NIH Stroke Scale Assessment: Scoring a Zero for CVA Signs

NIHSS scores guide critical stroke treatment decisions. For tPA thrombolytic therapy, scores of 5 or below indicate treatment benefits may not outweigh bleeding risks, while scores of 22+ suggest completed infarction with hemorrhage risk. Most facilities apply tPA for NIHSS 6-25 points. For mechanical thrombectomy, anterior circulation occlusion requires NIHSS ≥6 with ASPECTS ≥6, while posterior circulation requires NIHSS ≥10 with ASPECTS ≥6. NIHSS has limitations: floor effect (score 0 may miss significant MRI abnormalities), posterior circulation bias (underestimates vertigo/ataxia), and left hemisphere bias (language items favor left hemisphere strokes). These limitations should be considered in clinical decision-making.

NIHSS scores guide thrombolysis eligibility: scores of 4-25 indicate appropriate candidates (moderate severity), while scores below 4 or above 25 suggest poor prognosis. Very high NIHSS scores correlate with low ASPECT scores, indicating large affected areas where thrombolysis could worsen outcomes by causing hemorrhagic transformation. Exceptional cases may warrant discussion with patients/families about thrombolysis after full consent.

The NIHSS (National Institutes of Health Stroke Scale) is an internationally accepted 15-item neurological examination tool used to assess stroke severity in patients suspected of acute stroke, evaluating consciousness, language, neglect, sensation, visual fields, extraocular movements, motor strength, ataxia, and dysarthria; scores below 4 indicate patients are generally not suitable for thrombolytic treatment, while scores below 6 may indicate mild strokes insufficient for mechanical thrombectomy intervention.

The NIHSS (National Institutes of Health Stroke Scale) evaluates neurological deficits including consciousness, gaze, visual fields, facial paralysis, motor function, ataxia, sensation, and language to assess stroke severity; the ASPECTS (Alberta Stroke Program Early CT Score) uses CT imaging to evaluate early ischemic changes in the middle cerebral artery territory across 10 brain regions (caudate, internal capsule, lentiform nucleus, insula, and M1-M3 territories), with scores of 7 or above indicating candidacy for thrombolysis, while scores below 7 or evidence of hemorrhage contraindicate this treatment.

Stroke mimics range from 6-20% of cases. Hypoglycemia is easiest to identify and treat with finger stick. Hyperglycemia (DKA, HHS) causes metabolic encephalopathy. Complex migraines (25% have focal deficits) and hemiplegic migraines mimic MCA strokes. Demyelinating disorders (MS, PML) cause stroke-like symptoms. Seizures are most common mimic, with Todd's paralysis lasting 48 hours. Functional hemiparesis is a somatoform disorder diagnosed after excluding all other causes. Essential initial tests include finger stick blood sugar, electrolytes, EKG, troponin, PT/INR, and chest X-ray. NIH Stroke Scale assesses consciousness, visual/sensory-motor systems, speech, and neglect. Scores <4 indicate mild stroke (observation), >22 indicate severe stroke (poor prognosis). The 22 group is the 'money shot' for thrombolytic treatment.

Stroke mimics are conditions presenting with focal neurological deficits that are not acute ischemic stroke. The most common include seizures, sepsis, toxic metabolic situations (hypoglycemia, hyperglycemia), syncope, Bell's palsy, and conversion disorder. Key predictors distinguishing stroke from mimics include: past medical history (ischemic heart disease increases stroke probability, cognitive impairment suggests mimic); presentation features (exact time of onset with focal signs predicts stroke, while loss of consciousness, headache, seizure suggests mimic); vital signs (systolic BP >150, diastolic >90 predict stroke); and NIH Stroke Scale score (higher scores predict real stroke).

Emergency stroke assessment requires distinguishing true stroke from mimics: severe hypoglycemia (requires immediate glucose measurement), complex migraine, psychogenic crisis, hypertensive encephalopathy, and postictal states. NIHSS provides standardized assessment including level of consciousness, verbal responses, motor commands, gaze, visual fields, facial palsy, limb strength, ataxia, sensation, language, and dysarthria. NIHSS <4 indicates mild stroke, but treatment decisions should be individualized based on disability, age, and collateral flow. The scale enables consistent communication across healthcare providers for tracking changes over time.

Key stroke mimics include: hypoglycemia (always check blood sugar), seizures (especially postictal state), Bell's palsy (face weakness, more common in younger populations, difficult to differentiate from stroke), migraine (complex migraines with neurological symptoms can mimic stroke), and intoxication (drugs/alcohol causing slurred speech and gait disturbance). When in doubt, especially with older patients and risk factors, treat as stroke rather than attempting differentiation.

Stroke recognition requires activation of the stroke code (código ictus). Assessment includes motor function (hemiplegia/hemiparesis), speech (aphasia/dysarthria), and visual function. Up to 30% of suspected strokes are actually stroke mimics, including hypoglycemia (reversible with glucose), postictal paralysis, and migraine with aura. Hypoglycemia must always be ruled out as it can mimic stroke symptoms. The NIH Stroke Scale (NIHSS) quantifies severity by evaluating consciousness, gaze, visual fields, facial palsy, motor function, limb ataxia, sensory function, and language. NIHSS scores guide treatment decisions and prognosis assessment.

Stroke unit admission requires systematic assessment including time of symptom onset, nature of symptoms, evolution, current medications, and cardiac history. The NIH Stroke Scale (NIHSS) is a standardized tool scoring 0-42 points across 11 items evaluating consciousness, motor function, sensory function, visual function, language, and cognition. Scores of 1-4 indicate minor stroke, 5-15 indicate moderate stroke, and scores above 15 indicate severe stroke. The NIHSS is used to assess initial severity, determine thrombolytic eligibility, track neurological changes, and predict prognosis.

This comprehensive section covers ischemic stroke as the second leading cause of death globally and the leading cause of disability. Unlike myocardial infarction, stroke survivors often face lifelong functional dependence. The diagnosis is clinical, based on sudden neurological deficit associated with a vascular territory. The NIHSS (National Institutes of Health Stroke Scale) assesses: consciousness/alertness, verbal response, motor function, gaze, facial palsy, limb motor, ataxia, sensation, language, and extinction/neglect. It should be performed before neuroimaging and combined with symptom onset time and imaging to guide treatment decisions. Stroke diagnosis is clinical, not requiring neuroimaging to confirm the diagnosis. Neuroimaging (CT/MRI) differentiates ischemic from hemorrhagic stroke and guides treatment. Key data for stroke management: symptom onset time, NIHSS score, ASPECTS score, last known well time, arrival time, and thrombolysis time. The delta between arrival and thrombolysis should be <60 minutes for optimal outcomes. Stroke management requires ongoing assessment: NIHSS monitoring, blood pressure control (to prevent hemorrhagic transformation), heart rate control, and glucose management. Hyperglycemia is associated with worse outcomes and hemorrhagic transformation. The ASPECTS (Alberta Stroke Program Early CT Score) evaluates early ischemic changes on CT: caudate, lentiform nucleus, insula, and internal capsule. Score ranges from 0-10, with higher scores indicating better prognosis. ASPECTS ≥6 allows thrombolysis; ASPECTS <6 precludes thrombolysis. Stroke workup includes: CT/MRI brain, carotid/vertebral imaging, renal function, metabolic profile, TSH, CBC, HbA1c, lipid profile, B12, troponin, BNP, and echocardiography. For patients <50 years, add transesophageal echocardiography and autoimmune panel. TIA (Transient Ischemic Attack) is an ischemic event without permanent infarction but behaves clinically like stroke. TIA patients have the highest risk of stroke in the next 72 hours and should not be discharged. All TIA patients require the same workup and secondary prevention as stroke patients.

When assessing patients with repeated strokes, NIHSS scores should include all current neurological deficits, including residual symptoms from previous strokes. This provides a comprehensive picture of current functional status. The scale should be used in conjunction with neurological examination.

NIHSS scores guide critical treatment decisions including thrombolytic therapy and endovascular interventions. Lower scores indicate better candidates for thrombolytic treatment, most effective within 3-4.5 hours of symptom onset. NIHSS scores are used to plan rehabilitation services, determine appropriate care levels, and predict discharge needs. Higher scores indicate greater rehabilitation requirements and increased likelihood of requiring specialized rehabilitation facilities. NIHSS scores at admission predict functional outcomes and disability levels, with higher scores correlating with poorer outcomes. The scale is used in clinical trials to stratify patients and ensure balanced treatment groups. NIHSS scores are also used for stroke registry documentation, quality reporting, and tracking outcomes across different hospitals and regions.

The NIH Stroke Scale (NIHSS) is an international standard for assessing stroke severity, determining treatment eligibility, and predicting prognosis. Scores guide rehabilitation planning: scores around 10 indicate inpatient rehabilitation, while scores above 16 require transfer to rehabilitation centers. NIHSS scores should be monitored at 2 hours post-trombolysis and daily during hospitalization, with a 4-point change indicating deterioration. Training can be provided to physicians or nurses through demonstration and educational materials. The ROSIER score (Recognition of Stroke in Emergency Department) complements NIHSS by incorporating clinical history elements including syncope, seizures, facial asymmetry, arm weakness, language problems, and visual field deficits. CT scans have limited sensitivity (30%) for early ischemic stroke, and a normal CT does not rule out stroke. NIHSS has reduced sensitivity for posterior circulation strokes, requiring alternative assessment approaches.