13.1.1.1 Classical trigeminal neuralgia

Description:

Trigeminal neuralgia developing without apparent cause other than neurovascular compression.

Diagnostic criteria:

  1. Recurrent paroxysms of unilateral facial pain fulfilling criteria for 13.1.1 Trigeminal neuralgia
  2. Demonstration on MRI or during surgery of neurovascular compression (not simply contact), with morphological changes1 in the trigeminal nerve root.
Note:

Typically atrophy or displacement.

Comments:

Nerve root atrophy and/or displacement due to neurovascular compression are independently associated with the signs and symptoms of 13.1.1 Trigeminal neuralgia. When these anatomical changes are present the condition is diagnosed as 13.1.1.1 Classical trigeminal neuralgia.

The common site of neurovascular compression is at the root entry zone, with compression by an artery more clearly associated with symptoms than compression by a vein. MRI techniques to measure volume and cross-sectional area of the root are available. Atrophic changes may include demyelination, neuronal loss, changes in microvasculature and other morphological changes. While the exact mechanisms of how atrophic changes in the trigeminal nerve contribute to the generation of pain, some evidence suggests that, when present preoperatively, they predict a good outcome following microvascular decompression.

Many patients with 13.1.1.1 Classical trigeminal neuralgia have a memorable onset of pain.

13.1.1.1 Classical trigeminal neuralgia usually appears in the second or third divisions. The pain rarely occurs bilaterally (sequentially rather than concomitantly).

13.1.1.1 Classical trigeminal neuralgia may be preceded by a period of atypical continuous pain termed pre-trigeminal neuralgia in the literature.

Between paroxysms. most patients are asymptomatic. In the subform 13.1.1.1.2 Classical trigeminal neuralgia with concomitant continuous pain, there is prolonged background pain in the affected area.