Sincipital meningocele.
A large proportion of patients with these congenital defects die shortly after birth. The tumor, when large, may be ruptured during delivery. Occasionally the sac ruptures spontaneously, which accident is usually followed by purulent meningitis from infection, though it may possibly lead to spontaneous recovery. The principal danger is the liability to such accident.
Fig. 382
Sincipital hydrencephalocele; two views. (All of these from the Buffalo Clinic.)
The encephaloceles are divided into the cenencephaloceles, containing solid brain substance, and hydrencephaloceles, consisting of the protrusion of a dilated brain cavity—i. e., a thin area of brain enclosing fluid communicating with one of the ventricles. Most of the large tumors pertain to the latter class. The more brain material such a tumor contains the more it pulsates, especially if the patient cry or strain; the smaller, too, is the skull—i. e., the greater the tendency toward microcephalus.
Congenital cysts of brain and membranes, in a measure traumatic, are classified by Rawling, as follows:
1. According to situation: (a) within the calvarium, subosteal, subdural, subarachnoid or intracerebral; (b) projecting through an opening in the skull, with or without ventricular communication.