Cauda Equina Syndrome Caused by Pseudogout Involving the Lumbar Intervertebral Disc
On September 19, 2011, a 59-yr-old male presented with severe lumbago and progressive neurological symptoms, including right-sided foot drop, numbness at both legs, and residual urine sensation. The patient felt a sudden onset of aggravated low back pain (LBP) after sleeping uncomfortably with leaning his body backward in his car seat 2 days prior to presentation. After that time, he experienced numbness in both legs, weakness on his right leg, urinary retention, and a worsening limping gait. He had undergone an uncomplicated L4-L5 discectomy 15 yr prior, and had a 2-month history of LBP, which was being managed conservatively. He had no arthralgia and no history of peripheral joint disease. His body temperature was 36.5℃ and he had no history of a recent febrile episode or febrile disease. On examination, he had weakness of 3/5 of the right ankle and big toe dorsiflexion, and saddle hypesthesia to light touch and pin-prick. A foley catheter was placed and 700 mL of residual urine was noted. Magnetic resonance imaging (MRI) of the lumbar spine revealed an extradural heterogeneous mass-like lesion in the anterior epidural space at the intervertebral disc space of L4-L5, which was severely compressing the thecal sac (). Computed tomography (CT) showed a patchy calcified lesion (). At this time, we did not know whether the lesion found on the MRI was a herniated disc with calcification or an extradural tumor.\nSince we were under the impression that this was a case of CES, an emergent surgery was performed to decompress the thecal sac. We performed a total laminectomy at L4 and a posterior interbody fusion at L4-L5 was performed. During the operation, white to pink firm tissues in the anterior epidural space were found to be compressing the thecal sac. As we traced the margin of the lesion, we found some portion of the lesion was in continuity with the disk space through the annular defect. No neoplastic cells were found on the frozen pathological section. We assumed that the epidural mass-like lesion in the MRI was extruded, sequestered, and partially calcified nucleus pulposus. So after incision around the annular defect, we removed the epidural mass-like lesion and intervertebral disc all together in a piecemeal fashion. However, biopsy of the intervertebral disc and epidural mass-like lesion was determined to be CPPD deposits consistent with pseudogout (). Postoperatively, his symptoms of saddle hypesthesia and numbness on both legs were improved markedly. He regained his feeling of micturition and was able to void all urine on his own. He had no pain or abnormal calcifications on radiography of other joints. Results of blood tests, which included uric acid, calcium, phosphate, and a thyroid function test were all within normal limits. He was followed up for 6 months after the surgery. At the 6 month follow-up, his urination was nearly normal and his right ankle dorsiflexion had improved to a motor power of 4+/5.