Trigeminal Neuralgia

Abstract

Trigeminal neuralgia causes episodic pain afflicting the areas of the face supplied by the trigeminal nerve. The pain is unilateral in 97% of cases; when it does occur bilaterally, the same division of the nerve is involved on both sides. The second or third division of the nerve is affected in most patients, and the first division is affected less than 5% of the time. The pain develops on the right side of the face in 57% of unilateral cases. The pain is characterized by paroxysms of electric shock–like pain lasting from several seconds to less than 2 minutes. The progression from onset to peak is essentially instantaneous. Trigeminal neuralgia occurs in many patients because of tortuous blood vessels that compress the trigeminal root as it exits the brainstem. Acoustic neuromas, cholesteatomas, aneurysms, angiomas, and bony abnormalities may also lead to compression of the nerve. Carbamazepine is considered first-line treatment for trigeminal neuralgia. In fact, a rapid response to this drug essentially confirms the clinical diagnosis. Baclofen may be of value in some patients who fail to obtain relief from carbamazepine or gabapentin. The use of trigeminal nerve block with local anesthetic and steroid is an excellent adjunct to drug treatment of trigeminal neuralgia. This technique rapidly relieves pain while medications are being titrated to effective levels. In some patients who fail to respond to medical management and nerve blocks, microvascular decompression of the trigeminal nerve may be required.

Keywords

trigeminal neuralgia, acoustic neuroma, multiple sclerosis, baclofen, trigeminal nerve block, gasserian ganglion block, carbamazepine, retrogasserian glycerol, microvascular decompression

ICD-10 CODE G50.0

The Clinical Syndrome

Trigeminal neuralgia occurs in many patients because of tortuous blood vessels that compress the trigeminal root as it exits the brainstem ( Fig. 10.1 ). Acoustic neuromas, cholesteatomas, aneurysms, angiomas, and bony abnormalities may also lead to compression of the nerve. The severity of the pain produced by trigeminal neuralgia is rivaled only by that of cluster headache. Uncontrolled pain has been associated with suicide and should therefore be treated as an emergency. Attacks can be triggered by daily activities involving contact with the face, such as brushing the teeth, shaving, and washing ( Fig. 10.2 ). Pain can be controlled with medication in most patients. Approximately 2% to 3% of patients with trigeminal neuralgia also have multiple sclerosis. Trigeminal neuralgia is also called tic douloureux.

Signs and Symptoms

Trigeminal neuralgia causes episodic pain afflicting the areas of the face supplied by the trigeminal nerve. The pain is unilateral in 97% of cases; when it does occur bilaterally, the same division of the nerve is involved on both sides. The second or third division of the nerve is affected in most patients, and the first division is affected less than 5% of the time. The pain develops on the right side of the face in 57% of unilateral cases. The pain is characterized by paroxysms of electric shock–like pain lasting from several seconds to less than 2 minutes. The progression from onset to peak is essentially instantaneous.

Patients with trigeminal neuralgia go to great lengths to avoid any contact with trigger areas. In contrast, persons with other types of facial pain, such as temporomandibular joint dysfunction, tend to rub the affected area constantly or apply heat or cold to it. Patients with uncontrolled trigeminal neuralgia frequently require hospitalization for rapid control of pain. Between attacks, patients are relatively pain free. A dull ache remaining after the intense pain subsides may indicate persistent compression of the nerve by a structural lesion. This disease is hardly ever seen in persons younger than 30 years unless it is associated with multiple sclerosis.

Patients with trigeminal neuralgia often have severe depression (sometimes to the point of being suicidal), with high levels of superimposed anxiety during acute attacks. Both these problems may be exacerbated by the sleep deprivation that often accompanies painful episodes. Patients with coexisting multiple sclerosis may exhibit the euphoric dementia characteristic of that disease. Physicians should reassure persons with trigeminal neuralgia that the pain can almost always be controlled.

Testing

All patients with a new diagnosis of trigeminal neuralgia should undergo magnetic resonance imaging (MRI) of the brain and brainstem, with and without gadolinium contrast medium, to rule out posterior fossa or brainstem lesions and demyelinating disease ( Fig. 10.3 ). Magnetic resonance angiography is also useful to confirm vascular compression of the trigeminal nerve by aberrant blood vessels ( Fig. 10.4 ). Additional imaging of the sinuses should be considered if occult or coexisting sinus disease is a possibility. If the first division of the trigeminal nerve is affected, ophthalmologic evaluation to measure intraocular pressure and to rule out intraocular disease is indicated. Screening laboratory tests consisting of a complete blood count, erythrocyte sedimentation rate, and automated blood chemistry should be performed if the diagnosis of trigeminal neuralgia is in question. A complete blood count is required for baseline comparisons before starting treatment with carbamazepine (see “ Treatment ”).