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NeuroSurgery MCQ

1. Which of the following are true about the history of neurosurgery?
A. The history of trepanation dates back to the Neolithic period.
B. The earliest known writing dealing with surgical topics is the Ebers papyrus.
C. The writings of Hippocrates contain the first recorded descriptions of trepanation.
D. The three key developments that were necessary to permit successful intracranial and intraspinal surgery were anesthesia, asepsis, and the concept of localization of different functions in different areas of the nervous system.
E. Victor Horsely of London was the first surgeon to specialize in neurosurgery.
Answer: ACDE

DISCUSSION: Many skulls from the Neolithic period have been found, some of which contain cranial defects with evidence of bone healing, indicating that these individuals underwent trepanation during life and survived the operation. The earliest known writing dealing with surgical topics is the Edwin Smith papyrus. In the works of Hippocrates is the first written account of trepanation. During the second half of the nineteenth
century, general anesthesia was introduced and the principles of asepsis were developed. These steps were important for all areas of surgery, including neurosurgery. In addition, it became recognized that certain areas of the nervous system were especially important for certain neurologic functions and that intracranial and intraspinal abnormalities might be localized by the history and neurologic examination findings, thus providing a more specific target for neurosurgical exploration through the small bony openings to which surgeons were restricted at the time. Victor Horsley of London was the first surgeon to prepare himself specifically for surgery of the nervous system and to concentrate his efforts in that area.

2. The neurosurgeon who has had the most profound influence on the development of neurosurgery is:
A. Fedor Krause of Germany.
B. William Macewen of Scotland.
C. Harvey Cushing of the United States.
D. Egas Moniz of Portugal.
E. Goeffrey Jefferson of England.
Answer: C

DISCUSSION: Harvey Cushing (1869–1939) laid the groundwork for much of what is done in neurosurgery. For example, he standardized operative procedures and introduced many techniques and instruments that are still in use. He also made careful and detailed studies of intracranial tumors and established their classification. By his own multifaceted career and through his many students from around the world he influenced the development of neurosurgery to a degree not equaled before or since.

3. Which of the following conditions can be evaluated by magnetic resonance imaging (MRI)?
A. Stroke is suspected in a patient with a cardiac pacemaker.
B. Computed tomography (CT) shows a skull base tumor.
C. A coma patient with CT-demonstrated subarachnoid hemorrhage and an aneurysmal clip.
D. A patient with intractable complex partial seizure.
E. A lung cancer patient whose plain film of the lumbar spine shows a compression fracture of the L2 vertebral body.
Answer: BDE

DISCUSSION: MRI has proved to be a better modality than CT for evaluation of disease of the central nervous system (CNS), such as diseases at the base of the skull (particularly the sellar and cerebellopontine angle cistern regions) and for most tumors, white matter disease (e.g., multiple sclerosis), early stroke, congenital abnormalities, vascular malformations, and spinal disease. New techniques of MRI such as fast spin echo (FSE) pulse sequence have been developed to detect mesial temporal sclerosis, which is the most common cause of intractable complex partial seizure. Differentiating pure compression fracture from metastatic disease of the vertebral bodies in a patient with known primary cancer is also possible by new MRI technique; however, for patients with certain types of metal (pacemaker, surgical clip, or foreign body, which may move in the magnetic field and cause injury to the patient or significant artifacts) within the bodies, MRI is contraindicated.

4. Which of the following statements about neuroradiologic imaging modalities is/are correct?
A. Diffusion-weighted MRI can differentiate tumor from edema and identify the nonenhancing part of the tumor.
B. For evaluating the stenosis of the carotid bifurcation, MR angiography (MRA) is the most accurate imaging modality.
C. Myelography is still useful in detecting some diffuse spinal disease such as cerebrospinal fluid (CSF) seeding.
D. For evaluating the bony detail of patients with facial trauma, CT is a better imaging modality than MRI.
E. Decreased amount of N-acetyl aspartate (NAA) and increased amount of lactate can be shown in the MR spectroscopy (MRS) of a patient with acute stroke.
Answer: ACDE

DISCUSSION: Diffusion-weighted MR is a new development in MR applications and is sensitive to microscopic motion of water protons (Brownian motion). Initial applications have involved imaging of early stroke and neoplasia. Early evidence also suggests that diffusion-weighted imaging can differentiate tumoral edema from tumor and identify the nonenhancing part of the tumor. Doppler sonography, MRA, and CT angiography (CTA) are all useful for evaluating the stenotic condition of carotid bifurcation noninvasively. However, sonography is very operator dependent, and MRA commonly overestimates the degree of carotid stenosis resulting from the turbulence, dephasing at points of stenosis or irregularity. CTA obtained by spiral or helical CT has a good correlation rate with carotid angiography (92%). Conventional carotid angiography remains the most accurate imaging modality for evaluation of the stenosis of carotid bifurcation. Although CT and MRI have taken the place of myelography in evaluating neurologic diseases, it is still useful in detecting diffuse subarachnoid seeding, which may be difficult to identify on MRI. The bone detail and calcification are poorly identified on MR, so in a patient with facial trauma, CT is a better modality than MR. With MRS, metabolites within a selected region of interest (ROI) can be investigated, and spectral peaks that reflect the concentrations of the metabolite within the ROI can be obtained. The metabolites include lactate, neuronal marker (NAA), phosphorus metabolites, creatine, and choline. Reduction in the NAA level and elevation in lactate level could be noted in acute stroke.

5. Which of the following are true about intracranial tumors?
A. The most common location of brain tumors of childhood is the posterior cranial fossa.
B. With few exceptions, examination of the CSF is of no value in the diagnosis of an intracranial tumor.
C. Even the most malignant of primary brain tumors seldom spread outside the confines of the central nervous system (CNS).
D. The majority of astrocytomas can be cured surgically.
E. Primary neoplasms of astrocytic, oligodendroglial, or ependymal origin represent gradations of a spectrum from slowly growing to rapidly growing neoplasms.
Answer: ABCD

DISCUSSION: In children, brain tumors are more commonly situated below the tentorium than above it. In adults, the reverse is true. Cytologic examination of CSF may provide critical diagnostic information in a patient with meningeal carcinomatosis or subarachnoid spread of a primary brain tumor such as a medulloblastoma, but in most instances CSF examination is not of significant value. Furthermore, in a patient with a brain tumor lumbar puncture may be dangerous; it may promote brain herniation. If there has not been a surgical breach of the dura mater, primary brain tumors seldom spread to areas outside the intracranial and intraspinal compartments. Most gliomas, including astrocytomas, cannot be cured by surgical resection. The pilocytic astrocytoma of the cerebellum and the optic nerve glioma are exceptions to that rule. Neoplasms of astrocytic, oligodendroglial, or ependymal origin vary histologically along a spectrum from benign to malignant, with no sharp dividing line. Furthermore, even the most benign-looking ones tend to recur after surgical resection.

6. The intracranial tumor most likely to be encountered in a middle-aged man with the acquired immunodeficiency syndrome (AIDS) is:
A. Glioblastoma multiforme.
B. Ependymoma.
C. Meningioma.
D. Oligodendroglioma.
E. Lymphoma.
Answer: E

DISCUSSION: Primary intracranial lymphomas occur with increased frequency in patients who are immunocompromised, such as recipients of organ transplants and patients with AIDS.

7. Patients who have survived a subarachnoid hemorrhage from a ruptured intracranial aneurysm are at risk for:
A. Rehemorrhage.
B. Cerebral artery vasospasm.
C. Ischemic stroke.
D. Hydrocephalus.
Answer: ABCD

DISCUSSION: Twenty percent of patients who suffer a subarachnoid hemorrhage from a ruptured intracranial aneurysm experience a second hemorrhage in the ensuing 2 weeks. Following subarachnoid hemorrhage, the patient is at risk for developing vasospasm, an idiopathic narrowing of the intracranial arteries that reside in the subarachnoid space. Vasospasm manifests clinically as cerebral ischemia or stroke. Blood within the subarachnoid space hinders normal flow and absorption of spinal fluid, frequently resulting in mild hydrocephalus. Although this hydrocephalus usually resolves in the days or weeks following the hemorrhage, in some cases it persists, necessitating a ventricular shunt.

8. Intracranial hemorrhages resulting from chronic arterial hypertension:
A. Most often originate in the basal ganglia.
B. Most often originate in the subarachnoid space.
C. Can present as an enlarging cerebellar mass.
D. Should not be treated surgically when they occur in the cerebellum.
Answer: AC

DISCUSSION: The most frequent site of a hypertensive hemorrhage is the basal ganglia. Blood may appear in the spinal fluid after the hemorrhage has dissected through the brain parenchyma into the cerebral ventricles. Approximately 10% of hypertensive hemorrhages originate in the cerebellum. Rapid removal of a cerebellar hemorrhage can be life saving.

9. The physician is most effective in treating:
A. Cerebral contusions.
B. Epidural hematomas.
C. Cerebral lacerations.
D. Hypoxia.
Answer: BD

DISCUSSION: The physician can do very little to repair damage incurred at the time of the head trauma such as cerebral contusions and lacerations. The physician's job is to thwart secondary injuries to the brain. Enlarging intracranial mass lesions, especially hematomas, are a common cause of secondary brain injury. Evacuation of an epidural, subdural, or intracranial hematoma can be life saving. Metabolic insults are another cause of secondary neurologic injury. Hypoxia, hypotension, and hypocapnia are avoidable secondary insults that should be treated at the scene of the accident. Unfortunately, a large percentage of trauma patients still arrive at the emergency room with metabolic abnormalities.

10. The evaluation of a comatose patient with a head injury begins with:
A. The cardiovascular system.
B. Pupillary reflexes.
C. Establishment of an airway.
D. Computed tomography (CT) of the brain.
Answer: C

DISCUSSION: The treatment of every comatose patient begins with an assessment of the patient's respiratory system, followed shortly thereafter with an assessment of the patient's cardiovascular system. The unconscious patient's normal protective pharyngeal reflexes are compromised, making mechanical airway obstruction and aspiration pneumonia common events. Hypotension, secondary to intra- or extracorporal hemorrhage, is deleterious to the patient's cerebral injury. Neurologic assessment is undertaken only after the patient's respiratory and cardiovascular status are secured.

11. An epidural hematoma:
A. Is usually arterial in origin.
B. Is usually accompanied by a skull fracture.
C. Should be suspected only in comatose patients.
D. Can be diagnosed from a brain CT scan.
Answer: AB

DISCUSSION: An epidural hematoma is a blood clot situated between the skull and the dura. Epidural hematomas are usually arterial in origin and most often are secondary to hemorrhage from the middle meningeal artery. Approximately 90% of adult patients with an epidural hematoma have a concomitant skull fracture. Such skull fractures are much less common in children under the age of 2 years. The epidural hematoma is best diagnosed before transtentorial herniation and the development of third cranial nerve palsy (“blown pupil”). The outcome of therapy is directly related to the patient's level of consciousness before surgery. The clinical diagnosis of an epidural hematoma is rarely confirmed by brain CT.

12. Which of the following statements is/are true?
A. Cranial osteomyelitis most frequently arises from the spread of bacteria through the bloodstream from an infection elsewhere in the body.
B. Subdural empyema is ordinarily treated by administration of antibiotics without the need for surgical drainage.
C. Bacterial meningitis may lead to the development of hydrocephalus.
D. A bacterial brain abscess commonly presents as a mass lesion of the brain, without systemic signs of infection such as fever or leukocytosis.
E. Bacterial brain abscesses are difficult to visualize by CT.
Answer: CD

DISCUSSION: Cranial osteomyelitis can arise from hematogenous spread, but more often it results from direct spread from an infected paranasal sinus, inoculation by a penetrating object, or operative infection of a craniotomy bone flap. Subdural empyema ordinarily cannot be brought under control with antibiotics alone, and it does require surgical drainage. One of the sequelae that can follow bacterial meningitis is hydrocephalus, which is usually due to the obliteration of subarachnoid spaces and interference with CSF reabsorption. A brain abscess, per se, is not ordinarily accompanied by systemic signs of infection; these can be present if the patient also has meningitis or an active infection elsewhere. CT, especially after intravenous administration of a contrast agent, is an excellent way to demonstrate a brain abscess.

13. Complete excision of a brain abscess used to be the preferred method of treatment, and it is still performed occasionally today. Most commonly, now, a brain abscess is treated by:
A. Systemic antibiotic administration.
B. Aspiration and drainage of the abscess through a small opening in the skull.
C. Injection of antibiotics into the abscess.
D. Aspiration and drainage of the abscess plus systemic antibiotic administration.
E. Marsupialization of the abscess.
Answer: D

DISCUSSION: In the past, the preferred treatment of a brain abscess was total surgical excision. Now that such abscesses can be followed closely by CT, aspiration and drainage is usually employed, at least initially, to reduce the mass effect, provide information about the pathogens, and lower the risk of intraventricular rupture while the abscess is treated by systemic administration of antibiotics.

14. Which of the following statements are true?
A. Extradural neoplasms are usually benign.
B. A typical type of intramedullary tumor is a meningioma.
C. An intradural extramedullary neoplasm is ordinarily treated by a combination of surgical resection and radiotherapy.
D. Extradural neoplasms are usually malignant.
E. A hemangioblastoma is a benign intramedullary tumor that has the potential for surgical cure.
Answer: DE

DISCUSSION: Extradural neoplasms are usually malignant, the most common type being a metastasis to a vertebra from a primary carcinoma elsewhere in the body. A meningioma is an extramedullary tumor arising from the meninges surrounding the spinal cord rather from within the cord itself. Most intradural extramedullary neoplasms are benign tumors (meningiomas, neurofibromas, schwannomas) that are treated by surgical excision without postoperative radiotherapy. Despite its name, the hemangioblastoma is a benign tumor. It typically arises within the spinal cord and can be cured if it is completely removed surgically.

15. Which of the following statements about intraspinal dermoid and epidermoid tumors and lipomas are true?
A. They are benign lesions.
B. They can be found within the spinal subarachnoid space.
C. They can be found within the spinal cord.
D. They are most common in the lumbosacral area.
E. They are at times associated with spinal dysraphism.
Answer: ABCDE

DISCUSSION: Intraspinal dermoid and epidermoid tumors and lipomas are benign lesions that can be found within the subarachnoid space or the spinal cord, or both. They are most common in the lumbosacral area. Dermoid and epidermoid tumors can be associated with spinal dysraphism and in particular with a dermal sinus tract that opens onto the back, usually in the lumbosacral region. Lipomas are also associated with spinal dysraphism, at times in the form of a lipomyelomeningocele with a tethered spinal cord.

16. Which of the following statements are true?
A. The usual symptomatic lumbar disc herniation occurs in a posterolateral direction.
B. Approximately 95% of lumbar disc herniations occur at the L5–S1 or L4–L5 level.
C. Sciatica is a term used to denote pain felt along the distribution of the sciatic nerve.
D. Weakness of dorsiflexion of the foot is a mechanical sign of a lumbar disc herniation.
E. X-ray films of the lumbosacral spine are obtained to demonstrate the presence and location of a lumbar disc herniation.
Answer: ABC

DISCUSSION: Most symptomatic lumbar disc herniations do occur in a posterolateral direction, impinging on the overlying nerve root. About 95% of lumbar disc herniations occur at the L5–S1 or L4–L5 level. Approximately 4% occur at the L3–L4 level, and less than 1% at the L2–L3 or L1–L2 level. Sciatica is a term used to refer to pain along the course of the sciatic nerve. A ruptured lumbar disc typically causes low back pain and ipsilateral sciatica. The mechanical signs of a lumbar disc herniation include paravertebral muscle spasm, lumbar scoliosis, tenderness over one or more of the lower lumbar spines, limitation of low back motion, limitation of straight leg raising, and a positive popliteal compression test. Weakness of dorsiflexion of the foot is a neurologic sign, not a mechanical sign. Plain x-ray films of the spine do not demonstrate the presence and location of a lumbar disc herniation except in the rare instance of a calcified disc herniation. Myelography, CT, or MRI is needed to visualize the herniated disc.

17. A right-sided disc herniation at the L5–S1 level typically may cause:
A. Low back pain and right sciatica.
B. Weakness of dorsiflexion of the right foot.
C. A diminished or absent right ankle jerk.
D. Diminution of sensation over the medial aspect of the right foot, including the great toe.
E. Weakness of dorsiflexion of the left foot.
Answer: AC

DISCUSSION: A lumbar disc herniation at the L5–S1 or L4–L5 level typically causes low back pain and ipsilateral sciatica. If a ruptured L5–S1 disc causes weakness, it ordinarily involves plantar flexion of the ipsilateral foot. Although a diminished or absent ankle jerk can be caused by either an L5–S1 or an L4–L5 disc herniation, it is more common with the former. The L5–S1 disc herniation ordinarily affects the S1 nerve root, which supplies the lateral aspect of the foot, including the small toe.

18. Which of the following statements are true?
A. A symptomatic cervical disc herniation usually occurs in an anterolateral or anterior direction and can be removed by a surgical approach through the front of the neck.
B. Cervical spondylosis represents a combination of degenerative disc disease and osteoarthritis in the cervical spine.
C. The joints of Luschka are the main spinal facet joints.
D. The term cervical myelopathy refers to pain and/or neurologic dysfunction in the distribution of one or more cervical nerve roots.
E. Full neck extension frequently accentuates the neck and arm pain of a patient with a cervical disc herniation.
Answer: BE

DISCUSSION: A symptomatic cervical disc herniation usually occurs in a posterolateral direction, although a directly posterior (central) herniation may occasionally occur. The posterolateral herniated disc can be removed by either a posterior or an anterior approach, but the anterior approach is preferred for the central herniation because the surgeon can remove the ruptured disc without manipulating (and possibly injuring) an already compromised spinal cord. Cervical spondylosis represents a combination in the cervical spine of degenerative disc disease and osteophyte formation (including that from osteoarthritis of the apophyseal joints and the joints of Luschka). The cervical spine contains the joints of Luschka, which are not present elsewhere in the spine. These joints, one on each side of the disc, are separate from the more posteriorly situated facet joints (apophyseal or interpedicular joints). The term cervical myelopathy refers to dysfunction of the cervical portion of the spinal cord. Pain and/or neurologic dysfunction in the distribution of one or more cervical nerve roots is termed cervical radiculopathy. Neck movement, especially extension, often intensifies the neck and arm pain of a patient with a cervical disc herniation.

19. A 36-year-old man developed neck and left arm pain. He noted paresthesias in the left index and long fingers. He was found to have weakness of the left triceps muscle and a diminished left triceps jerk. His left-sided disc herniation is most likely to be at:
A. C3–C4.
B. C4–C5.
C. C5–C6.
D. C6–C7.
E. C7–T1.
Answer: D

DISCUSSION: This patient has all of the neurologic components of the most common cervical disc syndrome, that caused by a herniation at the C6–C7 level with compression of the C7 nerve root.

20. Which of the following statements are true?
A. The fascicles in a peripheral nerve divide and recombine along their course.
B. Neurapraxia is a type of nerve injury in which the nerve is still in continuity but individual axons are disrupted.
C. Recovery from neurotmesis requires surgical repair.
D. Axonal sprouting begins 1 to 2 months after transection of a peripheral nerve.
E. The patient's age influences the rate and success of nerve regeneration.
Answer: ACE

DISCUSSION: Fascicles within a peripheral nerve do divide and recombine along their course, forming funicular plexuses. If a segment of a nerve is removed and the remaining ends are reapproximated, the fascicles will not match exactly. In neurapraxia (first-degree nerve injury) anatomic continuity of the axons is preserved, but there is selective demyelination. Surgical repair is not necessary. Recovery does not depend on regeneration and occurs within days or weeks. With neurotmesis there is significant disorganization in the nerve or actual disruption of its continuity, which precludes recovery without surgical repair. Axonal sprouting ordinarily begins 10 to 20 days after transection of a peripheral nerve. The patient's age affects the rate and success of nerve regeneration: the younger the patient is, the faster and more complete is the recovery.

21. Which of the following statements are true?
A. The Hoffmann-Tinel sign localizes the level of a nerve injury.
B. Causalgia is a term used to denote the etiology of pain.
C. Secondary repair of a lacerated nerve 3 to 8 weeks after injury has several advantages.
D. A surgeon who finds at delayed (3 to 8 weeks) exploration that a clinically nonfunctioning nerve is in continuity should resect the injured portion of the nerve and suture together the ends.
E. If a nerve is found to be disrupted at delayed (3 to 8 weeks) exploration, the surgeon should find the two ends of the nerve and suture them together.
Answer: C

DISCUSSION: The Hoffmann-Tinel sign identifies the most distal point of small nerve fiber regeneration. As nerve regeneration progresses, this point moves farther away from the level of the nerve injury. Causalgia is a specific severe pain syndrome that may accompany a partial injury to a mixed peripheral nerve. As compared with primary repair, the extent of damage to a nerve can be better assessed and the correct amount trimmed off, with a secondary repair 3 to 8 weeks after the injury; the epineurium and perineurium are stronger and can be sutured more easily; optimal operating room conditions can be arranged; and there is no time for wallerian degeneration (i.e., the involved neurons are capable immediately of regenerating new distal segments, and the regenerating axons can penetrate the repair site before a significant amount of scar forms). If a clinically nonfunctioning nerve is in continuity when it is explored some weeks after the initial injury the surgeon may find it helpful to stimulate the nerve electrically proximal to the injury and to look distally for evidence of muscle contraction or transmission of nerve action potentials. If there is no evidence of transmission across the area of injury, the injured portion of the nerve should be excised and the cut ends sutured together. If there is transmission across the area of injury, surgical treatment should be limited to external neurolysis. A disrupted nerve should be reapproximated surgically, but only after each end has been trimmed back to healthy fascicles. The trimmed nerve ends must not be under tension when they are sewn together.

22. Which of the following lesions is not one of the cutaneous stigmata of occult spinal dysraphism?
A. Midline lumbar capillary hemangioma.
B. Focal hairy patch over the thoracolumbar spine.
C. Dermal sinus located above the midsacrum.
D. Midline subcutaneous lipoma.
E. Café-au-lait spot over the thoracolumbar spine.
Answer: E

DISCUSSION: Café-au-lait spots are not a feature of spina bifida occulta. The other four skin features all may be associated with significant intradural pathology and warrant further investigation, most commonly with magnetic resonance imaging (MRI). A dermal sinus tract that overlies the coccyx is a pilonidal sinus and is not likely to be associated with intradural pathology.

23. Myelomeningoceles are congenital malformations of the spinal cord. Which of the following findings are not commonly associated?
A. Hydrocephalus.
B. Chiari II malformation.
C. A midline dorsal spinal mass easily noted at birth.
D. Skin, bone, and dural defects superficial to the neural placode.
E. Mandatory urinary incontinence.
Answer: E

DISCUSSION: Myelomeningoceles are usually associated with hydrocephalus and the Chiari II malformation. The myelomeningocele sac is a midline dorsal spinal mass associated with defects in the skin, bone, and dura overlying the neural placode, and the sac is readily apparent at birth. Although the innervation of the bladder is dysmorphic, the majority of patients can achieve social urinary continence through the use of clean intermittent bladder catherization.

24. Which of the following signs does Horner's syndrome include?
A. Ptosis.
B. Facial hyperhidrosis.
C. Miosis.
D. Exophthalmos.
E. Mydriasis.
Answer: AC

DISCUSSION: Horner's syndrome is due to loss of sympathetic innervation to the head and neck and includes ptosis, anhidrosis, miosis, and the appearance of enophthalmos. The pupil is small owing to loss of the tonic dilating effect of the sympathetics in the presence of continued parasympathetic activity. There is sympathetic innervation to Muller's muscle in the upper lid. Sympathetic nerves supply the sweat glands. It commonly follows stellate ganglion resection and involves removal of the T1 cord level sympathetic outflow.

25. Cordotomy results in which of the following?
A. Contralateral loss of pin appreciation.
B. Vagal instability.
C. Contralateral loss of temperature appreciation.
D. Ipsilateral loss of pin and temperature appreciation.
E. Contralateral loss of two-point discrimination.
Answer: AC

DISCUSSION: Cordotomy results in a lesion of the spinothalamic tract, which is a crossed pathway carrying signals for pain and temperature.

26. Surgical therapy for epilepsy should be considered in patients with:
A. Seizures poorly controlled with antiepileptic medications.
B. A single epileptic focus.
C. Seizures arising from multiple areas of cerebral cortex.
D. Seizures arising within the cortical motor strip.
Answer: AB

DISCUSSION: Because seizure surgical procedures can never be guaranteed to alleviate seizures, it is only undertaken when medical therapy fails to control the patient's seizures at doses that do not produce intolerable side effects. Most surgical procedures are aimed at removing a single epileptogenic area of cerebral cortex and are rarely employed in patients with multiple areas of epileptogenic cortex. Eloquent areas of cerebral cortex such as those subserving speech or hand functions generally are not intentionally resected in an attempt to achieve seizure control.

27. The epileptogenic area of cerebral cortex is localized by:
A. Direct identification.
B. Observing the patient's seizures.
C. Electroencephalography.
D. Visualizing cortical abnormalities on cerebral imaging studies.
Answer: BCD

DISCUSSION: Since the exact anatomy of an epileptogenic focus remains obscure, the focus of the patient's seizures is determined by concordance of the clinical manifestations of the seizures, abnormalities demonstrated by cerebral imaging, and abnormalities demonstrated by electroencephalography.

28. Which of the following stereotactic procedures would be performed primarily to alter the function of the brain?
A. Stereotactic biopsy of a brain tumor in the right posterior thalamus.
B. Stereotactic radiotherapy of an arteriovenous malformation in the right ventrolateral thalamus.
C. Stereotactic radiofrequency lesion of the right ventrolateral thalamus for Parkinson's disease.
D. Stereotactic craniotomy for excision of arteriovenous malformation in the right posterior thalamus.
Answer: C

DISCUSSION: The biopsy of a lesion, radiotherapy treatment of an arteriovenous malformation, and excision of an arteriovenous malformation are all procedures for structural lesions of the brain that can be imaged by either CT or MRI. These structural lesions may or may not cause neurologic changes, but the treatment directed at them is intended principally to keep lesion-induced damage from increasing (for example, with the development of hemorrhage). On the other hand, the thalamus is expected to have a normal structural appearance and function in Parkinson's disease, when the neurochemical abnormality is located in the substantia nigra and the striatum (caudate and putamen). Thus, a lesion is made in the thalamus principally to affect the function of the brain, altering a normal component of one of the motor circuits to compensate for the changes in the other parts (i.e., the basal ganglia).

29. What is the critical difference between frame-based and frameless stereotactic procedures?
A. The use of digitized imaging studies such as CT and MRI.
B. The use of rendered three-dimensional images and a three-dimensional digitizer.
C. Rigid fixation of the patient's head to the operating room table.
D. The presence of a lesion in the brain on digitized imaging studies.
E. The absence of a lesion in the brain on digitized imaging studies.
Answer: B

DISCUSSION: Frame-based and frameless procedures both use digitized imaging studies as the basis for converting the scan coordinate system into a treatment coordinate system. Both types of procedures also require rigid fixation of the patient's head to the operating room table and can be performed in the presence or absence of a lesion. The critical difference is the use of a rendered, three-dimensional image and the three-dimensional digitizer, which together allow the alignment to be generated between the patient's imaging studies and the patient; this alignment occurs in frame-based stereotactic procedures because of the imaging study performed after the frame is applied.

30. A 54-year-old patient with a history of successful renal transplantation is hospitalized with a diverticular abscess. Surgical exploration and drainage of the abscess with a Hartmann’s procedure is eventually required. Although the patient’s septic appearance resolves, the patient complains of severe headache and altered mental status is observed. A grand mal seizure follows. Which of the following statement(s) is/are true concerning this patient’s management?

a. An intracranial epidural abscess is the likely diagnosis
b. A bacterial brain abscess secondary to hematogenous spread from the pericolonic infection is the likely diagnosis
c. The abscess expected in this case is usually solitary
d. Appropriate parenteral antibiotic treatment should be sufficient in this high risk patient.
e. Despite aggressive surgical and medical management, mortality rates associated in this patient may exceed 30%
Answer: b, d, e

A brain abscess is a purulent lesion of brain tissue, beginning as a focal infection, usually in the white matter surrounded by a typical inflammatory response. Brain abscesses usually are secondary to focal infection elsewhere. Abscesses that develop by direct intracranial extension are usually solitary and are typically found in the frontal and temporal lobes. Multiple brain abscesses that develop in the septic patient are often related to bacterial endocarditis, pneumonia, and diverticulitis. Abscess formation is frequent among patients with compromised immunity either from an underlying illness or during pharmacologic immunosuppression (i.e., during organ transplantation). Signs and symptoms of brain abscess are related to its mass effect. Headache, focal neurologic deficits, and impaired mentation are often noted. There may be little or no evidence of infection and the patient may be afebrile. Seizures may occur. Intracranial epidural abscesses are quite uncommon and are usually caused by a local extension of osteomyelitis or by hematogenous spread from a distant suppurative focus.
In cases of early abscess formation or high surgical risk, medical therapy alone with the appropriate parenteral antibiotic may be sufficient. The most effective therapy is drainage of the purulent material with simultaneous administration of appropriate intravenous antibiotics. Although needle aspiration may be successful, craniotomy with evacuation and removal of the abscess wall may be necessary. Surgical drainage reduces the mass effect, thereby reducing the most critical and dangerous aspect of the infection. It also allows accurate bacteriologic analysis. Despite aggressive surgical and medical management, mortality rates associated with brain abscess approach 40%, especially in the malnourished, chronically debilitated, or immunosuppressed patient.

31. All intracranial nervous system tumors can be malignant in behavior due to their location. Which of the following tumor(s) is/are usually considered to be histologically benign?

a. Astrocytoma
b. Meningioma
c. Schwannoma
d. Medulloblastoma
e. Craniopharyngioma
Answer: b, c, e

Astrocytomas arise from the glial (stromal or supporting) cells of the brain. These tumors are infiltrative and rarely can be totally excised. High-grade astrocytomas (grades III and IV) are the most common primary intracranial tumor constituting 25% of all intracranial tumors and 50% of all gliomas. For the most part meningiomas are benign tumors that arise from the arachnoid layer of the meninges occurring in the fourth through sixth decades of life. Meningiomas can occur in a variety of sites and together constitute about 17% of intracranial tumors. The treatment for meningiomas is surgical, however, total resection is uncommon, frequently resulting in recurrence. Malignant histologic appearance of meningiomas is far less common than a benign appearance. Schwannomas are benign tumors that arise from the Schwann cells that surround axons as they leave the CNS by way of the cranial nerves. Schwannomas constitute 8% of all intracranial tumors and are almost twice as common in females as males. Medulloblastomas are part of the primitive neuroectodermal classification of brain tumors. They are thought to arise from primitive cells of the cerebellum, most likely the external granular layer. They constitute 8% of all gliomas. Two-thirds of medulloblastomas occur in children, with the average age of onset being 14 years. They commonly metastasize throughout the subarachnoid space by way of the CSF and are rarely found outside the CNS. Treatment involves aggressive surgical removal of the tumor followed by radiation of the brain. Chemotherapy is commonly used as well. Craniopharyngiomas are histologically benign and arise from nests of squamous cells within the pituitary gland. They may be found in the intrasellar or suprasellar locations but are always along the craniopharyngeal canal. Over 50% occur in the first two decades of life. Although craniopharyngiomas can be cured with surgical removal or controlled with radiation, many of these histologically-benign tumors cannot be removed safely.

32. A 54-year-old physician with a history of lung cancer presents after a grand mal seizure with a several month history of increasing headaches. Which of the following statement(s) is/are true concerning this patient?

a. Lung cancer as well as breast, kidney, testicular and colon cancer are the most common primary sites to metastasize to the brain
b. A symptomatic, solitary metastatic brain lesion should be removed if surgically accessible
c. If excision is complete, no further chemo-or radiation therapy is indicated
d. Symptoms of cranial nerve palsies, radiculopathies and nuchal rigidity are suggestive of meningeal carcinomatosis
e. Cytologic examination of CSF is almost always positive with meningeal metastasis
Answer: a, b, d

The percentage of intracranial tumors representing metastases approach 25%. Malignant cells invade the CNS hematogenously and tend to lodge at the grey and white matter junction. Although any malignancy has the potential to metastasize to the brain, the most common primary sites are the lung, breast, kidney, testes, colon, and skin. The presenting symptoms are determined by the site or sites of the metastases. Symptoms commonly include headache, mental status changes, seizures and hemiparesis. In general, a symptomatic solitary lesion that is surgically accessible should be removed if the patient has at least a six-month life expectancy. Surgery should not be undertaken for multiple lesions or in patients who are severely afflicted by their primary disease. Whole brain irradiation is almost always indicated after surgical resection. There is little evidence that chemotherapy plays a significant role. Tumor metastasis to the leptomeninges (meningiocarcinomatosis) is also common particularly in adults with lymphoma, breast, and lung cancer. Patients may present with cranial nerve palsies, radiculopathies, obstructive hydrocephalus. They often have signs and symptoms suggestive of meningitis. Analysis of the CSF is usually critical, often revealing increased opening pressure, elevated white blood cell count and protein levels, and a decreased glucose. Cytology should always be obtained, however it is not universally positive for malignant cells.

33. The management of a skull fracture is highly dependent on the type and location of the fracture. Which of the following statement(s) is/are true concerning skull fractures?

a. A simple nondepressed linear skull fracture is of no significant consequence
b. Most depressed skull fractures require surgery to elevate the depressed bone fragment regardless of neurologic status
c. Basal skull fractures involve the base of the calvarium and may be suggested by bruising about the eye or behind the ear
d. CSF rhinorrhea associated with a basal skull fracture requires prompt surgical exploration and repair of the defect
e. Prophylactic antibiotics are indicated in all basal skull fractures associated with CSF rhinorrhea or otorrhea
Answer: b, c

Skull fractures are classified according to whether the skin overlying the fracture is intact (closed) or disrupted (open or compound), whether there is a single fracture line (linear), several fractures radiating from a central point (stellate), or fragmentation of the bone (comminuted), and whether the edges of the fracture line had been driven below the level of the surrounding bone (depressed) or not. Simple skull fractures (linear, stellate, or comminuted nondepressed) require no specific treatment. They are, however, potentially serious and can be fatal if they cross major vascular channels in the skull, such as the groove of the middle meningeal artery or the dural venous sinuses. Depressed skull fractures often require surgery to elevate the depressed bone fragments. If there are no adverse neurologic signs and the fracture is closed, repair may be done electively. Basal skull fractures involve the floor of the calvarium. Bruising may occur about the eye (raccoon sign) or behind the ear (Battle sign), suggesting a fracture involving either the anterior or middle fossa, respectively. Any associated cerebrospinal fluid (CSF), rhinorrhea, or otorrhea should be treated expectantly. Traumatic CSF leaks typically stop within the first 7 to 10 days. Should a leak persist, lumbar CSF drainage can be implemented to seal the leak by lowering CSF volume and intracranial pressure. If this therapy fails, surgical exploration and oversewing of the defect with a facial patch graft is indicated. Less than 5% of patients actually require surgical repair. Prophylactic antibiotics are no longer used since prospective studies have failed to demonstrate any significant benefit from their use.

34. Which one or more of the following statement(s) is/are true concerning spinal cord injuries?

a. Incomplete spinal cord lesions may result in the Brown-Sequard syndrome which is manifest by contralateral loss of motor function and position-vibratory sensation with ipsilateral loss of pain and temperature sensation below the level of the injury
b. The presence of hypotension associated with a cervical spine injury following blunt trauma would suggest invariably the presence of blood loss in association with the neurologic injury
c. Cervical spine malalignment can almost always be reduced by skeletal traction
d. An indication for early operation following spinal cord injury is neurologic deterioration in a patient with initially incomplete cord lesion
e. The natural history of a cord injury in which some function is preserved immediately after the injury is progressive loss of function despite appropriate treatment
Answer: c, d, e

Injuries to the spinal cord can be either complete, resulting in total loss of function below the level of the injury or incomplete which may be manifest in the Brown-Sequard syndrome. This syndrome is manifested by ipsilateral loss of motor function and position-vibratory sensation with contralateral loss of pain and temperature sensation below the level of the injury. Anatomically, this presentation is explained by hemisection of the cord. In addition to the neurologic deficit, acute spinal cord injury is accompanied by many systemic responses. Blood pressure is generally low if the cord injury is above the T-5 level. Such an injury effectively denervates the sympathetic nervous system, which leads to increased venous capacitance and decreased venous return. The resulting hypotension is controlled by the administration of intravenous fluids.
The goals of treatment of a spinal injury are to correct spinal alignment, to protect undamaged neural tissue, to restore function to irreversibly damaged neural tissue, and ultimately to achieve permanent spinal stability. Reduction and immobilization of any fracture or dislocation must receive top priority to meet these objectives. Cervical spine malalignment can almost always be reduced by skeletal traction. Traction may be applied using skull tongs or halo apparatus. Both are seated percutaneously through the outer table of the skull while the patient is kept supine and immobilized. The indications for early operation on patients with spinal cord injury include the inability to close the fracture or dislocation satisfactorily by closed methods, neurologic deterioration in a patient with initially incomplete cord lesion, and severe compression of the spinal cord by an intraspinal mass shown on myelography or MRI. Either the anterior or posterior approach may be used, depending on the nature of the spine injury and the degree of instability. If cord function is preserved immediately after injury, additional function usually returns if the cord and spine are protected from secondary injury. Patients with complete injuries rarely recover function below the level of the lesion.

35. A 48-year-old man presents with chronic back pain with radiation into the buttock, posterior thigh, and calf. Which of the following statement(s) is/are true?

a. In the lumbar spine, more than half of clinical problems arise from L-2 to L-3 and L-3 to L-4 intervertebral discs
b. Imaging studies with CT or MRI followed by myelography is necessary for the diagnosis in most patients
c. Initially, medical management is indicated in all patients who do not have neurologic deterioration
d. Surgical treatment is reserved for the patient with acute or progressive neurologic deficit, chronic disabling back pain, or both
e. Anal sphincter muscle disturbances can be expected in most patients and are of no clinical significance
Answer: c, d

Herniated lumbar intervertebral discs often produce some degree of nerve compression. The severity of the syndrome depends on the degree of root compression. In the lumbar spine, more than 90% of clinical problems arise from the L-4 to L-5 and L-5 to S-1 intervertebral discs. Diagnosis is based on history of back pain usually with radiation into the buttock, posterior thigh, and calf at both levels. Pain may be exacerbated by coughing, sneezing, or straining. Bending and sitting accentuate the discomfort, whereas lying down characteristically relieves it. Thorough evaluation of back pain is necessary because of the multitude of causes for such symptoms. Plane films of the lumbosacral spine can identify congenital or bony changes. Disc space narrowing is an unreliable sign, however, of symptomatic disease since narrowing of the disc space can occur without clinical symptoms. Myelography can be diagnostic in symptomatic lumbar disc disease, but CT alone delineates the lesion in most cases. MRI has replaced myelography and CT at some centers in the workup of lumbar radiculopathy. With contrast, it can be extremely helpful in previously-operated cases.
Initially, medical treatment is indicated in all patients who do not have neurologic deterioration. Bed rest, local heat, analgesics, and skeletal muscle relaxants are usually effective within a few days. Physical therapy and limited exercise often help when the acute episode passes. With an aggressive conservative management, most patients improve sufficiently to return to full activity. Recurrent symptoms may be treated in a similar fashion, often successfully. Surgical treatment is reserved for a patient with acute or progressive neurologic function, chronic disabling pain, or both. The acute onset of weakness or sphincter disturbances constitute an emergency, demanding prompt diagnosis and early operation.

36. Which of the following statement(s) is/are true concerning intracranial aneurysms?

a. Over 85% of cerebral aneurysms occur in the carotid or anterior circulation
b. Most intracranial aneurysms are congenital
c. Up to 20% of patients with cerebral aneurysms have multiple aneurysms
d. Most patients with intracranial aneurysms present with signs and symptoms of subarachnoid hemorrhage with severe headache followed by neck stiffness and photophobia
e. Once the diagnosis of aneurysmal rupture is confirmed, surgery should be performed immediately
Answer: a, b, c, d

Most intracranial aneurysms are congenital, evolving and developing during life. They are typically found at the bifurcation of major vessels of the circle of Willis with over 85% occurring in the carotid or anterior circulation. Up to 20% of patients with aneurysms will have multiple aneurysms. Patients with intracranial aneurysms most commonly present with signs and symptoms of subarachnoid hemorrhage. In fact, 80% of nontraumatic subarachnoid hemorrhages are caused by aneurysm rupture. The patient notes a sudden severe headache commonly followed by neck stiffness and photophobia due to associated meningeal irritation caused by subarachnoid blood. Transient loss of consciousness may occur. Some patients may develop a focal neurologic deficit or become comatose due to acute rise in ICP.
The diagnosis of subarachnoid hemorrhage is usually made clinically and confirmed either by noting blood within the subarachnoid spaces on CT scan or finding bloody CSF with xanthochromia on a lumbar puncture. The CT scan should be obtained first since it spares the patient an LP and also eliminates the potential risk of brain-stem compression from herniation if an unsuspected mass lesion is present. Complete cerebral angiography is then used to identify and delineate the aneurysm and, at the same time, rule out multiple aneurysms or an associated arterial venous malformation. Once the diagnosis of aneurysmal rupture is confirmed, the patient is placed on a medical regimen to reduce the risk of rebleeding. This includes strict bed rest with the head elevated. Blood pressure is tightly controlled below 150 mm Hg systolic. Careful observation is necessary to watch for signs of raised ICP which may be attributable to delayed hydrocephalus. Anticonvulsants are started for seizure prophylaxis. The ultimate treatment of aneurysms is microsurgical dissection and obliteration, usually by placing a metallic clip on the aneurysm’s neck by way of a craniotomy. The timing of surgery depends on the clinical grade of the patient. Good grade (I and II) patients should undergo operation within 72 hours of rupture. Poor grade (III and IV) should continue intensive medical management until they improve to a lower grade because mortality is higher with higher grades. Surgically accessible unruptured aneurysms should be operated on electively to prevent rupture.

37. The severity of a brain injury reflects the result of both the primary injury and resulting complications constituting the secondary injury. Which of the following statement(s) concerning brain injury is/are true?

a. Increased intracranial pressure (ICP) contributes to secondary brain injury by reducing cerebral perfusion pressure producing cerebral ischemia
b. Intracranial hypertension is one of the most important factors affecting outcome for brain injury
c. In using the Glasgow Coma Scale (GCS), the higher the score, the poorer the neurologic status
d. Comatose patients who require emergent surgery for other injuries should have their ICP monitored
e. Corticosteroids are the first line treatment for elevation of ICP
Answer: a, b, d

Elevated intracranial pressure (ICP) contributes to secondary brain injury by reducing cerebral perfusion pressure which, by definition, is the difference between the mean arterial blood pressure and the cerebral venous pressure. For all clinically-relevant purposes, the cerebrovenous pressure is identical to ICP. Thus, when ICP increases and the mean arterial blood pressure remains stable, cerebral perfusion pressure decreases. When cerebral perfusion pressure falls below 70 mm Hg, cerebral blood flow is compromised, producing cerebral ischemia and compounding the primary injury with secondary insult. In studies of head injury mortality, intracranial hypertension appears to be one of the most important factors affecting outcome. For this reason, aggressive management to circumvent cerebral blood flow reduction and secondary injury is imperative. Initial clinical assessment is essential. Although extensive neurologic testing is limited in uncooperative or unresponsive patients, certain features of examination are crucial. The Glasgow Coma Scale (GSC) uses a numerically scored elevated eye-opening and motor behavior, both spontaneously and in response to stimulation. The higher the score generated in assessment, the better the patient’s neurologic status. This scale also provides useful information regarding the ultimate outcome of the head-injured patient. ICP monitoring may be indicated especially in patients with marked depression or deterioration in neurologic function. Comatose patients who require emergent surgery for other injuries should also be monitored, since frequent neurologic assessment is not possible during general anesthesia. The steps in management to prevent ICP elevation include elevation of the head to facilitate venous return. Sedation reduces posturing and reflexively combative activity which both worsen ICP. Hyperventilation keeps arterial carbon dioxide levels between 25 and 28 mm Hg and lowers cerebral blood volume and ICP. Mild dehydration with judicious sodium replacement and prompt treatment of inappropriate secretion of the antidiuretic hormone (SIADH) protects the brain from insult secondary to fluid overload. If ICP remains elevated despite these measures, mannitol, 0.5 to 1 g/kg and furosemide, 0.1 mg/kg can be used to reduce cerebral edema. Deep sedation with narcotics and even the use of paralyzing agents may be helpful. Corticosteroids are occasionally used, but have no proven benefit.

38. A 15-year-old boy is struck by a baseball in the side of the head. He briefly looses consciousness but quickly returns to a lucid state. Which of the following statement(s) is/are true concerning his subsequent course.

a. The initial neurologic finding may be dilatation of the ipsilateral pupil
b. If the patient has a normal neurologic examination at the time of emergency room assessment, he can be discharged safely to home
c. A head computed tomography (CT) scan should be performed regardless of the current neurologic examination
d. The likely mechanism of injury arises from a tear of a branch of the middle meningeal artery as it courses through a grove in the skull at the area of impact
e. If, after an initial lucid interval, a rapid progression to coma with fixed and dilated pupils and decerebration occurs, the most likely CT finding would be a subdural hematoma
Answer: a, c, d

Hemorrhage between the inner table of the skull and the dura mater most commonly arises from a tear of the middle meningeal artery or one of its branches that course through a grove in the lateral skull. Arterial bleeding strips the dura from the undersurface of the bone and produces still more bleeding because the small bridging veins from the dura to the skull are torn. The result is an epidural hematoma which may rapidly increase in size and compress the cerebral cortex. An epidural hematoma classically follows a blow to the head which causes a brief period of unconsciousness. After the patient regains consciousness, there may be a lucid interval during which there are no abnormal neurologic symptoms or signs. As the hematoma enlarges, hemispheric compression occurs. With time the medial portion of the temporal lobe is forced over the edge of the tentorium causing compression of the oculomotor nerve and subsequent dilatation of the ipsilateral pupil. Similarly, compression of the ipsilateral cerebral peduncle causes contralateral hemiparesis, which progresses to decerebrate posturing. Coma, fixed and dilated pupils, and decerebration is the classic triad suggestive of transtentorial herniation. Epidural hematomas are curable lesions, but the mortality rate remains high because the severity of the injury is often not recognized early. A patient may be seen during a lucid interval and discharged. Later, the patient becomes unconscious because of progressive brain compression by the expanding hematoma. Because of the danger of misdiagnosis, any patient with a history of a blow to the head leading to a period of unconsciousness should have a CT scan.

39. Which of the following statement(s) is/are true regarding peripheral nerve injuries?

a. Neuropraxia is temporary loss of function without axonal injury; structure damage does not occur
b. Axonotmesis is disruption of the axon and axon sheath associated with traumatic injury
c. Neurotmesis is disruption of the axon with preservation of the axon sheath which usually preserves sensory and motor function
d. Electromyography (EMG) is useful in the early assessment of nerve injuries
e. Regeneration in a peripheral nerve occurs at a rate of 1 mm/day, so improvement may not be obvious for many months
Answer: a, e

Peripheral nerve injuries may be categorized functionally. Neuropraxia is a temporary loss of function without axonal injury and structural damage does not occur. Axonotmesis is a disruption of the axon with presentation of the axon sheath. Wallerian degeneration of the distal axon fragment occurs. Stretched or prolonged compression causes this functional and structural loss. Regeneration of the proximal axon occurs, but functional recovery depends on the associated injuries, the amount of healthy proximal axon remaining after injury, and the age of the patient. Neurotmesis is disruption of both the axon and axon sheath with corresponding loss of function and is caused by transection of a nerve. Regeneration occurs, but function rarely returns to normal. Clinically, sensory motor changes correspond with the peripheral nerve involved. Detailed history and a precise neurologic examination can localize the site of injury with accuracy. EMG is not useful within the first three weeks of injury but is highly effective for monitoring the status of the degeneration and regeneration process that occurs later.
Regeneration in a peripheral nerve occurs at 1 mm/day (roughly 1 inch each month), so improvement may not be obvious for months. Factors that adversely affect the return of function include advanced age of the patient, proximal nerve injury, extensive nerve tissue loss, associated soft tissue injury, and mixed sensory motor function. Unfortunately, incomplete neurologic recovery is often the rule.


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