Spasm is the prominent feature of tetanus ; muscular rigidity more frequently occurs in connection with disease of the brain : it sometimes supervenes on paralysis, causing perraanent contrac tion, or it remains as a consequence of convulsion, especially in childhood ; in other instances it arises slowly and spontaneously in long-protracted disease, and in such circumstances it must be regarded as a serious symktom.
Strabismus occasionally exists as a condition of muscular spasm, but is more commonly due to paralysis. It is one of the incidents in general convulsion, and is transient, except when followed by paralysis of the antagonistic muscle. In inflammation within the cranium it is frequently produced by irritation of the origin of the motor nerves, and is then a very common cause of double vision.
§ 2. Paralysis, as a symptom of disease of the brain, must be studied especially with relation to its extent and duration, and also the mode of its incursion. It is one of those disorders which, in a truly scientific classification, could find no place except as a symptom of disease ; but we are met by the impossibility of ascertaining the exact condition of the nervous structures during life, and we also know that, while it is dependent on a great variety of causes, its features present characters which are constant and invariable ; thus in some cases we cannot get beyond the fact of paralysis being present, while in others, the primary cause having been removed, the function of the muscles only retnains in abey ance until they are roused by the repeated application of some local stimulus. It has therefore seemed necessary to assign to it a separate place in our classification (see Chap. XV.), and then the question of its causes and extent will be more fully examined. We may here remark that paralysis of cranial nerves must be more important than that of solitary nerves in any other part of the body, because the lesion is so. much the more likely to be within the skull, and similarly, either hemiplegia or paraplegia, extending to the nerves originating next to the foramen magnum, is more serious than when either disease is limited to the lower limbs. Again, hemiplegia is more important than paraplegia, because the two hemisphere,s of the brain are more distinct than the two halves of the spinal cord, and affections of one side are therefore more likely to have a cranial than a spinal origin.
The fact of the paralysis being complete or incomplete, does not so much affect the situation of the lesion as its character, and is chiefly of importance because the one is a reality about which there can be no question, while the other may either be overlooked by the observer or may be simulated by diseased imagination or perverted will. It is to be remembered that we are only dealing now with one symptom, and if we are to attain to correct diag nosis we must compare it with the other evidence of cerebral disease, and not hastily conclude that, because the apparent para lysis is such a,s might have a cranial origin, this is any sufficient ground for assuming its existence.
Ptosis is a symptom not readily to be passed over : difficulty in articulation, thickness of speech, stammering and stuttering or hesitation, in persons who have had no such .previous affection, are also of much importance in relation to disease of the brain, indicating, a,s all these do, some affection of cranial nerves. Their anatomical relations may help us to trace the point at which dis eased action is going on; and where two or more nerves issuing by different foramina are simultaneously affected, we have at le,ast strong presumptive evidence that the cause of the paralysis lies within the cramum.
Strabismus again comes under consideration, as it often is due to paralysis. We have to inquire whether it be recent or of old standing : in its chronic state there is generally retraction of one muscle with elongation of its antagonist, which is of no moment as a symptom of disease now going on, as it is either the remnant of some convulsive attack in childhood, or the consequence of some defect of vision; in its recent state it is very frequently the evidence of irritation and muscular spasm, but is also occasionally seen along with paralysis of other cranial nerves, as the effect of pressure, e. g„ along with dilatation of the correSponding pupil.