The patient was operated by me 03-January-2019 for extruded disc L5-S1 and was discharged the next day. Upon visiting the clinic 10 days after surgery, there was 10 cc collection of CSF from the wound. Lasix was administered but the collection was increasing over the time and the wound had collection about 30 cc which was evacuated 20-January-2019.

On examination: The power of both feet is normal and complaining of pain in lower sacrum. MRI lumbar spine performed 21-January-2019 showing the CSF leak at the level of the operation and no recurrence of the disc of L5-S1 level.

The previous wound was opened and exploration of the dura was undertaken to see the source of the leak. There was a dural defect at the lower most of the dura away from the axilla near the scar with ligamentum flavum. The bony lower defect around the dural defect was extended to put repair stitches using 6 zero nylon. The patient was put in Reverse Trendelenburg position with Valsalva maneuver. No CSF leak. Surgicele was added and Glue-Bran was irrigated over the Surgicele to provide more strong wall over the repaired dural site. The patient was put in Reverse Trendelenburg position with Valsalva maneuver another time. No CSF leak. Routine closure of the wound.

Smooth postoperative recovery. He was sent to the ward.

There is a new phenomenon that there is delayed CSF leak which was not present during surgery, but taking place several days after surgery. Three cases were observed among the 173 cases where BPRF was applied. The common sign among them, that the motor stimulation was very high reaching above 6V. This fact, confirming that the affected root was severely anatomically damaged before surgery and despite the fact we use bipolar stimulation, we must with caution elevate the threshold of stimulation above 5.5V to avoid thermal damage to the involved dural sheet of the root. It could be that the effect of such event causing the appearance of such dural tear several days after the surgery.