Another peculiarity of the rickety state is the curious impressibility of the nervous system which manifests itself by the ready occurrence of various forms of spasm. Reflex convulsions are common, and laryngismus stridulus is practically confined to the subjects of rickets. Catarrh of the larynx is also liable to be accompanied by spasm, and therefore catarrhal croup (laryngitis stridulosa), as is elsewhere stated, is a frequent cause of anxiety. These subjects need not be further referred to in this place, as they all receive consideration in special chapters.
One other not uncommon complication is chronic hydrocephalus. On account of the small size of the brain in many cases of rickets, fluid is effused into the cranial cavity to fill up the resulting space. The amount of serosity is, however, seldom large and rarely comes to be a source of clanger.
An occasional complication, although not a common one, is acute tuber culosis. The disease is probably in all cases the result of an acquired ten dency due to the presence in the body of a softening cheesy deposit. It certainly is proportionately less frequent in rickety subjects than in children free from this disorder of nutrition but it is necessary to be aware that rickets does not exclude tuberculosis.
a mild case of rickets the prominent features are the swelling of the epiphyseal ends of the long bones, the tardy eruption of the teeth, and the backwardness in learning to walk. If we notice the wrists to be large in a young child, we should at once count the number of his teeth and ask if he is able to stand alone. If .a child ten months old shows no sign of a tooth, if his wrists are large, and if when held upon his feet his limbs double up helplessly beneath him, • there can be little doubt that he is the subject of rickets. Even before the swelling of the articular ends of the bones has come on the onset of the disease may be suspected. Big, fat, flabby infants are generally slightly rickety, and if a child sweats profusely about the head, and is kept covered at night only with great difficulty, we can have little doubt that the characteristic signs of rickets are about to appear. In such a case attention should be at once directed to the child's diet, the regularity with which he is taken out of doors, and the state as to ventilation of his sleeping-room, so that any errors in management may be promptly corrected.
In a marked case of rickets the deformity of the chest, the bending of the bones, the enlargement of the joints and beading of the ribs are sufficiently characteristic. Even the position of the patient as he sits with his legs crossed and his head fallen back between his shoulders, supporting his feeble spine by his hands placed before him on the floor, enables us dt once to recognize the case as one of well-defined rickets.
The complete uselessness of the lower limbs in many of these cases is often a serious anxiety even to parents who regard the other symptoms with comparative indifference, for they fear lest the child should be "going to be paralysed." But although the patient has no idea of even placing his feet upon the ground, and cries bitterly when any attempt is made to persuade him to do so, power of movement of the legs is unimpaired. If the skin of the legs be pinched or gently pricked he at once draws his limbs out of the way. Of other local symptoms :—The nature of the an tero-posterior spinal curvature is readily shown by lifting the child up under the arms, when the weight of the pelvis and legs at once causes the spinal distortion to disappear. A lateral curvature is distinguished from the effects of pleurisy by noting the presence of signs of rickets and the absence of those of effusion into the chest cavity. The rickety head differs from a skull dilated by excess of fluid by its shape. Instead of being glob ular it is elongated from before backwards, with a characteristic squareness of the forehead, and moreover this shape of head is associated with other well marked signs of rickets. The fontanelle does not always furnish trustworthy evidence ; for although often depressed in rickets and raised in hydrocephalus, these conditions may be reversed. Certainly a depressed fontanelle is compatible with a fairly copious effusion of intra-cranial fluid.
In the present state of our knowledge no differential diagnosis can be made, during life at any rate, between rickets and osteo-malacia. Cases where softening and deformity of bone are present must be assumed to be rickets. Fortunately, for all practical purposes, a distinction in any indi vidual case is unnecessary, as the measures to be adopted for the relief of the patient are the same whatever be the correct pathology of the osseous lesions.