Medical School · Year 3 · Emergency Medicine · includes a quiz and discussion video

Seminar 05: Neurological Emergencies

Year 3: Emergency Medicine Clerkship

Learning Objectives

By the end of this seminar, students will be able to:

1. Rapidly assess and manage acute stroke
2. Differentiate causes of altered mental status
3. Recognize and treat status epilepticus
4. Evaluate and manage severe headache
5. Identify signs of increased intracranial pressure
6. Perform emergent neurological interventions

Seminar Outline

I. Acute Ischemic Stroke

Acute ischemic stroke results from interruption of cerebral blood flow causing neuronal injury and death, with treatment success critically dependent on time from symptom onset to intervention. The FAST mnemonic provides rapid screening identifying Face drooping, Arm weakness, Speech difficulty, and Time to call emergency services, capturing the most common stroke presentations while emphasizing urgency. The NIH Stroke Scale provides standardized severity quantification through assessment of consciousness, gaze, visual fields, facial palsy, motor function, ataxia, sensation, language, dysarthria, and extinction, with scores ranging from zero to forty-two and higher scores indicating more severe deficits. Stroke mimics including hypoglycemia, seizure with postictal paralysis, complex migraine, and conversion disorder must be considered, though these considerations should never delay evaluation and treatment when stroke is the leading diagnosis.

Time targets for stroke care reflect the critical relationship between reperfusion delay and brain tissue salvage, with the mantra "time is brain" emphasizing that approximately 1.9 million neurons die each minute during ischemic stroke. Door-to-CT time should not exceed twenty-five minutes, as rapid imaging excludes hemorrhage and enables thrombolytic therapy. Door-to-needle time for intravenous alteplase should remain under sixty minutes, representing a key quality metric for stroke center performance. The traditional 4.5-hour window for IV thrombolysis remains standard, though extended windows up to nine hours are now available for selected patients with favorable perfusion imaging. Mechanical thrombectomy for large vessel occlusion extends the treatment window to twenty-four hours in appropriately selected patients with salvageable penumbra on advanced imaging.

Intravenous thrombolysis with alteplase remains the cornerstone of acute ischemic stroke treatment, dissolving thrombus to restore cerebral perfusion before irreversible neuronal death occurs. Inclusion criteria require age eighteen or older, diagnosis of ischemic stroke causing measurable neurological deficit, and onset within 4.5 hours of last known well time. Major exclusion criteria include evidence of intracranial hemorrhage, blood pressure exceeding 185/110 despite treatment, platelet count below 100,000, INR above 1.7, recent major surgery or trauma, active internal bleeding, and history of intracranial hemorrhage. The 0.9 mg/kg dose with ten percent as bolus and remainder infused over sixty minutes requires blood pressure monitoring and management during and after administration. Symptomatic intracranial hemorrhage occurs in approximately six percent of treated patients but overall outcomes favor treatment when appropriately selected.

Mechanical thrombectomy has revolutionized treatment of large vessel occlusion stroke, providing direct clot retrieval when IV thrombolysis alone proves insufficient or contraindicated. Indications include occlusion of the internal carotid artery, M1 or M2 segments of the middle cerebral artery, or basilar artery with NIHSS score of six or higher or significantly disabling deficit. The time window extends to twenty-four hours when perfusion imaging demonstrates mismatch between irreversibly injured core and salvageable penumbra with favorable collateral circulation. Pre-morbid functional independence, typically defined as modified Rankin Scale zero to one, predicts patients most likely to benefit. Thrombectomy is performed in addition to rather than instead of IV thrombolysis when both are indicated, and patients should receive alteplase if eligible while arranging thrombectomy.

<image>Panel A: FAST stroke recognition algorithm with facial droop, arm drift, speech testing, and time emphasis for emergency activation. Panel B: Time targets displayed on timeline showing door-to-CT under 25 minutes, door-to-needle under 60 minutes, and treatment windows. Panel C: IV alteplase eligibility criteria with inclusion and exclusion factors and dosing protocol. Panel D: Mechanical thrombectomy indications showing large vessel occlusion patterns and perfusion imaging selection criteria.</image>

II. Hemorrhagic Stroke

Intracerebral hemorrhage results from rupture of blood vessels within brain parenchyma, causing direct tissue destruction and mass effect with prognosis generally worse than ischemic stroke of similar location. Hypertension represents the most common cause, producing hemorrhage in characteristic deep locations including basal ganglia, thalamus, pons, and cerebellum. Cerebral amyloid angiopathy causes lobar hemorrhage in elderly patients without hypertension, carrying risk of recurrence that may influence anticoagulation decisions. Other etiologies include underlying vascular malformations, coagulopathy from anticoagulation or thrombocytopenia, hemorrhagic conversion of ischemic stroke, tumor bleeding, and cocaine or amphetamine use. Presentation typically includes sudden onset headache, focal neurological deficits corresponding to hemorrhage location, and frequently decreased level of consciousness.

Intracerebral hemorrhage management focuses on preventing hematoma expansion, managing blood pressure, reversing coagulopathy when present, and addressing complications including increased intracranial pressure and hydrocephalus. Blood pressure reduction to systolic below 140 mmHg for patients presenting with systolic 150-220 mmHg appears safe and may reduce hematoma expansion, though overly aggressive reduction may compromise perfusion of at-risk brain tissue. Anticoagulation reversal is urgently indicated for patients on warfarin, with four-factor prothrombin complex concentrate preferred over fresh frozen plasma due to faster and more complete reversal, combined with vitamin K for sustained effect. Direct oral anticoagulant reversal uses idarucizumab for dabigatran and andexanet alfa for factor Xa inhibitors when available. Seizure prophylaxis is not routinely recommended but seizures when they occur require treatment.

Subarachnoid hemorrhage from aneurysm rupture classically presents with sudden severe headache often described as the worst headache of the patient's life, frequently with associated nausea, vomiting, neck stiffness, and photophobia. The thunderclap headache reaching maximum intensity within seconds to minutes demands evaluation for SAH regardless of other features, as misdiagnosis carries devastating consequences with rebleeding mortality exceeding forty percent. Syncope, altered mental status, and focal neurological deficits may accompany the headache depending on hemorrhage location and severity. The Hunt-Hess grading scale classifies severity from Grade I with mild headache to Grade V with comatose posturing, correlating with outcome and guiding management intensity.

Subarachnoid hemorrhage diagnosis requires CT imaging followed by lumbar puncture when CT is negative and clinical suspicion remains high. CT sensitivity exceeds ninety-five percent within six hours of symptom onset but declines thereafter as blood resorbs and becomes isodense. When CT is negative or equivocal, lumbar puncture demonstrating xanthochromia, the yellow discoloration from hemoglobin breakdown products, confirms the presence of blood that has been in the subarachnoid space long enough for breakdown to occur. Red blood cells in CSF without xanthochromia may represent traumatic tap requiring comparison of cell counts between sequential tubes. Once SAH is confirmed, CT angiography identifies the responsible aneurysm for treatment planning. Management includes emergent neurosurgical consultation, blood pressure control avoiding hypotension, nimodipine to reduce vasospasm, and definitive aneurysm treatment through surgical clipping or endovascular coiling.

<image>Panel A: Intracerebral hemorrhage etiologies and typical locations showing hypertensive deep hemorrhage and amyloid angiopathy lobar distribution. Panel B: ICH management priorities including blood pressure targets, anticoagulation reversal agents, and complication monitoring. Panel C: Subarachnoid hemorrhage thunderclap headache presentation with associated symptoms and Hunt-Hess grading scale. Panel D: SAH diagnostic algorithm showing CT sensitivity timeline, lumbar puncture indications, and xanthochromia interpretation.</image>

III. Altered Mental Status

Altered mental status encompasses the spectrum from mild confusion to deep coma, representing a final common pathway for numerous pathophysiologic processes requiring systematic evaluation to identify treatable causes. The differential diagnosis is usefully organized using the mnemonic AEIOU-TIPS: Alcohol, Epilepsy, Insulin (hypoglycemia), Opiates, Uremia, Trauma, Infection, Psychiatric, and Stroke/Space-occupying lesion. Metabolic causes including hypoglycemia, uremia, hepatic encephalopathy, electrolyte abnormalities, and endocrine emergencies represent reversible etiologies demanding rapid identification. Infectious causes ranging from urinary tract infection causing delirium in elderly patients to meningitis and encephalitis require appropriate antimicrobial therapy. Structural causes including stroke, hemorrhage, mass lesions, and hydrocephalus require imaging for diagnosis and often neurosurgical intervention.

Initial evaluation combines immediate stabilization with rapid diagnostic testing to identify reversible causes requiring urgent treatment. Point-of-care glucose measurement should occur within minutes of presentation, as hypoglycemia causes neuronal dysfunction and injury that progresses to irreversible damage without treatment. Pulse oximetry identifies hypoxia as a contributor to altered consciousness. Physical examination focuses on vital signs suggesting infection, intoxication, or autonomic instability; pupillary examination indicating structural lesion or toxidrome; motor response lateralization suggesting focal pathology; and signs of trauma that might indicate intracranial injury. Laboratory evaluation includes comprehensive metabolic panel for electrolyte and renal assessment, complete blood count for infection screening, and additional studies guided by clinical suspicion.

Coma assessment requires systematic evaluation of brainstem function to localize lesions and predict prognosis. The Glasgow Coma Scale provides standardized scoring of eye opening, verbal response, and motor response, with lower scores indicating more severe impairment. Pupillary responses to light test midbrain function, with unilateral dilation and fixation suggesting uncal herniation with third nerve compression while bilateral fixed pupils may indicate midbrain damage or severe metabolic derangement. Corneal reflexes test pontine function. Motor responses ranging from appropriate localization to stimulus through decorticate posturing to decerebrate posturing to flaccidity reflect progressively rostral to caudal brainstem involvement. Respiratory patterns including Cheyne-Stokes breathing suggesting bilateral hemispheric or diencephalic dysfunction and apneustic breathing indicating pontine pathology provide additional localizing information.

Empiric treatment addresses immediately reversible causes while evaluation proceeds. Dextrose fifty percent, fifty milliliters, corrects hypoglycemia when present or suspected in any patient with altered mental status in whom glucose cannot be rapidly measured. Thiamine one hundred milligrams should precede or accompany dextrose administration in patients with possible chronic alcohol use or malnutrition to prevent precipitation of Wernicke encephalopathy. Naloxone 0.4 to 2 mg reverses opioid-induced respiratory depression and coma, with rapid response supporting the diagnosis. Flumazenil is not routinely administered due to seizure risk in patients with benzodiazepine dependence or mixed ingestions. Empiric antibiotics and dexamethasone are indicated when bacterial meningitis is suspected, with treatment initiation taking priority over diagnostic confirmation.

<image>Panel A: Altered mental status differential using AEIOU-TIPS mnemonic with metabolic, infectious, toxic, and structural categories. Panel B: Initial evaluation priorities showing glucose measurement, oxygenation assessment, and focused examination elements. Panel C: Coma assessment including GCS components, brainstem reflex testing, and respiratory pattern interpretation. Panel D: Empiric treatment protocol showing dextrose, thiamine, naloxone indications and administration sequence.</image>

IV. Seizures and Status Epilepticus

Seizures result from abnormal synchronized neuronal electrical activity causing clinical manifestations ranging from brief altered awareness to generalized tonic-clonic convulsions, with most seizures self-terminating within one to two minutes. Status epilepticus is defined as seizure activity lasting longer than five minutes or two or more seizures without return to baseline consciousness between episodes, representing a medical emergency with progressive neuronal injury and increasing treatment resistance over time. Refractory status epilepticus describes ongoing seizure activity despite first and second-line anticonvulsant therapy, requiring aggressive intervention often including intubation and continuous infusion of anesthetic agents. Non-convulsive status epilepticus presents with altered mental status without obvious motor manifestations, requiring electroencephalography for diagnosis and occurring in a substantial proportion of patients with unexplained coma.

Initial management during active seizure focuses on patient safety and preparation for pharmacological intervention while most seizures self-terminate without treatment. Positioning to protect from injury, maintaining airway patency without forcing objects between teeth, and supplemental oxygen address immediate safety concerns. Intravenous access should be established if not already present, though intramuscular or intranasal medication administration provides alternatives when access is delayed. Point-of-care glucose measurement and treatment of hypoglycemia addresses a common and immediately reversible seizure cause. The five-minute threshold for status epilepticus represents the trigger for anticonvulsant administration, as seizures exceeding this duration rarely self-terminate and cause progressive neurological injury.

Status epilepticus treatment follows a staged protocol with escalation as seizure activity persists despite intervention. First-line treatment at zero to five minutes consists of benzodiazepines, with intramuscular midazolam ten milligrams or intravenous lorazepam four milligrams demonstrating equivalent efficacy. Benzodiazepine administration terminates status epilepticus in approximately sixty percent of cases. Second-line treatment at five to twenty minutes adds an anticonvulsant such as levetiracetam sixty milligrams per kilogram, fosphenytoin twenty milligrams per kilogram phenytoin equivalents, or valproate forty milligrams per kilogram, with selection based on patient factors and institutional preference. Third-line treatment for refractory status epilepticus at twenty minutes and beyond typically requires intubation for airway protection and anesthetic infusion with propofol, midazolam, or pentobarbital titrated to seizure suppression on continuous EEG monitoring.

Post-ictal care addresses immediate patient needs while evaluating for underlying etiology and preventing recurrence. The post-ictal state typically lasts thirty to sixty minutes but may extend longer after prolonged seizures or status epilepticus. New-onset seizure requires evaluation for underlying cause including metabolic derangement, infection, structural lesion, and toxic exposure, typically including neuroimaging and laboratory studies. Patients with known epilepsy experiencing breakthrough seizures need assessment of medication compliance, potential triggers, and therapeutic drug levels when applicable. Driving restrictions following seizure are mandated by state law with variable seizure-free periods required before resuming driving. Safety counseling addresses fall precautions and supervision recommendations during the period of ongoing seizure risk.

<image>Panel A: Seizure and status epilepticus definitions showing five-minute threshold and distinction between convulsive and non-convulsive presentations. Panel B: Initial seizure management addressing safety, positioning, airway, and glucose assessment during active seizure. Panel C: Status epilepticus protocol showing first-line benzodiazepines, second-line anticonvulsants, and third-line anesthetic infusions with timing. Panel D: Post-ictal evaluation including new-onset workup, breakthrough seizure assessment, and driving restriction counseling.</image>

V. Meningitis and Encephalitis

Bacterial meningitis presents with the classic triad of fever, neck stiffness, and altered mental status, though all three findings are present in fewer than half of patients, making clinical suspicion essential when any concerning features are present. Headache represents the most common symptom, present in approximately ninety percent of patients. Photophobia, nausea, vomiting, and focal neurological deficits may accompany the classic triad. Kernig sign demonstrating pain with knee extension when hip is flexed and Brudzinski sign showing involuntary hip flexion with passive neck flexion have limited sensitivity but high specificity when present. Petechial or purpuric rash suggests Neisseria meningitidis infection and indicates need for droplet isolation precautions.

Diagnostic evaluation must proceed rapidly without delaying antibiotic administration when meningitis is suspected. Blood cultures should be obtained prior to antibiotics when this can be accomplished quickly but should never delay treatment. Lumbar puncture provides definitive diagnosis through cerebrospinal fluid analysis, with bacterial meningitis typically showing elevated opening pressure, neutrophilic pleocytosis often exceeding one thousand cells, elevated protein, low glucose relative to serum, and positive gram stain or culture. CT imaging before lumbar puncture is indicated only for specific findings suggesting increased intracranial pressure risk: focal neurological deficits, papilledema, altered consciousness, immunocompromised state, or history of central nervous system disease. When CT is required, antibiotics should be administered immediately before imaging rather than waiting for CT completion.

Empiric antibiotic treatment covers the most likely pathogens based on patient age and risk factors while awaiting culture results. Standard adult empiric therapy combines ceftriaxone for coverage of Streptococcus pneumoniae and Neisseria meningitidis with vancomycin for resistant pneumococcal strains. Patients over fifty years old, immunocompromised patients, and those with alcoholism require addition of ampicillin for Listeria monocytogenes coverage. Dexamethasone 0.15 mg/kg administered before or with the first antibiotic dose reduces mortality and neurological sequelae in pneumococcal meningitis and should be continued only if pneumococcus is confirmed. Healthcare-associated meningitis from neurosurgical procedures or devices requires broader coverage including vancomycin plus cefepime or meropenem.

Encephalitis produces altered mental status, seizures, focal neurological deficits, and behavioral changes reflecting brain parenchymal involvement rather than purely meningeal inflammation. Herpes simplex virus encephalitis represents the most common and treatable cause, characteristically affecting temporal lobes and presenting with fever, altered consciousness, behavioral changes, seizures, and focal deficits. MRI demonstrates temporal lobe signal abnormality, while CSF shows lymphocytic pleocytosis and positive HSV PCR. Empiric acyclovir ten milligrams per kilogram intravenously every eight hours should be initiated immediately when encephalitis is suspected, as treatment delays worsen outcomes. Other causes include other viruses, autoimmune encephalitis increasingly recognized as an important etiology, and paraneoplastic syndromes requiring different treatment approaches.

<image>Panel A: Meningitis presentation showing classic triad sensitivity, associated symptoms, and physical examination signs including Kernig and Brudzinski. Panel B: Diagnostic approach emphasizing antibiotic timing, CT indications before LP, and CSF analysis interpretation. Panel C: Empiric antibiotic regimens by patient population with ceftriaxone, vancomycin, ampicillin, and dexamethasone indications. Panel D: Encephalitis recognition showing HSV temporal lobe predilection, MRI findings, CSF PCR, and empiric acyclovir treatment.</image>

VI. Severe Headache

Evaluation of severe headache in the emergency department requires identifying dangerous secondary causes that may present similarly to benign primary headache disorders but carry significant morbidity and mortality without appropriate treatment. Red flag features demanding thorough evaluation include thunderclap onset reaching maximum intensity within seconds, description as the worst headache of life, new headache after age fifty, headache associated with fever and neck stiffness, presence of focal neurological deficits, headache in the setting of altered mental status, papilledema on fundoscopic examination, and progressive worsening over days to weeks. The presence of any red flag feature mandates evaluation for secondary causes before attributing symptoms to primary headache disorder.

Subarachnoid hemorrhage workup is essential for thunderclap headache given the catastrophic consequences of missed diagnosis and high rebleeding mortality. Non-contrast CT head demonstrates SAH with sensitivity exceeding ninety-five percent within six hours of symptom onset, appearing as hyperdense signal in the basal cisterns, sylvian fissures, and cerebral sulci. When CT is negative but clinical suspicion remains high, lumbar puncture is required, performed at least six hours after headache onset to allow time for xanthochromia development from red blood cell breakdown. Xanthochromia, the yellow discoloration best detected by spectrophotometry, distinguishes true subarachnoid blood from traumatic tap. Once SAH is confirmed, CT angiography identifies the responsible aneurysm for treatment planning.

Other dangerous secondary headache causes require consideration based on clinical features and risk factors. Cerebral venous thrombosis presents with headache, often accompanied by seizures and focal deficits, in patients with thrombotic risk factors including oral contraceptive use, pregnancy, and hypercoagulable states; MR or CT venography establishes the diagnosis. Idiopathic intracranial hypertension causes chronic headache with papilledema and visual obscurations in typically obese young women, diagnosed by elevated opening pressure on lumbar puncture after excluding mass lesion. Giant cell arteritis affects patients over fifty with new headache, jaw claudication, scalp tenderness, and constitutional symptoms, requiring urgent corticosteroid treatment to prevent irreversible vision loss, with elevated ESR and CRP supporting the diagnosis and temporal artery biopsy providing confirmation. Cervical artery dissection presents with headache, neck pain, and potentially stroke symptoms, often following minor trauma or neck manipulation.

Primary headache disorders including migraine, cluster headache, and tension-type headache remain the most common causes of severe headache but should be diagnosed only after excluding dangerous secondary causes. Migraine treatment in the emergency department typically employs non-opioid analgesics with dopamine antagonists, with ketorolac and metoclopramide representing a common effective combination. Cluster headache responds dramatically to high-flow oxygen at twelve to fifteen liters per minute and subcutaneous sumatriptan. Tension-type headache generally responds to simple analgesics. The emergency department approach prioritizes ruling out dangerous causes before providing symptomatic treatment, with discharge only after appropriate evaluation and with clear return precautions for worsening symptoms or new concerning features.

<image>Panel A: Headache red flags including thunderclap onset, worst ever severity, age over fifty, fever, focal deficits, and papilledema requiring secondary cause evaluation. Panel B: Subarachnoid hemorrhage workup showing CT sensitivity timeline, lumbar puncture indication, and xanthochromia interpretation. Panel C: Other dangerous secondary headaches including cerebral venous thrombosis, idiopathic intracranial hypertension, giant cell arteritis, and cervical dissection. Panel D: Primary headache emergency treatment with migraine, cluster, and tension-type management approaches after excluding secondary causes.</image>

VII. Increased Intracranial Pressure

Increased intracranial pressure results from expansion of brain tissue, blood, or cerebrospinal fluid within the rigid cranial vault, with progressive pressure elevation causing herniation syndromes and death without intervention. Normal intracranial pressure ranges from five to fifteen millimeters of mercury in adults, with pressures exceeding twenty millimeters considered elevated and pressures above forty severely elevated. The Monro-Kellie doctrine states that because the cranial vault is fixed, expansion of any intracranial component must occur at the expense of others, with initial compensation through CSF displacement into the spinal subarachnoid space followed by venous blood displacement. Once compensatory mechanisms are exhausted, small additional volume increases cause dramatic pressure elevations.

Recognition of elevated intracranial pressure relies on clinical signs that may develop gradually with slow-growing masses or acutely with hemorrhage or acute obstruction. Cushing's triad consisting of hypertension, bradycardia, and irregular respirations represents a late finding indicating impending herniation and brainstem compression. Papilledema on fundoscopic examination reflects transmitted pressure but requires time to develop and may be absent in acute presentations. Progressive decline in level of consciousness reflects global cerebral dysfunction from elevated pressure. Pupillary changes, particularly unilateral dilation and loss of reactivity, indicate uncal herniation with third nerve compression. Decerebrate or decorticate posturing reflects progressive brainstem involvement.

Emergency management of elevated intracranial pressure aims to reduce pressure and prevent herniation while addressing the underlying cause. Head of bed elevation to thirty degrees promotes venous drainage without compromising arterial perfusion. Brief hyperventilation to PCO2 of thirty to thirty-five millimeters of mercury causes cerebral vasoconstriction reducing cerebral blood volume, but prolonged hyperventilation worsens ischemia and should be avoided except as temporizing measure during herniation. Osmotic therapy with mannitol one gram per kilogram or hypertonic saline twenty-three point four percent thirty milliliters draws water from brain parenchyma, reducing brain volume. Seizure control prevents increases in cerebral metabolic demand and blood flow. Corticosteroids reduce vasogenic edema around tumors and abscesses but are not indicated for stroke or trauma. Neurosurgical consultation for decompressive craniectomy or external ventricular drain placement addresses severe refractory elevation.

Herniation syndromes represent the final pathway of uncontrolled intracranial pressure elevation, with specific patterns reflecting the direction of brain tissue displacement. Uncal herniation from temporal lobe mass effect causes the medial temporal lobe to herniate through the tentorial incisura, compressing the ipsilateral third cranial nerve to produce a dilated, fixed pupil followed by contralateral hemiparesis from cerebral peduncle compression. Central herniation causes symmetric downward displacement through the tentorium, producing progressive rostral-to-caudal brainstem failure with bilateral pupillary involvement and posturing. Tonsillar herniation forces cerebellar tonsils through the foramen magnum, compressing the medulla and causing respiratory arrest. Subfalcine herniation displaces the cingulate gyrus under the falx cerebri, potentially compressing the anterior cerebral artery territory.

<image>Panel A: Intracranial pressure pathophysiology showing Monro-Kellie doctrine, compensatory mechanisms, and decompensation with volume increases. Panel B: ICP elevation recognition including Cushing's triad, papilledema, declining consciousness, and pupillary changes. Panel C: Emergency ICP management with head elevation, brief hyperventilation, osmotic therapy, and neurosurgical interventions. Panel D: Herniation syndromes depicting uncal, central, tonsillar, and subfalcine patterns with anatomic correlates.</image>

VIII. Spinal Cord Compression

Spinal cord compression represents a neurological emergency requiring rapid diagnosis and treatment to preserve neurological function, with outcomes directly related to pre-treatment neurological status and treatment timing. Compression may occur at any spinal level from mass effect, with the thoracic spine most commonly involved due to its length and relatively narrow spinal canal. The clinical presentation reflects the level and completeness of cord involvement, with back pain often preceding neurological deficits by days to weeks. Weakness below the lesion level, sensory loss with a distinct level on examination, and bowel or bladder dysfunction characterize the classic presentation. Reflexes may be initially diminished in acute compression before evolving to hyperreflexia with upper motor neuron pattern.

Etiologies of spinal cord compression include both malignant and non-malignant causes requiring different treatment approaches. Metastatic epidural spinal cord compression represents the most common cause in adults, occurring in five to ten percent of cancer patients, most frequently from lung, breast, and prostate primary tumors and multiple myeloma. Epidural abscess from hematogenous spread or direct extension causes cord compression with associated infection, occurring more frequently in patients with diabetes, intravenous drug use, or immunocompromise. Disk herniation, particularly at cervical and lumbar levels, may cause acute compression from large central herniations. Epidural hematoma from trauma, anticoagulation, or spontaneous bleeding creates rapidly progressive compression requiring emergent evacuation.

Diagnostic evaluation centers on MRI as the imaging modality of choice, providing superior soft tissue characterization of the cord, surrounding structures, and pathologic processes. Whole-spine MRI is often indicated as multiple levels may be involved, particularly in malignancy. When MRI is contraindicated or unavailable, CT myelography provides an alternative though with inferior soft tissue resolution. Laboratory evaluation for suspected epidural abscess includes complete blood count, inflammatory markers, and blood cultures. Contrast-enhanced imaging distinguishes abscess from tumor and demonstrates the enhancing rim characteristic of abscess walls.

Treatment depends on the underlying etiology but proceeds urgently given the relationship between pre-treatment function and outcomes. High-dose corticosteroids, typically dexamethasone ten milligrams initially followed by four milligrams every six hours, reduce vasogenic edema and may improve neurological function, indicated for malignant compression and considered for other etiologies. Surgical decompression through laminectomy or other approaches provides definitive treatment when tumor removal or abscess drainage is required. Radiation therapy treats radiosensitive tumors and may be used alone or following surgical stabilization. For epidural abscess, surgical drainage combined with prolonged intravenous antibiotics represents standard treatment, though selected cases may be managed with antibiotics alone under close observation. The prognosis for neurological recovery strongly correlates with pre-treatment ambulatory status.

<image>Panel A: Spinal cord compression presentation showing back pain progression, weakness patterns, sensory levels, and bowel/bladder involvement. Panel B: Etiology comparison of metastatic disease, epidural abscess, disc herniation, and epidural hematoma with patient populations. Panel C: MRI diagnostic approach with whole-spine imaging rationale and CT myelography alternative when MRI unavailable. Panel D: Treatment by etiology showing corticosteroids, surgical decompression, radiation, and antibiotic approaches with timing emphasis.</image>

IX. Neuromuscular Emergencies

Myasthenic crisis represents life-threatening respiratory failure or severe bulbar weakness in patients with myasthenia gravis, requiring intensive care for airway management and specific immunotherapy. Precipitants include infection representing the most common trigger, surgical stress, medication changes including initiation of drugs that exacerbate myasthenia, and inadequate or excessive cholinesterase inhibitor dosing. Respiratory muscle weakness manifests as shortness of breath, weak cough, and paradoxical breathing pattern, while bulbar weakness causes dysphagia, dysarthria, and difficulty handling secretions. Negative inspiratory force and forced vital capacity measurements guide intubation decisions, with NIF less negative than negative thirty centimeters of water or FVC below twenty milliliters per kilogram indicating need for airway protection.

Treatment of myasthenic crisis combines respiratory support with immunotherapy to reduce the pathogenic autoantibodies at the neuromuscular junction. Intravenous immunoglobulin at two grams per kilogram divided over five days or plasmapheresis removing circulating acetylcholine receptor antibodies provides rapid improvement within days. The choice between IVIG and plasmapheresis depends on patient factors including venous access, renal function, and institutional preference, with similar efficacy. Cholinesterase inhibitors are typically held during crisis to reduce secretions complicating airway management. Medications that exacerbate myasthenia must be avoided, including aminoglycosides, fluoroquinolones, beta-blockers, and magnesium. Long-term immunosuppression intensification follows crisis resolution.

Guillain-Barre syndrome is an acute inflammatory demyelinating polyneuropathy causing ascending weakness with areflexia, typically following antecedent infection by one to four weeks, most commonly Campylobacter jejuni gastroenteritis or respiratory viral infection. Weakness begins distally and ascends over days to weeks, potentially involving respiratory muscles in thirty percent of cases. Autonomic dysfunction causing blood pressure and heart rate instability accompanies motor weakness in severe cases. Cerebrospinal fluid analysis demonstrates albuminocytologic dissociation with elevated protein and normal cell count. Treatment with IVIG or plasmapheresis reduces severity and duration, with close monitoring for respiratory failure using serial NIF and FVC measurements to guide intubation timing.

Botulism causes descending paralysis beginning with cranial nerve involvement and progressing to respiratory failure through toxin-mediated blockade of acetylcholine release at the neuromuscular junction. Clinical forms include foodborne botulism from ingestion of preformed toxin typically in improperly canned foods, wound botulism from toxin production in infected wounds particularly in injection drug users, and infant botulism from intestinal colonization. Presentation includes dilated poorly reactive pupils distinguishing it from myasthenic crisis, cranial nerve palsies, and descending symmetric weakness. Treatment combines supportive care including mechanical ventilation for respiratory failure with botulinum antitoxin to neutralize circulating toxin. Public health notification is mandatory given the potential for outbreak and bioterrorism concerns.

<image>Panel A: Myasthenic crisis recognition showing respiratory and bulbar weakness, precipitants, and NIF/FVC thresholds for intubation. Panel B: Myasthenic crisis treatment comparing IVIG and plasmapheresis with medication avoidance list. Panel C: Guillain-Barre syndrome ascending weakness pattern, autonomic instability, CSF findings, and treatment with respiratory monitoring. Panel D: Botulism descending paralysis pattern, dilated pupils, clinical forms, and antitoxin treatment with public health notification.</image>

X. Peripheral Neurological Emergencies

Cauda equina syndrome results from compression of the nerve roots below the conus medullaris, typically at the L2 level and below, causing a constellation of lower extremity weakness, saddle anesthesia, and bowel and bladder dysfunction requiring emergent surgical decompression. The cauda equina contains nerve roots rather than spinal cord, making this a lower motor neuron syndrome with areflexia rather than the hyperreflexia of cord compression. Classic presentation includes bilateral leg pain and weakness, saddle distribution sensory loss, urinary retention with overflow incontinence, and decreased rectal tone. Causes include large central disc herniation, tumor, epidural abscess, and hematoma. Emergent MRI of the lumbar spine confirms the diagnosis, with surgical decompression within forty-eight hours optimizing outcomes though earlier intervention is preferred when possible.

Acute vision loss demands urgent evaluation to identify treatable causes and prevent permanent blindness. Central retinal artery occlusion causes sudden painless monocular vision loss with a pale retina and cherry-red macula on fundoscopy, representing an ophthalmic emergency with retinal survival limited to approximately ninety minutes without intervention. Immediate treatments attempted include ocular massage to dislodge emboli, anterior chamber paracentesis to reduce intraocular pressure, and in some centers intra-arterial thrombolysis, though evidence for these interventions remains limited. Giant cell arteritis causing anterior ischemic optic neuropathy may present with vision loss preceded by transient visual obscurations, jaw claudication, and temporal headache; high-dose corticosteroids must be initiated immediately upon clinical suspicion to prevent fellow eye involvement, with temporal artery biopsy providing confirmation. Acute angle-closure glaucoma presents with eye pain, halos around lights, and fixed mid-dilated pupil, requiring urgent intraocular pressure reduction.

Diplopia evaluation distinguishes monocular causes from binocular causes with different diagnostic and management implications. Monocular diplopia persisting with the unaffected eye covered suggests ocular pathology such as lens abnormality or corneal irregularity rather than neurological disease. Binocular diplopia resolving when either eye is covered indicates extraocular muscle imbalance from cranial nerve palsy or orbital process. Third nerve palsy with pupil involvement, producing a dilated unreactive pupil, demands urgent evaluation for posterior communicating artery aneurysm given the proximity of pupillomotor fibers to this common aneurysm location. Sixth nerve palsy is often non-localizing and may indicate elevated intracranial pressure. Painful ophthalmoplegia suggests cavernous sinus pathology or Tolosa-Hunt syndrome.

Bell's palsy causes acute unilateral facial weakness involving both upper and lower face, distinguishing it from central lesions such as stroke that spare the forehead due to bilateral upper motor neuron innervation. Patients are unable to close the eye, raise the eyebrow, or move the corner of the mouth on the affected side. Eye protection is essential to prevent exposure keratopathy from incomplete closure, using lubricating drops, ointment, and taping or patching at night. Treatment with corticosteroids, typically prednisone sixty to eighty milligrams daily for one week, improves recovery when initiated within seventy-two hours of symptom onset. The role of antiviral agents remains controversial, with most evidence suggesting they add little benefit to corticosteroids alone. Prognosis is generally favorable with most patients recovering completely within months.

<image>Panel A: Cauda equina syndrome presenting features with saddle anesthesia distribution, urinary retention, and rectal tone assessment leading to emergent MRI. Panel B: Acute vision loss causes comparing central retinal artery occlusion, giant cell arteritis, and acute glaucoma with urgency of each. Panel C: Diplopia evaluation distinguishing monocular from binocular causes and identifying pupil-involving third nerve palsy requiring aneurysm evaluation. Panel D: Bell's palsy recognition distinguishing from stroke, eye protection requirements, and corticosteroid treatment timing.</image>

Summary

• Acute ischemic stroke requires door-to-CT under 25 minutes and door-to-needle under 60 minutes, with IV alteplase available within 4.5 hours and thrombectomy extending to 24 hours for large vessel occlusion with favorable imaging
• Subarachnoid hemorrhage presents as thunderclap headache and requires CT followed by lumbar puncture if negative, with xanthochromia confirming diagnosis
• Status epilepticus treatment follows staged protocol: benzodiazepines first-line, then anticonvulsants (levetiracetam, fosphenytoin, or valproate), then anesthetic infusions for refractory cases
• Bacterial meningitis requires emergent antibiotics with ceftriaxone plus vancomycin plus dexamethasone, adding ampicillin for patients over fifty or immunocompromised
• Elevated intracranial pressure management includes head elevation, brief hyperventilation, and osmotic therapy with mannitol or hypertonic saline for herniation
• Herniation signs include Cushing's triad and unilateral dilated pupil indicating uncal herniation requiring emergent intervention
• Spinal cord compression requires emergent MRI with high-dose dexamethasone and surgical consultation for decompression
• Guillain-Barre syndrome causes ascending weakness with areflexia treated with IVIG or plasmapheresis, monitoring NIF and FVC for respiratory failure
• Cauda equina syndrome presents with saddle anesthesia and bladder dysfunction requiring emergent MRI and surgical decompression
• Third nerve palsy with pupil involvement requires urgent evaluation for posterior communicating artery aneurysm

Key Terms

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