From the Guidelines
The facial nerve exam should assess cranial nerve VII function by evaluating facial muscle strength and symmetry, and should include inspection at rest, motor function testing, and evaluation of taste sensation and hyperacusis, as described in the most recent guidelines 1. The facial nerve exam is a crucial assessment for identifying conditions like Bell's palsy, stroke, or other neurological disorders affecting the facial nerve.
- Begin by inspecting the face at rest for asymmetry, drooping, or flattening of nasolabial folds.
- Then test motor function by asking the patient to raise eyebrows, close eyes tightly (against resistance), show teeth, smile, puff cheeks, and purse lips.
- Note any weakness, asymmetry, or inability to perform these actions.
- For a complete assessment, evaluate taste sensation on the anterior two-thirds of the tongue using sweet, salty, or sour substances.
- Also check for hyperacusis by asking about sound sensitivity.
- Document findings by comparing sides (e.g., "symmetric facial movement" or "right-sided facial droop"). The facial nerve has five main branches (temporal, zygomatic, buccal, mandibular, and cervical), and understanding which branches are affected can help localize the lesion.
- Central lesions (like strokes) typically spare the forehead due to bilateral innervation, while peripheral lesions affect all branches. The House-Brackmann facial nerve grading system can be used to grade the severity of facial paralysis, with grades ranging from 1 (normal) to 6 (total paralysis) 1. In cases where imaging is necessary, MRI is the preferred modality for evaluating the intracranial and extracranial portions of the facial nerve 1.
From the Research
Facial Nerve Examination Procedure
The proper procedure for a facial nerve examination involves several steps, including:
- Assessment of facial asymmetry [ 2 ]
- Electrophysiological tests to evaluate facial nerve function [ 3 ]
- Use of a facial nerve function index (FNFI) to monitor the return of facial nerve function [ 4 ]
- Evaluation of facial nerve activity using objective topographic methods [ 5 ]
Key Components of the Examination
The examination should include:
- Assessment of the degree of paresis [ 6 ]
- Evaluation of the patient's age and time until first signs of recovery [ 6 ]
- Use of facial landmark estimation (FLE) algorithm and facial asymmetrical feature (FAF) to quantify facial nerve paralysis [ 2 ]
Diagnostic Tools
The following diagnostic tools may be used: