Overview

The Recognition of Stroke in the Emergency Room (ROSIER) scale is a validated, bedside clinical instrument designed to assist emergency department clinicians in rapidly distinguishing patients with acute stroke from those presenting with stroke mimics. The scale integrates seven structured clinical items into a composite score ranging from -2 to +5, combining positively weighted focal neurological features with negatively weighted exclusionary criteria that flag presentations more consistent with non-stroke diagnoses. A score greater than zero indicates probable stroke and should trigger immediate activation of the acute stroke pathway.

The ROSIER scale occupies a critical position in the acute stroke care continuum, providing the first structured clinical filter between emergency triage and definitive imaging-based diagnosis. By equipping non-specialist emergency clinicians with an explicit, reproducible assessment algorithm, the scale enables more consistent stroke recognition, reduces inappropriate stroke pathway activations for mimic presentations, and accelerates time-sensitive interventions including intravenous thrombolysis and mechanical thrombectomy for eligible patients. Its incorporation into emergency department protocols internationally reflects its demonstrated utility in improving the sensitivity and specificity of stroke identification compared with unstructured clinical impression alone.

Background and Development

The ROSIER scale was developed by Nor and colleagues at the University of Edinburgh, with the landmark derivation and validation study published in Lancet Neurology in 2005. The investigators conducted a prospective cohort study enrolling consecutive patients referred to the emergency department with a suspected acute stroke, using consultant neurologist assessment as the diagnostic reference standard. A systematic pool of candidate clinical variables was evaluated for its ability to discriminate confirmed stroke diagnoses from stroke mimic diagnoses in the study cohort.

The final instrument was derived from multivariate logistic regression analysis identifying the variables with the strongest independent discriminatory contribution and the greatest clinical feasibility for bedside assessment. Two negatively scored exclusionary variables (loss of consciousness or syncope and seizure activity at onset) and five positively scored neurological deficit variables (facial weakness, arm weakness, leg weakness, speech disturbance, and visual field defect) were retained in the final scale, which achieved an area under the ROC curve of approximately 0.90, a sensitivity of 92%, and a specificity of 83% for stroke identification in the derivation cohort.

Subsequent prospective external validation studies in the United Kingdom, mainland Europe, China, and the United States replicated the scale's diagnostic performance across diverse emergency department populations, confirming its generalizability and supporting its incorporation into acute stroke clinical pathways internationally. The consistency of its performance metrics across settings with substantially different patient demographics, healthcare systems, and stroke prevalence rates established the ROSIER scale as the most widely adopted structured stroke recognition instrument for in-hospital emergency department use.

Clinical Problem: Stroke Mimics in the Emergency Department

A fundamental challenge in emergency stroke diagnosis is the high prevalence of non-stroke conditions that present with acute focal neurological symptoms clinically indistinguishable from ischemic or hemorrhagic stroke. These stroke mimics collectively account for 15 to 30% of all patients presenting to the emergency department with suspected stroke, and their accurate identification has important implications for both patient safety and resource utilization.

Misclassifying a stroke mimic as a true stroke exposes the patient to the risks of unnecessary neuroimaging with contrast agents or interventional procedures, inappropriate anticoagulation or thrombolysis with attendant hemorrhagic risk, and potentially delayed diagnosis of the actual underlying condition. Conversely, misclassifying a true stroke as a mimic results in delayed neuroimaging, failure to initiate time-sensitive reperfusion therapy within the treatment window, and progressive neurological injury from ongoing ischemia. The asymmetry of these consequences, with the cost of missing a true stroke generally exceeding the cost of over-investigating a mimic, informs the emphasis on high sensitivity in stroke recognition tools.

The ROSIER scale was specifically designed to navigate this diagnostic tension, achieving high sensitivity for true stroke while improving specificity relative to simpler tools through the inclusion of negatively weighted exclusionary criteria that target the most common and clinically distinctive stroke mimic presentations.

Prerequisite: Blood Glucose Assessment

Before the ROSIER scale is applied, blood glucose measurement is a mandatory clinical prerequisite. Hypoglycemia (blood glucose below 3.5 mmol/L, approximately 63 mg/dL) is one of the most clinically important and reversible stroke mimics, capable of producing focal neurological deficits including hemiparesis and aphasia that are completely indistinguishable from acute ischemic stroke on clinical examination. Administration of intravenous dextrose to a hypoglycemic patient may result in complete and immediate neurological recovery, confirming hypoglycemia as the etiology.

Applying the ROSIER scale before correcting hypoglycemia risks generating a high score that reflects hypoglycemia-induced focal deficits rather than true stroke, potentially initiating unnecessary stroke pathway investigations and treatments. If hypoglycemia is identified and corrected but focal deficits persist despite restoration of euglycemia, ROSIER assessment may then proceed, with persistent deficits potentially representing concurrent structural pathology in the context of the metabolic insult.

ROSIER Scale Components and Scoring Rules

The ROSIER scale contains seven items, each scored as present or absent based on the clinical assessment performed in the emergency department. Items are assessed based on the acute presentation rather than pre-existing baseline deficits; all scored features must represent new changes from the patient's established neurological baseline to be scored positively.

Exclusionary Items: Negatively Scored

The two exclusionary items in the ROSIER scale each subtract one point from the total, reflecting their strong association with stroke mimic diagnoses. Their inclusion is a defining feature that distinguishes the ROSIER scale from simpler prehospital tools such as FAST, which score only inclusionary features.

Item 1: Loss of Consciousness or Syncope at Onset

Loss of consciousness or syncope is scored as present (-1 point) if the patient experienced impaired or complete loss of consciousness as a prominent presenting feature at the time of symptom onset. This item specifically targets syncope-predominant presentations, in which transient cerebral hypoperfusion from vasovagal, orthostatic, or cardiogenic causes produces transient neurological symptoms that may be mistaken for transient ischemic attack or stroke by patients, witnesses, or first-responders.

It is important to note that the negatively weighted item applies when loss of consciousness is a prominent feature of the onset, not merely when brief altered awareness accompanies an obvious acute hemispheric event. True hemispheric strokes causing large-territory ischemia or intracranial hemorrhage can produce impaired consciousness due to mass effect or elevated intracranial pressure, but in these cases the prominent focal neurological deficits, headache, or systemic features of the stroke syndrome dominate the presentation. Clinical judgment regarding the qualitative nature of the loss of consciousness is therefore important in applying this item accurately.

Item 2: Seizure Activity at Onset

Seizure activity is scored as present (-1 point) if there is a reliable history of seizure activity at the time of symptom onset or if active seizure activity is observed at presentation. This item specifically targets post-ictal neurological deficits (Todd paresis), which represent one of the most clinically significant and commonly encountered stroke mimics in the emergency department.

Todd paresis produces focal motor weakness or aphasia following a partial or generalized seizure, persisting for minutes to hours after ictal activity has ceased, due to post-ictal neuronal exhaustion in the affected cortical territory. The deficit is functionally indistinguishable from acute stroke weakness on clinical examination and will produce positive scores in the arm weakness, leg weakness, and facial weakness domains of the ROSIER scale. The seizure exclusionary item is the specific mechanism by which the ROSIER scale captures this mimic, reducing the total score to a level below the positive threshold in most cases of pure Todd paresis. A history of prior epilepsy, a witnessed convulsive event immediately preceding the weakness, and gradual improvement over the minutes to hours following presentation all support Todd paresis over acute stroke.

Inclusionary Items: Positively Scored

The five inclusionary items each add one point to the total score when present, reflecting the well-established focal neurological deficits that characterize the major stroke syndromes affecting anterior and posterior cerebral circulation territories. Each item must represent a new deficit, not explained by prior neurological disease or baseline disability.

Item 3: Asymmetric Facial Weakness

Facial weakness is scored as present (+1 point) when there is new, asymmetric weakness affecting the muscles of facial expression. Upper motor neuron facial weakness, which is the pattern produced by hemispheric or corticobulbar tract lesions, characteristically spares the upper face (forehead wrinkling and eye closure are preserved or only mildly reduced) while producing significant contralateral lower facial weakness with flattening of the nasolabial fold, drooping of the corner of the mouth, and inability to show the teeth symmetrically on the affected side.

Assessment requires specific examination of facial symmetry at rest and during voluntary facial movements. The examiner should ask the patient to smile, show their teeth, and raise their eyebrows, observing for asymmetry at each movement. Subtle facial weakness may be more apparent during emotional or spontaneous facial expression than during voluntary movement, and careful observation during conversation may reveal asymmetry not apparent on formal examination. Pre-existing facial asymmetry from prior stroke, Bell's palsy, or facial nerve injury must be distinguished from new acute weakness by comparison with prior photographs or collateral history from familiar contacts if available.

Item 4: Asymmetric Arm Weakness

Arm weakness is scored as present (+1 point) when there is new asymmetric weakness of one or both upper extremities. The standard clinical assessment is the pronator drift test: the patient holds both arms outstretched at shoulder height with palms facing upward and eyes closed for a minimum of ten seconds. Pronation and downward drift of one arm indicates pyramidal tract weakness on that side, as the subtle deficit in pronator inhibition causes gradual pronation even when the patient does not perceive weakness. More severe weakness may produce immediate limb drop, inability to maintain the outstretched position, or visible drift without the ten-second observation period.

The pronator drift test is particularly valuable because it can detect mild or moderate weakness not apparent in gross power testing and can be performed rapidly at the bedside with no equipment. Comparing the amplitude and symmetry of drift between the two arms is more informative than testing each arm in isolation, as subtle bilateral weakness may not be detected without contralateral comparison. In patients who cannot follow commands for the standard drift test due to altered consciousness or receptive aphasia, informal resistance testing against gravity or observation of spontaneous arm use during examination may provide substitute information.

Item 5: Asymmetric Leg Weakness

Leg weakness is scored as present (+1 point) when there is new asymmetric weakness of one or both lower extremities. The standard assessment involves having the supine patient elevate each leg to 30 degrees above the horizontal and maintain that position against gravity for a minimum of five to ten seconds. The examiner observes for inability to achieve the required elevation, progressive sinking toward the bed, or clear asymmetry in the ability to maintain the position between the two legs.

In patients who can stand, a brief observation of standing and gait is an additional high-yield assessment: hemispheric stroke producing corticospinal tract weakness creates a characteristic contralateral lower extremity circumduction gait pattern, and unsteadiness or leg dragging that is asymmetric and acute provides confirmatory evidence for leg weakness even when formal supine testing is inconclusive. Cerebellar or brainstem strokes may produce gait ataxia without clear limb weakness, which would not score positively on this item but would likely contribute to other items (speech, visual field, or arm weakness).

Item 6: Speech Disturbance

Speech disturbance is scored as present (+1 point) when there is new impairment of speech production, speech comprehension, or speech intelligibility not attributable to pre-existing conditions. This item encompasses two clinically distinct categories of speech pathology that may occur individually or in combination:

• Aphasia: Impairment of language function due to cortical or subcortical language network dysfunction. Expressive aphasia (Broca's) manifests as non-fluent, halting speech with word-finding difficulty, reduced phrase length, and effortful production, with relatively preserved comprehension. Receptive aphasia (Wernicke's) manifests as fluent but paraphasic speech with impaired comprehension and reduced insight into errors. Global aphasia combines severely impaired production and comprehension. Transcortical and conduction aphasia subtypes produce intermediate patterns.
• Dysarthria: Impaired articulation of speech sounds due to weakness, incoordination, or spasticity of the bulbar muscles (lips, tongue, palate, larynx) involved in speech production. Dysarthric speech retains correct word choice and grammatical structure but is slurred, indistinct, nasal, or monotone. It may result from corticobulbar tract lesions in hemispheric stroke, brainstem lesions directly affecting motor nuclei, or cerebellar lesions producing ataxic dysarthria with scanning, irregular cadence.

Assessment requires a direct speech sample: asking the patient to describe a simple scene, repeat a test phrase, or produce a short narrative. Comprehension testing through simple commands or yes/no questions identifies receptive aphasia. Pre-existing conditions including post-stroke aphasia, developmental speech disorders, or dementia-related language impairment must be identified from collateral history and excluded from the new deficit assessment.

Item 7: Visual Field Defect

Visual field defect is scored as present (+1 point) when there is new homonymous hemianopia or quadrantanopia, or other new visual field loss detected on confrontation testing. Homonymous visual field loss reflects damage to the contralateral visual cortex (posterior cerebral artery territory occipital lobe infarction), the optic radiations (deep temporal or parietal lobe lesions), or the lateral geniculate body, and is a characteristic feature of posterior circulation and posterior cortical strokes.

Confrontation visual field testing is performed by asking the patient to fixate on the examiner's nose while the examiner moves a finger or hand into the peripheral visual fields sequentially in each quadrant. Each eye is tested separately (with the contralateral eye gently covered). The patient is asked to indicate when they first see the stimulus entering from the periphery. Inattention hemianopia (neglect of contralesional stimuli when bilateral simultaneous stimuli are presented, with preserved detection when stimuli are unilateral) should also be tested, as this is a manifestation of parietal cortical lesions that may be missed with standard single-stimulus confrontation testing.

Visual field defects may be subtle and easily missed if confrontation testing is performed hastily or without bilateral simultaneous stimulus testing. Patients with posterior circulation strokes may not recognize their own hemianopic defect, providing no spontaneous complaint that would prompt visual field assessment in the absence of systematic examination.

Score Calculation and Interpretation

The ROSIER total score is calculated by summing all applicable item scores. The minimum possible score is -2 (both exclusionary items present, no inclusionary items present) and the maximum possible score is +5 (no exclusionary items, all five inclusionary items present).

ROSIER Item	Score if Present
Loss of consciousness or syncope at onset	-1
Seizure activity at onset	-1
Asymmetric facial weakness (new)	+1
Asymmetric arm weakness (new)	+1
Asymmetric leg weakness (new)	+1
Speech disturbance (new)	+1
Visual field defect (new)	+1
Total Score Range	-2 to +5

Total ROSIER Score	Interpretation	Recommended Action
+1 to +5	Stroke likely	Activate acute stroke pathway immediately; priority neuroimaging (non-contrast CT brain); stroke team or neurology notification; assess eligibility for thrombolysis and thrombectomy
0	Stroke possible but mimic more likely	Consider alternative diagnoses actively; further workup guided by clinical context; neuroimaging and neurology review appropriate if clinical suspicion remains
-1 to -2	Stroke unlikely; stroke mimic highly probable	Investigate for seizure disorder (Todd paresis), syncope, metabolic, or other non-stroke etiology; neuroimaging may still be appropriate depending on clinical context but is not emergent for stroke indication

Diagnostic Performance Across Validation Studies

The ROSIER scale has been prospectively validated in multiple independent cohorts internationally. Its diagnostic performance metrics are consistently strong, with sensitivity values prioritized over specificity in recognition of the asymmetric clinical consequences of missed stroke versus over-investigated mimic.

In the original Nor et al. 2005 derivation and validation study (n = 343):

• Sensitivity for stroke: 92% (95% CI: 89 to 95%)
• Specificity for stroke: 83% (95% CI: 77 to 89%)
• Positive predictive value (PPV): 90%
• Negative predictive value (NPV): 88%
• Area under the ROC curve: Approximately 0.90

External validation studies in Chinese emergency department populations (Nor et al. 2009; Perry et al. 2011; multiple other Asian cohorts) confirmed sensitivity in the range of 87 to 94% and specificity of 76 to 88%, with the variation attributable to differences in case mix, stroke prevalence in the study population, and clinician training level.

A systematic review and meta-analysis of ROSIER validation studies confirmed pooled sensitivity of approximately 89% (95% CI: 85 to 93%) and pooled specificity of approximately 83% (95% CI: 77 to 88%), establishing it as the best-performing structured stroke recognition instrument validated for emergency department use among non-specialist clinicians. Comparative studies against FAST (Face Arm Speech Test) demonstrate that the ROSIER scale offers meaningful improvements in specificity (approximately 10 to 15 percentage points higher) while maintaining comparable sensitivity, reflecting the added value of the two negatively scored exclusionary items in reducing mimic misclassification.

Common Stroke Mimics Identified by the ROSIER Scale

The ROSIER scale's negatively scored exclusionary items are specifically targeted at the most frequently encountered and clinically impactful stroke mimics. A broader understanding of the full spectrum of mimic diagnoses encountered in clinical practice contextualizes the scale's use.

Todd Paresis (Post-Ictal Paralysis)

Todd paresis is the most clinically challenging and consequential stroke mimic, producing focal motor deficits that may last from minutes to 24 to 48 hours following a partial or secondarily generalized seizure. The deficit is indistinguishable from stroke hemiparesis on clinical examination and produces positive ROSIER scores across the arm and leg weakness and sometimes facial weakness domains. The seizure activity exclusionary item (-1 point) is the primary mechanism by which the ROSIER scale identifies this mimic. Clinical features favoring Todd paresis include a known epilepsy history, a witnessed convulsive event preceding the deficit, progressive resolution over hours, absence of cortical signs (aphasia, hemianopia) disproportionate to the motor deficit, and normal or non-acute findings on early neuroimaging.

Hypoglycemia

Severe or prolonged hypoglycemia can produce focal neurological deficits mimicking stroke with striking fidelity, including hemiparesis, aphasia, and impaired consciousness. The mandatory requirement for blood glucose measurement before ROSIER score application specifically addresses this mimic. Rapid resolution of deficits with glucose administration confirms hypoglycemia as the primary etiology, though it is important to recognize that concurrent cerebrovascular disease may be unmasked or precipitated by hypoglycemic episodes, and persistent deficits despite euglycemia require neuroimaging.

Syncopal and Cardiovascular Presentations

Vasovagal syncope, carotid sinus hypersensitivity, orthostatic hypotension, and cardiac arrhythmia-induced syncope may produce transient neurological symptoms including brief limb weakness, visual disturbance, or speech difficulty attributable to generalized cerebral hypoperfusion. The loss of consciousness exclusionary item (-1 point) specifically targets these presentations, where syncope rather than focal cerebrovascular pathology is the primary mechanism. Systematic cardiovascular evaluation including orthostatic blood pressure measurements, cardiac monitoring, and echocardiography is appropriate in patients with prominent syncope as a presenting feature.

Complicated Migraine

Hemiplegic migraine (producing motor aura), aphasic migraine, and migraine with prolonged visual or sensory aura can produce focal neurological deficits persisting for minutes to hours that fulfill ROSIER inclusionary criteria. The ROSIER scale does not contain a migraine exclusionary item, meaning that complicated migraine presentations may produce positive scores despite representing a non-stroke etiology. Clinical features favoring migraine include a personal or family history of hemiplegic migraine, gradual sequential spread of the aura over 20 to 60 minutes (versus the typically sudden onset of stroke symptoms), prominent accompanying headache, age below 45 without vascular risk factors, and prior identical episodes with full resolution. Neuroimaging is necessary to exclude concurrent ischemic or hemorrhagic stroke in first-presentation complicated migraine.

Functional Neurological Symptom Disorder

Functional neurological presentations (historically termed hysterical or conversion disorder) including functional weakness, functional speech disturbance (non-organic dysphonia or aphonia), and non-epileptic attacks may produce symptoms that score positively on ROSIER inclusionary items without structural neurological pathology. Positive signs on examination suggesting functional etiology include Hoover sign (involuntary hip extension on the affected side when the patient extends the unaffected hip against resistance, confirming efferent motor pathway integrity), give-way or collapsing weakness that cannot be maintained against minimal resistance despite absence of true pyramidal tract signs, and inconsistency of deficit severity between distracted and direct examination. Neuroimaging is necessary to exclude structural disease, and neuropsychiatric evaluation is ultimately required for diagnosis.

Space-Occupying Lesions

Intracranial tumors (primary and metastatic), cerebral abscesses, and subdural hematomas may produce subacute or acute focal neurological deficits generating high ROSIER scores. These conditions require neuroimaging for identification and are appropriately captured within the stroke pathway activation that a positive ROSIER score initiates, as non-contrast CT brain performed for stroke assessment will identify these mass lesions, ensuring appropriate management regardless of whether the underlying pathology is cerebrovascular or structural.

Toxic and Metabolic Encephalopathies

Hyponatremia, hyperglycemic hyperosmolar states, hepatic encephalopathy, Wernicke's encephalopathy, and acute drug or alcohol toxicity can produce focal or global neurological dysfunction generating ROSIER item scores. These diagnoses are generally identified by targeted laboratory investigations and clinical history, and the mandatory glucose check before ROSIER application represents the minimum metabolic screening required before score interpretation. Comprehensive metabolic assessment should accompany neuroimaging in patients where clinical features suggest a toxic or metabolic contribution.

Comparison with Related Stroke Recognition Tools

The ROSIER scale occupies a specific niche within the broader ecosystem of stroke recognition instruments, designed for use by trained emergency clinicians in the hospital setting, in contrast to simpler tools designed for prehospital use by paramedics or the lay public.

FAST (Face Arm Speech Test)

FAST is a three-item prehospital tool (facial droop, arm weakness, speech disturbance) designed for use by ambulance crew and members of the public. Its extraordinary simplicity enables reliable application without medical training but results in sensitivity of approximately 72 to 85% and specificity of only 44 to 65% in emergency department populations. FAST lacks the exclusionary items that give the ROSIER scale its superior specificity and does not assess visual field defects or leg weakness. FAST is an appropriate first-line triage tool in the prehospital setting but is insufficient for emergency department-level clinical decision-making.

Cincinnati Prehospital Stroke Scale (CPSS)

Structurally identical to FAST, the CPSS scores facial droop, arm drift, and abnormal speech and was validated in the United States prehospital setting. Like FAST, it prioritizes simplicity and sensitivity for prehospital application and is not designed for in-hospital clinical assessment.

Los Angeles Prehospital Stroke Screen (LAPSS)

The LAPSS incorporates glucose measurement, age above 45 years, seizure exclusion, baseline ambulatory status, and three physical examination items (facial asymmetry, grip weakness, arm weakness). Its inclusion of seizure as an exclusionary criterion and the mandatory glucose assessment share conceptual elements with the ROSIER scale but within a prehospital checklist rather than a numeric scoring framework. LAPSS sensitivity of approximately 80 to 91% and specificity of 86 to 97% reflect its more restrictive application criteria and intended use in paramedic rather than physician assessment.

National Institutes of Health Stroke Scale (NIHSS)

The NIHSS is a 15-item neurological severity scoring instrument used after stroke diagnosis has been established to quantify impairment severity, guide treatment eligibility decisions (particularly for thrombolysis and thrombectomy), communicate neurological status between clinicians, and track recovery. It requires formal training for reliable administration and is not a diagnostic discrimination tool. The ROSIER scale and the NIHSS serve fundamentally different and sequential clinical purposes, with ROSIER enabling the diagnosis and NIHSS quantifying severity after the diagnosis is established.

Integration into the Acute Stroke Care Pathway

The ROSIER scale achieves maximum clinical impact when embedded within a clearly defined, multidisciplinary acute stroke care pathway that specifies the actions triggered at each score tier and the responsible clinical roles at each step.

Step 1: Pre-Assessment Triage

Emergency department triage nurses or paramedics applying FAST or similar prehospital tools identify patients with potential stroke and assign them to a priority assessment category. Immediate notification to the emergency physician and (in services with direct prehospital notification protocols) the stroke team is initiated. Basic vital signs, intravenous access, and capillary blood glucose are obtained immediately upon arrival.

Step 2: Blood Glucose Check and Correction

Capillary blood glucose is assessed before ROSIER scoring is initiated. If glucose is below 3.5 mmol/L (63 mg/dL), intravenous dextrose is administered and neurological assessment is deferred for 10 to 15 minutes to allow metabolic correction. If deficits persist after correction of hypoglycemia, ROSIER assessment proceeds. If deficits resolve completely, hypoglycemic stroke mimic is established and further stroke pathway activation is deferred pending clinical reassessment.

Step 3: ROSIER Assessment

The structured seven-item ROSIER clinical assessment is performed by the emergency physician or attending clinical team, ideally within 15 minutes of patient arrival. All seven items are assessed and documented explicitly, and the total score is calculated. Collateral history from accompanying relatives, carers, or paramedics regarding symptom onset, seizure activity, syncope, or pre-existing neurological baseline is obtained concurrently.

Step 4: Score-Directed Pathway Activation

A ROSIER score of +1 or above triggers immediate stroke pathway activation with priority access to neuroimaging, stroke team or on-call neurology notification, and preparation for potential thrombolysis or thrombectomy within the treatment window. A score of 0 prompts active alternative diagnosis consideration with clinical judgment governing the urgency and nature of further investigation. A score of -1 or below directs investigation toward seizure, syncope, or other non-stroke etiologies, with neuroimaging governed by clinical rather than stroke-specific indications.

Step 5: Neuroimaging

Non-contrast CT brain is the standard first-line imaging modality for all patients with positive ROSIER scores, enabling immediate exclusion of intracranial hemorrhage (which precludes thrombolysis), identification of established large-territory infarcts, and assessment of space-occupying lesions. CT angiography of the cervicocranial vessels is performed in centers with endovascular thrombectomy capability for all eligible patients (within the thrombectomy time window with appropriate clinical severity) to identify large vessel occlusions treatable by mechanical intervention. CT perfusion or MRI-DWI perfusion imaging provides additional assessment of ischemic penumbra in patients presenting beyond the standard thrombolysis window or in equivocal cases. MRI-DWI is the most sensitive modality for early ischemic change and is particularly valuable for posterior fossa infarcts that may not be visible on CT.

Step 6: Reperfusion Therapy Assessment

Concurrent with neuroimaging, eligibility for intravenous thrombolysis with alteplase (within 4.5 hours of known symptom onset) and mechanical thrombectomy (within 6 to 24 hours for selected large vessel occlusion patients per extended window criteria) is systematically assessed using institutional protocols. Blood pressure, anticoagulant medication history, bleeding risk factors, and baseline NIHSS score are key determinants of thrombolysis eligibility. Large vessel occlusion on CTA and appropriate penumbra imaging findings determine thrombectomy candidacy.

Limitations and Clinical Caveats

Posterior Circulation Stroke

The five ROSIER inclusionary items predominantly capture the motor, speech, and visual deficits characteristic of anterior circulation (carotid territory) ischemic stroke. Posterior circulation strokes affecting the vertebrobasilar territory frequently present with symptoms that are entirely absent from the ROSIER inclusionary items: vertigo, nausea and vomiting, dysphagia, diplopia, ataxia and gait instability, hiccoughs, Horner syndrome, and isolated facial numbness. A patient with a large brainstem infarct presenting with isolated severe vertigo, vomiting, and truncal ataxia may score 0 on the ROSIER scale despite having a life-threatening posterior circulation stroke. Clinical vigilance for posterior circulation presentations must never be replaced by a low or zero ROSIER score.

Transient Ischemic Attack

Transient ischemic attack (TIA) represents a neurological emergency with a very high short-term stroke risk (approximately 10 to 15% within 90 days, with the greatest risk in the first 48 hours) and requires the same urgency of assessment and management as completed stroke. Patients with TIA who have completely recovered neurological function by the time of ROSIER assessment may score 0 or below on the scale simply because no acute deficit is detectable, falsely suggesting low stroke probability. The ROSIER scale must never be applied to exclude TIA when the history clearly describes a transient focal neurological episode consistent with TIA, regardless of the current examination findings.

Patients with Pre-existing Neurological Deficits

The ROSIER scale requires assessment of new deficits from baseline. In patients with prior stroke, demyelinating disease, spinal cord injury, or other conditions producing baseline focal neurological deficits, accurate distinction of new from chronic deficits depends on collateral history from caregivers, family members, or prior medical records. In the absence of reliable baseline information, any deficit must be conservatively treated as potentially new, which may result in overestimation of the ROSIER score. When baseline uncertainty exists, a lower threshold for neuroimaging should be applied to supplement clinical scoring.

Patients with Reduced Consciousness or Cooperation

Accurate ROSIER scoring of the pronator drift test, visual field confrontation, and speech assessment requires a minimum level of patient cooperation and wakefulness. Patients with significantly impaired consciousness (GCS below 12 to 13), severe agitation, or profound receptive aphasia precluding instruction comprehension may not be assessable across all seven items. In these patients, partial scoring based on observable items and qualitative clinical impression must supplement the formal instrument, acknowledging that the formal score may underestimate disease severity when key items cannot be assessed.

Language and Communication Barriers

The speech disturbance item requires assessment of language production and comprehension in the patient's primary language. Clinicians assessing patients who do not share a common language must use professional interpreter services to assess whether speech abnormalities represent true aphasia or dysarthria versus language barrier effects. Scoring the speech item in the absence of adequate language assessment may produce both false positives (interpreter-unassisted apparent aphasia in a fully fluent speaker of a different language) and false negatives (missed aphasia in a patient assessed in a non-primary language).

Quality Improvement Applications

Systematic documentation of ROSIER scores in electronic medical records supports multiple quality improvement and audit functions. Retrospective correlation of recorded ROSIER scores with final confirmed diagnoses enables calculation of institutional sensitivity, specificity, and predictive values, identifying whether the scale is being applied consistently with its validation performance in the local patient population. Systematic under-performance (for example, a higher rate of missed posterior circulation strokes than expected from published validation data) can direct targeted educational interventions emphasizing the ROSIER scale's limitations for posterior circulation assessment.

Time-stamp documentation of the ROSIER score together with the time of blood glucose measurement, neuroimaging initiation, and treatment administration enables time-interval analysis across the entire acute stroke care pathway, identifying bottlenecks and delays for quality improvement initiatives. National audit programs in the United Kingdom (Sentinel Stroke National Audit Programme, SSNAP) and equivalent programs internationally increasingly incorporate structured colposcopic assessment documentation requirements, including standardized stroke recognition tool documentation, as quality metrics for accredited stroke center certification.

Key Clinical Takeaways

• The ROSIER scale is a seven-item validated clinical instrument for distinguishing stroke from stroke mimics in the emergency department, with a total score range of -2 to +5 and a positive threshold of greater than zero for probable stroke.
• Blood glucose must be checked and hypoglycemia corrected before the scale is applied; focal deficits resolving with glucose administration confirm hypoglycemia as the etiology without need for stroke pathway activation.
• Two exclusionary items (loss of consciousness or syncope, and seizure activity at onset) subtract one point each, specifically targeting syncope-predominant presentations and Todd paresis as the most consequential stroke mimics encountered in clinical practice.
• Five inclusionary items (facial weakness, arm weakness, leg weakness, speech disturbance, visual field defect) each add one point when present as new deficits from baseline.
• The scale achieves approximately 92% sensitivity and 83% specificity for stroke in prospective validation cohorts, with consistent replication across international validation studies.
• Posterior circulation strokes, TIA with resolved deficits, and atypical stroke presentations may score zero or below despite representing genuine stroke; clinical judgment must always complement the scale in these scenarios.
• A ROSIER score of +1 or above should trigger immediate stroke pathway activation including priority neuroimaging and stroke team notification; a score of -1 or below should redirect investigation toward non-stroke etiologies while not categorically excluding neuroimaging if clinical concern persists.
• The scale is not validated for pediatric use and requires careful baseline comparison in patients with pre-existing focal neurological deficits from prior stroke or other neurological disease.