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Show Journal of Clinical Neuro- ophthalmology 10( 2): 131- 134, 1990. Bilateral Orbital Encephaloceles An Unusual Cause of Exophthalmos Oguz <:: ataltepe, M. D., and Osman Ekin Qzcan, M. D, © 1990 Raven Press, Ltd., New York We report a case of bilateral orbital encephaloceles associated with exophthalmos of the left eye. Orbital encephaloceles, especially bilateral ones, are very rare. The surgical approach to the repair of this defect and reasons for preferring a transcranial approach are described and discussed. Key Words: Exophthalmos- Orbital encephalocelePorencephalic cyst. From the Department of Neurosurgery, Hacettepe University Medical School, Ankara, Turkey. Address correspondence and reprint requests.. to ~ r.' .0.. E. Ozcan, Hacettepe Oniversitesi Tip Fakultesl, Noro § lrur) l Bolumu, 06100, Ankara, Turkey. 131 Encephalocele is the extracranial protrusion of brain tissue through a congenital defect of the skull bones. Naso- orbital encephaloceles, which are very rare, are included in the fronto- ethmoidal encephalocele group according to the classification of Suwanwela and Suwanwela ( 1). This article describes a case of bilateral orbital encephaloceles associated with a porencephalic cyst. CASE REPORT This 2- month- old male child was admitted to the hospital with a gradually increasing swelling located at the inner angle of the left orbit and exophthalmos of the left eye, which had been noticed soon after birth. The child was the first baby of a 27- year- old mother; he was born at term following an uneventful pregnancy. The delivery was spontaneous and transvaginal. Examination showed an exophthalmos in the left eye and a fluctuating mass of about 1 cm in diameter between the left medial cathus and root of the nose. The left eyeball had been pushed laterally and slightly upward. Chemosis was noted in the left eye, and the movement of the left eye was more restricted than that of the right eye. Both pupils and optic discs were normal. The rest of the neurological examination was within normal limits. Plain skull films revealed orbital enlargement on the left side. Computed tomography ( CT) demonstrated bilateral orbital masses and a large porencephalic cyst in the left fronto- temporal region. There was a large orbital mass in the left, extending from the back of the globe to the apex of the orbit. There was also a second retrobulbar mass in the right orbit, which was smaller than the left one and did not push the bulbus to the same extent. Both of the orbital masses were in continuity with 132 O. C; ATALTEPE AND O. E. OZCAN the frontal lobe through bone defects in the medial walls of the orbits ( Figs. 1- 3). In surgery, an intracranial approach through bifrontal craniotomy was used. Both intradural and extradural explorations of the defects were done. Extradural exploration revealed that the dura was protruding into the orbits through the defects in the medial walls of the orbital cavities. When the dura was opened, it was seen that brain tissue of the frontal lobes was herniating into the orbital cavities. The brain was amputated at the opening. Bone defects of 1 cm in diameter on the left and 5 mm in diameter on the right were seen. Both of the bone defects were widened, and periorbital tissue was exposed bilaterally. Behind the periorbita, there was herniated brain tissue firmly adhering to the posterior wall and filling the orbital cavity. The masses were easily separated from the optic nerve and the extraocular muscles. Herniated portions were totally removed from both sides. Then periorbital tissue was sutured and dural defects were FIG. 1. Preoperative CT scan. Coronal section shows the bilateral orbital encephaloceles and left exophthalmos FIG. 2. Preoperative CT scan. Coronal section shows the bone defects of the orbital walls. repaired with fascial grafts. Otogenous bone grafts were placed extradurally to cover the bony defects. The porencephalic cyst was opened into the basal cisterns. Histological examination of the resected tissue showed findings typical of encephalocele, including degenerated neuronal tissue with proliferated glial cells. In the early postoperative period, it was observed that the left exophthalmos disappeared and the eye movements returned to normal ( Figs. 4 and 5). Postoperative CT scan demonstrated normal localization of the eyeballs in the orbital cavities and the diminished mass effect on the mid- FIG. 3. Preoperative CT scan. Bilateral orbital encephaloceles and a porencephalic cyst are seen on axial section. BILATERAL ORBITAL ENCEPHALOCELES 133 FIG. 4. The patient before the operation, with left exophthalmos. brain following decompression of the left middle fossa cyst ( Fig. 6). On follow- up clinical examination after 16 months, the patient had full range of extraocular movement bilaterally. The exophthalmos of the left eye had disappeared, and he could fixate with either eye; both pupils and optic discs were normal. Formal visual acuity testing was not possible with a Snellen chart since the baby was 18 months old, but he was interested in bright objects in both eyes. Visual evoked potentials were performed and on stimulation with flash, PI latencies were found to be within normal limits, although a slight delay was noted in the left eye. DISCUSSION Encephalocele is the extracranial herniation of brain tissue and cerebrospinal fluid in a meningeal sac through a bone defect or natural opening during the embryological period. The incidence in FIG. 5. Appearance of the left eye after the operation. Western countries is 1 of 35,000 people, whereas in Thailand it is 1 of 5,000 ( 2,3). Encephalocele may be located in any part of the skull, the occipital region being the most common location. Anterior or sincipital encephaloceles located around the na- FIG. 6. Postoperative CT scan. J Clin Neuro- ophthalmol. Vol. 10. No. 2. 1990 134 O. (: ATALTEPE AND O. E. OZCAN sal root constitute 15- 20% of all cranial encephaloceles ( 4); orbital encephaloceles are rare types of this group. Suwanwela and Suwanwela ( 1) classified orbital encephaloceles into two groups: nasoorbital encephaloceles, a subgroup of frontoethmoidal encephaloceles, and spheno- orbital encephaloceles, a subgroup of basal encephaloceles. Consul and Kulshrestha ( 5), on the other hand, classified orbital encephaloceles into anterior and posterior groups. The anterior group, which is more common, develops from the junction of the frontal and lacrimal bones, cribriform plate, and nasal process of the superior maxilla. Posterior orbital encephaloceles arise from the sphenoidal fissure, optic foramen, posterior ethmoidal foramen, or in the roof or medial wall of the orbit. According to these classifications, our case is included in the bilateral naso- orbital or anterior orbital encephaloceles. In the literature, bilateral orbital encephaloceles are reported to be very rare ( 6). Various eye abnormalities- including microphthalmos, hydrophthalmos, iris coloboma, and enophthalmos-- have been reported in association with orbital encephaloceles ( 6- 8). Also, orbital encephaloceles frequently cause exophthalmos. In a series of 31 patients with orbital encephaloceles reviewed by Strandberg ( 7), 28 had unilateral exophthalmos. Although bilateral orbital encephaloceles were present in our case, exophthalmos occured only on the left side, significantly limiting movement of the left eye. Early surgery in the treatment of orbital encephalocele is important because of the limited eye movement and exophthalmos. It also prevents damage of the optic nerve and protects the orbita J L/ ln '~ l'Ilrll- tlpll: II.... II/ IIII, '".' 1' 1./, , .. " 1: 1:- 1!) from further herniation into the defect. The removal of the mass is also necessary to prevent the asymmetrical growth of the orbital cavity. Various surgical techniques have been used, including puncture of the sac, ligation of the carotid artery, enucleation followed by encephalocele excision, superior nasal approach, and lateral orbitotomy ( 6- 8). However, it seems better to use the transcranial route to reach and repair the bone and dura defect, as this approach provides a wide surgical field and removal of herniated brain tissue is thereby easier to complete. Also, in using this approach, the encephalocele sac can be amputated firmly from the frontal lobe, and a wide dissection plane of the orbital wall is perfectly exposed ( 1,2,9). REFERENCES 1. Suwanwela C Suwanwela N. A morphological classification of sincipital encephalomeningoceles. J Neurosurg 1972; 36: 201- 11. 2. Reigel DH. Encephalocele. In: McLaurin RL, Epstein F, eds. Pediatric neurosurgery. New York: Grune & Stratton, 1982: 49- 60. 3. Suwanwela C Chaturapom H. Fronto- ethmoidal encephalomeningocele. J Neurosurg 1966; 25: 172-- 82. 4. Whatmore WJ. Sincipital encephalomeningoceles. Br J Surg 1973; 60: 261- 70. 5. Consul BN, Kulshrestha DP. Orbital meningocele. BrJOphtha/ mo/ 1965; 49: 374-- 6. 6. Chohan BS, Parmar IPS, Bhatia IN. Anterior orbital meningoencephalocele. Am J Ophtha/ mo/ 1969; 68: 144-- 6. 7. Strandberg B. Cephalocele of posterior part of orbit. Arch Ophtha/ mo/ 1949; 42: 254-- 65. 8. Cohen M. Orbital meningoencephalocele associated with microphthalmia. JAMA 1927; 89: 746-- 9. 9. Rapport RL, Dunn RC Alhady F. Anterior encephalocele. J Neurosurg 1981; 54: 213- 9. |
