Trigeminal neuralgia is characterized by sudden brief episodes of electric shock-like pains, abrupt in onset that terminates in the distribution of one or more divisions of the trigeminal nerve. There are several classification systems for trigeminal neuralgia. For this review, the focus was specifically on classical trigeminal neuralgia defined by the International Headache Society as neuralgia in the trigeminal distribution developing without apparent cause other than neurovascular compression (1). This as opposed to other painful trigeminal neuropathies due to neural damage such as post-herpetic trigeminal neuropathy or post-traumatic trigeminal neuropathy.
Despite its low incidence, trigeminal neuralgia is one of the most frequently seen neuralgias in the older adult population and its treatment frequently presents a challenge as current options such as oral medications, radiofrequency rhizotomies and microvascular decompressions are not always effective (1).
Peripheral nerve stimulation, which has been utilized for neuropathic pain for more than 50 years, has been shown to be effective in several case report studies for classical trigeminal neuralgia that have failed those measures previously mentioned. The objective of this review was to investigate the clinical effectiveness of subcutaneous peripheral nerve stimulation for trigeminal neuralgia (2).
Materials and Methods
MEDLINE, EMBASE and Cochrane Controlled Trials Register databases were searched in July 2017, unrestricted by date, with keywords targeted toward treatment of trigeminal neuralgia with subcutaneous peripheral nerve stimulation. 1,689 abstracts in total were found. Conference proceedings, reviews, expert opinions, and articles not translatable to English were initially excluded. Two independent reviewers then screened the remaining 424 titles for relevance. The reviewers independently completed full-text reviews of the remaining publications to select the articles included in this study.
A total of five case reports or case series were identified which reported the outcomes of 24 patients with classic trigeminal neuralgia following subcutaneous peripheral nerve stimulation. A detailed analysis of the methods, outcome measures, and conclusions of all four studies identified by this review is provided (table 1).
24 patients with classical trigeminal neuralgia underwent trial of subcutaneous peripheral nerve stimulation. The criteria for a successful trial varied but was related to reduction in pain. 15 of these 24 patients underwent permanent lead placement. The outcome measures of permanent placement between studies varied, but most assessed pain reduction and a single study evaluated the number of pain attacks pre- and post-permanent lead placement. Follow-up intervals also varied during the trial period and permanent lead placement between the studies.
Overall, the majority of patients experienced significant and sustained pain relief with subcutaneous peripheral nerve stimulation. The overall complication rate was relatively low in each of these procedures with the most common complications being electrode malfunction, device infection, and device malfunction.
Based on the current literature, subcutaneous peripheral nerve stimulation appears to be a promising alternative for management of refractory trigeminal neuralgia. However, due to the heterogeneity of how success was measured in regards to stimulator trial and permanent electrode placement a unified analysis of the results was unable to be performed. In addition there were a limited number of patients in each of the included studies thus more research is needed with control groups to further determine its clinical effectiveness and potential long term complications.