Neurosurgery Flashcards
- A 43-year-old man experiences lower back pain
after lifting a heavy object off the ground. The
following morning, he notices that the pain has
begun to radiate down the posterolateral aspect
of the right leg and across the top of the foot to
the big toe. The pain is severe, electric in quality, associated with paresthesia over the same
distribution, and made worse by coughing. On
examination, it is found that he has an area of
diminished sensation to pinprick over the
dorsum of the right foot and mild weakness in
his right extensor hallucis longus muscle. The
deep tendon reflexes are all intact. What is the
most likely diagnosis?
(A) Lumbar spinal fracture with compression
of the cauda equina
(B) Herniated lumbar disk on the right at
the level of L4–L5
(C) Herniated lumbar disk on the left at the
level of L4–L5
(D) Herniated lumbar disk on the right at
the level of S1–S2
(E) Intermittent claudication
- (B) The patient has a right-sided L5 radiculopathy, most likely resulting from a disk herniation
at the right L4–L5 interspace. The key to this
diagnosis is in understanding the dermatomal
anatomy of the lower extremity. The L5 dermatomal distribution involves the lateral calf
and the dorsomedial aspect of the foot. The dermatome also typically includes the big toe.
- A 48-year-old woman has a lower back pain
and hypoesthesia in the left S1 dermatomal distribution (left calf and lateral left foot). What is
the most likely cause?
(A) A lesion at the right L4–L5 interspace
(B) Pathology where the nerve exits the
spinal canal immediately above the
pedicle of S3 vertebra
(C) A herniated nucleus pulposus
(D) Compression by the L5 lamina
(E) A lesion outside the vertebral column
- (C) Thoracic, lumbar, and sacral nerves exit off
the spinal canal immediately below the pedicle
of the corresponding numbered vertebra. The
left S1 root, for example, passes immediately
dorsal to the L5–S1 disk, where it can be susceptible to compression by a herniated nucleus
pulposus. The root then swings laterally to exit
immediately caudal to the left L5 pedicle. For
a correlation between level of disk herniation
and the root affected, see the table below.
Level of Herniation Root Affected
L1–L2 L2
L2–L3 L3
L3–L4 L4
L4–L5 L5
L5–S1 S1
- A 35-year-old secretary complains of severe
pain in the neck that radiates down the right
arm. The pain is electric in quality and affects
specifically the radial aspect of the right forearm
and the thumb. She also describes numbness
and paresthesia over the same distribution. On
physical examination, she is found to have an
area of diminished sensation to pinprick over
the right wrist and thumb. The right biceps
tendon reflex is diminished, but there is no loss
of muscle strength. She has right C5–C6 disk
compression and radiculopathy affecting which
of the following?
(A) The right C4 root
(B) The right C4 mixed spinal nerve
(C) The right C4 anterior primary rami
(D) The right C6 root
(E) The right C6 spinal ganglion
- (D) This patient has radiculopathy of her right
C6 root. To make this diagnosis, it is essential
to understand the dermatomal anatomy of the
upper extremity. The C6 dermatome includes
the radial aspect of the distal forearm and
hand. The C4 dermatomes include the deltoid
region. The biceps tendon jerk is mediated by
the C5 and C6 roots.
A 47-year-old man presents to the emergency department after falling from his bicycle. He claims that
his neck was suddenly and violently hyperflexed.
Although he is currently complaining of neck pain,
his chief complaint is weakness of the arms. On
examination, he is found to have profound symmetric weakness of both hands and wrists. His
biceps and triceps are moderately weak. The lower
extremities are only minimally weak, and he is able
to ambulate, albeit with some difficulty. His sensation to all modalities is within normal limits. Plain
radiographs of his neck reveal no fracture or dislocation, but there is evidence of severe spondylosis
with osteophytes narrowing the neural canal at
C3–C4, C4–C5, and C5–C6.
4. What is the most likely mechanism of injury? (A) Brachial plexus injury (B) Epidural hematoma (C) Contusion of the spinal cord (D) External carotid artery occlusion (E) Internal jugular vein occlusion
- (C) The mechanism of injury was a contusion to
the cervical spinal cord. This probably occurred
when the violent hyperflexion of the neck
caused the cervical cord to bump against the
osteophytic ridges of the spine. The typical clinical picture of a spinal cord contusion is a central cord syndrome.
A 47-year-old man presents to the emergency department after falling from his bicycle. He claims that
his neck was suddenly and violently hyperflexed.
Although he is currently complaining of neck pain,
his chief complaint is weakness of the arms. On
examination, he is found to have profound symmetric weakness of both hands and wrists. His
biceps and triceps are moderately weak. The lower
extremities are only minimally weak, and he is able
to ambulate, albeit with some difficulty. His sensation to all modalities is within normal limits. Plain
radiographs of his neck reveal no fracture or dislocation, but there is evidence of severe spondylosis
with osteophytes narrowing the neural canal at
C3–C4, C4–C5, and C5–C6.
5. What is this pattern of motor findings that results from this injury termed? (A) Central cord syndrome (B) Cervical radiculopathy (C) Cauda equina syndrome (D) Lhermitte sign (E) Posterior cord syndrome
- (A) The central spinal cord syndrome describes
the following pattern of weakness: (a) weakness
in upper extremity is greater than weakness in
lower extremity; (b) weakness in distal muscles
is greater than weakness in proximal muscles
and limb girdle. This results from the distribution
of motor fibers within the corticospinal tracts of
the cervical cord. Fibers supplying the upper
extremity and more proximal muscles are more
centrally located and, thus, more susceptible to
dysfunction from a central injury. Within the
spinal cord, sensory fibers are more peripherally located and, thus, less frequently affected.
Sensory deficits, when present, are often variable and inconsistent. A Lhermitte’s sign or syndrome also results from stenosis of the cervical
canal, causing compression of the spinal cord.
The patient develops severe numbness and
paresthesia of the upper extremities as the result
of sustained hyperextension of the neck.
A 57-year-old woman is referred to you for evaluation of difficulty with ambulation. Her chief complaint is weakness of her left leg that has been slowly
progressive over the last 6 months. On neurologic
examination, her mental status and cranial nerve
findings are within normal limits. She has marked
(grade 4–5) weakness of both her left leg and arm.
On her left side, she has diminished sensation to
light touch and vibration below the C5 dermatome.
Sensation to pinprick and temperature are severely
diminished on the right side below approximately
the C8 dermatome. Her deep tendon reflexes and
muscle tone are increased on the left.
6. This pattern of neurologic deficits is which of the following? (A) Spondylolisthesis (B) Brown-Sequard syndrome (C) Central cord syndrome (D) Guillain-Barré syndrome (E) Poliomyelitis
- (B) Brown-Sequard syndrome (Fig. 11–3)
describe (a) weakness of muscle ipsilaterally
below the spinal cord lesion, (b) impaired sensation to light touch and vibration ipsilaterally
below the spinal cord lesion; and (c) impaired
sensation to pain and temperature contralaterally below the spinal cord lesion.
A 57-year-old woman is referred to you for evaluation of difficulty with ambulation. Her chief complaint is weakness of her left leg that has been slowly
progressive over the last 6 months. On neurologic
examination, her mental status and cranial nerve
findings are within normal limits. She has marked
(grade 4–5) weakness of both her left leg and arm.
On her left side, she has diminished sensation to
light touch and vibration below the C5 dermatome.
Sensation to pinprick and temperature are severely
diminished on the right side below approximately
the C8 dermatome. Her deep tendon reflexes and
muscle tone are increased on the left.
7. This pattern of neurologic deficits is explained by injury to the spinal cord with damage to which of the following? (A) Anterior horn cells (B) Peripheral neuropathy (C) Central cord (D) Right half (right hemicord) (E) Left half (left hemicord)
- (E) The motor deficit is on the left ipsilateral
side. Brown-Sequard syndrome is caused by
unilateral injury or dysfunction following
hemisections of the spinal cord. In the human
nervous system, motor and sensory functions
on one side of the body are under the direct
control of the opposite side of the brain. All
major motor and sensory tracts decussate. The
decussation of the various tracts occurs at different levels of the neuraxis.
- A 73-year-old man presents for evaluation of
weakness in his lower extremities and recurrent
falls. On further questioning, the patient admits
to having frequent spasms affecting both of his
lower extremities. He also claims that his legs
occasionally feel as if ants were crawling all over
them. On neurological examination, he is found
to have a slightly unstable gait and with minimal flexion of the knees. His strength is slightly
but symmetrically diminished in both lower
extremities and both triceps muscles. There is
decreased sensation to vibration and light touch
below approximately the level of the nipples
bilaterally. In both lower extremities, muscle
tone is markedly increased, and deep tendon
reflexes are hyperactive. Babinski’s reflex is present bilaterally. What is the most likely diagnosis?
(A) A thoracic spinal cord compression (B) A thoracic radiculopathy (C) A cervical myelopathy (D) Cerebellar tumor (E) Intracranial aneurysm
- (C) On subsequent MRI of the cervicothoracic
spine, this patient is found to have severe
spondylosis at multiple levels of the spine.
There is spinal cord compression by a large
osteophyte at the level of C6–C7. The patient
has all the signs and symptoms of cervical
spinal cord dysfunction. The weakness affecting the triceps muscles in addition to the lower
extremities indicates that the lesion is above
the level of the thoracic cord. Absence of similar symptoms on the face as well as the absence
of cranial nerve abnormalities indicate that
the lesion is not intracranial. The diffuseness of
the symptoms as well as the fact that they are
associated with increased reflexes and tone
indicate that the problem lies within the CNS
(upper motor neuron) rather than the peripheral nervous system (lower motor neuron).
- An 87-year-old woman is referred to you for
evaluation of lower back pain. It is exacerbated
by walking or prolonged standing and occasionally made better by bending over. Physical
examination reveals a thin, elderly woman
who walks with a cane with her lower back
moderately flexed. Motor power in her lower
extremities is normal, but she has impaired
sensation to light touch and vibration below
the L4 dermatome bilaterally. Deep tendon
reflexes are normal in her upper extremities
but absent in both lower extremities. You refer
her for magnetic resonance imaging (MRI) of
the lumbosacral spine. What will be the most
likely finding on this study?
(A) Lumbar spinal stenosis
(B) A fracture of the odontoid process
(C) A herniated L3–L4 disk causing unilateral
compression of the L4 root
(D) Spinal cord compression at the level of
L1 vertebra level
(E) Spinal cord compression at the T1
vertebra level
- (A) The clinical presentation indicates a lower
motor neuron lesion. The clinical diagnosis is
neurologic claudication secondary to lumbar
spinal stenosis, which is commonly seen in elderly persons in whom (as a consequence of
wear and tear over the years) bony structures
of the lumbar spine hypertrophy and develop
osteophytes. These bony changes, in turn, lead
to stenosis of the spinal canal and intervertebral
foramina. Thus, the result is compression and
dysfunction of multiple lumbosacral nerve
roots bilaterally. Bending over opens the
lumbar canal and relieves the stenosis.
- A 33-year-old man is brought to the emergency
department after being involved in a major
motor vehicle accident. He is unable to move his
legs and complains of severe pain in his mid
to lower back. On physical examination, he is
found to have exquisite tenderness over some of
the bony prominence of his lower back, but no
gross physical deformity can be appreciated. On
neurologic examination, flaccid paralysis of both
lower extremities and complete anesthesia to all
sensory modalities below approximately the L3
dermatome are noted. Catheterization of his
bladder yields approximately 700 mL of urine.
Plain radiographs of the spine reveal compression fracture in the body of L3 with greater than
50% of loss in its height. A computed tomography (CT) scan through this area reveals a burst
fracture of the body of L3. There are large fragments of bone driven dorsally with an 80% canal
compromise. What is the cause of weakness?
(A) Compression of the conus medullaris
(B) Compression of the spinal cord at the
level of L3
(C) Compression of the cauda equina
(D) Rupture of the anterior spinal ligament
(E) Associated epidural hemorrhage
- (C) This patient has suffered a traumatic fracture of L3 in which bony fragments were displaced dorsally to compress the cauda equina
at that level. It is important to remember that
the spinal cord does not extend along the entire
length of the spine. The conus medullaris, the
most caudal tip of the spinal cord, ends in 98%
of people at or above L2 vertebrae. Thus, it is
highly unlikely for an L3 fracture to cause compression of the spinal cord or conus medullaris.
A 17-year-old boy suffers a hyperextension injury of his
neck when he jumps headfirst into a shallow pool. He
does not lose consciousness. He arrives at the emergency department holding his neck stiffly and complaining of severe neck pain. He says the pain is
particularly severe whenever he tries to move his head.
He says he has no neurologic symptoms such as weakness, numbness, or paresthesia. On physical examination, he is found to have no areas of ecchymosis or deformity on the cervical spine. He has exquisite pain
on deep palpation of the bony prominence of the midcervical spine. There are no neurological signs. Routine
plain radiographs (anteroposterior [AP], lateral, openmouth view) of the cervical spine in the neutral position show no fracture or subluxation of the bony
elements. There is, however, thickening of the pretracheal space ventral to the body of C6, suggesting softtissue swelling.
- What would the next step in management
involve?
(A) Analgesics alone
(B) A hard cervical collar
(C) Internal fixation of the cervical vertebra
(D) Burr holes and traction
(E) Plaster cast to face, neck, and thorax
- (B) The most appropriate step is to place him in
a hard cervical collar to protect his neck and
obtain plain lateral radiographs in flexion and
extension. In this boy, the continuous neck pain
and the prevertebral swelling on the plain radiographs are strongly suggestive of an injury to
the ligamentous structures of the cervical spine.
A severe ligamentous tear can lead to instability of the spine from excessive movement
between adjacent vertebrae. Ligamentous
injury must be ruled out by obtaining lateral
radiographs in flexion and extension to demonstrate any excessive movement between adjacent vertebrae. This excessive movement, if
missed, can result in compression of the cervical spinal cord and a serious neurologic deficit.
These studies require supervision by appropriate specialist consultants.
A 17-year-old boy suffers a hyperextension injury of his
neck when he jumps headfirst into a shallow pool. He
does not lose consciousness. He arrives at the emergency department holding his neck stiffly and complaining of severe neck pain. He says the pain is
particularly severe whenever he tries to move his head.
He says he has no neurologic symptoms such as weakness, numbness, or paresthesia. On physical examination, he is found to have no areas of ecchymosis or deformity on the cervical spine. He has exquisite pain
on deep palpation of the bony prominence of the midcervical spine. There are no neurological signs. Routine
plain radiographs (anteroposterior [AP], lateral, openmouth view) of the cervical spine in the neutral position show no fracture or subluxation of the bony
elements. There is, however, thickening of the pretracheal space ventral to the body of C6, suggesting softtissue swelling.
- What would be the most appropriate radiologic examination?
(A) Plain lateral radiographs in flexion and
extension to rule out occult ligamentous
tear and instability of the cervical spine
(B) A CT scan of the cervical spine to rule
out the possibility of a bony fracture not
seen on plain radiographs
(C) Lateral tomogram of the cervical spine
to rule out the possibility of an occult
fracture
(D) Angiography
(E) Ultrasound of the neck
- (A) A CT scan of the cervical spine is more sensitive for fractures of the spine than are plain
Answers: 1–12 251
Figure 11–3.
Brown-Sequard syndrome. The lesion depicted here is at a lower
spinal cord level than that described in the text. (Reproduced, with
permission, from Lindner HH: Clinical Anatomy. Appleton &
Lange, 1989.)
radiographs. Because CT images are in the axial
plane, only one vertebral body can be seen at a
time. This makes CT scanning entirely inadequate to rule out all but large subluxation
resulting from the most major ligamentous disruptions. Sagittal MRI of the cervical spine in
this case may show swelling or hematoma
within the soft tissues of the spine. MRI, however, is poor in demonstrating bony anatomy
and detail. Furthermore, without flexion and
extension of the neck, an MRI of the cervical
spine is no better in showing bony instability
than plain radiographs in the neutral position.
A 63-year-old woman with a history of local inoperable breast cancer is referred to you for the evaluation of
new-onset diplopia. Upon questioning, she admits that
diplopia occurs mostly when she attempts to look at
objects in the distance and when she attempts to look
toward the left side. In addition, she reports having
severe headaches and an electric-type discomfort
affecting her right deltoid region for approximately
3 weeks. On neurologic examination, she is found to
have left abducens (sixth) nerve palsy; the rest of her
cranial nerves are intact. She also has mild weakness of
the right deltoid and a diminished biceps tendon jerk
on the same side. Findings on an MRI of the brain with
intravenous contrast are unremarkable.
13. In this patient, what would be the most likely site where metastasis occurs? (A) Brain (B) Orbital cavity (C) Meninges (D) Cerebellum (E) Optic chiasm
- (C) Meningeal carcinomatosis results when
malignant cells gain access to the CSF and are
able to disseminate within it. Cells most commonly adhere to and affect the neural structures traversing the CSF, such as cranial nerves
and peripheral nerve roots. Cells cause dysfunction at multiple sites of the CNS. This
patient has a left abducens nerve palsy and a
right C5 radiculopathy, making the diagnosis of
meningeal carcinomatosis highly likely.
A 63-year-old woman with a history of local inoperable breast cancer is referred to you for the evaluation of
new-onset diplopia. Upon questioning, she admits that
diplopia occurs mostly when she attempts to look at
objects in the distance and when she attempts to look
toward the left side. In addition, she reports having
severe headaches and an electric-type discomfort
affecting her right deltoid region for approximately
3 weeks. On neurologic examination, she is found to
have left abducens (sixth) nerve palsy; the rest of her
cranial nerves are intact. She also has mild weakness of
the right deltoid and a diminished biceps tendon jerk
on the same side. Findings on an MRI of the brain with
intravenous contrast are unremarkable.
- What would the next step in management
involve?
(A) An MRI of the cervical spine to rule out
metastatic deposits within the cervical
roots
(B) A CT scan of the brain with intravenous
contrast
(C) A lumbar puncture to measure opening
pressure and obtain cerebrospinal fluid
(CSF) for cytologic analysis
(D) Repeated breast biopsy
(E) No further tests until further symptoms
develop
- (C) In the presence of meningeal carcinomatosis (also called carcinomatous meningitis), the
lumbar puncture CSF examination may reveal
elevated protein and positive cytology. The sensitivity of MRI to detect small tumor deposits
within the intracranial compartment is much
greater than that of a CT scan. Thus, a CT scan
is unlikely to be helpful in this clinical scenario.
- A 57-year-old woman presents to the emergency
department with new-onset seizures. She was
witnessed by her husband to have a generalized seizure lasting approximately 1 minute. She
has smoked 1 pack of cigarettes a day for over
40 years. In the past 3 months, she has lost 25 lb
in weight. On examination, she appears thin
and nervous but findings on her neurologic
examination are otherwise essentially within
normal limits. Plain radiographs of the chest
obtained in the emergency department show a
4-cm nodule in the upper lobe of her right lung.
To exclude cerebral metastasis as a cause of her
seizure, what should the next test requested be?
(A) An electroencephalogram (EEG)
(B) A CT scan of the brain with intravenous
contrast
(C) A spinal tap to measure opening pressure
and obtain CSF for cytology
(D) An MRI of the brain with intravenous
contrast
(E) Doppler ultrasound
- (D) An adult with new onset seizures is considered to have a brain tumor until proved otherwise. The best test available to detect metastatic
deposits in the brain is the MRI with intravenous
contrast. MRI is exquisitely sensitive in diagnosing brain metastasis, sometimes detecting
them by the brain edema they induce even when
the lesion itself is too small to be seen. The EEG
may likely show the presence of seizure activity
and even localize it to a particular region of the
brain; it will not, however, answer the question
of what pathologic process is responsible. Also,
in this case, because a mass lesion is expected,
performing a spinal tap is relatively contraindicated for the fear of inducing uncal herniation in
a patient who may have increased ICP.
A 58-year-old woman is admitted from the emergency
department with a history of approximately 2 weeks
of headache. She has a history of breast cancer. Her
headache is severe, particularly in the mornings when
she wakes up. It is accompanied by occasional vomiting. She says she experiences no focal weakness,
numbness, or paresthesia. On physical examination,
she is found to have a mild weakness of her left arm.
An MRI of the brain with intravenous contrast reveals
the presence of a neoplasm in the right motor cortex
that is considered responsible for her weakness.
16. If the MRI shows multiple brain metastasis, what should be the treatment required in addition to corticosteroids? (A) Whole-brain radiotherapy (B) Craniotomy to resect the lesion responsible for her left arm weakness (C) Chemotherapy (D) Placement of an Ommaya reservoir for use in treatment by intrathecal chemotherapy (E) No further treatment
- (A) The optimal management of any intracranial
neoplasm includes use of corticosteroids. These
significantly diminish the amount of tumorinduced brain edema and are remarkably effective in ameliorating symptoms caused by CNS
neoplasms. The current recommendation for the
treatment of multiple brain metastasis is treatment with a full course of fractionated radiation to the whole brain. This is geared to treat all
visible lesions within the parenchyma as well as
those that may still be too small to be detected.
Intrathecal chemotherapy is effective in treating meningeal carcinomatosis, where the primary site of involvement is the meninges and
the surface of the brain. The two available agents
for this modality of treatment have very poor
penetration into deeper regions of the brain
when administered intrathecally.
A 58-year-old woman is admitted from the emergency
department with a history of approximately 2 weeks
of headache. She has a history of breast cancer. Her
headache is severe, particularly in the mornings when
she wakes up. It is accompanied by occasional vomiting. She says she experiences no focal weakness,
numbness, or paresthesia. On physical examination,
she is found to have a mild weakness of her left arm.
An MRI of the brain with intravenous contrast reveals
the presence of a neoplasm in the right motor cortex
that is considered responsible for her weakness.
17. If the MRI shows a single brain metastasis, what should be the next step in management? (A) Whole-brain radiotherapy (B) Craniotomy to resect the lesion responsible for her left arm weakness (C) Chemotherapy 240 11: Neurosurgery (D) Placement of an Ommaya reservoir for use in treatment by intrathecal chemotherapy (E) No further treatment
- (B) Surgical resection is recommended only for
cases involving a single brain metastasis that is
surgically accessible in patients with a reasonable life expectancy. It is also relatively indicated in patients with multiple brain lesions in
whom one particular lesion is imminently lifethreatening. Intravenous chemotherapy has,
unfortunately, yielded poor results in the
treatment of brain metastasis. This is particularly so in this patient, because her tumors are
already likely to be resistant to the chemotherapeutic agents with which she has already been
treated.
- A 63-year-old woman presents with a severalweek history of headaches and difficulties with
speech. A sister who lives with her claims that
her language “has recently not been making
much sense” and that she is a bit confused. Her
condition seems to be deteriorating. On neurologic examination, she has a moderately
severe aphasia, with difficulty understanding
language and following commands, and she
makes frequent paraphasic errors when she
speaks. There are no other motor or sensory
deficits. An MRI with intravenous contrast
reveals the presence of a ring-enhancing mass
lesion within the substance of the left temporal
lobe. The lesion is approximately 3 cm in greatest diameter, poorly demarcated from the surrounding brain, and surrounded by a moderate
amount of cerebral edema. Findings on routine admission tests, including a chest x-ray
and serum chemistry, are unremarkable. What
is the most likely diagnosis?
(A) Low-grade cerebral astrocytoma
(B) Glioblastoma multiforme
(C) Metastasis to the brain from an occult
primary cancer
(D) Meningioma
(E) Glomus tumor
- (B) Glioblastoma multiforme is a highly malignant neoplasm, arising from glial cells or their
precursors within the CNS. It is the most
common of all primary malignancies of the CNS
and its peak incidence is within the fifth to seventh decade of life. A low-grade astrocytoma is
a tumor derived from glial cells of astrocytes.
Fig. 11–4, shows a large cystic giant astrocytoma
on T2 weighted MRI where fluid is shown as a
white area with midline shift (not glioblastoma
multiforme presented in this question).
- A 64-year-old man presents with headache and
left-sided upper extremity weakness. The MRI
findings suggest that this is a glioblastoma
multiforme. This is because the tumor exhibits
which of the following?
(A) It is regular in shape.
(B) It is well demarcated from surrounding
brain tissue.
(C) It shows a ring pattern of enhancement
with intravenous contrast and has a
nonenhancing necrotic center.
(D) It shows an absence of surrounding
white-matter edema.
(E) It arises from the carotid body.
- (C) Glioblastoma multiforme grows rapidly, and
the tumor often contains a necrotic core that
occurs as its growth surpasses its blood supply.
Additional features on MRI include irregular
shape, poor demarcation from surrounding
252 11: Neurosurgery
brain tissue, and the presence of variable
amount of surrounding white-matter edema.
- A 63-year-old woman presents for workup to
determine the reason for a gradual hearing loss
over approximately 5 years and intermittent
tinnitus over the last several months. Findings
on physical and neurologic examination are
entirely within normal limits, except for the
presence of sensorineural hearing loss in the
left ear. She has no cranial nerve deficits. An
MRI of the brain with gadolinium reveals the
presence of an extra-axial tumor in the region
of the left cerebella-pontine angle. What is the
most likely diagnosis?
(A) Epidermoid tumor (cholesteatoma)
(B) Glioblastoma multiforme
(C) Meningioma
(D) Acoustic neuroma
(E) Glomus tumor
- (D) This cerebella-pontine angle tumor is most
likely an acoustic neuroma. This is the most
commonly encountered neoplasm in this
region. It arises from the Schwann cells that
form the myelin sheath of the vestibular division of the eighth cranial nerve (hence a more
accurate name is vestibular schwannoma). This
tumor typically arises within the internal
acoustic canal and growths in the direction of
least resistance—through the meatus into the
cerebellopontine angle cistern.
A 4-year-old boy is brought to the emergency department with the complaint of approximately 2 weeks of
headache and vomiting. He was seen in the emergency department 1 week earlier with the same complaints. At that time, his parents were told that the
probable cause was a gastrointestinal virus, and
the boy was sent home. His symptoms have not
improved. On general examination, the child appears
somewhat dehydrated and has a dry mouth and
sunken eyes. His examination findings are also
remarkable for the presence of bilateral papilledema
and marked nystagmus. An MRI with intravenous
contrast is obtained that reveals the presence of a
2-cm mass in the posterior fossa. The mass is entirely
within the fourth ventricle and appears to be arising
from the vermis of the cerebellum. It enhances uniformly with contrast. The lateral and third ventricles
are moderately dilated with hydrocephalus.
21. What is the most likely diagnosis? (A) Acoustic neuroma (B) Craniopharyngioma (C) Medulloblastoma (D) Brain metastasis (E) Polycystic cerebellar astrocytoma
- (C) An astute neurologist once said that in neurologic diagnosis, as in real estate, location is
everything. He alluded to the fact that in the
diagnosis of neurologic ailments, one can often
generate lists of possible diagnoses based solely
on the location of the lesion in question. With
unusual exceptions, each location within the
CNS is likely to be associated with a certain type
of neoplasm. The medulloblastoma (also called
a primitive neuroectodermal tumor or PNET) is
a highly aggressive and rapidly growing tumor
that most often arises within the cerebellar
vermis. It usually grows locally as a roughly
spherical mass to bulge into and obliterate
the adjacent fourth ventricle. Ependymoma or
choroid plexus papilloma should also be considered in the differential diagnosis.
A 4-year-old boy is brought to the emergency department with the complaint of approximately 2 weeks of
headache and vomiting. He was seen in the emergency department 1 week earlier with the same complaints. At that time, his parents were told that the
probable cause was a gastrointestinal virus, and
the boy was sent home. His symptoms have not
improved. On general examination, the child appears
somewhat dehydrated and has a dry mouth and
sunken eyes. His examination findings are also
remarkable for the presence of bilateral papilledema
and marked nystagmus. An MRI with intravenous
contrast is obtained that reveals the presence of a
2-cm mass in the posterior fossa. The mass is entirely
within the fourth ventricle and appears to be arising
from the vermis of the cerebellum. It enhances uniformly with contrast. The lateral and third ventricles
are moderately dilated with hydrocephalus.
- If at craniotomy the tumor found is not that
listed in question 21 and the pathologist reports
that it is a benign lesion, what is that lesion?
(A) Ependymoma
(B) Choroid plexus papilloma
(C) Polycystic (cystic) cerebellar astrocytoma
(D) Teratoma
(E) Dermoid cyst
- (B) Choroid plexus papillomas are benign
tumors of the CNS that arise from the cells that
form the choroid plexus. These tumors can be
found wherever choroid plexus is present,
including the lateral and fourth ventricles.
They cause symptoms of increased ICP, most
commonly by causing massive degrees of
hydrocephalus. This can be from two mechanisms—obstruction of normal CSF pathways or
production by the tumor of excessive volumes
of CSF. (Remember that CSF is produced
mainly by the choroid plexus.) Ependymomas
are also highly malignant tumors usually
found in the fourth ventricle of children. Its
precursor cell is the ependymal cell that lines
the ventricular system. As medulloblastomas,
these tumors are highly aggressive and fast
growing. Contrary to the former, however,
ependymomas tend to arise from the floor of
the fourth ventricle (the dorsal surface of the
brainstem).
A 5-year-old girl undergoes debulking of medulloblastoma. She undergoes a repeat MRI of the brain
with intravenous contrast, which shows a small
amount of enhancement consistent with limited residual tumor. She is given a full course of radiotherapy
to the posterior fossa and does very well for 6 weeks,
until she experiences difficulty in walking. Physical
examination at this time indicates moderate weakness of both lower extremities (particularly on the
right side) but strength in her upper extremities and
cranial nerves are normal. Her sensation to light touch
and vibration are intact, but she has diminished sensation to pinprick throughout her left leg.
- What should be the next step in management?
(A) Repeat the MRI of the brain to rule out
an early recurrence
(B) Obtain a single-photon-emission CT
(SPECT) scan of the brain to rule out the
possibility of radiation-induced toxicity
(C) Begin treatment with chemotherapy for
the residual tumor within the brain
(D) Obtain an MRI or myelogram of the
entire spinal axis to rule out the
possibility of “drop metastasis” from the
medulloblastoma
(E) Obtain an ultrasound of the lumbar spine
- (D) Obtain an MRI or myelogram of the entire
spinal axis to rule out the possibility of “drop
metastasis” from the medulloblastoma. The
constellation of emerging new symptoms
points toward spinal cord dysfunction; the
Answers: 13–23 253
Figure 11–4.
Large cystic giant astrocytoma on T2 weighted MRI where fluid is shown as a white area. Midline shift.
most likely cause is the presence of drop metastasis from the medulloblastoma. Primary CNS
neoplasms rarely metastasize outside of their
site of origin. Exceptions to this statement
include both medulloblastoma and ependymoma. These tumors shed viable cells into the
CSF, where they are transferred to such distant
areas as the intracranial or, more commonly,
the spinal subarachnoid space. There they can
lodge and replicate to form tumor nodules that
can compress adjacent neural structures. The
test of choice for diagnosing the presence of
these drop metastasis is a MRI of the spine with
intravenous contrast or a myelogram.
A 5-year-old girl undergoes debulking of medulloblastoma. She undergoes a repeat MRI of the brain
with intravenous contrast, which shows a small
amount of enhancement consistent with limited residual tumor. She is given a full course of radiotherapy
to the posterior fossa and does very well for 6 weeks,
until she experiences difficulty in walking. Physical
examination at this time indicates moderate weakness of both lower extremities (particularly on the
right side) but strength in her upper extremities and
cranial nerves are normal. Her sensation to light touch
and vibration are intact, but she has diminished sensation to pinprick throughout her left leg.
- What should treatment of this girl involve?
(A) Removal of recurrent medulloblastoma
and neck dissection
(B) Ventriculoperitoneal shunt
(C) Repeat irradiation to the posterior cranial
fossa
(D) Complete craniospinal irradiation with
local boosts to the areas where tumor
nodules are detected
(E) Cortisone alone
- (D) Treatment of drop metastasis consists primarily of complete craniospinal irradiation with
local boosts to the areas where tumor nodules
are detected. Chemotherapy, particularly a combination of procarbazine, lomustine (CCNU),
and vincristine (PCV), is usually given to treat
disease that is locally recurrent after maximal
irradiation. Radiation-induced toxicity or radionecrosis is highly unlikely to be the cause of
these newly developed symptoms. The first
reason for this is that the child’s new symptoms
and findings appear to be exclusively spinal in
origin. Second, radiation-induced necrosis, a
feared complication of CNS irradiation, is never
observed in such a short interval after completing treatment.
- A 35-year-old man is brought to the hospital
unconscious after being resuscitated in an ambulance from the site of a motor vehicle accident.
No other history or information is available.
On general inspection, he is found to have multiple bruises over his body and has a massively
swollen left thigh. His vital signs are stable with
a heart rate of 100 beats per minute (bpm) and
a blood pressure of 150/75 mm Hg. He is
obtunded and does not follow commands or
open his eyes. He withdraws his left arm and
leg from painful stimuli, but not his right. His
left pupil is 3 mm in diameter, and it is sluggishly reactive to light, while his right is 5 mm
in diameter and fixed. Corneal reflexes are present bilaterally. His pulse rate is 120 bpm and respiration rate is 40 breaths per minute. To avoid
injury to his spinal cord by an unstable cervical
spine, an order is issued to not perform testing
of his doll’s eye reflex. Intracranial hemorrhage
causing increased intracranial pressure (ICP) is
suspected, along with a right uncal herniation.
What is the next step in management?
(A) Intubation of his airway for
hyperventilation and administration of
intravenous mannitol
(B) Immediate CT scanning of the brain to
confirm the presence of the suspected
intracranial hemorrhage
(C) Intubation of his airway for
hyperventilation and intravenous
administration of corticosteroids
(D) Immediately evacuation of the suspected
intracranial hematoma
(E) Controlled hypoventilation
- (A) Intubation will accomplish two purposes.
First, it will protect the airway and prevent
the possibility of aspiration. Second, it will
allow controlled hyperventilation (PCO2 of
25–30 mm Hg), which causes cerebral vasoconstriction, which, in turn, transiently lowers
ICP and reduces intracranial intravascular
blood volume. Mannitol will reduce intracerebral pressure and volume. The role of corticosteroids in the management of cerebral
trauma is controversial at best. Their advocates propose that corticosteroids work by
reducing the amount of traumatically induced
brain edema. Even these investigators concur
that their effect is not immediate and that they
take at least 4–6 hours to work. The subdural
space is between the inner layer of dura and
the arachnoid.
26. In the management of a 64-year-old woman struck by a car, mannitol is given to do which of the following? (A) Increase CSF formation (B) Increase the respiratory rate 242 11: Neurosurgery (C) Increase the pulse rate (D) Replace extensive fluid loss (E) Lower raised ICP
- (E) Mannitol is a complex sugar that remains in
the intravascular space because of its high
molecular weight. When it is given in large
doses (1–2 g/kg of body weight), water is
extracted from the cerebral interstitium by its
osmotic effect, causing reduction in total brain
volume. Both these measures are temporizing
steps to allow enough time for definitive diagnosis and treatment to take place. The effect of
hyperventilation on ICP rapidly wears off after
a few hours. Over time, mannitol will diffuse
into the cerebral interstitium, losing its effectiveness and even exacerbating cerebral edema.
A note of caution, however, mannitol is an
osmotic diuretic and as such must be given
with extreme caution in the setting of hypotension due to excessive blood loss.
- A 17-year-old boy is brought to the emergency
department after he was assaulted. Witnesses
claim that he was hit on the head with a lead
pipe, after which he was unconscious for several minutes. No seizure activity was witnessed. On arrival, he complains of a headache,
particularly severe at the point where he was
hit in the right frontoparietal region. On examination, he is found to have swelling and ecchymosis over this region. He is awake, alert, and
fully oriented. A complete neurologic examination reveals no deficit. Plain radiographs of
the skull show a linear, nondepressed skull
fracture in the frontoparietal skull that crosses
the groove of the medial meningeal artery.
During the following hour, he becomes sleepier
and begins to vomit. A repeat neurologic examination at that time reveals him to be lethargic
but without weakness, numbness, paresthesia,
or other focal deficit. What is the most likely
cause of the neurologic deterioration?
(A) Diffuse axonal injury (DAI)
(B) Todd’s phenomenon
(C) Subdural hematoma
(D) Epidural hematoma
(E) Trigeminal ganglion hematoma
- (D) This is the classic presentation of an acute
epidural hematoma (Fig. 11–5) transient traumatic loss of consciousness, followed by a lucid
interval and then by neurologic deterioration.
Epidural hematomas are frequently associated
with linear skull fractures, which cause injury
to the middle meningeal artery located immediately deep to the overlying fracture. They are
more common in younger individuals, because
in younger people, the dura mater is less firmly
adherent to the inner table of the skull. Todd’s
phenomenon is a transient focal weakness or
paralysis that results after a seizure. The particular pattern of weakness is often a clue to the
site of the seizure focus within the brain.
- Following a sudden impact in an accident, the
34-year-old race car driver becomes unconscious and is admitted to the hospital. A CT
scan is performed, and a right space-occupying
lesion is noted (Fig. 11–1). What is the most
likely diagnosis?
(A) Corpus callosum injury
(B) Pituitary apoplexia
(C) Acute subdural hematoma
(D) Acute epidural hematoma
(E) Chronic subdural hematoma
- (C) Acute subdural hematomas (Fig. 11–1)
occur most commonly when violent accelerations or deceleration injuries of the head cause
tearing of the bridging veins within the subdural potential space. They generally imply a
much more severe injury to the brain itself than
in the case of their epidural counterpart. For
this reason, they are associated with cerebral
contusions in over 30% of cases.
