In this section:
- For GRADE evaluation of interventions for Trigeminal neuralgia, see table.
- Despite a lack of RCT data, observational evidence supports the use of microvascular decompression to relieve symptoms of trigeminal neuralgia.
- Microvascular decompression has been shown in at least two prospective comparative cohort trials to have superiority over stereotactic radiosurgery for initial complete pain relief, durability of response (up to 5 years), and preservation of trigeminal sensation.
- Multiple well-conducted observational studies have concordantly demonstrated that microvascular decompression has a greater magnitude of therapeutic effect than any medical or surgical intervention for trigeminal neuralgia. As such, this procedure is unlikely to be compared against best medical therapy in an RCT.
- Microvascular decompression requires general anaesthesia and can, albeit rarely, be associated with surgical complications, of which a less than 5% risk of ipsilateral hearing loss appears to be the most common.
Benefits and harms
We found no systematic review or RCTs of microvascular decompression in people with trigeminal neuralgia.
As Clinical Evidence was unable to perform a second appraisal of results retrieved by the contributor's search, we may have missed studies that could affect our overall assessment of this intervention.
Although unlikely to be evaluated in RCTs, there is some observational evidence to support the use of microvascular decompression to reduce painful attacks of trigeminal neuralgia. Many of these studies are of poor quality. However, a number of ‘highly’ rated observational studies (based on the Surgical Trigeminal Neuralgia Score) are discussed here.
Two well-conducted observational studies that used independent assessors to evaluate outcomes found 70% to 80% of people being pain-free at 5 years. The main adverse effect with microvascular decompression is ipsilateral hearing loss, which usually occurs in less than 5% of cases, and is usually permanent. Hearing loss rates can be kept even lower by routine use of intra-operative monitoring with auditory brainstem evoked responses (ABR). The risk of hearing loss associated with microvascular decompression is small, but it may be a prohibitive consideration for people with pre-existing contralateral hearing impairment, or for those rare individuals whom, from a professional career stand-point, would prefer to remain incapacitated by trigeminal neuralgia pain than face the small risk of ipsilateral hearing loss. Other rare adverse effects associated with microvascular decompression include aseptic meningitis, infarcts, haematomas, and cerebrospinal fluid leaks.
Two concordant prospective comparative cohort studies have compared microvascular decompression versus stereotactic radiosurgery. The first study (80 people) found that microvascular decompression significantly increased the proportion of people with pain relief immediately after treatment, at 2 years, and at 5 years compared with stereotactic radiosurgery (immediately after treatment: 100% with microvascular decompression v 78% with stereotactic radiosurgery, reported as significant, P value not reported; at 2 years: 88% with microvascular decompression v 80% with stereotactic radiosurgery, P = 0.01; at 5 years: 77% with microvascular decompression v 45% with stereotactic radiosurgery, P = 0.002). The second study (140 people) found that microvascular decompression significantly increased the proportion of people with complete pain relief at 1 year and 4 years after treatment compared with stereotactic radiosurgery (at 1 year: 84% with microvascular decompression v 66% with stereotactic radiosurgery; at 4 years: 77% with microvascular decompression v 56% with stereotactic radiosurgery; HR 2.5 with 95% CI 1.4 to 4.6, P = 0.003). In addition, people who had stereotactic radiosurgery had significantly higher numbness rates (35% with stereotactic radiosurgery v 18% with microvascular decompression, P = 0.04).
Pain relief with microvascular decompression is usually immediate, therefore, it can be considered for the emergency management of people with trigeminal neuralgia in acute extremis. However, this procedure does require the use of general anaesthesia.
The large therapeutic effect size with microvascular decompression of up to 70% to 80% of people achieving immediate complete pain relief (note: 50% pain relief from baseline is generally used as an endpoint in drug trials) and up to 60% to 70% remaining pain-free at 10–20 years following surgery means there are ethical concerns with using RCTs to compare microvascular decompression with medical therapies. It also suggests that it is reasonable to consider microvascular decompression as a first-line therapy in certain circumstances (e.g., in younger patients, those with major side effects from anticonvulsant drug use, and those unable and/or unwilling to tolerate the potential side effects of antiepileptic drugs).
Microvascular decompression has a lower treatment success rate for those with multiple sclerosis-related trigeminal neuralgia, as they may be experiencing pain caused by a different mechanism to idiopathic trigeminal neuralgia. It is, therefore, generally not considered a first-line surgical therapy for people with multiple sclerosis-related trigeminal neuralgia.