Nerve Root Herniation Secondary to Lumbar Puncture in the Patient With Lumbar Canal Stenosis

Study Design. A very rare case of nerve root herniation secondary to lumbar puncture is reported. Objective. To describe the characteristic clinical features of this case and to discuss a mechanism of the nerve root herniation. Summary of Background Data. There has been no previous report of nerve root herniation secondary to lumbar puncture. Methods. A 66-year-old woman who experienced intermittent claudication as a result of sciatic pain on her right side was evaluated by radiography and magnetic resonance imaging, the results of which demonstrated central-type canal stenosis at L4–L5. The right sciatic pain was exacerbated after lumbar puncture. Myelography and subsequent computed tomography showed marked stenosis of the thecal sac that was eccentric to the left, unlike the previous magnetic resonance imaging finding. Results. At surgery, a herniated nerve root was found through a small rent of the dorsocentral portion of the thecal sac at L4–L5, presenting a loop with epineural bleeding. The herniated nerve root was put back into the intrathecal space, and the dural tear was repaired. Conclusion. Lumbar puncture can be a cause of nerve root herniation in cases of lumbar canal stenosis. The puncture should not be carried out at an area of stenosis.