Trigeminal neuralgia: a practical guide

Abstract

Trigeminal neuralgia (TN) is a highly disabling disorder characterised by very severe, brief and electric shock like recurrent episodes of facial pain. New diagnostic criteria, which subclassify TN on the basis of presence of trigeminal neurovascular conflict or an underlying neurological disorder, should be used as they allow better characterisation of patients and help in decision-making regarding medical and surgical treatments. MR imaging, including high-resolution trigeminal sequences, should be performed as part of the diagnostic work-up. Carbamazepine and oxcarbazepine are drugs of first choice. Lamotrigine, gabapentin, pregabalin, botulinum toxin type A and baclofen can be used either alone or as add-on therapy. Surgery should be considered if the pain is poorly controlled or the medical treatments are poorly tolerated. Trigeminal microvascular decompression is the first-line surgery in patients with trigeminal neurovascular conflict while neuroablative surgical treatments can be offered if MR imaging does not show any neurovascular contact or where patients are considered too frail for microvascular decompression or do not wish to take the risk.

Keywords: headache; pain; trigeminal nerve; trigeminal neuralgia.

Figure 1

International Classification of Headache Disorders Edition 3 subclassification of trigeminal neuralgia.

Figure 2

MR scan of the trigeminal nerve and intraoperative pictures during microvascular decompression in patient with classical trigeminal neuralgia. (A) Axial MR 0.5 mm volumetric SPACE sequence through the pons showing neurovascular conflict between the right superior cerebellar artery (SCA) and the right trigeminal nerve (V). (B) Intraoperative view of the right cerebellopontine angle, prior to right microvascular decompression, showing conflict between the right SCA and V. (C) Black and white rendition of the previous photograph with labelling of the superior cerebellar artery, V, and more superficial seventh and eighth nerve complex (VII/VIII). (D) The superior cerebellar artery has been mobilised and transposed superiorly towards the tentorium. It is held in place with a small piece of Teflon (T). (E) A small drop of fibrin glue (F) has been applied to ensure that the T does not migrate. A small ‘dent’ in the course of the trigeminal nerve can be seen at the site of the previous neurovascular conflict. SPACE, sampling perfection with application optimised contrasts using different flip angle evolution.

Figure 3

Proposed algorithm for the treatment of trigeminal neuralgia. *Microvascular decompression (MVD) appears effective even in idiopathic TN and may be more effective than stereotactic radiosurgery. **If any of carbamazepine, oxcarbazepine, lamotrigine, gabapentin or pregabalin have not been tried then trials of these agents should be considered. ***Internal neurolysis is best avoided after MVD as there is a suggestion that there is a higher risk of anaesthesia dolorosa. ****Consider MVD if the secondary cause is optimally treated and there is evidence of neurovascular conflict; exercise caution in MS with ipsilateral pontine plaque. MS, multiple sclerosis; TN, trigeminal neuralgia.