The patient was operated by me 05-March-2018 for extruded disc L2-3. Then he came to the clinic 04-July 2021 complaining of numbness of the left anterior thigh. MRI of the left knee done 2 months ago showed meniscal tear but his knee recovered but still feeling strange sensation with occasional fall.

On examination, the patient feeling pain in the left hip region with strange feeling of the left anterior thigh. SLRS was 75 degrees left side with tightness. There is hypotrophy of the left quadriceps muscle and the iliopsoas left side. No signs for meralgia paresthetica.

The patient was sent for investigation and MRI of the lumbar spine showed extruded disc L3-4 with left foraminal occlusion. MRI of the pelvis showed acute avascular necrosis left hip and dynamic studies ruled out overmobility. He was sent for cardio consultation.

The C-arm was used to verify the L3-4 level. Left L3-4 hemiflavotomy with extended foraminotomy left L4 root. The extruded disc was removed lateral to the axilla and left sided intradiscal cleaning L3-4 was achieved.  Using MultiGen, bipolar motor stimulation of the left L4 root was not achieved even with 3.5 Volts, A bipolar pulsed mode RF with 42 Celsius, 240 sec, 2 Hz and 20 msec duration to the left L4 root  was achieved using 2 bended catheters 10 mm exposed length. Further bipolar motor stimulation of the left L4 root was achieved with 2.2 Volts. The patient was put in Reverse Trendelenburg position with Valsalva maneuver and hyperventilation. No CSF leak. A piece of fat tissue was used to cover the root territory to minimize the postoperative scar formation. Routine closure of the wound. Smooth postoperative recovery. The power of the right foot still the same. He was sent to the ward.

MultiGen

The patient after full recovery showed normalization of the power of the left quadriceps and iliopsoas muscle.

There is still an estimated postoperative disc recurrence around 7%, since the disc space is not completely shallow.

This is the 215th 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 nerves did not change dramatically 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.