Utility of surgical tumor resection for normal-pressure hydrocephalus associated with spinal schwannoma in the cauda equina: A case report and review of the literature

INTRODUCTION AND IMPORTANCE: Generally, schwannoma increases the concentration of protein in cerebrospinal fluid (CSF) and causes normal-pressure hydrocephalus (NPH) due to absorption disorders of CSF. Cases of NPH caused by spinal schwannoma in the cauda equina are very rare. Here, we report a case of spinal schwannoma-related NPH in the cauda equina successfully treated by surgical resection alone. CASE PRESENTATION: A 78-year-old man presented with a 3-month history of gradually worsening memory disturbance. Neurological examination on admission showed dementia, hemiparesis of the left lower limb and gait disturbance. Computed tomography (CT) of the head revealed ventricular dilatation. CSF pressure was 150 mmH(2)O. CSF analysis showed a normal cell count and a highly elevated protein level (3842 mg/dL). Magnetic resonance imaging (MRI) of the lumbar spine demonstrated an enhanced intradural extramedullary mass in the cauda equina at the L3-L4 level. We suspected schwannoma causing NPH and tumor resection with posterior L3–4 laminectomy was performed as a priority. Marked recovery of cognitive dysfunction and gait disturbance was evident postoperatively, and CT 4 months later showed narrowing of the ventricles. CLINICAL DISCUSSION: If NPH due to spinal schwannoma is suspected as a result of lumbar puncture in a patient with dementia, confirmation of spinal schwannoma by lumbar MRI is absolutely necessary, and tumor resection alone may avoid unnecessary shunt placement. CONCLUSION: These findings suggest that if a spinal schwannoma located in the cauda equina causes symptoms due to NPH, removal of the tumor should be considered a priority.