WSHIMA - Case 18: Trigeminal neuralgia PRINCIPAL DIAGNOSIS: Right typical severe trigeminal neuralgia (status post 2 prior gamma knife radiosurgery treatments).
Severe typical trigeminal neuralgia refractory to 2 times gamma knife radiosurgery treatment and medical management.
POSTPROCEDURE DIAGNOSIS: Same
PRINCIPAL PROCEDURE: Right retrosigmoid craniotomy for microsurgical microvascular decompression of trigeminal nerve (with Teflon pledgets).
Use of operative microscope.
Onlay Duragen for duraplasty.
Titanium mesh cranioplasty, less than 5 cm in greatest diameter.
INDICATIONS FOR SURGERY:
The patient is a 42-year-old female who had 2 prior gamma knife radiosurgery treatments of the right trigeminal nerve for typical trigeminal neuralgia. She had a very good result from this treatment including 7 years of pain-free time off of all medications. Unfortunately, her pain recurred.
DESCRIPTION OF PROCEDURE:
The patient was brought to the Operating Room, placed supine on the operating table. General anesthesia was induced. The patient was intubated. Preoperative antibiotics were given. The patient was pinned in Mayfield pin headrest. The head was turned to the left. Mannitol, Decadron, and perioperative antibiotics were given. We sterilely prepped and draped the patient, we came on skin with a scalpel in a linear incision in the right retroauricular area. We used Bovie electrocautery to expose the right suboccipital region. I should note that she had a very shallow posterior fossa and we did actually expose the right C1 process. We placed a bur hole in the transverse sinus. We stripped the dura with a Penfield #3. We used a craniotome followed by a drill to blue line the transverse sigmoid junction. At this point, we brought in the operative microscope. I opened the dura in a linear fashion quite nicely. I placed a cottonoid rubber dam over the lateral superior cerebellum, I was able to visualize the tentorium and the arachnoid overlying the cistern. I opened this sharply. CSF egressed from within. I could visualize the superior petrosal vein. I bipolar electrocauterized this and cut it sharply. I now opened up the arachnoid quite durally, I should note it was quite thickened and adherent to the tentorium, cochlear nerve, and the dorsal part of the brain stem. There were two very small arterials, I was able to sharply dissect away from the root entry zone. I then turned my attention towards the VII/VIII complex and could visualize a very large compressive vein. This took a period of time to dissect away from the undersurface of the trigeminal nerve. I was able to do so and I used a right angle directed bipolar to coagulate this vein and cut it sharply. There was some bleeding from the proximal portion. We placed a small piece of Gelfoam and a piece of fibrillar over this are, and the bleeding ceased. At this point, I was able to dissect around the circumference of the nerve. This was difficult due to a large osteoma at the petrous face, but I was able eventually to free up all the arachnoid around the nerve. At this point, I felt pretty good about the decompressive nature of the operation and I placed 4 small Teflon micropledgets so as to displace the two aforementioned arterials and to keep the nerve well-decompressed and from the lateral vein from recanalizing. We thoroughly irrigated hemostased. We placed a piece a 1 x 1 Surgicel in the lateral cerebellum. I removed all patties and rubber dams. We closed the dura in a watertight fashion with 4-0 nylon sutures. We placed a strip of Duragen over this area with Tisseel. We then molded titanium mesh cranioplasty to the suboccipital region without any difficulty. We closed the subcutaneous tissue, muscle, fascia, and dermis with layered Vicryl sutures and used a 3-0 nylon suture for the skin in a running fashion.