The patient came to the clinic 05-May-2010 complaining of LBP for 5 months with bilateral sciatica, more to the right. MRI lumbar spine performed 06-Jaanuary-2010 showing severe LCS L4-5. He could walk for less than 300 meters. SLRS at that time was 60 degrees right side with pain, hypalgesia both L5 roots territory and weak dorsiflexion both feet -4/5. The patient then disappeared and came back 18-February-2017 with clinical deterioration and inability to walk more than 100 meters, LBP and bilateral sciatica with intermittent claudication. MRI lumbar spine performed 25-July-2016 showing severe segmental stenosis L4-5. Dynamic studies showing II degree spondylolisthesis L4-5. The patient now having diabetes mellitus for 3 years with arterial hypertension.

On examination, the patient is not limping with exaggerated scoliotic stance and walking bended anterior. SLRS was 50 degrees with pain right side and 15 degrees with pain in the left. There is weak dorsiflexion both feet -4/5. The patient then was admitted 22-May-2017 and new MRI with dynamic studies and lab investigations were performed and cardio consultation was achieved.

Skeletonization of the spinous processes of L3,4 and L5. Check for instability was positive for L4 lamina. Transpedicular distraction reduction fixation of L4-5 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 right lower screw showed motor response to 1.5 V. The screw was adjusted to be directed more lateral. Another attempt of stimulation was repeated and the right upper screw showed response to 3.4, for what it was repositioned more lateral and more vertical. The three screws now not responding even to 8 V except the right lower screw responding to 4.5V. Decompressive laminectomy of L4, and upper third of L5 was achieved. Foraminotomy of L5 roots both sides was performed. The right L5 root was intact and the right pedicle of L5 was intact medial and inferior. Using MultiGen, bipolar motor stimulation of the right L5 root was achieved with 0.8 V. The left L5 was achieved with 1.5 V. A bipolar pulsed mode RF with 42 Celsius, 240 sec, 2 Hz and 20 msec duration to both L5 roots was achieved using 4 bended catheters 10 mm exposed length in 2 stages. Further bipolar motor stimulation of the right L5 root was achieved with 0.8 V, the left L5 was with 1.4 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 he was sciatica free. He was sent to the ward.

The patient has several problems, which require surgical correction, stenosis at 1 levels with spondylolisthesis.

This is the 120th 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.

We stopped the previous experiments confirming that there is no harm of the BPRF application and will keep it for future drop foot as treatment.

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 0.8 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 upper right screw which in the first stage of stimulation, did not respond to 8.0V, but later got response to 3.4V could be anesthesia protocol troubleshooting. The propofol could be to blame.

These data showing that the motor response of the screws could be a parameter showing that the far the root from the screw, the root will not respond even to currents more than 8 V, even the anatomical structures are not violated.