[A case of solitary syringobulbia].

A case of solitary syringobulbia without syringomyelia diagnosed by MRI was reported. A 63-year-old female, who had a history of progressive gait disturbance for 9 months, was admitted to our department because of severe headache. Neurological examination revealed that the patient was suffering from right pyramidal sign as well as left deep sensory disturbance without apparent impairment of cranial nerves or nystagmus. The somatosensory evoked potential stimulated by the left median nerve showed delay in latency and low amplitude, however, the auditory brainstem response showed normal records bilaterally. A syringobulbia associated with platybasia, basilar impression, obstructive hydrocephalus and Arnold-Chiari malformation was diagnosed by the neuroradiological examinations including plain X-ray films of the skull, CT scan and MRI of the brain. Subsequent to the decompression around the cisterna magna by suboccipital craniectomy and laminectomy of the atlas, the opening of the Foramen Monro which was obstructed by a thick membrane was carried out, and prevention of communication between the fourth ventricle and the syrinx was accomplished by using a piece of muscle. This operative procedure was thought to be compatible with Gardner's operation for syringomyelia. The patient showed gradual improvement of gait disturbance as well as headache 3 months after surgery, and this neurological improvement was proved by decrease in the size of the known syringobulbia on MRI, and by normalized somatosensory evoked potential stimulated by the median nerve. Pathophysiology of the solitary syringobulbia with relatively acute onset of the neurological symptoms was assumed to have taken place in the following manner.(ABSTRACT TRUNCATED AT 250 WORDS)