14 Baboons suffer from rachitis very extensively. In the Transactions of the Pathological Society of London (xxxiv., 1883, pp. 310, 312) I. B. Sutton gives the description of two baboons, one of which was six months, the other one year and six months old, when they died. The careful description of the specimens exhibited leaves no doubt as to the rachitical nature of the changes in both the periosteum and the tissue of all the bones of the body.
Of undoubted total cranio-sclerosis Huschke reports but ten cases—those of Malpighi (1697), Cuvier (1822), Ribalt (1828), J. Forster and Bojanus (1826), Ilg (1822), Kilian (1822), Otto (1822), Vrolik (1848), Albers (1851), Huschke (1858). The disease does not affect the auditory bones, the condyles of the maxillary and occipital bones, nor the styloid process of the temporal bone. It is recognizable in the posterior part of the cranium and basis cranii, but affects mostly the bones of the face and the frontal, parietal, and cribroid bones. Thus, the disease takes its origin in the anterior portion of the skull, particularly in the superior maxilla, and proceeds upward and backward, terminating in the basis cranii in the neighborhood of the infundibulum and appendices. But two of all the cases were observed during life. In all the disease was traced back to early life. The chemical composition of the bones was greatly changed in all. Instead of the normal proportion of earthy to organic material = 2.1 (or 1.5):1, it was from 3.5 to 4.4:1. Particularly the carbonate of lime was greatly increased.
The brain and its meninges participate, in many respects, in the changes worked by rachitis, and mainly in the abnormal vascularization of the bones. They are very much congested, and succulent. A section through the brain shows a great many large and small blood-points. This hyperæmia may give rise to over-nutrition, which assumes the character of real hypertrophy of the brain. When that hyperæmia, however, becomes excessive, effusion will take place into the cavities, the tissue of the arachnoid, and the substance of the cerebrum, which latter looks peculiarly brilliant, elastic, and sometimes white, in consequence of the blood-vessels being emptied by the pressure on the part of the enlarged mass of the cerebrum upon the blood-vessels. Thus, instead of cerebral hyperæmia there may be anæmia. Every form of hydrocephalus may follow the rachitical process. Afterward, when the craniotabes has healed, the secondary effusions will generally also disappear, but not a few cases of hydrocephalus may be traced to rachitis occurring during the first half year of life. When that occurs, the intellectual faculties may suffer, while, on the contrary, complete recovery not infrequently exhibits an unusual degree of mental development, for the same reason which improves the chances of the development of the bone. The degrees of physiological and pathological nutrition and over-nutrition are very variable in their nature and results.
This condition of the cranial contents is not the only one brought about by rachitis. The softness of the cranial bones permits a direct pressure on the brain. The side on which the infant for the most part reposes gets flattened, and the brain is also compressed. The skull consequently bulges out in the opposite direction. This anomaly, as stated above, is sometimes visible through life, though in the large majority of cases after recovery from rachitis has taken place this asymmetry will gradually disappear. Before that can occur, however, the infant is liable to suffer from the rachitical changes. Convulsions are by no means rare. Vogel has, however, been able to produce an attack of convulsions by pressing upon the softened spots of the cranium. Permanent or temporary contractures of the fingers and toes I have seen in several instances. Gerhardt looks upon rachitis as one of the causes of tetany.
A frequent symptom of the cerebral changes which take place during, and in consequence of, craniotabes is the crowing inspiration, or laryngismus stridulus, of infants. It may be mild or severe. The mild form is very frequent, and consists in the occurrence of a shrill inspiratory sound while the baby is either quite placid or excited or crying. It is frequently overlooked entirely, is usually overcome after a number of months, and gives rise to serious trouble in but very few instances. The severe form is of a different nature. While the baby is awake or asleep, without any premonitory symptoms, while playing or crying, placid or excited, all at once respiration will cease. This will take place, usually, after expiration. The limbs are hanging down, as it were lifeless, the face turns pale, then purple, and slight convulsive twitching may set in for ten or twenty seconds. There appears to be a complete paralysis, and death from apnoea seems to be imminent. All at once, a long, deep crowing inspiration will be heard, respiration will commence again, and the whole terrible attack is overcome. It may return a number of times every day, or sometimes not for several days, during a period of many weeks or several months. The attacks which set in after inspiration are apt to be more dangerous. In such an one, but also in the other kind which sets in after the expiratory movement, death may occur suddenly, or the attack may be followed by a convulsion which may terminate fatally like any other eclamptic seizure. In this manner it is that the majority of cases of rachitis perish which terminate fatally during the active progress of the morbid process. In this connection, however, it may be well to add that craniotabes is not the only cause of laryngismus, particularly when the latter is found in the second year of life, or even later. But almost every case, without any exception, which is observed during the first eight or nine months is due to that very cause; and a good many cases occurring later, when the craniotabic bones have become normal, arise from the effects, either meningeal or encephalic, of the rachitic process. Still, complications of craniotabes with a large size of the thymus gland may occur, and enlargements of the tracheal and bronchial lymphatic glands are quite frequent, as we shall see below.15
15 Z. Oppenheimer prefers the name rachitic asthma in place of laryngismus, and suggests an explanation of the symptoms from a strictly anatomical point of view. If not correct, it is at all events interesting, as everything this ingenious writer proposes. He points to the ligament situated between the spinæ intrajugulares of the temporal and occipital bones, which, as long as it is of normal consistency, separates the jugular vein from the pneumogastric nerve. As it is covered with periosteum and dura, it is apt to ossify, and forms an osseous partition in the foramen jugulare, which participates in all the changes taking place in the periosteum. As this becomes softened and succulent, so will the ligament, either on both sides or on either. Its influence on the neighborhood depends on its size or succulence (as also on the difference in width of the foramen jugulare or lacerum, which corresponds with the difference in size of the transverse sinuses). The irritation of the pneumogastric is perhaps easily explained thereby, but in very exceptional cases only the accessory nerve would be affected. As, however, the latter controls the sterno-cleido mastoid and trapezius, and also the laryngeal muscles, and is apt to provoke cardiac paralysis during diastole, the occurrence of sudden death would be best accounted for.
While the size of the cranium is normal, or sometimes more than normal, the face undergoes some changes which result in absolute or relative diminution of size. These depend mostly on a reduction in the volume of the jaws. Glisson knew of it, and therefore looked for the cause of rachitis in the process of dentition. Now, both maxillæ are liable to become rachitical at an early date, as early indeed as the bones of the cranium. Rachitical deposits and softening take place in them very generally. The lower maxilla is flat anteriorly, it loses its rounded outline, is shorter in longitudinal direction, while the rami are thick and clumsy; the whole bone is shorter than normal, and sometimes asymmetric. Its changed appearance is greatly due to the effect the muscles, with their powerful insertions, produce on the softened bone; mainly the masseter, also the mylohyoid, which draws the lateral portions inward, and the geniohyoid, which pulls at the central portion. Of the latter, the lower portion is drawn out, the inner and the alveolar part inward. Thus, the teeth, mainly the incisors, of the lower jaw are turned inward to such an extent that, as those of the upper look outward, the two rows of teeth do not touch but cover each other. Besides, the periosteal proliferation around the alveoli is excessive, sometimes so much so as not only to crowd the teeth into irregular positions, but even to absorb and annihilate alveolar processes in the course of the morbid changes. The cases in which the number of teeth are actually diminished by rachitis are not at all rare. In the superior maxilla the last-described anomaly is also observed. Periosteal thickening is mainly noticed about the intermaxillary bone—sometimes to such an extent that above and behind it a considerable impression takes place. The shape of the upper jaw is more spherical than normal, and the cheek-bones become very prominent.
The belief that maxillary rachitis is now and then met without any other symptom of rachitis I do not share. What I said of craniotabes is also valid in regard to this form.
Irregular teething is a constant companion of maxillary rachitis, but is also present where the latter is not well, or not at all, marked. As a rule, the first teeth protrude late, about the ninth or tenth or twelfth month. That the first year and more should elapse without any tooth is of frequent occurrence in rachitis. Cases in which the first teeth do not come before the second year is completed are not very uncommon; in some there are none even when the child is much older. In most cases the retardation of dentition goes hand in hand with very marked retardation in the development of the rest of the bones and in the closure of the cranial fontanel. But not in every case of rachitis is there a retardation in the process of teething. In some a few teeth appear at the regular period (at the completion of the seventh or eighth month), or even at a very early age (in the fourth or fifth month); after which there is an interruption in the protrusion of teeth for an indefinite period. Evidently, the period in which rachitis is developed exerts its influence on the teething process. When it exists at a very early age, it will retard teething until recovery takes place. Still, it is possible that a moderate amount of periosteal and osteal hyperæmia and over-irritation matures the teeth abnormally. In all those cases, however, in which rachitis does not occur before the second half of the first year, the first teeth will appear at the normal time, and a long period will follow in which no teeth at all will make their appearance. Then, again, when the whole process comes to a standstill, and recovery takes place with solidification of the bones, and even eburnation, the teeth will come in rapid succession. Whether they will, as is frequent, decay almost as soon as formed, or whether they will be unusually hard, solid, and yellowish, depends on the stage of the disease in which they made their appearance, and on the complications aggravating the case. Of very grave import in this respect are digestive disorders before and during the course of the disease.
The vertebral column suffers also. In the normal infant it is straight, but in the rachitic it exhibits a kyphotic deformity very soon. When such a baby of three or six months is sitting up, the middle portion of the back is protruding, as in Pott's disease. In almost every case, however, this kyphosis is but apparent and the result of muscular debility. In order to arrive at a diagnosis at once, it is sufficient to place the patient on his face and support the head, and raise the lower extremities and pelvis in the air. If the kyphosis is but functional, the prominence disappears at once. By nothing can the muscular insufficiency of early rachitis be better demonstrated than by this little experiment. But actual deformity is also found in rachitis. It softens both the vertebræ and intervertebral cartilages, and either their anterior or posterior portion may be irregularly developed, and be either too high or too low. Besides, the articulating surfaces are sometimes too convex. Thus the causes of both kyphosis and scoliosis are amply furnished, and complications of the two are quite frequent, and the deformities resulting therefrom quite formidable. Scoliosis is mostly to the left; kyphosis generally complicated with lordosis, and sometimes the vertebral column exhibits a spiral shape.