Muscle contractions are frequent but irregular. They are typically brief (a second or so) but can be more prolonged and "tonic," ie, for tens of seconds. They typically start in the eyelid and spread to other muscles in the face. Spasms may be worse in the setting of stress, anxiety, or fatigue.
Symptoms may be controlled by botulinum toxin injections, and in some cases, surgical microvascular decompression is performed.
G51.39 – Clonic hemifacial spasm, unspecified
13753008 – Hemifacial spasm
Differential Diagnosis & Pitfalls