[A case of spinal dural arteriovenous fistula associated with normal pressure hydrocephalus]

A 62-year-old male presented with urinary incontinence, gait disturbance and dementia for 6 months. Neurological examination revealed severe paraparesis (1/5), sensory disturbance below Th10, neurogenic bladder and absence of patellar and achilles tendon reflexes. CT scan showed mild brain atrophy and symmetric ventriculomegaly with periventricular lucency. Magnetic resonance imaging (MRI) showed a linear flow void lesion on the dorsal surface on the back of his swollen lower spinal cord. Myelography showed a filling defect and flow disturbance of contrast medium in lower thoracic levels, suggesting the presence of adhesive arachnoiditis. Spinal angiography demonstrated a fistula formation between dural branches of bilateral L4 lumbar arteries and ventral spinal and radicular veins on the surface of the dura mater of L4/5 levels. Considering his past history of repeated lumbar puncture for tuberculous meningitis at the age of 22 years, a diagnosis of acquired spinal dural arteriovenous fistula probably due to repeated lumbar puncture was made. Fistulas were embolized with N-butyl cyanoacrylate. And normal pressure hydrocephalus was treated by ventriculoperitoneal shunt. Follow-up CT scans showed a decrease of the size of the ventricular system. Etiology of acquired spinal arteriovenous fistula has been reported. In the case, repeated lumbar puncture may be a possible cause of arteriovenous fistula in the lower spinal dura mater. However, the reason why it took so long to form a fistula after the lumbar puncture remains to be elucidated. We suggest that an increased protein concentration due to disturbance of cerebrospinal fluid flow might be a cause of normal pressure hydrocephalus (NPH).