NODDING SPASM The most conspicuous symptom of this disease is a more or less continuous rotating, nodding or shaking of the head. The combination of these movements of the head with nystagmus which, while it is not observed in every stage of the disease, is found practically always if the ease remains under observation for any length of time—as well as with a number of other peculiarities that return again and again in patients of this type and which w-e shall describe later. will justify the description of nodding spasm as a separate clinical picture. The differentiation from other diseases which resemble it superficially, but possess an entirely different pathogenesis as well as prognosis, we owe in the main to the work of Raudnitz, to which later contributions by Ausch, Thomson and others, have added but little. Raudnitz, who made a careful analysis of the clinical picture describes it in the following words:— "The children are at most three years of age, generally between the sixth and twelfth month of life. At this time the movements of the head, consisting of nodding, shaking or rotation, make their appearance; the excursions are quite limited, and the velocity is barely equal to that of the pendulum of a clock. The trunk takes part in the movements only to the extent of responding by a slight, purely mechanical move ment to the nodding of the head. Movements similar to those of the head do not occur in the face (except about the eyes), in the trunk or in the extremities. An oblique position and lagging of the head when the eyes are turned in certain directions, are observed in some cases. At the height of the disease there is always nystagmus, which very frequently is confined to or at least more pronounced in one eye. Nystagmus appears later than the other phenomena and, as a rule, disappears earlier than the convulsive movement of the head; but there are cases in which nystagmus is the most prominent feature, and pos sibly also some in which it constitutes the only symptom. Nystagmus and movements of the head very frequently alternate, the former occurring during intentional or enforced rest of the head.
Peculiar temporary positions of the eyes, adduction, and more rarely abduction of one eye, and convulsive movements of the lids are of frequent occurrence; lachrymation is rare. All these phenomena,
which disappear during sleep, bear a distinct relation to the movements of the eyes, quite frequently to movements in certain directions only. The convulsive movements and oblique position of the head cease if, in cases in which the nystagnitts is confined to, or most prominent in one eye, the affected eye is bandaged or, in CaSCS with bilateral nystag mus, if both eyes are bandaged. Movements of the head coming on when the eyes are bandaged are absolutely normal. The phenomena of nodding spasms are not attended by any disturbance of conscious ness, nor are they followed by exhaustion. Other IlerVOIIS symptoms are absent in the majority of cases, and the mental development does not appear to be injuriously affected. The disease ends in complete recovery, but may continue for two years, during which time there are distinct relapses or exacerbations." When we compare Raudnitz's masterly description of the disease and its course with former descriptions, we note that the chief progress lies in the recognition of the fact that the movements of the head and of the eyes depend on the child's desire to look in certain directions.
Raudnitz's observations impressed him with the importance of the etiologic influence of dark lodgings and insufficient or one-sided illumination in the production of the disease. In the majority of these cases he found that the children were forced, by the position which they habitually occupied and by the insufficient illumination—in order to turn toward the window, or whatever other scanty source of light there was, or to examine a plaything which they held in their hands— to turn the eyes constantly to one side, or to rotate the eyeballs upward. This, in his opinion, is the manner in which the motor disturbance is brought about, and it is analogous to the nystagnius of miners. In support of this theory Raudnitz cites the observation, which has also been made by others, that the disease usually begins (luring the dark months of winter.