The patient was operated by me 17-October-2021 for fracture of the right sacroiliac joint due to complicated proton beam therapy for malignant chordoma. Fixation was done and the patient improved and he could walk. Direct attack for the chordoma at that time was avoided due to swelling of the back due to radiation, which predicts the possibility of no heeling of the wound and put in observation and Keytruda. The patient was checked twice every year and was stable, but clinically showed hypalgesia of the perianal region both sides since 2023. The patient then came 23-November-2025 complaining of pain of the left side of the pelvis  down to the left gastrocnemius muscle with left sciatica. Numbness of the left foot for 2 months.

On examination, the patient in pain, limping with exaggerated scoliotic stance with difficult walking. SLRS was 90 degrees right side without pain and 70 degrees with pain left side. There is analgesia in leg down from the below the knee extending the left perianal region.

The patient sent for investigations, which done the same day showing progression of the tumor to the left side with enlargement of the tumor size 147% in comparison to the last one. The tumor destroyed the left sacroiliac junction and expanded to the left paraspinal space. Whole body PET-ct-scan done to rule out metastasis which was negative.

The aim of surgery at this stage is to try to resect the tumor, since the skin is healthy. Midline incision over the sacrum and the L4, 5 laminae. The tumor was destroying the left part of the sacrum and the tumor was growing out the bony boundaries, pushing the neural structures to the right. Piece-meal resection of the tumor, which had multicompartments, intermingled with nerves. Using bipolar stimulation both S2 ,3 and S4 were identified and preserved. The nerves were severely adherent to the tumor dirt and the dirt was left  to preserve the functional integrity of the nerves. It was possible to see the anterior border of the tumor perforating the and anterior sacral wall. There was CSF leak at the S1 level from a small tear, which was stitched by 5 zero nylon. Valsalva maneuver was applied and no CSF leak.  Using Armada iliac screws 8.5X 80 mm to the right S1 and 8.5X70 mm to the left  and 2 transpedicular screws 6.5X45 mm to the L4 body, fusion and stabilization of the spine and the pelvis was archived with bended rods and cross connector. Attrax bone graft 20 cc were applied lateral to the rods. It was noted that the roots in the left side were responding to stimulation better than the right.

Routine closure of the wound. Smooth postoperative recovery. The power of the feet not affected. the sensation to the left leg and left perianal area recovered after the surgery. He was sent to the ward.

Too early now.

The chordoma get out of control during the last 4-5 months for what surgery was mandatory.

This is the 294th case using the MultiGen. This procedure regained routine acceptance.  It became a usual part of the spine and peripheral nerves surgery. Click here for reference.

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 was 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 5 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 or above the level of the axilla.

Before doing motor stimulation in peripheral nerve surgery with tourniquet. always release the tourniquet before performing motor stimulation.