Trigeminal neuralgia - CNS causes of headache

Trigeminal neuralgia

Definition

Intermittent excruciating pain in the distribution of one or more branches of the trigeminal nerve.

Aetiology/pathophysiology

Trigeminal neuralgia is generally idiopathic. There appears to be demyelination of the trigeminal nerve root, in some cases it is hypothesised that this occurs due to compression by a vessel, tumour or cyst. Multiple sclerosis is a well-described cause.

Clinical features

Severe, brief stabbing or electric shock-like pain, usually unilateral, and affecting part of the face (ophthalmic, maxillary or mandibular branch(es)). Severe pain may lead to facial grimacing (‘tic doloureux’). It may be precipitated light touch in the distribution of the affected nerve, or other actions such as chewing, talking, exposure to cold air. If there are neurological signs on examination then an underlying pathology should be suspected.

Investigations

The diagnosis is clinical. In certain patients, MRI to exclude MS, or an underlying tumour is indicated (i.e. under the age of 40, bilateral symptoms, no response to conservative therapy, sensory loss).

Management

Carbamazepine can be effective. Combination therapy, by adding other anti-epileptic drugs or clonazepam may be useful. Refractory neuralgia may require surgical treatment such as microvascular decompression or alcohol injection into the Gasserian ganglion.

Prognosis

Remissions for months or years may occur, often followed by recurrence.