Intramedullary neurenteric cyst without any associated malformation. One case evaluated by RMI and electron microscopic study.

A 46 years old woman presented with several years history of low back pain. For five years she suffered from weakness of the left lower limb and three years later she experienced an episode of right foot weakness. She suffered too from occasional urinary urgency. The examination showed decreased power and diminished sensory perception in the left leg. On myelography, a block at L2 level was observed. RMI evaluation showed an intramedullary cyst in the anterior part of the spinal cord without any enhancement of its wall by the Gadolinium. At operation a thin-wall cyst was found containing clear fluid. After a biopsy of the wall, a cystosubarachnoid shunt was performed. Histological examination of the surgical sample showed a simple cuboidal epithelium lying on collagen fibrills. Electron microscopic studies showed ciliated cells with a clearly-visible basement membrane. The diagnosis of neurenteric cyst was confirmed. In the postoperative course the patient complained about sensory loss of the legs and the perineal area. Six months later, she exhibited a sensory disturbance of the feet and the right sacral area, a motor deficit of the distal left leg without urinary disturbance. Neurenteric cysts are dysraphic lesions which can be observed without other abnormalities. They are usually extramedullary and the intramedullary forms are very rare: among 5 cases reported in the literature, one has been evaluated by RMI. In the absence of enhancement by the Gadolinium, the other possible diagnosis seems an ependymal cyst. Contrary to extramedullary forms the postoperative course of intramedullary neurenteric cysts are not always eventful. Because the cyst wall cannot be removed, repeated RMI are desirable in the follow-up.