Microvascular decompression (MVD) is a surgery to relieve abnormal compression of a cranial nerve causing trigeminal neuralgia, glossopharyngeal neuralgia, or hemifacial spasm. MVD involves opening the skull (craniotomy) and inserting a sponge between the nerve and offending artery triggering the pain signals. Medications often provide initial relief, but when drugs become ineffective or cause side effects, MVD is an option.
What is microvascular decompression (MVD)?
MVD is a surgical procedure to relieve the symptoms (pain, muscle twitching) caused by compression of a nerve by an artery or vein. Surgery involves opening the skull (craniotomy) and exposing the nerve at the base of the brainstem to insert a tiny sponge between the compressing vessel and the nerve. This sponge isolates the nerve from the pulsating effect and pressure of the blood vessel.
Trigeminal neuralgia is an irritation of the fifth cranial nerve causing severe pain that usually affects one side of the face, normally in the forehead, cheek, jaw, or teeth (Fig. 1). To treat trigeminal neuralgia, a sponge is placed between the trigeminal nerve and the superior cerebellar artery or a branch of the petrosal vein. By removing the compression, the painful symptoms are relieved.
Figure 1. Trigeminal neuralgia can be caused by an artery or vein compressing the trigeminal nerve root as it originates at the brainstem
What happens during surgery?
Patients are admitted to the hospital the morning of the procedure. You will meet with a nurse who will ask your name, date of birth, what procedure you’re having, and the side of your facial pain. They will explain the pre-op process and discuss any questions you may have. An anesthesiologist will meet with you and explain the effects of anesthesia and its risks. They will place an intravenous (IV) line in your arm and then transport you to the operating room.
There are 5 steps of the procedure. The operation generally takes 2 to 3 hours.
Step 1: prepare the patient
In the OR room, general anesthesia is administered while you lie on the operating table. Once asleep, your body is rolled over on its side and your head is placed in a 3-pin skull fixation device, which attaches to the table and holds your head in position during the procedure. Next, the area behind your ear is prepped with antiseptic. A hair-sparing technique may be used, where only a 1/4-inch wide area along the proposed skin incision is shaved.
Step 2: perform a craniectomy
A 3-inch curved skin incision is made behind the ear. The skin and muscles are lifted off the bone and folded back. Next, a 1-inch opening is made in the occipital bone with a drill (Fig. 2). The bone is removed to expose the protective covering of the brain called the dura. The dura is opened with surgical scissors and folded back to expose the brain.
Figure 2. A skin incision is made behind the ear (dashed line) and a 1-inch craniectomy (solid line) is made in the skull.
Step 3: expose the nerve
Retractors placed on the brain gently open a corridor to the trigeminal nerve at its origin with the brainstem. The surgeon exposes the trigeminal nerve and identifies any offending vessel causing compression (Fig. 3). The vessel and nerve are often restricted by thickened connective tissue that must be dissected free with scissors and knife.
Figure 3. The superior cerebellar artery is adherent to the trigeminal nerve causing compression and painful trigeminal neuralgia attacks.
Step 4: insert a sponge
The surgeon cuts an appropriate size of teflon sponge and inserts it between the nerve and the vessel (Fig. 4). Sometimes a vein is adherent to the nerve and causing compression. In these cases, the vein is cauterized and moved away.
Figure 4. A sponge is inserted between the nerve and the blood vessel causing compression.
Step 5: closure
Once the sponge is in place, the retractor is removed and the brain returns to its natural position. The dura is closed with sutures and made watertight with tissue sealant. Since the bone opening is very small, it is not replaced. Instead, a titanium plate covers the skull opening and is secured with tiny screws (Fig. 5). The muscles and skin are sutured back together. A soft adhesive dressing is placed over the incision.
Figure 5. A circular titanium plate secured with screws covers the craniectomy made in the skull.