Stroke Mimics: Evaluation and Management
Starting IV alteplase is probably recommended in preference over delaying treatment to pursue additional diagnostic studies in suspected stroke cases, even when stroke mimics are a consideration, because the risk of symptomatic intracranial hemorrhage in stroke mimics is quite low 1.
The Clinical Reality
Stroke mimics represent approximately 19% of suspected stroke presentations (range 1-64%), with higher rates in prehospital settings (27%) compared to patients who receive thrombolysis (10%) 2. In hospitalized patients specifically, about half of all in-hospital stroke alerts are ultimately stroke mimics 3.
Most Common Stroke Mimics
The most frequently encountered stroke mimics differ by setting:
In-hospital patients 3:
- Toxic-metabolic encephalopathy (most common at 30%)
- Sedative medications (particularly opioids and benzodiazepines)
- Seizures (19.5%)
- Syncope
- Sepsis
Emergency department patients 4, 2:
- Seizures and postictal paralysis
- Migraines
- Psychiatric/functional disorders
- Peripheral vestibulopathy
- Hypertensive crises
Key Clinical Differentiators
Features MORE likely to indicate a stroke mimic 5, 6, 7:
- Younger age (consistently associated across studies)
- Female sex
- Lower NIHSS scores (particularly ≤5)
- Altered mental status as the SOLE symptom without focal deficits 3
- Lower vascular risk burden (less atrial fibrillation, hypertension, diabetes)
- Presentation beyond the therapeutic window
Features MORE likely to indicate true stroke:
- Older age
- Higher NIHSS scores (moderate-to-severe deficits)
- Multiple vascular risk factors
- Objective, focal neurologic deficit in a specific vascular distribution
- Presentation within therapeutic window
Critical Pitfall in Hospitalized Patients
Beware of diagnostic delays in hospitalized patients 3. Common errors include:
- Attributing postprocedural dysarthria to anesthetic agents
- Presuming postoperative weakness is from local pain
- Waiting to see if deficits resolve spontaneously
The median time from symptom recognition to neuroimaging is 4.5 hours for in-hospital stroke versus 1.2 hours in the ED—an unacceptable delay 3.
Evaluation Algorithm
Assume stroke until proven otherwise for any sudden-onset, objective, focal neurologic deficit 4
Obtain head CT noncontrast immediately as first-line imaging 4
Consider MRI with diffusion-weighted imaging when available—it is the most sensitive and specific modality 4, 8
Do NOT delay thrombolysis to pursue additional diagnostic studies if stroke is suspected 1
Obtain neurology consultation in the majority of cases 4
The Thrombolysis Decision
The guideline is clear: the risk of symptomatic intracranial hemorrhage in stroke mimics is quite low (Class IIa recommendation) 1. This is supported by real-world data showing that hemorrhagic transformation and in-hospital mortality occurred only in MRI-confirmed stroke patients, not in stroke mimics 6.
Among stroke mimics who received thrombolysis 5:
- Most had standard contraindications (being beyond therapeutic window, very mild symptoms)
- Only 1.76% were actual candidates who declined treatment
- The treatment appears safe in this population 6, 9
Stroke mimics who receive thrombolysis have favorable outcomes 6:
- Shorter hospital length of stay
- Higher rates of discharge home (86% vs 55%)
- No hemorrhagic complications
Specific Considerations for Functional Stroke Mimics
Functional neurological disorders are increasingly diagnosed but remain challenging 9. These patients require:
- Open, clear communication about their condition
- Psychoeducation
- Physiotherapy
- Long-term follow-up
However, do not withhold thrombolysis based on suspicion of functional symptoms alone—the potential benefit in true stroke outweighs the low risk in mimics 1.
The 2CAN Score for In-Hospital Stroke Risk
For hospitalized patients, the 2CAN score helps predict stroke likelihood 3:
- Clinical deficit score ≥2: 3 points
- Clinical deficit score 1: 1 point
- Recent cardiac procedure: 1 point
- History of atrial fibrillation: 1 point
- New patient (<24 hours from admission): 1 point
Score ≥2 has 92% sensitivity and 70% specificity for stroke.
Bottom Line for Clinical Practice
When facing diagnostic uncertainty in the acute setting, err on the side of treating with thrombolysis 1. The evidence strongly supports that delaying treatment to rule out mimics causes more harm than administering alteplase to a stroke mimic. The safety profile in mimics is excellent, while the consequences of withholding treatment from a true stroke patient are devastating for mortality and morbidity.