- Mad cow disease and prion infections
- Leber hereditary optic neuropathy
- Intracranial infection
- Insufficient blood supply to the cerebral arteries
- Increased intracranial pressure
- Hypoxic-ischemic encephalopathy
- Huntington's disease
- Hereditary multi-infarct dementia
- Hemiballismus
- HHH syndrome
- Generalized myasthenia gravis
- Flail Arm Syndrome
- Facial spasm
- Facial nerve dysfunction
- Estrogen-related migraine
- Early-onset Parkinson's disease