Microvascular decompression (MVD) is a neurosurgical procedure designed to treat chronic symptoms caused by nerve irritation. This technique addresses the root cause: physical compression of a cranial nerve by an adjacent blood vessel, typically an artery. The goal is to relieve this pressure, known as neurovascular compression, resolving the painful or spasmodic condition. By moving the offending vessel and placing a permanent cushion between it and the nerve, MVD aims to restore normal nerve function.
Conditions Treated by Microvascular Decompression
Microvascular decompression treats conditions where a cranial nerve malfunctions due to constant irritation from a pulsating blood vessel. Continuous contact causes the nerve’s protective myelin sheath to break down, leading to abnormal signaling and producing painful or involuntary movement symptoms.
The most frequent condition treated is Trigeminal Neuralgia (TN), which causes intense, shock-like facial pain, often triggered by simple actions like chewing or brushing teeth. Compression of the trigeminal nerve (Cranial Nerve V), responsible for facial sensation, results in these sudden, severe bursts of pain. MVD is a highly effective treatment that addresses this underlying vascular cause.
Another condition is Hemifacial Spasm (HFS), involving involuntary twitching or spasms of the muscles on one side of the face. This occurs when the facial nerve (Cranial Nerve VII) is compressed, leading to erratic electrical signals. Less commonly, MVD is used for Glossopharyngeal Neuralgia, which causes severe pain in the throat, tongue, ear, or tonsil area due to compression of the glossopharyngeal nerve (Cranial Nerve IX).
The Steps of the Surgical Procedure
MVD is performed under general anesthesia. The patient is positioned on their side, and the head is secured to allow precise surgical access. The area behind the ear is prepared, often involving clipping hair to create a sterile field.
A small, curved incision is made behind the ear. The surgeon performs a retromastoid craniectomy, drilling a small opening into the occipital bone of the skull. This “keyhole” grants access to the posterior fossa, the area at the base of the skull where the cranial nerves originate.
The dura mater, the protective membrane covering the brain, is carefully opened. The neurosurgeon uses an operating microscope to navigate through the cerebrospinal fluid and gently move aside the cerebellum to visualize the affected cranial nerve. This microscopic approach minimizes manipulation of brain tissue while allowing clear identification of the nerve.
The surgeon searches along the nerve’s root entry zone for the offending blood vessel, often a loop of the superior cerebellar artery or a vein. This vessel is identified as the source of compression and is gently moved away from the nerve using micro-instruments. Decompression involves placing a permanent, soft cushioning material, typically a Teflon felt sponge, between the nerve and the blood vessel.
The Teflon material acts as a permanent buffer, preventing the vessel’s pulsations from irritating the nerve fibers. Once separation is stable, the dura mater is sutured closed. The small bone opening may be covered with a synthetic patch or bone cement, and the skin layers are closed with sutures or staples.
Recovery and Post-Operative Expectations
Immediately following MVD, patients are monitored closely in a recovery area for neurological status and pain management. The typical hospital stay ranges from three to five days. Headaches, nausea, and discomfort at the incision site are common and managed with medication during this initial period.
Upon returning home, patients must limit physical activity, including lifting and strenuous exercise, for approximately four to six weeks to allow the surgical site to heal fully. A gradual return to normal daily activities is encouraged as energy levels improve. Patients should avoid any activity that could place undue strain on the healing tissues.
MVD has a high success rate, but potential risks exist, as with any neurosurgical procedure. Complications may include temporary or permanent hearing loss on the side of the surgery due to the close proximity of the auditory nerve. Other infrequent risks involve facial weakness, numbness, balance issues, or cerebrospinal fluid leakage.
For Trigeminal Neuralgia, the immediate success rate for complete or significant pain relief is often between 80% and 95%. Long-term relief rates remain high, with 70% to 80% of patients remaining pain-free or significantly improved five to ten years after the operation. This long-lasting relief is a primary benefit of MVD.