Surgical treatment of trigeminal neuralgia - Home Study Program

AORN Journal,  Nov, 2003  by Cassi Brown

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TREATMENT

Medical and surgical approaches are available for treatment of trigeminal neuralgia. Several medications currently are available for treating trigeminal neuralgia. Carbamazepine, the usual initial medical therapy, also is diagnostic because most patients with classic trigeminal neuralgia respond to this treatment. Initially, 100 mg per day is prescribed and increased as needed. Some patients experiencing severe pain have been able to tolerate as much as 1,200 mg per day. Carbamazepine may cause dose-dependent bone marrow depression, so complete blood counts (CBCs) must be monitored. Other side effects include mental slowing, dizziness, imbalance, and sedation. Side effects often preclude chronic use, especially in patients whose jobs require concentration or dexterity. (2,3) Fifty percent of patients treated with carbamazepine become tolerant during a period of years. (4) Other medications used alone or in partnership with carbamazepine are baclofen, phenytoin, and, recently, gabapentin. Medical therapy gradually becomes less effective because of the progressive nature of trigeminal neuralgia; therefore, patients should be prepared for eventual surgical treatment. Surgical treatment consists of neurodestructive procedures, stereotactic radiosurgery, and MVD. Peripheral neurectomy, peripheral and ganglionic alcohol blocks, and cryotherapy have not proven as efficacious as other procedures and, therefore, will not be discussed.

NEURODESTRUCTIVE PROCEDURES. There are three percutaneous rhizotomy procedures used to treat trigeminal neuralgia: glycerol, balloon compression, and radiofrequency. These procedures result in partial numbness of the patient's face and risk of corneal denervation with secondary keratitis.

Glycerol rhizotomy is an outpatient procedure performed under fluoroscopy with local anesthesia and mild sedation. A needle is placed via a percutaneous approach through the foramen ovale into the trigeminal cistern. Patients then are asked if they feel typical trigeminal neuralgia pain. If they respond affirmatively, a small test dose of a neurotoxic substance, such as glycerol, is injected, after which additional small doses are injected incrementally. Patients usually perceive the injection as tingling or burning along the affected divisions of the nerve. Initial pain relief occurs in more than 80% of patients and usually is immediate, but 12-month recurrence rates vary from 10% to 50%. (6)

Balloon compression rhizotomy, which is performed as an inpatient procedure under general anesthesia with fluoroscopic control, inserts a guide needle via a percutaneous approach into the patient's foramen ovale. A balloon catheter is advanced through the needle into Meckel's cave. The balloon is filled slowly with contrast solution until it occupies the cave, ensuring adequate compression of the ganglion. Compression times vary from one to six minutes. On emergence from anesthesia, nearly all patients experience immediate pain relief and mild sensory loss. Six percent to 15% of patients report troublesome dysesthesia (ie, odd, unfamiliar feelings, including burning sensations) after the procedure. (1,5) These range from significant discomfort to pain requiring medical treatment. Patients usually are discharged the morning after surgery. Recurrence is reported in 6% to 14% of patients in the first year. (1-3)