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Orbital meningocele.

1965; BMJ; Volume: 49; Issue: 7 Linguagem: Inglês

10.1136/bjo.49.7.374

1468-2079

BN Consul, OP Kulshrestha,

Ocular Disorders and Treatments

ORBITAL meningoceles are very rare congenital abnormalities in which the meninges, with the enclosed spinal fluid, herniate into the orbit.The protrusion is usually through a defect in the bony walls of the orbit or, much less commonly, at the site of natural openings like the optic foramen and sphenoidal fissure.In the embryonic development of the bony orbit gaps occur through which herniation of the meninges takes place.When only the meninges, with enclosed spinal fluid, make up the orbital tumour it is a meningocele; when part of the brain tissue is also prolapsed it is an orbital encephalocele; if the cerebral ventricle is included in the tumour it is a hydrencephalocele.The anterior variety is much more common, occurring between the junction of the frontal and lacrimal bones, cribriform plate, and nasal process of the superior maxilla.The tumour protrudes from the inner angle either towards the lids or the root of the nose, it not infrequently resembles a distended lacrimal sac, and it is often multilocular in this situation.The posterior type is less common, where herniation occurs either through the sphenoidal fissure, optic foramen, posterior ethmoidal foramen, or in the roof or medial wall of the orbit.The majority of these cystic herniations contain some brain substance, although the latter may undergo extreme atrophy and degeneration owing to long-continued pressure, so that the pia-arachnoid may become hardly recognizable and the dura thin and fibrous.In meningoceles abnormalities of the eyes are not common.The abnormalities encountered are microphthalmos, coloboma of the iris, hydrophthalmos, and apparent anophthalmos (Duke-Elder, 1952).Pahwa and Patney (1963) reported three cases of meningo-encephalocele with association of microcornea and enophthal- mos in one of these.This condition constitutes one of the very rare causes of exophthalmos.The clinical picture usually becomes evident at birth or in early infancy.The cysts are fluctuant to a variable degree and some can be reduced by direct pressure.Pulsation of such cysts is uncommon as the pedicle is usually small.On radiographic examination bony defects opposite the cyst may be seen.In the absence of pulsation or bony defects aspiration of fluid, resembling cerebrospinal fluid, from the cystic tumour will confirm the diagnosis.