Pain in the head may depend in different cases upon neuralgia, rheumatism, overfulness of blood {congestion hyperaemia); blood-poisoning (as by alcohol, opium, etc.); fever (remittent, typhoid, etc.); disease of the brain, sympathetic irritation (as with uterine disorder, etc.).

Skill as well as care may often be necessary to make out, in an actual case, to which of these a headache belongs. Neuralgic headache is nearly always on one side only or chiefly, and extends to the face also ; it is shooting or darting, and there is with it some tenderness on pressure. Rheumatism of the scalp is usually accompanied by stiffness of the muscles that move the head and neck-. Headache from fulness of blood or fever is attended by heat of the head; the pain is then apt to be throbbing in character. Pain from disease of the brain is generally in one spot, either fixed or in spells (periodic or paroxysmal) ; and some other sign of brain disease is also present with it.