EVALUATION OF SENSORY SYMPTOMS

Sensory symptoms may arise from lesions in the peripheral nerve, or in central sensory pathways from the dorsal columns and spinothalamic tracts as they traverse the spinal cord and brainstem, to the thalamus, internal capsule, and cortical regions of the brain. The sensory system is notoriously difficult to evaluate because the physician needs to rely on patient perceptions for both the history and examination. Examination should focus on both primary sensory change (touch, pinprick, joint position, and vibratory sense) and “cortical” sensory changes such as the inability to recognize an object by touch and loss of two-point discrimination. The neurological history should focus on defining the type of sensory symptom (paresthesia, pain, allodynia, numbness, etc.) and the pattern of sensory loss, which depends on the onset, location, duration, progression, and associated symptoms. Common patterns of sensory loss include hemisensory change (brain or brainstem pathology or cervical spine disease if face is spared), spinal level (myelopathy), dermatomal (radiculopathy), length-dependent, often called “stocking–glove” (peripheral neuropathy), single nerve distribution (mononeuropathy), and multiple nerve distributions (mononeuropathy multiplex). Recent medication and habit changes should be investigated (e.g., habitual leg crossing can cause peroneal neuropathy). Accompanying weakness and changes in deep tendon reflexes may help to localize the lesion; for example, distal symmetric sensory loss, associated with distal weakness, loss of muscle tone, and decreased tendon reflexes would suggest a peripheral motor-sensory neuropathy.

EVALUATION OF VISUAL SYMPTOMS

The most common visual symptoms resulting from neurological disorders include double vision (diplopia) and loss of vision, which could be localized to one or both eyes. For diplopia it is important to ascertain whether the double vision disappears with closure of either eye (monocular diplopia usually results from non-neurological causes such as lens dislocation), and the effect of horizontal and vertical eye movements on the degree of double vision. The examination should include observation of smooth pursuit to each of the cardinal directions of gaze, watching for misalignment of the eyes and noting the position in which it is most prominent. Associated features such as retro-orbital pain should raise suspicion of inflammation or a compressing brain aneurysm; associated hemiparesis would suggest a central lesion such as midbrain or pontine stroke; associated pain, eye redness, and chemosis suggest a local inflammatory lesion secondarily affecting the extraocular nerves or muscles that control eye movement; and associated ptosis or proximal muscular weakness would raise the question of a neuromuscular junction disorders such as myasthenia gravis.

    Similarly, for visual loss it is essential to inquire whether the symptoms are localized to one eye or both eyes and to distinguish visual hemifield defects from unilateral loss of vision. Unilateral loss of vision suggests a prechiasmal lesion such as demyelinating diseases of the optic nerve (multiple sclerosis) or retinal or ocular ischemia (internal carotid artery stenosis, giant cell arteritis). Bilateral acute loss of vision usually localizes to the occipital-parietal lobes and can result from ischemia (cardiac arrest, top-of-the-basilar embolus, reversible cerebral vasoconstriction syndromes), brain edema (hypertensive encephalopathy), or demyelinating diseases. Hemi–visual field loss (hemianopia) usually implicates post-chiasmal lesions localizing to the lateral geniculate nucleus or occipital or temporal lobe from diseases such as stroke or brain tumor. Other visual symptoms include mild ptosis with miosis (components of the Horner syndrome, commonly resulting from carotid artery dissection) and positive visual phenomena such as scintillations and fortification spectra associated with unilateral headaches in patients with migraine.

COMMON NEUROLOGICAL CONDITIONS

SEIZURES

A seizure is defined as “a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.” Seizures can be primary or idiopathic, or secondary to head trauma, infection, stroke, metabolic insults, brain tumors, and other etiologies. Epilepsy is a brain disorder characterized by recurrent seizures due to underlying genetic abnormalities or acquired injury, and by the neurobiological, cognitive, psychological, and social consequences of recurrent seizures. In patients with epilepsy, seizures can be precipitated by minor factors (viral infection, lack of sleep, etc.) but are not referred to as provoked or secondary seizures. Seizures will affect about 5% of people at least once during their lifetime. Among these, a smaller percentage will develop epilepsy. The prevalence of epilepsy in developed countries is about 5 per 1000.

    Seizures can be classified as partial or generalized, with subtypes within each group (table 93.2). Focal seizures may spread to involve the entire brain (secondary generalization), whereas generalized seizures involve the entire brain from their onset and may have their genesis in the thalamus.

Table 93.2 CLASSIFICATION OF SEIZURES (INTERNATIONAL LEAGUE AGAINST EPILEPSY)

    The most common differential diagnoses for seizures include syncope, transient ischemic attack, nonepileptic seizures (also referred to as pseudoseizures or psychogenic seizures), panic attacks, migraine, dystonia, cataplexy, and nonepileptic myoclonus (e.g., after cardiac arrest). History taking should focus on distinguishing seizures from their mimics and, further, on characterizing the type of seizures because medical treatment is dependent on the subtype. Features more typical of seizure include the presence of urinary incontinence, tongue biting, loss of awareness, adventitious movements (synchronized when diffuse), vocalizations, preceding aura, and a prolonged postictal confusional state. While more common in seizures, convulsions and even urinary incontinence and tongue biting may occur in syncope, but patients usually return to baseline more rapidly. The examiner should carefully assess for possible provoking factors (drug intoxication or withdrawal, head trauma, meningitis/encephalitis, severe metabolic disturbance) and inquire about similar prior events, including febrile seizures in childhood and any personal or family history of seizure. For patients with a known seizure disorder, a full medication history should be obtained, including current medications and their doses, recent compliance, past antiepileptic medications and any allergies or adverse reactions, recent emotional and physical stressors such as lack of sleep, change in eating patterns, illness, or surgery. Additionally, it is important to know if the semiology of the current event is similar to or distinct from that of past seizures and if the patient has ever suffered from status epilepticus in the past. Medical and neurological physical examination should be performed to rule out ongoing or intermittent seizure, to uncover any signs of infection, trauma, drug intoxication, or other concurrent illness, and to rule out any neurocutaneous syndrome with a thorough skin examination. Vital signs, emergent blood glucose measurement, and clinical status should be observed carefully until the patient has returned to a baseline mental status.

    Diagnostic evaluation after a first seizure should be directed at uncovering precipitating factors. Blood glucose, complete serum chemistries, liver function tests, complete blood count, arterial blood gas when appropriate, serum and urine toxicology, levels of any antiepileptic drugs being taken for psychiatric or pain disorders, urinalysis and culture, chest x-ray, electrocardiogram (EKG), and lumbar puncture, when indicated, to rule out inflammation or infection of the central nervous system (CNS) should be performed. Serum prolactin may help differentiate nonepileptic seizure from an epileptic seizure if drawn within 30 minutes of the event and compared to the patient’s baseline. Prolactin can rise after syncope and cannot be used to differentiate seizure from syncope. It is rarely used in practice because of its temporal and diagnostic limitations. Electroencephalogram (EEG) is an essential study in the evaluation of possible seizure, but is rarely indicated in the emergency setting. In the absence of persistent neurological deficit, history of trauma, or clinical suspicion for intracranial abnormality, acute imaging of the brain with computed tomography (CT) or magnetic resonance imaging (MRI) is not required and can be arranged on an outpatient basis. Otherwise, it should be done as a part of the acute evaluation. The yield of CT or MRI after a first unprovoked seizure is about 10%, identifying disorders such as stroke, tumor (Figure 93.1), or neurocysticercosis. MRI is more sensitive than CT and is the preferred imaging modality if available. The workup for epileptic patients presenting with seizures of their typical semiology but increased duration or frequency is similar, although lumbar puncture is not indicated without compelling evidence for a CNS infection. It is not uncommon for a patient to be brought to the emergency department for a typical seizure that has occurred in public, and if reliable, these patients need not be reinvestigated for etiology.

    The first decision in treatment of epilepsy is whether an antiepileptic drug (AED) is necessary. For many causes of provoked seizures such as alcohol withdrawal or other metabolic disturbances, treatment should be directed at the underlying process, and an AED is not necessary. In the case of symptomatic etiologies with possible structural changes—such as tumor, stroke, or head trauma—an AED is usually initiated and continued for at least a year. For those patients with recurrent seizures or a seizure in the setting of a clear irreversible cause, AED treatment should be initiated. In patients with a single unprovoked seizure of unknown cause, other factors may weigh in the decision to start treatment. The presence of risk factors such as an abnormal EEG, family history, abnormal neurological examination, presentation with status epilepticus, and postictal Todd’s paralysis, argue for treatment. Social factors such as the ability to drive or work may also contribute to the decision. Apart from AED treatment, patients should be instructed to avoid any factors that clearly precipitate their seizures, such as sleep deprivation, alcohol, or stress. They should also be advised to refrain from activities during which a seizure could lead to injury of themselves or others, including driving, operating heavy machinery, working at a height, or swimming or bathing alone. Each state has different regulations regarding driving, and the patient should be directed to the appropriate governing body.

    In terms of choosing an AED, many factors contribute to the first-line choice for each patient, including the subtype of seizure, age of the patient, side effects, comorbid illnesses, and drug interactions (table 93.3). In general, certain agents have been shown to be more effective controlling partial or secondarily generalized seizures, including carbamazepine, valproic acid, phenytoin, and many of the newer agents, especially lamotrigine and oxcarbazepine. For primarily generalized epilepsies, first-line agents include valproic acid, lamotrigine, topiramate, and zonisamide. Levetiracitam is a useful adjunctive treatment. Ethosuximide has efficacy specific to absence seizures. Lacosamide, clobazam, and rufinamide are newer agents which were more recently approved by the FDA. Lacosamide is approved for partial onset seizures, while clobazam and rufinamide are approved as adjunctive therapy in Lennox-Gastaut syndrome.

    Pregnancy poses a particular problem for epilepsy treatment, as all AEDs are at least potentially teratogenic. Valproic acid and carbamazepine in particular should be avoided. This must be balanced with the adverse effects on the fetus of hypoxia from severe seizures. In women who require AED treatment for seizure control, the medication is usually continued at the lowest effective dose. Folic acid supplementation should be administered to help protect against neural tube defects.

    The risk of recurrence after a first seizure of any kind ranges from 25% to 80% depending on other risk factors. Prognosis depends on many factors, including age, specific epilepsy syndrome, underlying lesions, and response to AED treatment. In general about 80% of patients will have a remission or good control with AED treatment. Most of the remaining 20% with poor control despite multiple AEDs and/or surgery are comprised of patients with infantile spasms or seizures related to a severe underlying lesion.

HEADACHE

Headache is the most common neurological symptom in the outpatient setting. The 2004 International Classification of Headache Disorders Revision II (ICHD-II) classifies all headaches as either primary or secondary disorders. Primary headaches fit a recognized pattern with typical characteristics, and an underlying disease state is not the cause of the headache. Subcategories of primary headache disorders include migraine, tension headache, cluster and trigeminal autonomic type headaches, and other primary headaches. Table 93.4 shows the management of the common types of primary headache disorders. Secondary headache disorders are ones that result from an underlying process, which can be vascular, hemorrhagic, neoplastic, CSF-pressure related, substance use or withdrawal induced, inflammatory, or infectious. Table 93.5 shows the key features of the most common causes of secondary headaches and their initial management.

Table 93.5 COMMON SECONDARY HEADACHE DISORDERS

    With a 10–18% prevalence of migraine, and 20–30% prevalence of tension-type headache in the general population, the vast majority of headaches are benign. However, headache can also be symptomatic of potentially ominous etiologies, leading to concern on the part of both the physician and the patient that a secondary etiology of headache may be overlooked without brain imaging. An informed physician can often allay these concerns with an appropriate medical history, thorough neurological examination, and a basic understanding of the differential diagnosis for headache. Only then should imaging be considered, the guidelines for which are presented in table 93.6. Imaging is usually not indicated in patients with a primary headache disorder and normal neurological examination.

ISCHEMIC STROKE

Stroke is defined as an acute neurological event secondary to ischemia or hemorrhage. Ischemic stroke results from ischemia of brain tissue secondary to either thrombosis or emboli to the cerebral vessels. Stroke ranks as the second leading cause of death worldwide, and approximately 795,000 people have new or recurrent stroke each year in the United States. On average, every 40 seconds someone in the United States has a stroke. Risk factors for stroke include age, hypertension, hyperlipidemia, smoking, diabetes, acute myocardial infarction, cardiac arrhythmias such as atrial fibrillation, cardiomyopathy, and others. Primary ischemic stroke and transient ischemic attacks (TIAs) conveniently divide into four subtypes: (1) large artery atherothrombotic (approximately 15%); (2) cardioembolic (approximately 60%); (3) small vessel lacunar (15%–20%); and (4) other well-defined causes (5%), such as arterial dissection and cerebral arteritis. The symptoms of stroke are variable, depending on the etiology and vascular territory affected (table 93.7).

    Patients presenting with symptoms of stroke should be admitted or referred to the nearest hospital for emergent care. Emergency management should include evaluation of the hemodynamic and respiratory stability of the patient with vital signs and brief clinical history and neurological examination including an assessment of the National Institutes of Health (NIH) stroke scale score. Brain imaging should be performed as soon as possible to determine the extent of the infarction and exclude mimics such as brain hemorrhage or tumors (Figure 93.2).

    The time of onset should be determined, and a neurologist should be consulted emergently for evaluation and to determine eligibility for intravenous tissue plasminogen activator (IV tPA), which is US FDA approved for administration within 3 hours after stroke symptom onset. Recent results of the European Cooperative Acute Stroke Study (ECASS-3) show evidence of an expanded time window between 3.0 and 4.5 hours for persons experiencing acute ischemic stroke symptoms, however this has not been endorsed by the U.S. FDA. The dose of tPA is 0.9 mg/kg, 10% administered as a bolus and the remaining 90% by intravenous infusion over 1 hour. Major contraindications to intravenous tPA include an ischemic lesion measuring greater than one-third territory on noncontrast CT, evidence for brain hemorrhage, head trauma, prior history of intracerebral hemorrhage or stroke within 3 months, rapidly resolving or minimal deficits, suspicion of subarachnoid hemorrhage, recent trauma or surgery within the prior 15 days, active internal bleeding or recent gastrointestinal bleeding, recent lumbar puncture or noncompressive arterial puncture within 7 days, bleeding diathesis (INR >1.7, PT >15 sec, PTT >40 sec, platelets 100,000/μL, or known bleeding diathesis), uncontrolled hypertension (systolic blood pressure >185 mm Hg or diastolic blood pressure >110 mm Hg despite medications), and seizures at onset. Patients receiving IV tPA should be closely monitored for at least 24 hours for changes in neurological status and for blood pressure control. Anticoagulation, catheterization, arterial puncture, and antiplatelet agents should be avoided for 24 hours. A follow-up head CT scan should be obtained at 24 hours, or earlier if there is a change in neurological examination. If the patient remains stable, he or she may be transferred to the floor for further diagnostic evaluation and management.

    Intra-arterial tPA or mechanical clot retrieval using FDA-approved devices such as the MERCI catheter, Penumbra device, Solitaire Flow Restoration device, and the Trevo Pro Retriever, is frequently offered as an additional acute stroke treatment strategy. While these devices are approved by the FDA for clot removal, three recent phase III trials failed to show clinical benefit with intra-arterial clot retrieval in patients with acute stroke and proximal arterial occlusion. Nevertheless, many academic tertiary stroke centers continue to offer intra-arterial treatment in select patients (e.g., those with proximal middle cerebral artery occlusion presenting within 6 hours, or basilar artery occlusion presenting within 12 hours, provided there is a significant volume of salvageable tissue detected on acute brain imaging studies).

    Brain MRI using diffusion-weighted imaging has high sensitivity and specificity (over 95%) for ischemic stroke. The further diagnostic evaluation should be based on the suspected underlying pathophysiology. For example, vascular imaging should be performed using CT-angiography, MR-angiography, catheter angiography, or vascular ultrasound (carotid Duplex imaging) for suspected artery-to-artery stroke from carotid artery atherosclerosis or dissection, or to assess the patency of the “culprit” artery, which can influence the acute management. Cardiac evaluation using EKG, transthoracic or transesophageal ultrasound, and Holter monitoring is indicated for suspected cardioembolic stroke. Blood tests such as protein C, protein S, antithrombin III levels, and antiphospholipid antibodies may be indicated in young individuals with ischemic stroke or venous sinus thrombosis. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels may be obtained on suspicion of underlying malignancy, bacterial endocarditis, or systemic vasculitis, with additional infectious or inflammatory workup such as cerebrospinal fluid examination, brain biopsy, temporal artery biopsy, and serum toxicology screen requested on a case by case basis.

    Secondary prevention with an antiplatelet agent (aspirin, clopidogrel, aspirin-dipyridamole combination) or an anticoagulant agent such as warfarin, if indicated, should be initiated within 24 hours after admission. Blood tests to assess vascular risk and help decision making about preventive medications include a complete blood count, lipid panel, lipoprotein-a level, ESR, CRP, homocysteine level, homocysteine level, and liver and renal function tests. Prophylaxis against deep vein thrombosis with subcutaneous low-molecular-weight heparin, and the prompt evaluation of swallow function with implementation of measures to prevent aspiration pneumonia, are important. Patients should be evaluated by physical, occupational, and speech therapy if they have persistent deficits. If there is significant carotid stenosis (either moderate or severe) on vessel imaging, and depending on the surgical risk, the patient may be considered for carotid endarterectomy or stenting. The decision to use antiplatelets or anticoagulants for stroke prevention depends on the underlying pathophysiology; in general, warfarin is used only for high-risk cardiac sources such as atrial fibrillation, left ventricular thrombus, cardiomyopathy, and prosthetic heart valves, and for cerebral artery dissection and venous sinus thrombosis. Stroke prevention therapy with cholesterol-lowering agents (statins), antihypertensive medications (preferably thiazide diuretics and angiotensin-converting enzyme inhibitors), or antidiabetic agents must be initiated as per the latest American Heart and Stroke Association treatment guidelines. After patients have been medically stabilized, if they exhibit persistent deficits and cannot be cared for at home, they should be considered for inpatient rehabilitation or a nursing facility. Stroke unit care, prevention of acute poststroke complications, appropriate stroke preventive medications, and rehabilitation constitute the mainstay of therapy for ischemic stroke.

INTRACEREBRAL HEMORRHAGE

Intracerebral hemorrhages (ICHs) can be classified based on location (parenchymal, subdural, epidural, subarachnoid) or underlying etiology (primary hypertensive or secondary to ruptured berry aneurysms, vascular malformations, neoplasms, cerebral venous sinus thrombosis, blood dyscrasias, coagulopathies, etc.). Symptoms can vary depending on the location within the brain or spinal cord and may include coma or altered sensorium, weakness, sensory loss, aphasia, visual field deficits, headache, vomiting, and ataxia. The onset is typically acute, although symptom onset may be subacute, for example, with subdural hematomas or in patients with underlying brain tumor.

    Hypertensive ICHs are commonly located in the basal ganglia, thalamus (Figure 93.3), pons, and cerebellum. Chronic hypertension results in lipohyalinosis of small blood vessels, vessel wall weakening, and eventual rupture. Clinical examination may reveal clues to the location, for example, downward eye deviation with thalamic hemorrhage, deep coma with pinpoint pupils in pontine ICH, and severe headache, vomiting, nystagmus, and ataxia with cerebellar ICH. Space-occupying effects lead to raised intracranial pressure with consequent signs of brain herniation.

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