## Clinical Diagnosis **Key Point:** The constellation of facial drooping (including forehead), inability to close the eye, and loss of taste on anterior two-thirds of tongue indicates **Bell's palsy** (CN VII paralysis), likely due to inflammation/compression of the facial nerve in the temporal bone. ## Pathophysiology Bell's palsy involves: 1. Motor involvement of CN VII → facial weakness (including forehead, because CN VII supplies all muscles of facial expression) 2. Taste involvement via chorda tympani (branch of CN VII) → loss of taste anterior two-thirds of tongue 3. Possible involvement of nerve to stapedius → hyperacusis ## Management Algorithm ```mermaid flowchart TD A[Acute facial paralysis + taste loss]:::outcome --> B{Onset < 72 hours?}:::decision B -->|Yes| C[High-dose corticosteroids]:::action C --> D[MRI brain to exclude stroke/tumor]:::action D --> E[Consider antivirals if HSV suspected]:::action B -->|No| F[Limited benefit from steroids]:::action E --> G[Eye care: lubricants, taping, protective glasses]:::action G --> H[Follow-up at 3-4 weeks]:::outcome ``` ## Why Immediate Corticosteroids + MRI? **High-Yield:** - Corticosteroids (e.g., prednisolone 1 mg/kg/day for 7 days, then taper) reduce inflammation and improve recovery if given **within 72 hours of onset** - MRI is essential to exclude structural lesions (stroke, tumor, parotid pathology) that mimic Bell's palsy - Early intervention significantly improves prognosis **Clinical Pearl:** Bell's palsy is a **diagnosis of exclusion**. Red flags requiring imaging: gradual onset, bilateral involvement, recurrent episodes, or atypical features (vesicles in ear canal = Ramsay Hunt syndrome). ## Supportive Care - Eye protection is critical: artificial tears, lubricating ointment at night, protective glasses, eye taping during sleep - Prevents corneal abrasion and sight-threatening complications [cite:Harrison 21e Ch 379] 
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