The patient was operated by me 21-June-2015 cervical canal stenosis, after what the upper limbs improved and slight improvement of the lower limbs. The patient came several times and in 05-June-2016 he could walk without crutches, but drop left foot was noted. The planterflexion both feet was normal and dorsiflexion right foot was 3/5. The patient then came 24-May-2017 telling that walking is deteriorating the last 2 months 

On examination, the patient is limping with exaggerated  scoliotic stance, walking bended anterior. SLRS was 70 degrees with tightness both sides. There is weak dorsiflexion right foot -3/5, weak planterflexion right foot 3/5, drop left foot with weak planterflexion left foot 3/5.

The patient was sent for investigations and MRI whole spine performed showing good alignment of the cervical spine, but severe stenosis L2-3, 3-4 and L4-5. Dynamic studies ruled out overmobility and Lab investigations were within normal limits. The patient was sent for cardio evaluation and to stop aspirin 10 days before surgery.

Decompressive laminectomy L3,4, lower half of L2 and upper half of L5 was achieved. Foraminotomy of L3,4,5 roots was performed both sides. Using MultiGen, bipolar motor stimulation of the right L4 was achieved with 1.5 V, the left L4 with 2.9 V. The right L5 was achieved with 4.3 V, the left L5 with 3.0 V but only planterflexion. A bipolar pulsed mode RF with 42 Celsius, 240 sec, 2 Hz and 20 msec duration to L4, L5 roots both sides was achieved using 4 bended catheters 10 mm exposed length. Further bipolar motor motor stimulation of the right L4 was achieved with 1.6 V, the left L4 with 2.8 V. The right L5 was achieved with 3.0 V, the left L5 with 2.6 V but only planterflexion. Routine closure of the wound.

Smooth postoperative recovery. The power of the right foot normalized and the planterflexion left foot regained full power, but the drop left foot remained. He was sciatica free. He was sent to the ward.

The patient still having an estimated postoperative recurrence around 7%, because the disc space is still not shallow.

This is the 126th 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 stimulation power of motor stimulation of the right L5 root before and after application was 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.

The drop foot of long-standing duration is less likely to recover.