The face displays a wide range of involuntary movements that originate at all levels of the motor system. In Part 2 of this article, excessive facial movement is discussed, complementing the discussion of facial weakness in last month’s issue of Medicine Today.
- The common theme in many disorders of excessive facial movement is loss of control over the dopaminergic pathways that regulate involuntary facial expression.
- Tics probably result from loss of regulatory control normally exerted by the cerebral cortex over dopaminergic and other neurotransmitter systems, and may be suppressed by dopaminergic antagonists.
- Brief muscular twitches and jerks are observed in facial myoclonus, which may appear after an hypoxic brain injury such as cardiac arrest or other encephalopathy, and should be distinguished from focal motor seizures involving the face.
- Benign essential tremor may produce rhythmic oscillations of the head (titubation), jaw or voice. Propranolol can be used if there are no contraindications.
- In hemifacial spasm and focal dystonias, injection of affected muscles with botulinum toxin type A is a safe and now first line therapy.