Monosodium urate crystal deposition in joints and periarticular connective tissue is a characteristic feature of chronic gout. Tophi are typically found in the joints of the appendicular skeleton; extraskeletal tophi are less commonly seen. Reports of tophi in the axial skeleton are rare, and there are only 6 reports of tophaceous deposits causing neurologic symptoms secondary to spinal cord or nerve root compression. We report the first case of radiculopathy caused by a tophus in a patient who did not have a history of polyarticular, tophaceous gout.Case report. The patient, a 76-year-old woman, was in good health except for low back pain of several years duration, which had increased in severity in the 6 months prior to her admission. The pain radiated to her right buttock and right leg. Right lower extremity weakness and numbness ensued, resulting in footdrop and inability to ambulate. Pain in the right buttock had been noted several weeks before admission. She de- GOLDENBERG nied having any bladder or bowel problems. On initial evaluation, she denied a history of arthritis, trauma, or kidney stones.Results of the musculoskeletal examination were unremarkable, and no tophi were present. Neurologic examination demonstrated weak plantar and dorsiflexion on the left, absent on the right. Pinprick and light touch sensations were diminished over the dorsum of the right foot. The ankle jerk reflex was absent on the right, but all other reflexes were normal.Laboratory investigations demonstrated the following: peripheral blood leukocyte count of 9,800 cells/mm3 with a normal differential cell count, hematocrit of 41%, platelet count of 373,000/mm3, blood urea nitrogen value of 47 mg/dl, creatinine level of I .2 mg/dl, uric acid value of 8.6 mg/dl, glucose level of 150 mg/dl, and Westergren erythrocyte sedimentation rate of 80 mm/hour.Roentgenograms of the back revealed degenerative changes of the lumbar spine and osteophyte formation at L3 and L4; there was no evidence of bone erosions, disc space narrowing, or vertebral collapse. A myelogram revealed obliteration of the L4-L5 neural foramina, with ventral indentation of the dural sac at that level. A computerized tomogram of the lumbosacral spine showed normal results. A technetium bone scan demonstrated no abnormal uptake in the spine. An electromyogram showed evidence of an L5-S 1 radiculopathy. Lumbar puncture yielded clear cerebrospinal fluid with a glucose level of 58 mg/dl, protein 34 mg/dl, 15 red blood cells, and no white blood cells.The patient underwent a decompressive laminectomy at L5. At surgery, the L5 pedicle, facets, and