Surgical modalities for trigeminal neuralgia

A Cochrane review «Neurosurgical interventions for the treatment of classical trigeminal neuralgia»1 «Zakrzewska JM, Akram H. Neurosurgical interventions for the treatment of classical trigeminal neuralgia. Cochrane Database Syst Rev 2011;9:CD007312. »1 included 11 RCTs with 496 participants with trigeminal neuralgia. The evaluated interventions were peripheral (5 trials, n=180) and percutaneous interventions applied to the Gasserian ganglion (5 trials, n= 229) and two modalities of stereotactic radiosurgery (Gamma Knife) treatment (1 trial, n=87). No studies addressing microvascular decompression, being the only non-ablative procedure, met the inclusion criteria. Three studies had sufficient outcome data for analysis. Two techniques of radiofrequency thermocoagulation (RFT) of the Gasserian ganglion (2 trials, n= 127) was assessed: pulsed RFT resulted in return of pain in all patients by 3 months. When this group were converted to conventional (continuous) treatment, they achieved pain control comparable to the group that had received conventional treatment from the outset. Sensory changes were common in the continuous treatment group (n=40). When radiation treatment was compared to the trigeminal nerve at one or two isocentres in the posterior fossa, there were insufficient data to determine if one technique was superior to another. Increased age and prior surgery were predictors for poorer pain relief. Relapses were nonsignificantly reduced with two isocentres (RR 0.72, 95%CI 0.30 to 1.71; n=70). A third study (n=54) compared two techniques for RFT for 10 to 54 months. Both techniques produced pain relief (not significantly in favour of neuronavigation [RR 0.70, 95% CI 0.46 to 1.04]) but relief was more sustained and side effects fewer if a neuronavigation system was used.

Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment), inconsistency (heterogeneity in interventions and outcomes) and imprecise results (limited study size for each comparison).

A systematic review «Tatli M, Satici O, Kanpolat Y, Sindou M. Various surgical modalities for trigeminal neuralgia: literature study of respective long-term outcomes. Acta Neurochir (Wien) 2008 Mar;150(3):243-55. »2 including 28 observational studies with a total of 10 493 subjects with trigeminal neuralgia was abstracted in DARE.

• Microvascular decompression (MVD) (16 studies, n=4 884): acute pain relief rates (APRR) ranged from 76.4 to 98.2% (average 91.1%, 10 studies), follow-up pain-free rates (FUPFR) ranged from 62 to 89% (average 76.6%) and recurrence rates (RR) ranged from 4 to 38% (average 18.3%). The major complications were hearing loss (1 to 19%) and mortality (0.37%, 17 out of 4 906 patients).
• Radiofrequency thermorhizotomy (RF-TR) (9 studies, n=4 683): APRR ranged from 81 to 98% (average 90.3%, 5 studies), FUPFR ranged from 20 to 83% (average 50.4%) and RR ranged from 18.1 to 80% (average 45.9%). This type of surgery was associated with the greatest number of complications, the most common being facial hyperaesthesia (5 to 98%), corneal hyperaesthesia (5 to 18%) and trigeminal motor weakness (4 to 24%).
• Percutaneous balloon microcompression (PBC) (2 studies, n=577): average APRR was 98.5%, the average FUPFR was 80.4% and the average RR was 19.6%. The major complication was symptomatic dysaesthesia.
• Stereotactic radiosurgery SRS (1 study, n=107): APRR was 80.4%, FUPFR was 58% and RR was 25%. The major complication was hyperaesthesia (20% after first SRS and 32% after second).
• Glycerol rhizotomy (GR) (2 studies, n=167): the average APRR was 63%, the average FUPFR was 38.5% and the average RR was 62.5%. The major complication was sensory deficit.
• Partial sensory rhizotomy (PSR) (2 studies, n=95): the average APRR was 79%, the average FUPFR rate was 52.5% and the average RR was 39%. The most common complications were facial hyperaesthesia (100%) and hearing loss (25%).
• MVD appeared to be associated with similar APRR and FUPFR as PBC, and significantly higher APRR than RF-TR, SRS, and PSR and GR. MVD was associated with the lowest RR.

Comment: The quality of evidence is downgraded by inconsistency (variability in results across studies, heterogeneity in interventions and outcomes).