Neurological Disorders

Learning Objectives

• Differentiate ischemic from hemorrhagic stroke by mechanism, presentation, and imaging findings
• Apply the FAST criteria and NIHSS concept to recognize acute stroke and trigger a time-critical workup
• State the eligibility window and major contraindications for IV thrombolysis and mechanical thrombectomy
• Classify seizures (focal vs generalized) and distinguish a seizure from epilepsy
• Compare the first-line antiepileptic drugs used for focal versus generalized seizures
• Distinguish migraine, tension-type headache, and cluster headache using their clinical fingerprints
• Recognize red-flag headache features that mandate urgent neuroimaging

Quick Answer

Neurological emergencies in general medicine center on three high-yield areas: stroke (sudden focal neurologic deficit from vascular occlusion or bleed), seizures/epilepsy (transient abnormal electrical discharges causing motor, sensory, or consciousness changes), and headache disorders (primary, like migraine and tension headache, versus secondary headaches with dangerous underlying causes). These matter because stroke and status epilepticus are time-critical — "time is brain" — and missing a secondary headache red flag can mean missing a subarachnoid hemorrhage or mass lesion. Exams test rapid pattern recognition: distinguishing stroke subtypes on CT, seizure classification, and headache "red flags" that separate benign migraine from a neurosurgical emergency.

Stroke

What it is and why it matters

A stroke is a sudden interruption of blood supply to the brain causing focal neurological deficit lasting more than 24 hours (or with imaging evidence of infarction). It's a leading cause of death and long-term disability worldwide, and unlike many neurological diseases, a large fraction of the damage is preventable if treatment starts within hours.

Ischemic stroke (about 85% of strokes)

Caused by a thrombus or embolus occluding a cerebral artery, cutting off oxygen and glucose to brain tissue. Common mechanisms:

• Large-artery atherosclerosis — plaque rupture or in-situ thrombosis, often carotid or intracranial
• Cardioembolism — atrial fibrillation is the classic source; look for irregularly irregular pulse
• Small-vessel (lacunar) disease — chronic hypertension damages penetrating arterioles, producing pure motor or pure sensory lacunar syndromes
• Cryptogenic — no cause found despite workup

Hemorrhagic stroke (about 15% of strokes)

Bleeding into brain parenchyma (intracerebral hemorrhage) or the subarachnoid space (subarachnoid hemorrhage, classically from a ruptured berry aneurysm). Chronic hypertension is the leading cause of intracerebral hemorrhage; sudden "worst headache of my life" points to subarachnoid hemorrhage.

Clinical recognition — FAST

• Face drooping
• Arm weakness
• Speech difficulty
• Time to call emergency services

Other clues depend on the vascular territory: MCA stroke gives contralateral face/arm-predominant weakness plus aphasia (if dominant hemisphere) or neglect (if non-dominant); ACA stroke gives leg-predominant weakness; posterior circulation stroke gives vertigo, diplopia, ataxia, or crossed signs.

Why the CT scan comes before anything else

You cannot tell ischemic from hemorrhagic stroke by symptoms alone — both can look identical clinically. A non-contrast CT head is done immediately because thrombolytics given to a hemorrhagic stroke patient would be catastrophic. This single imaging decision is the fork in the entire management pathway.

Treatment

Ischemic: IV thrombolysis (alteplase or tenecteplase) within 4.5 hours of clearly known symptom onset if no contraindication (e.g., active bleeding, recent surgery, uncontrolled hypertension, anticoagulation with high INR). Mechanical thrombectomy extends the window to roughly 24 hours in selected large-vessel-occlusion patients confirmed on CT/MR perfusion imaging. Long-term: antiplatelets, statin, blood pressure control, and treating the cause (anticoagulation for atrial fibrillation, carotid endarterectomy for significant carotid stenosis).

Hemorrhagic: aggressive blood pressure control, reversal of any anticoagulant, and neurosurgical evaluation for evacuation or aneurysm clipping/coiling if subarachnoid hemorrhage.

Seizures and Epilepsy

Definitions that examiners love to test

A seizure is a single transient episode of abnormal, excessive, synchronous neuronal electrical activity. Epilepsy is a disease defined by a tendency toward recurrent, unprovoked seizures — practically, two unprovoked seizures more than 24 hours apart (or one seizure plus a high recurrence risk, e.g., an epileptogenic lesion on MRI).

Classification

• Focal (partial) seizures — start in one hemisphere. Focal aware (previously "simple partial," consciousness preserved) versus focal impaired awareness (previously "complex partial"). Can secondarily generalize.
• Generalized seizures — involve both hemispheres from onset, with loss of consciousness. Subtypes: tonic-clonic (classic convulsion), absence (brief blank staring, common in children), myoclonic, atonic, tonic.

Why it matters clinically

Correct classification drives drug choice. Treating a generalized epilepsy with a drug that can worsen absence or myoclonic seizures (e.g., carbamazepine can exacerbate absence seizures) is a classic exam trap.

Seizure type	First-line drug
Focal seizures	Carbamazepine or lamotrigine
Generalized tonic-clonic	Valproate (avoid in women of childbearing age — teratogenic) or lamotrigine
Absence seizures	Ethosuximide or valproate
Status epilepticus (acute)	IV lorazepam/diazepam first, then IV phenytoin/fosphenytoin or valproate

Status epilepticus — a seizure lasting more than 5 minutes, or recurrent seizures without recovery of consciousness in between — is a medical emergency because ongoing seizure activity causes neuronal injury; treat it like you'd treat any airway-breathing-circulation emergency, with benzodiazepines as first-line.

Headache Disorders

Primary versus secondary

Primary headaches (migraine, tension-type, cluster) are the disease itself, with no underlying structural cause. Secondary headaches are a symptom of something else — hemorrhage, meningitis, tumor, venous thrombosis — and are the ones you must not miss.

The big three primary headaches

• Tension-type headache — bilateral, band-like, pressing quality, mild-to-moderate intensity, not worsened by routine physical activity. The most common headache type overall.
• Migraine — unilateral, pulsatile/throbbing, moderate-to-severe, aggravated by activity, associated with nausea/vomiting and photophobia/phonophobia; may be preceded by an aura (visual scintillations, sensory changes).
• Cluster headache — severe unilateral periorbital pain in bouts ("clusters") lasting weeks, with ipsilateral autonomic features (lacrimation, ptosis, miosis, nasal congestion); far more common in men; patients are restless/agitated during attacks (unlike migraine, where patients want to lie still in a dark room).

Red flags demanding urgent imaging ("SNOOP")

• Systemic symptoms (fever, weight loss, malignancy history)
• Neurologic deficit or altered consciousness
• Onset that is sudden/thunderclap ("worst headache of my life")
• Older age at onset (>50 years, new headache)
• Pattern change from the patient's usual headache, or papilledema

A thunderclap headache is subarachnoid hemorrhage until proven otherwise — non-contrast CT head, followed by lumbar puncture (looking for xanthochromia) if CT is negative but suspicion remains high.

Treatment snapshot

• Tension headache: NSAIDs/paracetamol; amitriptyline for prevention if frequent
• Migraine: NSAIDs/triptans for acute attacks; propranolol, topiramate, or amitriptyline for prevention
• Cluster headache: high-flow 100% oxygen and subcutaneous sumatriptan for acute attacks; verapamil for prevention

Key Terms

Term	Definition
FAST	Face, Arm, Speech, Time — public screening tool for recognizing stroke
Thrombolysis	Drug-induced dissolution of a clot (e.g., alteplase) to restore blood flow in ischemic stroke
Thrombectomy	Mechanical retrieval of a clot from a large cerebral vessel via catheter
Lacunar stroke	Small-vessel infarct in the deep brain structures caused by chronic hypertension
Aura	Reversible focal neurological symptom preceding or accompanying a migraine, usually visual
Status epilepticus	A seizure lasting over 5 minutes or recurrent seizures without return to baseline consciousness
Xanthochromia	Yellow discoloration of CSF from breakdown of red blood cells, confirming subarachnoid hemorrhage
Papilledema	Optic disc swelling from raised intracranial pressure, a red-flag exam finding in headache

Common Mistakes

Misconception: "All strokes should get thrombolysis immediately." Why it's wrong: Thrombolytics dissolve clots — giving them to a patient with a hemorrhagic stroke would worsen the bleeding and can be fatal. Correct: A non-contrast CT head must confirm the stroke is ischemic (not hemorrhagic) before any thrombolytic is given, and the patient must also fall within the eligibility window and have no contraindications.

Misconception: "A single seizure means the patient has epilepsy." Why it's wrong: Epilepsy requires a demonstrated tendency toward recurrence, not just one event — many single seizures are provoked (fever, hypoglycemia, alcohol withdrawal, drug toxicity) and never recur. Correct: Epilepsy is diagnosed after two unprovoked seizures more than 24 hours apart, or one unprovoked seizure with a clearly elevated recurrence risk (e.g., an epileptogenic brain lesion).

Misconception: "A severe headache is probably just a bad migraine." Why it's wrong: This assumption misses secondary causes; a sudden, maximal-at-onset ("thunderclap") headache or a new headache after age 50 can signal subarachnoid hemorrhage, meningitis, or a mass lesion, all of which need urgent workup rather than reassurance. Correct: Screen every headache for red flags (sudden onset, neurological deficit, fever, age >50, pattern change) before assuming a benign primary cause.

Comparison and Connections

Feature	Ischemic stroke	Hemorrhagic stroke
Cause	Vessel occlusion (thrombus/embolus)	Vessel rupture (hypertension, aneurysm)
Onset	Sudden, may fluctuate/stepwise	Sudden, often with severe headache
CT finding	May be normal early, later hypodense area	Hyperdense (bright) blood immediately
Key early treatment	Thrombolysis/thrombectomy	BP control, reverse anticoagulation, neurosurgery
% of strokes	~85%	~15%

Feature	Migraine	Tension-type headache	Cluster headache
Laterality	Usually unilateral	Bilateral	Strictly unilateral, periorbital
Quality	Pulsatile/throbbing	Pressing/band-like	Severe, boring/stabbing
Associated features	Nausea, photophobia, aura	None significant	Ipsilateral autonomic signs (tearing, ptosis)
Patient behavior	Wants to lie still, dark room	Continues activity	Restless, agitated, paces
Sex predominance	Female	Roughly equal	Male

Practice Questions

Recall 1: What are the four components of the FAST stroke screening tool? Answer guidance: Face drooping, Arm weakness, Speech difficulty, Time to call for help.

Recall 2: What is the time window for IV thrombolysis in acute ischemic stroke? Answer guidance: Within 4.5 hours of clearly established symptom onset, absent contraindications.

Understanding 1: Why must a CT scan be performed before giving thrombolytics in suspected stroke? Answer guidance: Ischemic and hemorrhagic strokes can present identically on clinical exam; thrombolytics would worsen a hemorrhagic stroke, so imaging must first rule out bleeding.

Understanding 2: Why can carbamazepine make some generalized epilepsies worse? Answer guidance: Carbamazepine is effective for focal seizures but can exacerbate absence and myoclonic seizures, so drug choice must match seizure classification, not just "an antiepileptic."

Application 1: A 68-year-old man develops sudden right facial droop, arm weakness, and slurred speech 90 minutes ago. CT head shows no bleed. What is the next step? Answer guidance: He is within the thrombolysis window with no hemorrhage seen — check for contraindications, then give IV thrombolysis (alteplase/tenecteplase); assess for large-vessel occlusion for possible thrombectomy.

Application 2: A 22-year-old woman has recurrent unilateral throbbing headaches with nausea and light sensitivity, relieved by lying in a dark room. What is the diagnosis and first-line acute treatment? Answer guidance: Migraine; acute treatment is NSAIDs or a triptan, with preventive therapy considered if attacks are frequent.

Analysis 1: A patient presents with the "worst headache of my life," sudden onset, and a normal neurological exam. The CT head is negative. What should be done next and why? Answer guidance: Perform a lumbar puncture looking for xanthochromia, because early subarachnoid hemorrhage can be missed on CT (sensitivity drops after the first 6-24 hours), and thunderclap headache is SAH until proven otherwise.

Analysis 2: Compare the management priorities in the first hour for a confirmed ischemic stroke versus a confirmed intracerebral hemorrhage. Answer guidance: Ischemic stroke prioritizes rapid reperfusion (thrombolysis/thrombectomy) within tight time windows; hemorrhagic stroke prioritizes stopping the bleed from worsening — aggressive blood pressure control, reversing any anticoagulation, and urgent neurosurgical evaluation, with no role for clot-dissolving drugs.

FAQ

Is "time is brain" just a slogan, or is it literally true? It's literal — during an ischemic stroke, an estimated 1.9 million neurons die every minute blood flow is not restored, which is why treatment delay directly correlates with worse functional outcomes.

Can a seizure occur without epilepsy? Yes. Provoked seizures from fever (febrile seizures in children), hypoglycemia, alcohol withdrawal, or drug toxicity do not count as epilepsy unless there's an ongoing unprovoked tendency to seize.

Why is atrial fibrillation such an important stroke risk factor? In AF, blood stagnates in the fibrillating atria (especially the left atrial appendage), promoting clot formation; a fragment can embolize to the brain, causing a cardioembolic stroke — this is why AF patients are risk-stratified (e.g., CHA2DS2-VASc score) for anticoagulation.

Why does cluster headache respond to oxygen when migraine doesn't? The exact mechanism isn't fully settled, but high-flow oxygen is thought to cause cranial vasoconstriction and modulate the trigeminal-autonomic reflex specifically implicated in cluster headache; it is not an effective migraine treatment.

Is a normal CT scan enough to rule out subarachnoid hemorrhage? Not always — CT sensitivity for SAH is very high in the first 6 hours but declines afterward, so a lumbar puncture for xanthochromia is still recommended if the CT is negative but clinical suspicion remains high.

Quick Revision

• Ischemic stroke (~85%) = vessel blockage; hemorrhagic stroke (~15%) = vessel rupture — CT distinguishes them, not symptoms
• FAST = Face, Arm, Speech, Time — public stroke recognition tool
• IV thrombolysis window: 4.5 hours from symptom onset; thrombectomy window: up to ~24 hours for large-vessel occlusion
• Never give thrombolytics without first excluding hemorrhage on CT
• Atrial fibrillation is a major cardioembolic stroke risk factor
• Epilepsy = tendency to recurrent unprovoked seizures (typically 2+ episodes >24h apart), not a single seizure
• Focal seizures start in one hemisphere; generalized seizures involve both from onset with loss of consciousness
• Avoid carbamazepine in absence/myoclonic seizures — it can worsen them; valproate/ethosuximide are preferred for absence seizures
• Status epilepticus (seizure >5 min) is an emergency: benzodiazepines first-line
• Migraine = unilateral, throbbing, photophobia, wants to lie still; cluster = unilateral periorbital, autonomic signs, restless; tension = bilateral, band-like
• Thunderclap headache = subarachnoid hemorrhage until proven otherwise — CT then LP for xanthochromia if CT negative
• SNOOP red flags mandate imaging: Systemic signs, Neuro deficit, Onset sudden, Onset after 50, Pattern change

Related Topics

Prerequisites: Basic neuroanatomy (cerebral vascular territories, cranial nerves), general physical and neurological examination technique

Related: Cardiology (atrial fibrillation and embolic risk), Radiology (CT/MRI interpretation of brain lesions), Pharmacology (antiepileptic drugs, thrombolytics, antiplatelets)

Next: Neuromuscular and movement disorders (Parkinson's disease, multiple sclerosis), Neurosurgery (aneurysm management, intracranial hemorrhage evacuation), Emergency Medicine (approach to altered mental status and coma)