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13. NEUROLOGY Kristine O’Phelan he purpose of the Oral Board Examination is to determine a candidate’s competency in neurosur gical disorders, but also in neurological disorders, which may mimic neurosurgical conditions. Clearly, this goal of the examination process must be kept in the back of your mind during questioning. It is not uncommon for a candidate to be presented imaging studies that clearly appear surgical; however, after care fully listening to the history and relevant neurological findings, it will become apparent that the imaging does not explain the patient’s symptoms. When this occurs, start by trying to localize the lesion within the neuraxis— brain, brainstem, spinal cord, peripheral nerve, neuro muscular junction, or the muscle itself. Clues such as hyporeflexia or hyperreflexia and absence of sensory symptoms are key. Then develop a differential diagno sis of neurological conditions that may present in these areas— demyelinating, inflammatory, axonal loss, and neuromuscular blockade. Some of the common neurological ailments that the Oral Board examinee needs to be well aware of include amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), Guillain- Barré syndrome, and Parsonage- T urner syndrome (brachial plexitis), some of which are covered either in this chapter or in other relevant chapters. CASE 1 A 50- year- old woman presents to the emergency depart ment with the complaint of headaches progressing over the past 3 weeks with worsening lethargy. She denies any recent fall or trauma, and she notes some decrease in her appetite and weight, which is attributed to the headache. She does not have fever, chills, cough, or vomiting. She notes that her headache is better in the morning when she first wakes up but then worsens after she is up out of bed. Computed tomography (CT) of the brain is performed (Figure 13.1). WHA T ARE THE FINDINGS? The non– contrast- enhanced CT of the head reveals moderate- sized chronic subdural hematomas without midline shift or acute hemorrhage. DO THESE EXPLAIN THE PA TIENT’S SYMPTOMS? These findings do not completely explain the patient’s symptoms because there is no significant mass effect. The patient then develops more lethargy and complains of diplopia. On examination, she has mild cranial nerve VI dysfunction bilaterally. Magnetic resonance imaging (MRI) is performed (Figure 13.2). WHA T ARE THE ABNORMALITIES? Contrast- enhanced MRI demonstrates diffuse meningeal enhancement without evidence of structural lesions within the brainstem. A midsagittal image demonstrates cerebellar tonsillar descent. WHA T IS THE DIFFERENTIAL DIAGNOSIS? The differential diagnosis includes spontaneous intracra nial hypotension versus a diffuse infectious, inflammatory, or neoplastic process. Cranial nerve dysfunction is not typical of spontaneous intracranial hypotension, so a meningeal process must be considered, although this is less likely given the lack of constitutional symptoms or prior diagnosis of neoplastic disease and lack of leptomeningeal enhancement. WHA T IS THE WORKUP? Y ou should order MRI and CT myelography of the spine. A  lumbar puncture can also be performed to document an abnormally low cerebrospinal fluid (CSF) pressure and exclude other infectious or neoplastic etiologies.

ms or prior diagnosis of neoplastic disease and lack of leptomeningeal enhancement. WHA T IS THE WORKUP? Y ou should order MRI and CT myelography of the spine. A  lumbar puncture can also be performed to document an abnormally low cerebrospinal fluid (CSF) pressure and exclude other infectious or neoplastic etiologies. Figure 13.1 A, B: Non– contrast- enhanced axial computed tomographic scans of the brain. Figure 13.2 A, B: Magnetic resonance images of the brain with gadolinium. A B Figure 13.3 A, B: Computed tomographic myelograms of the spine.

ms or prior diagnosis of neoplastic disease and lack of leptomeningeal enhancement. WHA T IS THE WORKUP? Y ou should order MRI and CT myelography of the spine. A  lumbar puncture can also be performed to document an abnormally low cerebrospinal fluid (CSF) pressure and exclude other infectious or neoplastic etiologies. Figure 13.1 A, B: Non– contrast- enhanced axial computed tomographic scans of the brain. Figure 13.2 A, B: Magnetic resonance images of the brain with gadolinium. A B Figure 13.3 A, B: Computed tomographic myelograms of the spine. NEUROLOGY • 155 The following study was performed (Figure 13.3). The CT myelogram study shows evidence of a small CSF leak in the lower thoracic spine along a nerve root sleeve on the right. Other typical findings can include dilation of the spinal epidural venous plexus, enhancement of the pituitary gland, and sagging of the cerebellar tonsils— also known as an acquired Chiari malformation . WOULD YOU RECOMMEND ANY T R E AT M E N T ? The patient should be placed in flat position with intrave nous (IV) hydration. T reatment includes an epidural blood patch. If a patient has a focal CSF leak that is resistant to several high- volume epidural blood patches, one can con sider surgical intervention. Surgical options include open suture repair versus a minimally invasive indirect repair. Many patients have an associated collagen disorder and may benefit from a genetic workup. CASE 2 A 32- year- old man without a significant past history is sent to your office by his primary care physician because of tin gling in his legs. He denies pain or weakness, reports no loss of bowel or bladder control, but was moving furniture when he noticed the tingling and thought he might have “thrown out his back.” On examination, he has full strength, he has decreased sensation to light tough and pinprick from T7 down, and the right plantar response is extensor. He has loss of abdominal reflexes, normal patellar and ankle jerk reflexes, and normal rectal tone. What is your next step? Obtain an MRI of the spinal cord with gadolinium contrast (Figure 13.4). WHA T ARE THE FINDINGS? This contrast- enhanced MRI of the thoracic spine demon strates an intradural intramedullary enhancing area, which expands the cord slightly and extends across multiple tho racic levels. WHA T IS THE DIFFERENTIAL DIAGNOSIS? The patient presents with acute onset of sensory distur bance in the legs with a distribution consistent with a spinal cord pathology. In a previously healthy patient without history of trauma, the differential diagnosis includes a neoplasm, infectious and inflammatory dis eases, and vascular malformations of the spinal cord. The abrupt onset of symptoms in this case favors an infectious or inflammatory etiology rather than a neoplasm. The contrast- enhanced MRI of the thoracic and lumbar spine is consistent with transverse myelitis. The examiner may press you for a tissue diagnosis— resist the temptation to biopsy the lesion. Serial imaging and clinical examination is the way to go. WHA T IS THE WORKUP? The workup consists of a lumbar puncture to send CSF for cell count, protein glucose, oligoclonal bands, and myelin basic protein as well as immunoglobulin G index; polymerase chain reaction (PCR) studies for herpes sim plex virus (HSV), varicella- zoster virus (VZV), and cyto megalovirus (CMV); Lyme titers and cytology; and Gram Figure 13.4 Magnetic resonance image of the thoracic spine with gadolinium.

ligoclonal bands, and myelin basic protein as well as immunoglobulin G index; polymerase chain reaction (PCR) studies for herpes sim plex virus (HSV), varicella- zoster virus (VZV), and cyto megalovirus (CMV); Lyme titers and cytology; and Gram Figure 13.4 Magnetic resonance image of the thoracic spine with gadolinium. 156 • G OODMAN ’S N EUROSURGERY O RAL B OARD R E v IEW stain and routine culture. Patients with acute transverse myelitis are at increased risk for developing MS. Imaging of the brain should be performed to look for demyelinating lesions. Additionally, transverse myelitis may be associated with several systemic inflammatory autoimmune diseases, such as systemic lupus erythematosus and Sj ög ren’s syndrome, as well as central nervous system (CNS) infec tions, such as W est Nile virus, herpesvirus, and CNS Lyme disease. WOULD YOU START ANY TREA TMENTS? T ransverse myelitis is an autoimmune demyelinating disease that affects the spinal cord with a predilection for thoracic levels. T reatment consists of high- dose steroids (methyl prednisolone, 1 g daily for 3– 5 days). Severe cases may also respond to plasma exchange therapy. CASE 3 A 40- year- old man comes to your office because of cervi cal stenosis. He has developed clumsiness in his hands for a week and now notes some imbalance and difficulty with gait. He reports no sensory changes. On examination you note ataxia out of proportion to weakness. He has mild proximal weakness in the limbs and bilateral facial weakness without sensory deficits. He is areflexic with neutral plantar responses. MRI results appear in Figure 13.5. WHA T ARE THE FINDINGS? The non– contrast- enhanced cervical MRI demonstrates severe cervical stenosis and spondylosis at C3- C4, C4- C5, C5- C6, and C6- C7, with a suggestion of intrinsic spinal cord changes at the sites of most severe compression. WHA T IS THE DIFFERENTIAL DIAGNOSIS? The rapid progression of motor symptoms, absence of a clinical sensory level, and areflexia make cervical myelopa thy unlikely. His symptoms are concerning for an acute polyneuropathy such as acute inflammatory demyelinat ing polyradiculoneuropathy (AIDP, or Guillain- Barré syndrome). Also in the differential diagnosis but less likely are diseases of the neuromuscular junction such as myasthenia gravis or diseases of the muscle. However, the absence of fatigable weakness for the former and the presence of facial weakness for the latter make these diagnoses less likely. WHA T IS THE WORKUP? The workup includes a diagnostic spinal puncture to send CSF for cell count, protein, glucose, and routine cultures. The lack of infectious markers and the presence of a cyto albuminemic dissociation would support the diagnosis of AIDP. A nerve conduction study should also be included in the workup, and changes within the first 2 to 3 weeks may include prolonged or absent F waves, and absent H reflexes reflecting demyelination at the level of the nerve A B Figure 13.5 A, B: T2- weighted sequence magnetic resonance images of the cervical spine.

f AIDP. A nerve conduction study should also be included in the workup, and changes within the first 2 to 3 weeks may include prolonged or absent F waves, and absent H reflexes reflecting demyelination at the level of the nerve A B Figure 13.5 A, B: T2- weighted sequence magnetic resonance images of the cervical spine. NEUROLOGY • 157 roots. There may be increased distal latencies, conduction blocks, and dispersion of motor responses in studies done later during the course of illness. WOULD YOU START ANY TREA TMENTS? Y es, you should start a course of either intravenous immune globulin (IVIG), 0.4 g/ kg/ day for 5  days, or plasma exchange, five exchanges over 10 days. The prognosis is variable— although most patients have some recovery of function, it is often incomplete. By 4 weeks, 65% will have some degree of motor recovery; by 6 months, 80% will be able to walk; and 60% will achieve a full recovery. Therapy with disease- modifying treat ments (IVIG and plasma exchange) decrease the time to recovery by 40%. Poor prognostic factors include older age, rapid onset, severe weakness, need for ventilator sup port, preceding diarrheal illness, and severely decreased distal latencies on nerve conduction studies with fibrilla tion potentials on needle electromyography (EMG). In this particular case, although the imaging tests are strongly suggestive of cervical stenosis and myelopathy, the clinical presentation is suggestive of a superimposed neurological condition and, in this case, AIDP. Listening to the history and neurological signs is critical in picking up the correct diagnosis. CASE 4 A 57- year- old right- handed woman presents to your office for evaluation of cervical stenosis. She reports that she first noticed weakness in her left hand 7 months ago. This was mostly in her thumb and second finger as well as her wrist extensors. Now she notices that her right foot feels floppy and she trips when she walks. There is no numbness or bowel or bladder problems. She has also become more emotional lately, which she feels is due to anxiety about her health. WHA T ARE THE FINDINGS? On examination, the patient is awake and alert, her speech is fluent, and she is fully oriented. Her left hand appears wasted with thenar and hypothenar atrophy. All thumb movements are impaired, as are finger and wrist extension more than flexion. Fasciculations are notable in the fore arm, triceps, and biceps. Left elbow flexion, extension, and shoulder abduction test at 2/ 5 strength. Scapular winging on the left greater than the right side, with some fasciculations, is noted over the shoulder girdle. Right wrist extension is 4/ 5 strength, and right leg functions are 5/ 5 strength, except for dorsiflexion, which is 3/ 5. Left leg has is 5/ 5 strength throughout. Sensory responsiveness is normal throughout. Deep tendon reflexes are 3+ in the bilateral biceps, triceps, and brachioradialis; 3+ in the left patella with crossed adduc tion; 2+ in the left ankle, and 4+ in the right patella and right ankle clonus. The patient has a positive Babinski’s sign on the right side, positive Hoffmann’s reflex bilaterally, and positive jaw- jerk reflex (Figure 13.6) MRI of the cervical spine demonstrates cervical canal stenosis with multilevel disk disease that is worse at C3- C4, C4- C5, and C5- C6, with some indentation in the thecal sac and spinal cord compression. Figure 13.6 A, B: T2- weighted sequence magnetic resonance images of the cervical spine.

jerk reflex (Figure 13.6) MRI of the cervical spine demonstrates cervical canal stenosis with multilevel disk disease that is worse at C3- C4, C4- C5, and C5- C6, with some indentation in the thecal sac and spinal cord compression. Figure 13.6 A, B: T2- weighted sequence magnetic resonance images of the cervical spine. 158 • G OODMAN ’S N EUROSURGERY O RAL B OARD R E v IEW WHA T IS THE DIFFERENTIAL DIAGNOSIS? The patient’s long history of progressive weakness with evidence of both upper and lower motor neuron signs on examination in the absence of any sensory findings is concerning for motor neuron disease. The most common form is ALS, also known as Lou Gehrig’s disease. Less likely would be a predominantly motor polyneuropathy in the setting of a cervical myelopathy. However, the chronic course of illness and lack of sensory level favor motor neu ron disease. The pathology is characterized by loss of motor neurons in the cerebral cortex, nuclei, and ventral horn of the spinal cord. In most cases, the etiology is unknown; however, in 5% to 10% of cases, a genetic cause is recognized. Muscle twitching (or fibrillations) is classical, including involvement of the tongue. Atrophy in the presence of long tract signs is highly suggestive. Swallowing, voice difficulty, and respiratory failure ensue. Most patients die of respiratory failure. WHA T IS THE WORKUP? Y ou should request a nerve conduction study to evaluate for selective involvement of the ventral (motor) roots and show evidence of axonal loss, decreased recruitment, and fasciculations and fibrillations on needle EMG. WOULD YOU START ANY TREA TMENTS? T reatment is predominantly supportive. Diseasemodifying treatments are limited. Riluzole has been shown to slow the progression of the disease, but does not change its outcome. Symptomatic management of associ ated dysarthria, dysphagia, respiratory muscle weakness, spasticity, pseudobulbar affect, and psychosocial difficul ties is recommended. CASE 5 A previously healthy 46- year- old man presents to the emergency department of an outside hospital complaining of new- onset right arm weakness. The arm is not painful, and he has no history of trauma or prior weakness. He noticed the symptoms a few days ago, and they have slowly wors ened. He denies any past medical history except a “stom ach flu” a week ago with low- grade fever, vomiting, and diarrhea. He denies any recent weight loss or prior history of weakness. While in the emergency department, he has a generalized tonic- clonic seizure, and he is treated with IV lorazepam, 4 mg, and IV fosphenytoin, 20 mg/ kg, is ordered. Initially, the convulsions stop, but right hand starts to shake and his eyes are gazing toward the right. A second dose of IV lorazepam, 4 mg, is given, and he is intubated for airway protection. The convulsions once again stop, and a ST A T electroencephalogram (EEG) is ordered to confirm that the seizures have resolved. WHA T ARE THE FINDINGS? The EEG demonstrates that there is ongoing ictal activity over the left parietal lobe consistent with nonconvulsive status epilepticus (NCSE). Up to 30% of patients with status epilepticus may develop NCSE after resolution of con vulsive activity, making it imperative to confirm resolution with an EEG. This is particularly important if the patient has not returned to his neurological baseline. The patient is treated with another 4 mg of IV lorazepam, and a sec ond anticonvulsant, valproic acid, is ordered. This is given as an IV loading dose of 20 mg/ kg followed by scheduled doses of 500 mg every 8 hours. All anticonvulsants should be given intravenously if possible until resolution of status epilepticus to avoid any variable absorption through the enteral route.

and a sec ond anticonvulsant, valproic acid, is ordered. This is given as an IV loading dose of 20 mg/ kg followed by scheduled doses of 500 mg every 8 hours. All anticonvulsants should be given intravenously if possible until resolution of status epilepticus to avoid any variable absorption through the enteral route. When there is an urgent need for surgery or a concern for coagulopathy, some clinicians may wish to use a different second anticonvulsant because valproate has a potential antiplatelet effect. Other appropriate secondline agents are levetiracetam and phenobarbital. If fos phenytoin, phenobarbital, or valproic acid is given, serum levels should be obtained to ensure that they are in the high therapeutic range. If the seizure activity continues after IV benzodiaze pines and despite two appropriately chosen and dosed anticonvulsants, an infusion of an anesthetic agent should be started. Midazolam (0.1 mg/ mg IV push followed by 0.05 to 3 mg/ kg/ hr infusion), propofol (50 to 150 mcg/ kg/ min), or pentobarbital (10 to 20 mg/ kg IV bolus followed by 0.5 to 10 mg/ kg/ hr infusion) may be used. All of these anes thetic agents have significant hemodynamic adverse effects, and this must be taken into consideration when admin istering them. The patient should be well hydrated, have hemodynamic monitoring placed, and have IV access for vasopressor therapy as needed. Over the following 4  days, the patient’s mental status continues to deteriorate. He is transferred to your hospital because of coma and abnormal findings on MRI. On examination, the patient is afebrile, normotensive, and not tachycardic. He has no eye opening, his pupils are symmetrical and reactive, he has a weak cough and gag reflex, and he extends weakly to painful stimulation. His

deteriorate. He is transferred to your hospital because of coma and abnormal findings on MRI. On examination, the patient is afebrile, normotensive, and not tachycardic. He has no eye opening, his pupils are symmetrical and reactive, he has a weak cough and gag reflex, and he extends weakly to painful stimulation. His NEUROLOGY • 159 heart and lung examinations are normal, he does not appear cachectic, and he has no rashes (Figure 13.7). MRI of the brain demonstrates diffuse changes affect ing the white matter tracks bilaterally, extending from the hemispheres down through the brainstem. There is moderate local mass effect without midline shift. There is little to no enhancement on gadolinium- contrast scans. WHA T IS THE DIFFERENTIAL DIAGNOSIS? The differential diagnosis includes a demyelinating white matter process such as acute disseminated encephalomy elitis (ADEM) or tumefactive MS. Less likely would be an infection with progressive multifocal leukoencephalopathy (PML) if the patient were immune suppressed, although this degree of edema is unusual with PML outside of the immune reconstitution syndrome. A  low- grade glioma would not be likely to present with such a rapid course, and other infectious diseases would not be likely to spare the gray matter in this pattern. WHA T IS THE WORKUP? The workup should include CSF studies for cell count, glucose, protein, and microbiology; PCR for HSV , VZV , and CMV; oligoclonal bands and myelin basic protein; and a CSF immunoglobulin G index. CSF cytology and flow cytometry should also be tested to evaluate for an underly ing neoplasm. An intracranial pressure monitor should be considered because there is evidence of mass effect and the patient is comatose. WOULD YOU START ANY TREA TMENT WHILE YOU ARE W AITING FOR RESULTS? ADEM is a rapidly progressing monophasic illness that can present after a viral illness. It is an autoimmune white matter demyelinating disease and can be associated with mass effect and severe alterations of consciousness, including coma. The treatment is focused on decreasing the immune response and includes high- dose steroid therapy (1 g IV daily for 5 days) and may be followed by IVIG or plasma exchange therapy. WHA T IS THE PA TIENT’S PROGNOSIS? The overall prognosis is good, and mortality is relatively low (5%). However, some patients are left with disability after recovery (full recovery occurs in 50% to 70% of cases). CASE 6 An 88- year- old man with a history of hypertension, coro nary artery disease, and sick sinus syndrome and has a car diac pacemaker that was placed 2  years ago. He presents after the acute onset of left- sided weakness and dysarthria, which started at the dinner table while he was eating with his family. There was no loss of consciousness, no traumatic fall, and no evidence of seizure activity. On examination, he is awake and alert, he follows directions, and he has a mild flattening of the left nasolabial fold and dysarthria. The strength of his left arm and leg is 4/ 5, and he has mild sensory loss with extinction to double AB C Figure 13.7 A– C, T1- weighted fluid- attenuated inversion recovery sequence magnetic resonance images of the brain with gadolinium contrast.

and he has a mild flattening of the left nasolabial fold and dysarthria. The strength of his left arm and leg is 4/ 5, and he has mild sensory loss with extinction to double AB C Figure 13.7 A– C, T1- weighted fluid- attenuated inversion recovery sequence magnetic resonance images of the brain with gadolinium contrast. 160 • G OODMAN ’S N EUROSURGERY O RAL B OARD R E v IEW simultaneous stimulation over the left arm and leg. His National Institutes of Health Stroke Scale score is 5. WHA T OTHER HISTORY DO YOU NEED? When was the known time that the patient was well? Has there been any recent trauma or bleeding? Any major sur gery? Does the patient take any anticoagulants? What is his fingerstick glucose level? The patient’s family tells you that he was last well 30 minutes before arrival to the emergency department and that he has not had any surgery, trauma, or bleeding prob lems. His medications include an aspirin, carvedilol, and lisinopril. His serum glucose concentration is 90 mg/ dL. WHA T TEST SHOULD YOU ORDER? CT scan of the brain demonstrates cerebral atrophy, which is appropriate for the patient’s age (Figure 13.8). There are no acute hemorrhage or signs of early ischemic changes on the CT scan. WHA T IS THE DIAGNOSIS? The diagnosis is acute ischemic infarction in the territory of the right middle cerebral artery (MCA). WHA T DO YOU DO? Speak to the family about the risks and benefits of IV tis sue plasminogen activator (tPA) and start the medication as soon as possible. IV tPA should be given for symptoms of acute ischemic stroke within the first 3 hours. Some studies show adequate safety data for up to 4 ½ hours, exclud ing patients older than 80  years, those with uncontrolled hyperglycemia, and those with very large strokes because high risk for rebleeding in this subgroup. Exclusion cri teria include any acute hemorrhage or large areas of early CT changes (>33% of cerebral hemisphere) on head CT or a history of spontaneous intracranial hemorrhage, international normalized ratio (INR) higher than 1.7, platelets less than 100,000, and uncontrolled hypertension with systolic blood pressure greater than 185  mm Hg despite therapy. Relative contraindications include recent major surgery (including intracranial or spinal surgery), trauma, gastrointestinal or genitourinary tract hemorrhage, and recent (3 months) acute myocardial infarction. Recent use of heparin with an elevated partial thromboplastin time or current use of a direct thrombin inhibitor or direct fac tor Xa inhibitor (with evidence of anticoagulant effect by appropriate laboratory tests) is also an exclusion for intra venous thrombolysis. INTRA VENOUS TISSUE PLASMINOGEN ACTIV A TOR IS ST ARTED— WHA T OTHER TESTS MAY BE HELPFUL? Imaging of the intracranial vessels (Figure 13.9) reveals a cutoff of the right M2 portion of the MCA. Perfusion studies show a mismatch between cerebral blood volume and cerebral blood flow; this confirms the presence of a proxi mal large vessel occlusion and an ischemic penumbra. WHA T WOULD YOU DO NEXT? The patient is taken to the angiography suite for acute mechanical thrombectomy and reperfusion. For patients with an acute stroke caused by occlusion of a proximal large vessel in the anterior circulation, mechanical thrombectomy using a second- generation stent retriever device is recommended if it can be performed within the first 6 hours at a stroke center with appropriate exper tise in the use of stent retrievers.

atients with an acute stroke caused by occlusion of a proximal large vessel in the anterior circulation, mechanical thrombectomy using a second- generation stent retriever device is recommended if it can be performed within the first 6 hours at a stroke center with appropriate exper tise in the use of stent retrievers. This recommendation is based on four multicenter open- labeled randomized con trolled trials (MR CLEAN, SWIFT PRIME, EXTEND IA, REVASCA T, references 1– 3, 10) 1 demonstrating improved clinical outcomes at 90  days when mechanical thrombectomy using second- generation stent retrievers Figure 13.8 Non– contrast- enhanced axial computed tomographic scan of the brain. NEUROLOGY • 161 was compared with standard therapy using intravenous thrombolysis alone. The patient’s neurological examination returned to baseline by the following morning. He underwent cardiac telemetry, an echocardiogram with bubble study, and imaging of his cervical and arch vessels to identify the etiology of his acute ischemic stroke and prescribe appropriate secondary stroke prevention. CASE 7 A 54- year- old previously healthy woman falls down five stairs at a music performance and is brought to the trauma center by ambulance. She reports no loss of consciousness but is complaining of a severe headache. There are no other associated injuries, and she reports taking no medications at home. Non– contrast- enhanced head CT (Figure 13.10) is performed and demonstrates a thin rim of acute subdural hemorrhage over the right frontal lobe without significant mass effect as well as a nondisplaced basal skull fracture. The patient was admitted for observation, serial imaging, and analgesia. Her examination remained stable, and she was discharged home uneventfully. Three weeks later, the patient is brought to the emer gency department by her family because of acute confusion. She had been well until several days before admission when she developed a dull aching headache that worsened when recumbent, but she was otherwise asymptomatic until the morning of admission when she was noted to be awake but “making no sense.” AB C Figure 13.9 A: Computed tomographic (CT) angiography reconstruction image. B, C: CT perfusion study. Figure 13.10 Non– contrast- enhanced brain computed tomography. A: None window. B: Brain window.

t she was otherwise asymptomatic until the morning of admission when she was noted to be awake but “making no sense.” AB C Figure 13.9 A: Computed tomographic (CT) angiography reconstruction image. B, C: CT perfusion study. Figure 13.10 Non– contrast- enhanced brain computed tomography. A: None window. B: Brain window. 162 • G OODMAN ’S N EUROSURGERY O RAL B OARD R E v IEW On examination, the patient is afebrile and normoten sive. She is awake and alert, but unable to follow directions consistently. She could produce words, but they did not make sense. Her motor examination showed full strength with symmetrical power. The results of repeat imaging with a non– contrast- enhanced CT scan of the brain are demonstrated in Figure 13.11. Acute hemorrhage in the left temporal lobe with mass effect at the level of the left cerebral peduncle. WHA T IS THE DIFFERENTIAL DIAGNOSIS? This patient’s history of prior trauma with a skull fracture that crosses the transverse sinus raises the concern for cerebral venous thrombosis. The facts that her blood pressure has not been elevated and that she does not have a prior diagnosis of hypertension argue against the diagnosis of spontaneous lobar hemorrhage related to hypertension. The patient also does not have any evidence of coagulopa thy or thrombocytopenia that would predispose her to intracranial bleeding, nor is she taking anticoagulants. The delay in presentation of 3 weeks argues against this acute event being related to the evolution of a posttraumatic temporal lobe contusion. WHA T FURTHER STUDIES WOULD YOU ORDER? Magnetic resonance venography (MRV; Figure 13.12) reveals loss of signal in the left transverse sinus with associ ated venous hemorrhage in the temporal lobe seen on gra dient echo sequences. MRV is the method of imaging used most commonly and is more accurate for large sinus thrombosis than cerebralvein thrombosis (CVT). CT venogra phy can also be useful in diagnosing CVT and intraarterial digital subtraction angiography is the “gold standard” and should be used when the diagnosis is in question. Other studies, such as serum D- dimer levels, can be used as a screening method, but they cannot be used to exclude the diagnosis of CVT. Similarly, lumbar puncture can be used to Figure 13.11 A, B: Non– contrast- enhanced axial computed tomography scans of the brain. Figure 13.12 Gradient echo sequence magnetic resonance imaging (A) and magnetic resonance venography  (B).

ed as a screening method, but they cannot be used to exclude the diagnosis of CVT. Similarly, lumbar puncture can be used to Figure 13.11 A, B: Non– contrast- enhanced axial computed tomography scans of the brain. Figure 13.12 Gradient echo sequence magnetic resonance imaging (A) and magnetic resonance venography  (B). NEUROLOGY • 163 exclude meningitis or evaluate isolated intracranial hyper tension, which can be associated with CVT and may affect vision. Screening for hypercoagulable states should be per formed in all patients with CVT. Screening laboratory tests include antithrombin III, activated protein C, protein S, factor V Leiden, prothrombin G20210A mutation, and anticardiolipin antibodies. CVT is rare, with incidence ranging from 0.22 to 1.3 per 100,000 population depending on region and gender. CVT is more common in women, and this seems to be related to gender- specific risk factors such as pregnancy and the puerperium, oral contraceptives, and hormone replacement therapy. Additionally, there are several non– gender- specific risk factors, such as malignancy, infection, and trauma, that should be considered. WHA T IS THE APPROPRIA TE THERAPY? Full anticoagulation is indicated to treat CVT. The goals of therapy are to prevent further clot propagation and to allow recanalization of the occluded sinus. Low- molecularweight heparin or unfractionated IV heparin can be used for this purpose. Endovascular therapy is typically reserved for those who do not respond to conventional anticoagulation. CASE 8 A 42- year- old healthy woman is admitted for elective resection of a sphenoid wing meningioma (Figure 13.13). Her course is complicated by moderate vasogenic edema related to the mass, and she is discharged in good condition on an oral dexamethasone (Decadron) taper. The patient presents to the emergency department 6 weeks after surgery with symptoms of lethargy, confu sion, headache, and fever. Brain MRI shows increased T2weighted signal in the right temporal lobe (Figure 13.14). An EEG was performed to evaluate the patient’s altered mental status (Figure 13.15). A lumbar puncture was performed, and CSF studies demonstrated a white blood cell count of 5, predominantly lymphocytes; red blood cell count of 100 with xanthochromia, protein of 65, and glucose of 50. WHA T IS THE DIFFERENTIAL DIAGNOSIS? Any patient who presents with fever and alteration of consciousness should be evaluated for CNS infection. Infectious etiologies include bacterial and viral organisms. Bacterial meningitis is the most common CNS infection occurring postoperatively, and empirical antibiotics should be started until CSF results are available. However, in this case, the CSF signature is not typical of bacterial menin gitis and is more suggestive of viral infection. Specifically, the lymphocytic pleocytosis with a minimally elevated protein and normal glucose is typical of viral encephalitis. Figure 13.13 Magnetic resonance image of the brain with gadolinium contrast. Figure 13.14 T2- weighted magnetic resonance image of the brain.

gitis and is more suggestive of viral infection. Specifically, the lymphocytic pleocytosis with a minimally elevated protein and normal glucose is typical of viral encephalitis. Figure 13.13 Magnetic resonance image of the brain with gadolinium contrast. Figure 13.14 T2- weighted magnetic resonance image of the brain. 164 • G OODMAN ’S N EUROSURGERY O RAL B OARD R E v IEW Additionally, the MRI changes in the temporal lobes and the EEG showing periodic lateralizing epileptiform dis charges (PLEDS) are typical for HSV encephalitis. What is the appropriate workup? Brain MRI is prefer able because CT scans may be normal. Abnormalities seen on brain CT are usually indicative of severe disease and a poor prognostic factor. A lumbar puncture should be per formed,; CSF tested for protein glucose and cell count; PCR testing for HSV types 1 and 2, Epstein- Barr virus, CMV , and VZV as well as routine Gram stain and bacte rial cultures. An EEG can be performed in patients with encephalopathy, although most will demonstrate non specific theta and delta slowing; occasionally, PLEDS are found, and these are more specific for HSV encephalitis. WHA T IS THE APPROPRIA TE THERAPY? HSV encephalitis is treated with acyclovir, 10 mg/ kg IV every 8 hours, and this should be started empirically as soon as the diagnosis is considered. T reatment should be continued for 14 to 21 days in immunocompetent patients. HSV type 1 is the most common cause of viral encephalitis worldwide. Untreated, the mortality in this disease can be as high as 70%. However, prognosis can be good if the infection is treated early and aggressively. NOTE 1. SWIFT PRIME: Stent- Retriever Thrombectomy after Intravenous t- PA vs. t- PA Alone in Stroke, MR CLEAN: Multicenter Randomized Clinical T rial of Endovascular T reatment for Acute Ischemic Stroke in the Netherlands, EXTEND- IA:  Extending the Time for Thrombolysis in Emergency Deficits — Intra- Arterial, REVASCA T: Endovascular Revascularization With Solitaire Device V ersus Best Medical Therapy in Anterior Circulation Stroke Within 8 Hours BIBLIOGRAPHY Berkhemer OA, Fransen PSS, Beumer D, et  al. A randomized trial of intraarterial treatment for acute ischemic stroke. N Engl J Med . 2015;372:11– 20. Campbell BCV , Mitchell PJ, Kleinig TJ, et al. Endovascular therapy for ischemic stroke with perfusion- imaging selection. N Engl J Med . 2015;372:1009– 1018. Jovin TG, Chamorro A, Cobo E, et  al. Thrombectomy within 8 hours after symptom onset in ischemic stroke. N Engl J Med . 2015;2296– 2306. Kiernan MC, Vucic S, Cheah BC, et  al. Amyotrophic lateral sclerosis. Lancet. 2011;377(9769):942– 955. Marchioni E, Ravaglia S, Montomoli C, et al. Postinfectious neurologic syndromes:  A  prospective cohort study. Neurology. 2013;80(10): 882– 889. Marin SE, Callen DJ. The magnetic resonance imaging appearance of monophasic acute disseminated encephalomyelitis: An update post application of the 2007 consensus criteria. Neuroimaging Clin N Am. 2013;23(2):245– 266. FP1-F3 F3-C3 C3-P3 P3-O1 FP2-F4 F4-C4 C4-P4 P4-O2 FP1-F7 F7-T3 T3-T5 T5-O1 FP2-F8 F8-T4 T4-T6 T6-O2 Mouth Comment Facial twitching 100 uV 1 sec Figure 13.15 Sixteen- channel electroencephalogram showing periodic epileptiform discharges.

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