Pain of the head and giddiness are among the local alterations of sensibility which frequently accompany disease of the brain, and yet they are the least to be relied upon : not only do they continually fail in giving notice of mischief going on within the cranium, but they are associated with so many other disorders, that in by far the greater number of instances they do not point to any serious lesion. Thus they are to be met with in dyspepsia and constipation, and in almost all the disorders of the digestive and assimilative processes; they constantly coexist with disorder of the circulation, disease of the heart, anaemia, and plethora, whether the head be too freely or too scantily supplied with blood : they are frequently associated with altered conditions of the blood itself; in fever, inflammation, chronic blood ailments, &o.
These belong to what we call functional disturbance of the brain : if rightly considered, they ought not to give rise to any important misconception; for in every instance the organ in which concomitant symptoms of disorder exist, ought to be carefully examined. For example, we know that vomiting and constipation are very often secondary to inflammation of the brain ; and if for a moment this circumstance be forgotten, and the attention be directed only to the local derangement, we find nothing there sufficient to account for the inflammatory fever which ie going on; the tenderness of abdominal in flammation is entirely wanting : on the other hand, in dyspeptic headache, however intense the pain, the evidence of inflammation cannot be traced, but the liability to disorder of the stomach is a fact easily made out. Useful informa
tion may be obtained in cases in which there is a possible connection between the head symptoms and disordered circulation or disease of blood, by inquir ing whether the pain be relieved or aggravated by assuming the horizontal posture. If the general symptoms be only those of fever we shall have more difficulty in determining whether the altered sensibility be caused by the fever, or whether it point to some more serious lesion, and ought to teach us that the fever itself is only symptomatic.
It must not be forgotten that the pain is sometimes external to the skull ; rheumatic, with tenderness of the skin and rheumatism in other parts ; in flammation of the scalp, in commencing erysipelas or disease of bone, inflamed pericranium, In all the functional disorders of the nervous system we must be careful neither too hastily to conclude that they are limited to the nerves to which the sensations are referred, nor too ready to ascribe them to disease of the central organs ; there are no such cases occurring in practice which are not occasionally associated with either condition.