The trigeminal nerve is the fifth cranial nerve and one of the largest in the head. It provides sensation to the face and is called trigeminal because it splits into three main branches. When neuralgia (nerve pain) occurs in the trigeminal nerve it causes severe and sudden face pain. It has an incidence rate of 12.6 per 100,000 person years and more commonly affects older age groups.
The causes of trigeminal neuralgia are unclear. Treatment of all people with classical trigeminal neuralgia begins with drug therapy, usually using one of several drugs also used to treat epilepsy, among which the gold standard remains carbamazepine. If drug therapy fails then surgical interventions may be used. Surgical treatments divide into two main categories, ablative (destructive) or non-ablative. These treatments can be done at three different sites: peripherally, at the Gasserian ganglion level, and within the posterior fossa of the skull.
The aims of this Cochrane review were:-
- to assess the efficacy of neurosurgical interventions for classical trigeminal neuralgia in terms of pain relief, quality of life and any harms.
- to determine if there are defined subgroups of patients more likely to benefit.
Detailed searches with no language exclusions were undertaken in a wide range of databases:-
- Cochrane Neuromuscular Disease Group Specialized Register,
- Cochrane Central
- Health Technology Assessment (HTA) Database,
- NHS Economic Evaluation Database (NHSEED)
- Database of Abstracts of Reviews of Effects (DARE)
They included Randomised controlled trials and quasi-randomised controlled trials of neurosurgical interventions used in the treatment of classical trigeminal neuralgia. with two authors independently assessing quality and extracting data. Original authors were contacted authors for clarification and missing information whenever possible.
- Eleven studies (496 participants) in all met some of the inclusion criteria stated in the protocol.
- Five studies (185 participants) involved peripheral interventions,
- Five studies(229 participants) had percutaneous interventions applied to the Gasserian ganglion,
- One study ( 87 participants) in which participantsunderwent two modalities of stereotactic radiosurgery (Gamma Knife) treatment.
- No studies addressing microvascular decompression (which is the only non-ablative procedure) met the inclusion criteria.
All but two of the identified studies had a high to medium risk of bias because of either missing data or methodological inconsistency. It was not possible to undertake metaanalysis because of differences in the intervention modalities and variable outcome measures.
The authors concluded:-
There is very low quality evidence for the efficacy of most neurosurgical procedures for trigeminal neuralgia because of the poor quality of the trials. All procedures produced variable pain relief, but many resulted in sensory side effects. There were no studies of microvascular decompression which observational data suggests gives the longest pain relief. There is little evidence to help comparative decision making about the best surgical procedure. Well designed studies are urgently needed.
Zakrzewska JM, Akram H. Neurosurgical interventions for the treatment of classical trigeminal neuralgia. Cochrane Database Syst Rev. 2011 Sep 7;9:CD007312. PubMed PMID: 21901707.