Ischemic Stroke, TIA, Hemorrhagic Stroke, and Mimics

Subtype thinking without delay

Acute focal neurologic symptoms are treated as stroke until the team proves otherwise, yet the mechanism changes risk and management. Roughly 87% of strokes are ischemic and about 13% are hemorrhagic (intracerebral or subarachnoid). Ischemic stroke, transient ischemic attack (TIA), intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), and mimics can all begin with sudden weakness, speech change, vision change, or confusion. The SCRN skill is to act quickly while collecting the details that steer imaging, treatment eligibility, monitoring, and family teaching.

Mechanisms and bedside clues

Ischemia, core, and penumbra

In ischemic stroke, blocked flow deprives tissue of oxygen and glucose. Energy failure halts the ATP-dependent ion pumps, the cell depolarizes, and glutamate floods the extracellular space; calcium pours in, triggering the ischemic cascade of excitotoxicity, oxidative stress, inflammation, and apoptosis. The infarct core (severely hypoperfused tissue) dies within minutes, but the surrounding penumbra is hypoperfused yet still viable and potentially salvageable if circulation is restored in time.

Collateral circulation explains why two patients with similar occlusions can look different on first assessment.

Ischemic subtypes

Ischemic strokes are commonly grouped as thrombotic (in-situ clot on atherosclerotic plaque, often large-artery or carotid), embolic (clot traveling from the heart or proximal vessel, classically from atrial fibrillation, which accounts for roughly 10-12% of ischemic strokes), and lacunar (small-vessel occlusion of a deep penetrator from chronic hypertension or diabetes).

TIA is not benign: a patient whose aphasia resolved in the ambulance may have a high short-term recurrence risk, especially with carotid stenosis, atrial fibrillation, or crescendo events. SCRN questions often punish answers that discharge the patient simply because symptoms disappeared. The historical "24-hour" definition of TIA is outdated; the modern tissue-based definition is a transient neurologic episode caused by focal ischemia without infarction on imaging, and many such patients have small infarcts and are reclassified as stroke.

Either way the urgency is identical: rapid risk stratification, vascular imaging, cardiac rhythm assessment for atrial fibrillation, and prompt antiplatelet or anticoagulation per the team.

Nurses also distinguish the clinical course of each mechanism. Embolic strokes often begin abruptly and maximally because a clot lodges all at once, sometimes with a history of palpitations or known atrial fibrillation. Thrombotic strokes may stutter or progress in a stepwise way as a clot grows on a plaque, occasionally preceded by TIAs in the same territory. Lacunar strokes produce small, deep, stereotyped syndromes (pure motor, pure sensory, ataxic hemiparesis) on a background of chronic hypertension or diabetes.

Recognizing the tempo helps the nurse describe the event accurately and anticipate whether the deficit may still be worsening.

Hemorrhage mechanisms and priorities

Intracerebral hemorrhage most often results from chronic hypertension causing degeneration of small penetrating arteries, lipohyalinosis, and rupture of Charcot-Bouchard microaneurysms, classically in deep nonlobar sites (basal ganglia, thalamus, pons, cerebellum). Subarachnoid hemorrhage is usually rupture of a saccular (berry) aneurysm into the subarachnoid space. Both hemorrhage types shift attention toward hematoma expansion, intracranial pressure, hydrocephalus, vasospasm risk (SAH), airway protection, and reversal of anticoagulant effect when ordered.

New vomiting, worsening headache, pupillary change, the Cushing pattern of bradycardia with hypertension, or decreasing arousal must never be treated as routine post-stroke fatigue and require urgent escalation.

The blood-pressure strategy diverges sharply by subtype, and this is a frequent exam point. In acute ischemic stroke that is not a thrombolysis candidate, permissive hypertension is generally tolerated and pressure is treated only when extreme (commonly above 220/120 mm Hg) to preserve penumbral perfusion. In ICH, guidelines favor controlled lowering toward a systolic goal in the 140 range (avoiding precipitous drops) to limit hematoma expansion. Aneurysmal SAH care adds vasospasm surveillance and nimodipine to reduce delayed cerebral ischemia.

The nurse who knows which bucket the patient is in can anticipate orders and flag dangerous deviations rather than treating every elevated pressure the same way.

Mimics: assess, do not dismiss

Mimics are common enough to test, but "mimic" is never permission to delay. A bedside glucose rapidly identifies hypoglycemia, a fully reversible cause. A witnessed seizure may explain Todd paresis, yet seizure can also occur at stroke onset. Migraine aura usually evolves over minutes with positive visual symptoms, but a first or atypical presentation still needs evaluation.

A strong SCRN answer usually combines three moves: maintain airway-breathing-circulation, verify glucose and last-known-well, and communicate the exact syndrome for imaging and team decisions. Routine teaching, oral intake, ambulation, or discharge planning comes later. The most useful early details are concrete: exact onset, symptom evolution, current medications, anticoagulant or antiplatelet exposure, recent surgery or bleeding, seizure activity, infection clues, and baseline disability.