The patient came to the clinic complaining of LBP with bilateral sciatica, more to the right with deterioration the last 5 months with numbness both feet and inability to walk more than 100 meters.

On examination, the patient is limping with exaggerated scoliotic stance. SLRS was 15 degrees with pain in both sides. There is weak dorsiflexion right foot -4/5, and dorsiflexion left foot 4/5.

The patient was sent for investigations and MRI lumbar spine performed the next day showing spondylolisthesis L3-4 with severe segmental stenosis. Dynamic studies confirmed the presence of spondylolisthesis L3-4. The patient was sent for cardio evaluation.

Skeletonization of the spinous processes of L3,4 and partial of L5. Check for instability was positive for L3 lamina. Transpedicular distraction reduction fixation of L3-4 was performed using OSI polyaxial screws 6.5x45 mm. The screws were checked by stimulation and 3 of them were not responding even to 8 V stimulation. The left upper screw showed motor response to 4.5 V. The screw was adjusted to be directed more lateral. Another attempt of stimulation was repeated and the same motor threshold was noted. Decompressive laminectomy of L3, 4 and upper third of L5 was achieved. Foraminotomy of L3,4 both sides was performed. The left L3 root was intact and the left pedicle of L3 was intact medial and inferior. Using MultiGen, bipolar motor stimulation of the right L3 root was achieved with 0.9 V. The left L3 was achieved with 0.9 V. The right L4 root respond to 0.9 V, the left L4 root respond to 0.9 V. Waiting 4 minutes the same procedure repeated and bipolar motor stimulation of the right L3 root was achieved with 1.2 V, the right L4 was with 1.3 V. The left L3 root respond to 0.9 V and the left L4 root respond to 0.9 V.  A bipolar pulsed mode RF with 42 Celsius, 240 sec, 2 Hz and 20 msec duration to both L3 and L4 roots was achieved using 4 bended catheters 10 mm exposed length in 2 stages. Further bipolar motor stimulation of the right L3 root was achieved with 0.1.2 V, the left L3 was with 0.5 V. Right L4 root respond to 1.3 V and the left L4 root to 0.9 V. Cross connector Nemesis 38-50 mm was applied. Harvested bone was applied lateral to the bended rods. All stages of surgery were performed with C-arm guidance.. Routine closure of the wound.

Smooth postoperative recovery. The power of both feet normalized and she was sciatica free. She was sent to the ward.

The patient has several problems, which require surgical correction, stenosis at 2 levels and spondylolisthesis.

This is the 117th 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.

It still unclear to evaluate the differences of pre and post application motor responses. The only sure thing that it tells that the electrodes did not migrate during the procedure and the nerve is functioning properly. Here there was considerable improvement of the threshold of stimulation power of motor stimulation of all the involved roots.

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. This trail was performed intentionally to confirm or exclude such this conclusion. Here we noticed that the motor response of the nerves improved after first stimulation, confirming that the improvement came as a result of previous stimulation and BPRF still adding further improvement.

It is well known that if the monopolar stimulation of the screw is absent with 8 V, it means that the screw is away from the neural elements. But in this case the left upper screw showed response to 4.5 V. The fact that the direct bipolar stimulation of the same involved root showed good response to 0.4 V confirming that the 4.5 V could be explained by leakage of currents through sufficient distance without violating the walls of the pedicle.

The difference in motor stimulation of the right side mostly due to change of electrodes positioning.