal approach include the middle meningeal artery (often sacrificed by cautery and packing of the foramen spinosum), trigeminal nerve (V3), lesser superficial petrosal nerve, greater superficial petrosal nerve, ICA (if there is a small dehiscence in the bone), as well as the arcuate eminence, which overlies the superior semicircular canal. Decreased tearing after surgery most likely resulted from injury of the greater superficial petrosal nerve, which provides parasympathetic supply to the lacrimal and nasal gland. Additional exposure to the posterior fossa during a subtemporal approach may be gained by removing the bone of Kawase's quadrilateral located in the medial petrous apex, medial to Glasscock's triangle. Kawase's quadrilateral is bounded laterally by the greater superficial petrosal nerve, medially by the petrous ridge and V3 of the trigeminal nerve, and at its base by the arcuate eminence. Glasscock's triangle is bounded laterally by a line from the foramen spinosum to the facial hiatus, medially by the GSPN, and at its base by the mandibular division of the trigeminal nerve

Answer 25

D. Hypoxia of the brainstem The Gushing response consists of the triad of hypertension, bradycardia, and an irregular breathing pattern. According to many authors, the most likely mechanism accounting for this response is reduction in oxygenation in an area just rostral to the medulla. For this reason it is also called the ischemic response

Answer 26

D. Palpable neck mass The most common clinical presentation of carotid body tumors is a palpable neck mass in the high cervical region. Less commonly patients present with hoarseness, dysphagia, and unilateral tongue atrophy and weakness due to the tumors' proximity to the vagus and hypoglossal nerves. These tumors are generally benign, although they do tend to locally invade adjacent tissue, which can make their resection difficult. An evaluation of the endocrine system may be warranted, especially in patients with hypertension and tachycardia. Some patients may harbor a pheochromocytomalike lesion that secretes excess catecholamines. In such patients, a-adrenergic blockade must be started about 2 weeks preoperatively to control hypertension, tachycardia, and the potential for arrhythmia. Preoperative planning is critical in these patients to reduce comorbidity. Some may require preoperative embolization to reduce the amount of bleeding during surgery

Answer 27

The most common clinical presentation of carotid body tumors is a palpable neck mass in the high cervical region. Less commonly patients present with hoarseness, dysphagia, and unilateral tongue atrophy and weakness due to the tumors' proximity to the vagus and hypoglossal nerves. These tumors are generally benign, although they do tend to locally invade adjacent tissue, which can make their resection difficult. An evaluation of the endocrine system may be warranted, especially in patients with hypertension and tachycardia. Some patients may harbor a pheochromocytomalike lesion that secretes excess catecholamines. In such patients, a-adrenergic blockade must be started about 2 weeks preoperatively to control hypertension, tachycardia, and the potential for arrhythmia. Preoperative planning is critical in these patients to reduce comorbidity. Some may require preoperative embolization to reduce the amount of bleeding during surgery

Answer 28

C. Dysphonia The most common surgical complication after vagal nerve stimulator (VNS) placement is infection. Transient vocal cord paralysis with hoarseness and swallowing problems is the second most common surgical complication of VNS. Temporary lower face numbness and weakness occur in about 0.7% of patients, likely related to high cervical incisions and superficial nerve injury

Answer 29

A. The lateral stability is significantly enhanced if the pedicle screw angle is 30 degrees or greater The internal stabilization of two adjacent segments of the lumbar spine with a pedicle screw construct having a pedicle-to-pedicle screw angle of zero and no transfixitor is not stable in lateral or rotational load, as each of the screws are free to turn in their screw holes in the body. Stability can be enhanced by the application of a transfixitor or angling the screws inward to form a pedicle-to-pedicle screw angle of 30 degrees

Answer 30

D. Multiple subpial transection (MST) was developed as a procedure to address seizure activity that extends beyond the area of resection and into eloquent cortex. The cerebral cortex has functional vertical columns, with its vertical orientation of incoming and outgoing fibers. Seizures, however, are believed to spread horizontally through the cortex. MST involves disconnecting the vertical columns of the cerebral cortex, which inhibits synchronization and spread of the 208 Intensive Neurosurgery Board Review seizure focus with minimal injury to the cortex. The most common problem faced by patients after this procedure includes subtle, transient deficits corresponding to the area of resection that typically improve. Permanent complication rates after this procedure are in the order of 5%

neurosurgery 2 Flashcards

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