A facial fatigability test: a method for detecting 'latent' facial motor lesions by fatigability

This is a simple test for the early recognition of a clinically 'latent' facial motor lesion, which detects the difference in fatigability between the two sides of the peri-oral musculature. Fatigue is produced by the patient's effort to maintain maximal contraction against lateral traction of the angles of the mouth by two weighted hooks. Fatigue is expressed as the distance between the midline of the philtrum and a mark on each hook. Distance plotted against time gives a 'facial fatigue curve'. In the authors ' experience the test has revealed pathological fatigability in 8 cases, 2 intrameatal and 4 large acoustic neuromas--1 of the four not yet confirmed by surgery--and 2 inflammatory processes in the internal auditory meatus, but failed in 1 of intrameatal acoustic neuroma.