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Neurosurgery

OPERATIVE PROCEDURE:

PREOPERATIVE DIAGNOSIS: RIGHT-SIDED TRIGEMINAL NEURALGIA REFRACTORY TO MEDICAL CARE

POSTOPERATIVE DIAGNOSIS: RIGHT-SIDED TRIGEMINAL NEURALGIA REFRACTORY TO MEDICAL CARE

ANESTHESIA: GENERAL ENDOTRACHEAL ANESTHESIA

PROCEDURE: On call to the operating room, the patient received 1 g of vancomycin and intravenous Soluset. She was taken to the operating room where arterial and venous lines were placed by the anesthesiologist. General endotracheal anesthesia was then performed. The patient was administered 80 mg of gentamicin intravenously. Foley catheter was placed under sterile conditions. T.E.D. stockings and Venodyne boots were placed on the lower extremities.

The patient was then given 500 mL of 20% mannitol intravenous Soluset. She was placed on the operating room table in the supine position; a rolled towel was placed under the right shoulder. A Mayfield head clamp was fixated with 60-pound inches of pressure. The occipital pins were placed in the left occipital region and a frontal pin was placed over the lateral aspect of the right supraorbital ridge. With 60-pound inches of pressure, the head was fixated now into position, turned to the left, with the chin almost to the point of the left shoulder. The neck was noted to be supple. Slight flexion was performed, but it was possible to place 2 fingers underneath the chin at all times.

With the fixator in position, it was now possible to visualize the right suboccipital region. This area was shaved, prepped and draped in the usual sterile manner. The skin was infiltrated with a solution of 1% lidocaine and epinephrine.

The incision was now made extending from a point parallel to the upper aspect of the pinna, proximally to 2 fingerbreadths medial to the right mastoid, and extending inferiorly to the neck for a total length of approximately 14 cm. The incision was extended through the skin, subcutaneous tissues and through the muscular layers down to the periosteum superiorly. A subperiosteal dissection was performed using Bovie and periosteal elevator and cut down into the nuchal musculature. The self-retaining retractors were positioned. The entire suboccipital bone on the right side was thereby exposed, as was the mastoid bone.

Now the Elan-E drill was used with the perforator to make a bur hole in the suboccipital bone. Using a dental instrument and the Rhoton microsurgical dissectors, the dura was separated from the inner table of the skull. A sequential suboccipital craniectomy was performed using a combination of Leksell rongeur and Kerrison rongeur. The craniectomy was carried from approximately the lateral third of the cerebellum laterally to a point up to the sigmoid sinus. The craniectomy was carried superiorly to the transverse sinus and inferiorly almost to the floor of the posterior fossa. The dura was noted to be very tenuous through most of this area, and there were several durotomies in this segment as this was such thin tissue.

Once sufficient exposure had been accomplished at both the transverse and sigmoid sinus, incision was made into the dura and extended in a C-shaped fashion centered toward the asterion. A middle incising incision was carried straight toward this point and thereby 2 leaves were folded, one superiorly and one laterally.

Up to this point, the operative procedure had been carried using loupe magnification and fiberoptic headlamp. Now these were removed and the operating microscope was draped, brought into the field, and used for the remainder of the operative procedure. The dural leaves were tacked superiorly using 4-0 Surgilon sutures.

Using a hand-held retractor to support the cerebellum medially, it was possible now to identify the 7-8 complex and then progressing superiorly to identify the tentorium. Arachnoidal adhesions to the tentorium were bipolar coagulated and sharply divided. The dissection was carried posteriorly and the 5th nerve identified superior and anterior to the 7-8 complex. The petrosal vein was noted just superior to the 5th nerve.

Under high microscopic magnification, it was now possible to identify that there are 2 vessels in close approximation to the 5th nerve. One, a large branch of the superior cerebellar artery, was emerging from in front of the trigeminal nerve and coming superiorly. This was deforming the trigeminal nerve and pushing it dorsally. The 2nd vessel was a large vein that was running parallel to the inferior portion of the trigeminal nerve and was compressing it only slightly. The petrosal vein was not compressing the nerve at any point.

The dissection was carried along the nerve proximally to the root entry zone and the origin of the nerve in the pons. There was no pressure at this area, but only the artery and vein as described above, which were both located within 1 cm of entry of the nerve into the pons. Now using Rhoton microdissectors and micronerve hooks, it was possible to mobilize the arterial loop away from the nerve. It was noted that each time this was displaced back, once the vessel was let go, it would flip back beneath the nerve. It was, therefore, not possible to keep it freely away from the 5th nerve.

Now, Teflon felt was brought into the field and cut into very small wisps. This was now wedged between this arterial loop of the superior cerebellar artery and the trigeminal nerve. Several pieces were fashioned between these so as to completely separate the nerve from the artery.

Next attention was directed to the inferior portion of the nerve where it was noted to be in close approximation to the vein. Again, several pieces of Teflon felt were wedged between the artery and the vein thereby separating these 2 structures. There was no other point of significant vascular compression at any point along the nerve, which was examined in its entirety. The area was irrigated with saline, and there was no bleeding noted.

A piece of Gelfoam was now placed over the area of the incised dura, which could not be closed in a watertight fashion. The dural leaves were folded over and loosely reapproximated. The 2nd layer of Gelfoam was placed exterior to the dura. Now the operating microscope was removed.

A cranioplasty was now performed in the following manner: A piece of titanium mesh was cut to the size and shape of the craniectomy and placed just under the craniectomy edges. The edges of the mastoid bone were copiously waxed with bone wax. Methyl methacrylate was prepared according to standard procedure, and as it hardened, it was placed into the craniectomy defect and molded and contoured so as to completely fill this area. As the acrylic hardened, it was copiously irrigated.

Now the self-retaining retractors were removed. The muscle layers were reapproximated with interrupted 2-0 Surgilon sutures. The fascia was reapproximated with closely spaced interrupted 2-0 Surgilon sutures. A medium Hemovac drain had already been placed in a subgaleal plane and sutured to the skin. The subcutaneous layers were closed with buried interrupted 3-0 Vicryl sutures. Surgical staples were used to reapproximate the skin edges. A dressing was applied.

The patient was removed from the Mayfield head clamp, and placed in the supine position. She was extubated in the operating room and brought to the recovery room in stable condition, moving all extremities and following commands.

OPERATIVE PROCEDURE:

FINDINGS: Subligamentous fragment with compression of origin of left L5 nerve root.

PROCEDURE:The patient was intubated by the Department of Anesthesia and carried under satisfactory general endotracheal anesthesia throughout the procedure. He was then turned into the prone position on the operating room table and placed in the Codman spinal frame. Pressure points were padded and the lumbar region was shaved. Initially prepared, a spinal needle inserted into the low back at L4-5 by palpation; indeed, first x-ray confirmed that this was the L4-5 level.

The needle was withdrawn, the skin was scratched and formal prep and drape were performed and 1% lidocaine was infiltrated in the midline.

A 2-inch incision was fashioned with a #10 blade. This was carried down through subcutaneous adipose tissue, and a graft of deep adipose tissue obtained for later use as a neuroplasty fat graft.

At this point, self-retaining retractor was placed deeper and electrocautery was utilized to incise lumbodorsal fascia in the midline. Paraspinous takedown was performed at this point utilizing electrocautery, Cobb's, twisted sponge, and fingertip dissection, exposing the lamina of L4, the lamina of L5, and the intervening facette. Ligamentum flavum was exposed, and Taylor self-retaining retractor was placed supporting the muscles laterally. This gave excellent exposure to ligamentum flavum.

It is worth noting that despite the partial collapse of the L4-5 disk space seen on x-rays and magnetic resonance imaging scans, and despite the age of the patient, i.e. 60, the patient actually had a very generous interlaminar distance, and actually his tissues appeared very young and pliable.

Ligamentum flavum at the superior aspect of L4-5 was opened in several layers with curettes, and then resected utilizing a Kerrison. Exploration within the canal with a Penfield #4 by palpation revealed that I was at the L4-5 disk space. I was able to remove a bit of the inferior aspect of L4, a bit of the superior aspect of L5 to give better exposure, and did a medial facetectomy as well with a Kerrison,in order to achieve better exposure in the canal.

A second x-ray was performed, at this point, with the tip of the Penfield #4 at the superior aspect of the L4-5 disk space. This confirmed I was at the appropriate level for surgery.

Prior to this, the surgical procedure had been performed utilizing the headlight and loupe magnification. These were removed and the operating microscope brought into the field. The bulk of the procedure was performed under microscopic magnification.

Under high power, I proceeded to dissect within the spinal canal, and carefully cauterized and incised with microinstruments, including the FD-43 microdissector, the epidural fat, displacing the fat superiorly and inferiorly, and dissecting all the way down to the vertebral body. I exposed the L4-5 disk space and the origin of the L5 nerve root. The origin of the L5 nerve root was right at the lateral aspect of the L4-5 disk space, where there was a focal subligamentous disk herniation, and it was clear that this had been compressing the origin of the L5 nerve root prior to the dorsal decompression.

Nerve root and thecal sac were carefully supported medially with Cottonoid pledgets. At this point, I incised the posterior longitudinal ligament and annulus of the disk. Immediately produced was a fragment of about 1 x 1 cm, which was a subligamentous fragment which was immediately underneath the origin of the L5 nerve root. This came out in 1 piece and was the piece that had primarily been compressing the L5 nerve root.

I proceeded now to enter the disk space itself, and removed a moderate amount of dried out, inspissated disk material, along with associated cartilaginous end-plate, which came off very easily. This was noted to be very dried out, consistent with the collapsed disk space seen on the MRI scan. Given the narrow disk space, which would only accommodate a narrow pituitary and not even a medium pituitary, I removed from this disk space quite a bit of disk material. Indeed, I ended up with a large cavity in the disk space, in which I could probe with the dental tube, pituitary, etc., and document excellent decompression of the centrum disk space.

Irrigation was performed throughout the procedure, especially through the disk space with antibiotic-containing solution. I could now document complete decompression of the thecal sac as well as the left L5 nerve root. I could pass the dental tool above and below the L5 nerve root at its foramen, go up and down the spinal canal, cross the midline, etc., including laterally in the region of the exited L4 nerve root and document excellent decompression.

A neuroplasty was now performed by taking the previously harvested fat and placing it over the thecal sac and L5 nerve root origin. Closure was accomplished in layers using 2-0 Surgilon for lumbodorsal fascia, 2-0 Surgilon for deep subcutaneous tissue, inverted 3-0 Vicryl for superficial subcutaneous tissue and Steri-Strips for skin. The incision length was 2 inches.

The patient was returned to the supine position after first placing the sterile dressing. He was then extubated and transported to the recovery room, where he was found to be awake, alert, comfortable and moving extremities well.

Terms: Codman spinal frame, Cottonoid™ (Codman), foramen, foraminotomy, Kerrison (forceps, rongeur), ligamentum flavum, lumbodorsal fascia, medial facetectomy, FD-43 microdissector,pituitary (curette, forceps, rongeur), Taylor self-retaining retractor

PROCEDURE:

The patient was brought to the operating room where a general anesthetic was administered per endotracheal tube. He was carefully positioned on the operating room table in the prone fashion on the 4-post frame. He was prepped and draped in the usual sterile fashion. Spinal needles were placed and a lateral x-ray was taken for needle localization.

Incision was made to the midline. The incision was carried down to the level of the fascia. Subcutaneous dissection was then carried out to the level of the left iliac crest and in a standard fashion corticocancellous and cancellous strips of iliac crest bone graft were harvested. The wound was irrigated. Gelfoam was rubbed into the bleeding interspaces. Excess Gelfoam was removed and the wound was closed in a sequential fashion. Attention was drawn back toward the lumbodorsal fascia.

At this time, 2 paraspinal incisions were made over the L4, L5 and S1 pedicles. The muscle-splitting approach was utilized. The transverse process of L4-L5 and the sacral ala was exposed bilaterally. On the left side, the L4-5 and L5-S1 interlaminar spaces were also identified. On the left side, the laminotomy was performed using the Midas-Rex and Kerrison rongeurs. After this was completed,the nerve roots were probed and found to be free. They were significantly stenotic at the L4-5 level with the L5 nerve root being severely inflamed and scarred at the foraminal entrance. The S1 level also had stenosis but not as severe. No free disk herniations were identified.

After completion of the decompression, attention was drawn back towards the lateral aspect of the spine. It should be noted that the wound was irrigated throughout the case with a jet irrigation system to maintain the sterility of the field. Pedicle screws were then placed in the standard fashion, first initiating the pedicle hole with a Leksell rongeur, then tapping an awl in place, finally passing the T-handled guide down the center of the pedicle, checking the pedicular walls with the sounding device, tapping it, rechecking with the sounding device to confirm there was no penetration, and finally placement of the appropriate 6.5-mm variable-angle TSRH pedicle screw.

After all the pedicle screws were placed, a lateral x-ray was taken confirming the surgical placement of the pedicle screws. After this was completed, the wound was again irrigated. The lateral aspects of the spine which were decorticated prior to placement of the pedicle screws carefully had abundant amounts of the cancellous and corticocancellous bone graft placed over these. The 1/4-inch TSRH rod was then carefully contoured to the appropriate size and shape. Top-loading devices were carefully affixed and the rod was carefully tightened into place. After this was completed, the thrombin fibrin clot was carefully placed over the exposed dura as an attempt to decrease scar formation.

The wound was again irrigated, then closed in a sequential fashion with the rods in place and the bone graft in the appropriate position. The wound was then closed in a sequential fashion, a sterile dressing was applied and the patient was returned to the recovery room in satisfactory condition. He tolerated the procedure well. There were no complications. Sponge and needle count was correct at the end of the operation.

Terms: Gelfoam, Kerrison rongeur, Leksell rongeur, Midas-Rex rongeur, TSRH, TSRH pedicle screws, TSRH rod