Treatment Options for Trigeminal Neuralgia

Role of Surgery in Trigeminal Neuralgia

Although the drugs used for the management of trigeminal neuralgia (TN) pain are highly effective for many people, approximately 25% to 50% of TN patients eventually stop responding to these medications. For these patients, surgery may be considered as a viable and potentially effective treatment option.

In general, surgical procedures for trigeminal neuralgia can be classified as either non-destructive or destructive:

  • Non-destructive procedures - treatment is intended to eliminate the underlying cause of the trigeminal neuralgia without causing injury or damage to the nerve. Microvascular decompression is the only type of non-destructive surgical procedure that can effectively be used to treat TN when the cause of the pain is due to vascular compression.

  • Destructive procedures - treatment is intended to control the pain by destroying or damaging sections of the trigeminal nerve. Examples include:

    • percutanous rhizotomy (gangliolysis)
    • stereotactic radiosurgery (Gamma Knife)
    • retrogasserian neurotomy
    • peripheral neurectomy
    • trigeminal tractotomy

Non-Destructive Procedures

Microvascular decompression

Microvascular decompression (MVD) is considered to be the only non-destructive surgical procedure that effectively eliminates the underlying cause of trigeminal neuralgia when the condition is due to compression of the trigeminal nerve by blood vessels (vascular compression). Microvascular decompression is referred to as a "non-destructive" surgical procedure because, unlike the other surgical procedures outlined below, it does not involve causing an injury or damage to the nerve. The goal of MVD is to alleviate the pain of TN by eliminating the cause of the pain which, in many cases, is due to vascular compression of the trigeminal nerve.

Microvascular decompression surgery is performed by a neurosurgeon in a hospital setting under general anesthesia. It is important to choose a neurosurgeon who is experienced with this surgical procedure and specializes in the treatment of trigeminal neuralgia. After the patient has received general anesthesia, the surgeon will create a suboccipital craniectomy (surgical removal of a portion of the skull in the suboccipital region) to access and view the trigeminal nerve. Using a special operating microscope, the surgeon will decompress (eliminate the compression) the nerve. Veins that are compressing the nerve are coagulated and divided. Arteries that are pressing against the nerve are repositioned and a pad of Teflon cotton is placed between the artery and nerve to prevent the artery from sliding back and pressing against the nerve. After the surgery, patients usually spend about 3 days in the hospital recuperating. Immediate pain relief is experienced by about 90% of patients who undergo MVD surgery and about 70% of patients will achieve long-term pain relief. Complications of MVD are rare but may include:

  • Facial numbness
  • Facial weakness
  • Hearing loss
  • Cerebrospinal fluid (CSF) leakage
  • Injury to the cerebellum (edema, contusion, or hematoma)

There have been some reports of pain recurring after 10-20 years but the reason is unclear since upon reoperation, new compression is rarely found.

Patients who have had less invasive surgeries to no avail are sometimes considered candidates for this surgery.

Destructive Procedures

Percutaneous Rhizotomy (Gangliolysis)

Unlike microvascular decompression (MVD) surgery which actually eliminates the vascular compression on the nerve that is often the cause of trigeminal neuralgia, a rhizotomy is a destructive surgical procedure that is intended to alleviate the pain associated with TN by destroying or damaging a section of the trigeminal nerve usually at the Gasserian ganglion or trigeminal nerve root. A rhizotomy is a percutaneous ("through the skin") procedure that can be performed on an outpatient basis either under local or brief general anesthesia and is less invasive than MVD surgery. In performing a percutaneous rhizotomy, the surgeon inserts a needle through the cheek into an opening at the base of the skull known as the foramen ovale to gain access to the Gasserian ganglion and trigeminal nerve root. Using one of three specific rhizotomy techniques described below, the surgeon will deliberately produce a controlled injury to the Gasserian ganglion and trigeminal nerve root in order to block the pain sensation associated with trigeminal neuralgia.

The three types of percutaneous rhizotomy procedures that are currently used for the surgical management of trigeminal neuralgia pain include:

  • Percutaneous Glycerol Rhizotomy - Once the surgeon has advanced and confirmed the correct position of the needle, the chemical glycerol is injected through the needle into the space surrounding the Gasserian ganglion and trigeminal nerve root resulting in mild injury to the nerve. Although most patients achieve early pain relief after undergoing this procedure, the pain may recur within a few years in up to 50% of cases.

  • Percutaneous Balloon Compression Rhizotomy - In this procedure, usually performed under general anesthesia followed by an overnight stay in the hospital, the surgeon advances a large-caliber needle to the area of the Gasserian ganglion and confirms the correct positioning of the needle. A balloon-tip catheter ( a tube with a balloon at its tip that can be inflated and deflated after placement) is then advanced through the needle and the balloon is inflated. Mechanical compression of the inflated balloon causes physical damage to the Gasserian ganglion trigeminal nerve root.

  • Percutaneous Radiofrequency Rhizotomy - In this procedure, usually performed under intravenous (IV) sedation, the surgeon advances a special radiofrequency electrode into the area of the Gasserian ganglion and verifies the correct positioning of the electrode. The electrode is then heated and the radiofrequency current that is generated produces thermal (heat) injury to the Gasserian ganglion and trigeminal nerve root/

Percutaneous rhizotomy surgical procedures for trigeminal neuralgia offer about an 80% chance for short-term pain relief (lasting at least one year) and about a 60% likelihood for longer-term pain relief (5 years or longer).

In general, the complication rate from percutanous rhizotomy surgical procedures for the treatment of TN is low. The most common complication is facial numbness. Although mild facial numbness is the goal of the procedure and is well tolerated by most patients, severe or extensive facial numbness can be quite bothersome. The most severe form of facial numbness is called anesthesia dolorosa. It involves constant, intense pain, burning and numbness in the region of the anesthesia. The risk of developing anesthesia dolorosa is higher with percutaneous radiofrequency rhizotomy (2% to 4% of cases) than with the other types of percutaneous rhizotomy procedures. Currently, there is no effective treatment for patients with anesthesia dolorosa. Other potential complications of percutaneous rhizotomy procedures include weakness of the masseter muscles causing a reduced chewing capacity and, in rare cases, injury to the cornea of the eye that can lead to keratitis (inflammation of the cornea) and blindness.

Stereotactic Radiosurgery (Gamma Knife)

This is a newer procedure that is being used for the treatment of trigeminal neuralgia. As is the case with the percutaneous rhizotomy procedures described above, stereotactic radiosurgery is also a destructive procedure designed to produce an injury to the trigeminal nerve in an effort to alleviate the pain. In this procedure, the injury to the trigeminal nerve root is accomplished using a gamma knife which delivers focused beams of cobalt radiation directly to the trigeminal nerve root without damaging the surrounding brain tissue or blood vessels. The "gamma knife" is actually not a knife at all but an instrument that uses focused beams of radiation to perform brain surgery; this type of surgery is also called stereotactic radiosurgery.

Although the results of stereotactic radiosurgery are similar to the percutaneous needle-based surgeries, the primary difference is the time required to achieve pain relief. With the percutaneous operations, most patients respond within the first few hours. After radiosurgery, pain relief is generally not noticed until 3-4 weeks after the procedure has been completed. As a result, patients with severe facial pain are generally not considered good candidates for stereotactic radiosurgery.

Retrogasserian Neurotomy

This surgical procedure involves sectioning the trigeminal nerve between the Gasserian ganglion and the pons. It was performed frequently during the first half of the 20th century but is done now performed only in very limited cases (e.g., patients who have undergone MVD surgery without pain relief or if no compression of the trigeminal nerve is discovered during surgery). Anesthesia dolorosa is the most dreaded complication of this procedure.

Peripheral Neurectomy

Peripheral neurectomy involves the excision of a segment of the trigeminal nerve. It is used only under limited circumstances such as patients who have failed to achieve pain relief from percutaneous rhizotomy procedures or patients who cannot tolerate undergoing MVD surgery due to advanced age or other underlying health problems. Rarely does peripheral neurectomy for trigeminal neuralgia achieve pain control beyond one year.

Trigeminal Tractotomy

In trigeminal tractotomy, the surgeon sections the descending fibers of the trigeminal tract in the medulla. It is carried out through a small suboccipital craniectomy and laminectomy of C1 and C2. This leads to a loss of pain and temperature sensation on one side of the face and in the larynx. It is not performed frequently and only if all other measures fail. It is critical that the surgeon be highly experienced in this procedure since there is a high complication and morbidity rate associated with inexperienced surgeons.