In a diabetic hypertensive woman with right‑sided facial weakness involving the forehead, how can I distinguish Bell’s palsy from an acute ischemic stroke?

Distinguishing Bell's Palsy from Acute Ischemic Stroke in a Diabetic Hypertensive Woman with Right-Sided Facial Weakness

In a diabetic hypertensive woman with right-sided facial weakness involving the forehead, the critical distinguishing feature is the presence or absence of additional neurologic deficits—Bell's palsy presents as isolated facial weakness with rapid onset over <72 hours, whereas stroke typically presents with sudden onset and accompanying symptoms such as limb weakness, dysarthria, ataxia, or other cranial nerve involvement. 1, 2

Primary Distinguishing Features

Forehead Involvement Pattern

• Both Bell's palsy and stroke can involve the forehead, contrary to traditional teaching that stroke always spares forehead muscles. Recent evidence shows that 76% of acute ischemic stroke patients with central facial palsy demonstrate upper facial weakness, particularly with tight eye closure. 3
• The presence of forehead involvement alone does NOT reliably distinguish between peripheral (Bell's palsy) and central (stroke) causes. 1, 3
• Bell's palsy affects the entire ipsilateral face including the forehead because the lesion is distal to bilateral cortical input, producing complete hemifacial weakness. 1, 2

Associated Neurologic Symptoms (Most Critical Differentiator)

• Stroke typically presents with additional neurologic deficits including dizziness, dysphagia, diplopia, limb weakness, sensory changes, ataxia, or dysarthria. 4, 1, 2
• Bell's palsy presents as isolated facial weakness without other cranial nerve involvement or neurologic deficits. 1, 2
• Document function of all cranial nerves (V, VI, VIII, IX, X, XI, XII)—any additional cranial nerve involvement excludes Bell's palsy and mandates urgent stroke evaluation. 1, 2

Onset Characteristics

• Bell's palsy has rapid onset over <72 hours with progressive worsening during this period. 1, 2, 5
• Stroke has sudden, abrupt onset often reaching maximal deficit within minutes to hours. 4, 1
• Gradual progression over days to weeks suggests neoplastic or infectious causes, not Bell's palsy. 1

High-Risk Features in This Patient

Diabetes and Hypertension as Stroke Risk Factors

• This patient's diabetes and hypertension significantly increase stroke risk and should lower the threshold for neuroimaging. 4, 5
• Diabetes and hypertension are also risk factors for Bell's palsy, but the combination mandates careful stroke exclusion. 5, 6

Immediate Assessment Algorithm

Step 1: Obtain vital signs and establish IV access immediately. 1

Step 2: Perform focused neurologic examination:

• Test all cranial nerves systematically (V, VI, VII, VIII, IX, X, XI, XII). 1, 2
• Assess for limb weakness, sensory deficits, ataxia, dysarthria, and dysphagia. 4, 1
• Evaluate eye movements, visual fields, and pupillary responses. 4, 1

Step 3: Apply decision rule:

• If ANY additional neurologic deficit is present → Acute stroke protocol with urgent diffusion-weighted MRI and vascular imaging (CTA or MRA). 1
• If isolated facial weakness with rapid onset <72 hours and no other deficits → Likely Bell's palsy, but consider imaging given vascular risk factors. 1, 2

Red Flags Requiring Urgent Stroke Imaging

• Sudden onset (maximal deficit within minutes). 4, 1
• Any other cranial nerve involvement (diplopia, dysphagia, dysarthria). 1, 2
• Limb weakness or sensory loss. 4, 1
• Ataxia, vertigo, or incoordination. 4, 1
• Altered mental status or encephalopathy. 7
• Severe hypertension (>200/140 mmHg) at presentation. 7

Diagnostic Imaging Strategy

When Stroke is Suspected

• Diffusion-weighted MRI is the gold standard for detecting acute ischemic stroke and should be performed urgently. 1
• Vascular imaging (CTA or MRA) is required to evaluate for large-vessel occlusion. 1
• ECG and continuous cardiac monitoring to identify atrial fibrillation or arrhythmias. 1

When Bell's Palsy is Suspected

• Routine imaging is NOT recommended for typical Bell's palsy presentations. 2, 5
• Reserve MRI with and without contrast for atypical features: bilateral weakness, isolated branch paralysis, other cranial nerve involvement, recurrent episodes, or no recovery after 2-3 months. 1, 2, 5

Critical Pitfalls to Avoid

• Do not assume forehead involvement confirms Bell's palsy—76% of stroke patients have upper facial weakness. 3
• Do not overlook subtle additional neurologic deficits—carefully test all cranial nerves and limb strength. 1, 2
• Do not delay imaging in high-risk patients (diabetes, hypertension, sudden onset, age >60). 4, 1, 7
• Rare pontine infarcts can present as isolated facial palsy mimicking Bell's palsy—maintain high suspicion in vascular risk patients. 8, 7
• Do not initiate Bell's palsy treatment (corticosteroids) until stroke is excluded in patients with vascular risk factors and atypical features. 1, 2

Immediate Management if Bell's Palsy is Confirmed

• Prescribe oral corticosteroids within 72 hours: prednisolone 50 mg daily for 10 days OR prednisone 60 mg daily for 5 days followed by 5-day taper. 5
• Implement eye protection immediately: lubricating drops every 1-2 hours while awake, ophthalmic ointment at bedtime, eye taping at night, sunglasses outdoors. 2, 5
• Monitor blood glucose closely in diabetic patients during steroid therapy—expect significant hyperglycemia requiring insulin adjustment. 5
• Do NOT order routine laboratory tests or imaging for typical presentations—this delays treatment. 2, 5

Follow-Up and Reassessment Triggers

• Refer to facial nerve specialist if recovery is incomplete at 3 months. 2, 5
• Urgent reassessment for new or worsening neurologic findings at any time. 2, 5
• Ophthalmology referral for ocular symptoms or persistent incomplete eye closure. 2, 5