The patient came to the clinic 18-May-2019 complaining of chronic LBP since he was 14 years age with intermittent course. 5 years later he got left sciatica. The last 8 months got bilateral sciatica more the left. MRI lumbar spine performed 15-May-2019 showed bilateral L5-S1 isthmolysis with fluid in the L5-S1 joints.

On examination, the patient in agonizing pain, limping with exaggerated scoliotic stance. SLRS 85 degrees right side with pain and 85 degrees left side with pain. There is no sensory nor motor deficit.

The patient was sent for investigations and dynamic studies showed I degree spondylolisthesis and CT-scan constructed with ORSVisual showed bilateral L5-S1 isthmolysis.

The patient then came 26-August-2021 with dramatic deterioration the last 20 days with exacerbation of the left sciatica and weak dorsiflexion left foot 4/5 and SLRS was 80 degrees both sides with pain. The investigations repeated and the same data were achieved.

Skeletonization of L5, lower half of L4 and upper sacrum the lateral processes of L5 were seen. Using ERISMA-LP EVOLUTION system, transpedicular screws, polyaxial to upper sacrum and monoaxial to L5 body were inserted 6x40 dimensions. Using MultiGen the right screws and lower left responded brisk at 4.0 Volts. Foraminotomy both S1 roots showed that the right S1 screw is in bone but 2 mm near the medial wall, for what the screw was reinserted 5 mm lateral to the first. Motor stimulation still showing response but to less degree. The root is away from the screw shaft. Bipolar stimulation of the right S1 root was achieved with 0.3 Volts. It became clear that the root is abnormally responding to any stimulation and the screw is far enough. The left lower screw also repositioned 5 mm lateral and no response to 4 Volts. The right L5 screw was also repositioned lateral and no monopolar stimulation even with 4 Volts.  Using bended rods fusion of the area was achieved and the bony material of the removed flail lamina was used lateral to the rods. The lamina of of L5 is flail, it was totally removed. Using MultiGen, bipolar motor stimulation of the right S1 root was achieved with 0.3 Volts. The left responded to 0.7 Volts. A bipolar pulsed mode RF with 42 Celsius, 240 sec, 2 Hz and 20 msec duration to both S1 roots  was achieved using 4 bended catheters 10 mm exposed length. Further bipolar motor stimulation of the right L5 root was achieved with 0.3 Volt and the left with 0.6 Volt. The patient was put in Reverse Trendelenburg position with Valsalva maneuver and hyperventilation. No CSF leak. A fat tissue with pedicle was used to cover the dura to minimize the postoperative scar formation and prevent postoperative CSF leak. Routine closure of the wound. Smooth postoperative recovery. The power of the left foot improved. He was sent to the ward.

Too early now.

This is the 227th 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 the threshold of motor stimulation of the affected nerve showed dramatic improvement after BPRF.

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.

This case is a demonstration that in rare cases when the root is responding to very small currents, it could mislead the surgeon that the screws are violating the medial wall of entry, despite the fact that the screws are in acceptable position and forces the surgeon to reposition the screws more far as in this case.