The patient came to the clinic 28-December-2019 with LBP for 10 years, numbness right foot for 3 years, then numbness and pain left foot for the last 4 months. Difficult walking the last 2 months with loss of sensation. Dripping of urine the last 6 months. MRI lumbar spine performed 24-Novembber-2019 showing tethered spinal cord at L3-4 level with small lipoma. The patient was operated for tethered cord at 4 years age at KHMC. There is a long ugly scar at the back of the patient.

On examination: The patient is limping with normal scoliotic stance and has weak dorsiflexion right foot 3/5, left foot 4/5 and planterflexion right foot -4/5. weak both quadriceps and iliopsoas muscles -4 in the right and 4/5 in the left. SLRS was 65 degrees with pain both sides. There is hypalgesia below the knees and wide perianal region extending more in the right.

The patient was sent for MRI of the brain and whole spine. There is no tonsilar herniation, but there is old vascular malformation of the left occipital lobe. The tethered cord with small lipoma behind L3-4 level.

Decompressive laminectomy of L3,4  lower part of L2 and upper part of L5 to expose the normal dura above and below to tethered area. The healthy dura above and below the lesion was exposed and followed until the margin of the pathologic dura. Sharp dissection of the dura circumferential to the border of the lipoma looking pathologic dura. All the running nerves were preserved and the lipoma was easily separated from the right side but it was needed to sharp dissect of the lipoma at the left lower part from the running nerves and dural sheet.  Using MultiGen, bipolar motor stimulation of all running nerves were achieved with 0.5 Volt. Stimulation of the spinal cord above the lesion was also achieved. The mass migrated up around 30 mm and all the pathologic non-neural bands were bisected. Using lyodura the dural defect was closed water-tightly with 4 zero nylon. The patient was put in Reverse Trendelenburg position with Valsalva maneuver and hyperventilation. There was oozing from the right lower corner, which was aided with further stitches. No CSF leak. Routine closure of the wound after removing the scar with cosmetic closure of the wound.

Smooth postoperative recovery. The power both legs normalized. She is sciatica free. She was sent to the ward.

The first surgery did not provide its final goal of untethering.

Instead of dissecting the non-harmful lipoma and the running inside of or along side roots, it is preferable to make circumferential incision of normally looking dura and inspect the tethering by non neural elements and look for its migration upward , then to water-tightly close the dura using artificial dura to avoid constriction. 

This is the 194th case using the BPRF mode with MultiGen. This procedure regained routine acceptance.  It became a usual part of the spine and peripheral nerves surgery. Click here for reference.

The running nerves above and below the lesion are acceptable in motor stimulation threshold, which denote excellent recovery.

With accumulation of data, it became clear that the irritated nerve with aberrant currents running in the C fibers up, not only causing no change or elevation of the required voltage to achieve motor response, but they could cause the preoperative weakness. Ablation of such currents results in facilitation of the motor response and improvement of function with disappearance of pain.

It is unclear why the roots have several motor response with different patients, despite the fact that the neurological status is the same and the anesthesia protocol also the same.

It could be that the nerve is recovering minute by minute after decompression and this can explain why the motor conductivity is improving after the BPRF application, which require 4 minute session in most cases.

After the 172d case, the elevation of motor stimulation above 5 V was abandoned to avoid delayed dural tear with subsequent CSF leak, which take place at the contact at the lower electrode shaft with the dura below the level of the axilla.