The patient came to the clinic 14-October-2020 complaining of difficult walking with numbness big toe right foot and bilateral sciatica more the right for more than a month with progressive course. The patient has arterial hypertension for one year.

On examination: The patient is limping with no scoliotic stance. There is weak dorsiflexion right foot 3/5 and left foot -3/5. There is hypalgesia right L5 root. There is severe OA right knee with effusion and pain.

The patient was sent for investigations and MRI lumbar spine, showing severe LCS L3-4, L4-5. Dynamic studies ruled out overmobility. MRI of the right knee showing synovitis with mucoid degeneration of ACL and meniscal tear of posterior horn of medial meniscus. ESR was 40 mm/h. RF Ig M was 21 IU/ml, Uric Acid was 7.9 mg/L. Urine for CXS showed E.Coli sensitive to Zinnat. The patient was sent for cardio consultation . The patient was advised to stop anticoagulants for 10 days before surgery and treat all associated problems.

Wide decompressive laminectomy L4, lower half of L3 and upper half of L5 with foraminotomy both L4 and L5 roots.  Using MultiGen, bipolar motor stimulation of left L4 with 1.8 Volt and left L5 roots  was achieved with 1.8 Volts. Bipolar motor stimulation of right L4 with 2.6 Volt and right L5 roots  was achieved with 1.9 Volts. A bipolar pulsed mode RF with 42 Celsius, 240 sec, 2 Hz and 20 msec duration to both L4 and L5 roots  was achieved using 4 bended catheters 10 mm exposed length. Further bipolar motor stimulation of left L4 with 2.6 Volt and left L5 roots  was achieved with 1.7 Volts. Bipolar motor stimulation of right L4 with 2.6 Volt and right L5 roots  was achieved with 1.5 Volts. The patient was put in Reverse Trendelenburg position with Valsalva maneuver and hyperventilation. No CSF leak. Routine closure of the wound.

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

The stenosis in this case is a progressive one and surgery will prevent further deterioration of her neurologic status.

This is the 204th 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 severely affected nerve improved at the left L5 roots improved dramatically, but the right L4 root still the same.

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.