- Severe myoclonic epilepsy in infants
- Rheumatic chorea
- Refsum disease
- Recurrent meningitis
- Primary light chain amyloidosis
- Postural hypotension
- Polymyositis
- Polyarteritis nodosa
- Occipital neuralgia
- Neurasthenia
- N-Acetylglutamate Synthase Deficiency
- Ménière's disease
- Mucopolysaccharidosis
- Motor aphasia
- Miller Fisher syndrome
- Median nerve