- Trigeminal neuralgia is a sudden, unilateral, brief, stabbing, recurrent pain in the distribution of one or more branches of the fifth cranial nerve. The diagnosis is made on the history alone, based on characteristic features of the pain.
- Pain occurs in paroxysms, which can last from a few seconds to several minutes. The frequency of the paroxysms ranges from a few to hundreds of attacks a day.
- Periods of remission can last for months to years, but tend to get shorter over time.
- The condition can impair activities of daily living and lead to depression.
- The annual incidence in the UK (based on GP practice lists and rather liberal diagnostic criteria) has been reported to be 26.8 per 100,000. However, studies in other countries such as the US and the Netherlands, with stricter definitions, have reported much lower incidence rates ranging between 5.9 and 12.6 per 100,000.
- Experts find that symptoms worsen over time and become less responsive to medication despite dose increases and adding further agents.
- Treatment success is defined differently in studies of medical and surgical therapies for trigeminal neuralgia.
- Treatment success in medical studies is usually defined as at least 50% pain relief from baseline. However, complete pain relief is the measure of treatment success in surgical studies.
- Carbamazepine is considered the gold-standard for the initial medical treatment of trigeminal neuralgia symptoms.
- Carbamazepine has been shown to increase pain relief compared with placebo, but also increases adverse effects, such as drowsiness, dizziness, rash, liver damage, and ataxia.
- Studies evaluating durability of response with carbamazepine are lacking, but consensus expert opinion suggests that it may have a greater than 50% failure rate for long-term (5-10 year) pain control.
- Based on the strength of published evidence, carbamazepine remains the best supported standard medical treatment for trigeminal neuralgia.
- There is consensus that oxcarbazepine is an effective treatment in people with trigeminal neuralgia and may have fewer adverse effects than carbamazepine, although there is a lack of RCT-based data to confirm this.
- Oxcarbazepine rarely provides complete or long-term pain relief, although studies evaluating durability of response with this drug are lacking.
- Lamotrigine is often used in people who cannot tolerate carbamazepine, but the dose must be increased slowly to avoid rashes, thus making it unsuitable for acute use.
- There is consensus that baclofen may be useful for people with multiple sclerosis who develop trigeminal neuralgia.
- We found no evidence comparing gabapentin versus placebo/no treatment or other treatments covered in this review in people with trigeminal neuralgia.
- Gabapentin does have support for use in treating other neuropathic pain conditions, particularly multiple sclerosis.
- 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 complete pain relief, durability of response (up to 5 years), and preservation of trigeminal sensation.
- However, 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.
- Well-conducted observational studies have demonstrated that microvascular decompression has a greater magnitude of therapeutic effect than any medical and surgical therapy for trigeminal neuralgia. As such, this procedure is unlikely to be compared against best medical therapy in an RCT.
- We found no RCT evidence comparing percutaneous destructive neurosurgical techniques (radiofrequency thermocoagulation, glycerol rhizolysis, balloon compression) or non-percutaneous destructive neurosurgical techniques (stereotactic radiosurgery) versus placebo/no treatment or other treatments covered in this review in people with trigeminal neuralgia.
- Observational data suggest that radiofrequency thermocoagulation may offer higher rates of complete pain relief than glycerol rhizolysis and stereotactic radiosurgery, but may also be associated with higher rates of complications (e.g., facial numbness and corneal insensitivity).
- In contrast to stereotactic radiosurgery, pain relief with microvascular decompression and percutaneous destructive neurosurgical techniques is immediate, but they require sedation and/or anaesthesia to perform, which are not required for stereotactic radiosurgery.