ENCEPHALOCELE.—Gr., Eyxkpcc7..oc, the brain, and x-;:).n,a tumor.
Definition and Varieties.—Encephalo cele, or hernia eerebri, means a protrusion of a portion of brain-substance with its membranes through an aperture in the skull, congenital in origin, and usually situated in the occipital region in the median line, less frequently in the naso frontal region, and rarely in other situ ations. Meningocele and hydrencephalo cele are closely allied conditions. Men ingocele means a protrusion of a portion of the membranes of the brain through an opening in the skull, the sac thus formed being distended by spinal fluid. Hydreneephalocele means a protrusion of the membranes and brain substance, which also contains within it a cavity continuous with the lateral ven tricles of the brain, and filled with cere bro-spinal fluid. The latter condition is the gravest and the most frequent in occurrence of the three, being next in frequency, and cele the rarest. All of these conditions are of yery rare occurrence. Forms of acquired hernia cerebri will more erly be considered elsewhere, in connec tion with the various causes of this con dition.
Symptoms.—In the three forms enu merated the disease is congenital, and is developed at some period of intra-uter ine life; and at birth presents a tumor of varying size, generally situated in. the occipital region, or in the naso-frontal region in the median line. In almost all cases the hernia emerges through an opening in the line of one of the cranial sutures.
The naso-frontal hernias leave the cranium between the frontal and nasal bones and form a tuinor in the median line in the rcg,ion of the glabella.
The naso-ethmoidal hernias leave the cranium between the frontal and nasal bones on the one side and the lateral' mass or labyrinth on the other. which is forced or displaced downward toward the nasal cavity. The tumor appears externaliy in the region of the border between the osseous and cartilaginous portions of the nose, hanging down toward the tip or the wing of the nose.
The naso-orbital hernias leave the cranium between the frontal, ethmoid, and laerymal bones. In the region of the latter they enter the orbit and pre sent at or near the inner eanthus of the• eye. The naso-ethinoidal and naso-orbital varieties are probably not distinguish able from each other, as they leave the.
cranium at the same place, namely: the nasal notch of the frontal and the cribri form plate of the etlimoid bone. Chris tian Fenger (Amer. Jour. Med. Sei., Jan., '95).
Cephalhmnatoma represents one of the risks through the child must pass during labor. The tumor consists of an infusion of blood between the peri osteum and bone, forming either two projections over the parietal bosses or more commonly a single projection upon one side. It is important to distinguish this condition from a sero-sanguinolcnt effusion, which is much more common, , and which is present at birth. This tumor is soft, but less fluctuating, and can be indented by the finger, a.s in cedema. It appears on the presenting portion of the fcctus, therefore is formed before its expulsion, and disappears shortly after birth—within one or two days. It never limits itself, as does the cephalhannatoma, to the border of the bones. The characteristics of the sero sa.nguinolent tumors are exactly oppo site to those of cephallilematoma. It is due to a circular compression at the base of the part which corresponds to the ring of the pelvis during engage ment, and always appears before the presenting part. Queirel (Annales de GynC•e. et d'Obstet., Jan., 1901).
Of 93 cases collected by Itouel, 63 cases were occipital, 16 were fronto-nasal, and 9 occurred in other situations; while of 105 cases collected by Schatz, 59 were occipital and 46 frontal. These hernial protrusions may occur in other situa tions. Thus, in the frontal region in stead of emerging between the cribiform plate of the ethmoid and the frontal bone, such a protrusion is sometimes lo cated in the interfrontal fissure high up, or in the anterior fontanelle; less fre quently they occur in the sagittal suture, or between the temporal and parietal bones, thus appearing upon the side of the head. The frontal tumors are smaller, as a rule, than the occipital growths, and are covered with a more vascular skin covering; so that they may give the appearance of certain forms of mevus. In extremely rare cases the opening has existed between the sphe noid and ethmoid bones, or between the sphenoid and its greater wing.