Spinal coning after lumbar puncture in prostate cancer with asymptomatic vertebral metastasis: a case report. A 60-year-old man was admitted to our hospital for complete urinary retention. Prostate cancer was diagnosed and anti-cancer chemotherapy was administered. Regression of prostatic enlargement was appreciated and difficult urination improved. At 6 months after the initial treatment vertebral metastasis of T10-11 was noted on a bone scintigram but there were no symptoms induced by bone metastasis. Orchiectomy was performed with the patient under lumbar anesthesia. Complete paralysis of both lower extremities occurred postoperatively. Computerized tomography and myelographic findings demonstrated complete subarachnoid block with an extramedullary spinal cord tumor. It was concluded that traction on the spinal cord producing neurological deterioration (spinal coning) occurred after removal of the cerebrospinal fluid by lumbar puncture. 