Cervical cord compression due to chondromatous change in a patient with metaphysial aclasis.

A 47-year-old man with progressive weakness and pain of the right arm and leg was admitted to the neurosurgical department. One year earlier he began to suffer from pain and paraesthesia around the right shoulder and in the lower cervical area which radiated to the right hand. For the last 4 weeks, weakness and paraesthesia in the right side limbs and urinary incontinence advanced progressively. Neurological examination revealed a severe weakness in right arm and leg with a mild spasticity. Muscles of the right shoulder girdle appeared slightly atrophic and deep tendon reflex was more brisk on the right side. There was hyperalgesia on the C3 to T8 dermatome in the right side and C7 to T8 dermatome in the left side and hypoalgesia below T9 level. Vibration and position sense in the lower extremities were impaired. Pantopaque myelography demonstrated an intramedullary spaceoccupying lesion with the lower level at CS. The cerebrospinal fluid contained 180 mg/dl protein. An emergency laminectomy from C3 to C6 was performed since quadriparesis developed suddenly following myelography. The dorsal column of the C4 appeared slightly expanded and was bluish in colour. A longitudinal incision at the right posterior column of C4 was performed. At a depth of 2 5 mm a purplish, firm, fairly well encapsulated tumour was encountered. It was possible to separate the tumour from the surrounding neural tissue. Total renloval of the mass, which was in the posterolateral portion of the cord near the dorsal root entry zone was accomplished, and the tumour did not seem to have any continuity with the posterior root. Microscopic examination revealed a dense cellular mass of bipolar spindle-shaped cells arranged in palisades. Two weeks after operation, volitional movement of both legs was noted and superficial sensations were also improving. On examination six months after operation, he was able to walk unaided for a short distance and had good function of both hands with no sphincter disturbance. There has been debate concerning the origin of the intramedullary spinal schwannoma, and various hypotheses have been advanced to explain the occurrence of this tumour. Schwann cells have been found along the endomedullary perivascular nervous plexuses,' I or along some aberrant endomedullary peripheral fibres9 in the spinal cord. Mason4 outlined the role of the so called "critical area" as source of the tumour. This area corresponded to the point where the posterior roots lose their sheaths on penetrating the pia mater, and could be the origin of these tumours. They might arise from pial cells, considered to be of neuroectodermal origin, which might be transformed into schwann cells, or schwann cells may accompany the spinal root inside the spinal cord for a short distance. The possible differentiation of multipotential mesenchymal elements of central nervous system into schwann cells has also been hypothesised.'° It seems more likely that the neoplasm in