Unusual syndromes in neurological practice.

Paroxysmal symptoms caused by phaeochromocytoma, headaches associated with sexual activity, numbness of one half of the tongue on sudden neck movement, visual hallucinations, drop attacks, episodic involuntary movements, and various genital sensations are described. At first encounter, some of these and other unusual syndromes may be mistaken for psychological disorders, but can usually be distinguished by their characteristic pattern and evolution of symptoms.