Differential Diagnosis for Resolved Left-Sided Weakness and Facial Drop
This presentation represents a transient ischemic attack (TIA) or minor stroke until proven otherwise, and the patient requires immediate emergency department evaluation with urgent neuroimaging within 24 hours, regardless of symptom resolution. 1, 2
Critical Clinical Context
Do not be falsely reassured by symptom resolution—patients with transient unilateral weakness are at highest risk for completed stroke, with peak danger in the first 48 hours. 1, 2 The resolution of symptoms does not eliminate stroke risk and may indicate a TIA, which is a medical emergency requiring the same urgency as an active stroke. 1, 3
Primary Differential Diagnoses
Highest Priority: Cerebrovascular Events
Transient Ischemic Attack (TIA): Most likely diagnosis given complete symptom resolution with unilateral weakness and facial droop—this is a very high-risk presentation demanding immediate stroke workup. 1, 2
Minor Ischemic Stroke with Early Recovery: Small infarct with rapid clinical improvement, but still requires full acute stroke evaluation and secondary prevention. 1, 4
Posterior Circulation Stroke: If any vertigo or ataxia accompanied the weakness, consider posterior circulation involvement which carries particularly high recurrent stroke risk. 2
Secondary Differential Considerations
Central Facial Palsy from Frontal Lobe Lesion: Ischemic stroke affecting the frontal lobe can present with isolated facial weakness that may initially mimic peripheral facial palsy, requiring detailed neurological examination to distinguish. 5
Pontine Infarction: Unusual "uncrossed paralysis" pattern where pontine lesions above the facial nucleus can cause contralateral face and body weakness, potentially confusing the clinical picture. 6
Blunt Cerebrovascular Injury (BCVI): If any history of recent neck trauma exists, consider delayed stroke from carotid dissection, which may have negative initial imaging but progress to infarction. 7
Hemiplegic Migraine: Can mimic stroke with unilateral weakness and facial symptoms, but this is a diagnosis of exclusion only after imaging rules out stroke. 1, 3
Todd's Paralysis: Post-ictal weakness following unwitnessed seizure, but requires exclusion of stroke first. 8
Hypoglycemia: Can present with focal neurological deficits, though typically resolves immediately with glucose correction. 8, 3
Immediate Management Algorithm
Step 1: Emergency Department Transfer (Within Minutes)
Transfer immediately to an ED with advanced stroke capabilities including on-site CT/MRI, vascular imaging, and access to thrombolysis/endovascular therapy. 1, 2 Do not delay transfer for any outpatient testing. 1
Step 2: Rapid Clinical Assessment (Within 15 Minutes of ED Arrival)
- Airway, breathing, circulation assessment 8
- Neurological examination using standardized stroke scale (NIHSS or Canadian Neurological Scale) to document any residual deficits and establish baseline. 8
- Vital signs including heart rate/rhythm, blood pressure, temperature, oxygen saturation 8
- Blood glucose measurement immediately to exclude hypoglycemia as a stroke mimic. 8, 3
- Time of symptom onset and resolution must be precisely documented. 3, 4
Step 3: Urgent Neuroimaging (Within 24 Hours, Ideally Immediately)
Brain CT or MRI without delay to differentiate ischemic from hemorrhagic stroke and exclude other pathology. 1, 2 Even with resolved symptoms, imaging is mandatory to identify infarction. 7
Noninvasive vascular imaging (CTA or MRA from aortic arch to vertex) should be performed within 24 hours to identify carotid stenosis requiring possible revascularization. 1, 2 Do not perform extracranial imaging alone—intracranial pathology may be missed. 1
Step 4: Essential Laboratory Investigations
Order immediately but do not delay imaging while awaiting results: 8, 1
- Complete blood count, electrolytes, coagulation studies (INR, aPTT) 8, 1
- Creatinine and estimated glomerular filtration rate 8, 1
- Random glucose or capillary glucose 1, 3
- Troponin 8, 1
- Lipid profile and hemoglobin A1c for subsequent risk stratification 1
Step 5: Cardiac Evaluation
12-lead ECG without delay to assess for atrial fibrillation and other cardioembolic sources. 8, 1, 2 This should not delay imaging decisions. 8
Continuous cardiac monitoring for detection of paroxysmal atrial fibrillation. 3
Echocardiogram as part of comprehensive stroke workup, though not emergently. 4
Critical Pitfalls to Avoid
Never assume resolved symptoms mean low risk—TIA patients have up to 20% risk of completed stroke within 90 days, with highest risk in first 48 hours. 1, 2
Do not discharge from ED without complete diagnostic evaluation, secondary prevention initiation, and follow-up plan. 8
Do not delay imaging or transfer while awaiting laboratory results—neurons over nephrons principle applies. 8, 1
Do not assume isolated facial weakness is peripheral facial palsy (Bell's palsy)—detailed neurological examination is essential to identify subtle central signs. 5
Do not overlook need for comprehensive vascular imaging from aortic arch to vertex—extracranial imaging alone misses intracranial pathology. 1
ECG and chest X-ray should not be performed before imaging unless patient is hemodynamically unstable—these can be deferred until after acute treatment decisions. 8
Risk Stratification for Ongoing Management
This patient falls into the VERY HIGH RISK category (unilateral weakness within 48 hours of presentation), requiring: 1, 2
- Immediate ED evaluation with advanced stroke capabilities
- Urgent neuroimaging and vascular imaging within 24 hours
- Admission for observation and secondary prevention initiation
- Comprehensive stroke workup including prolonged cardiac monitoring
- Early neurology or stroke specialist consultation