Trigeminal neuralgia (TN) is an excruciating shooting pain involving one or both sides of the face; occurring in isolation (also termed idiopathic) or as a symptom of MS or other neurological disorders. It is literally a pain for both the patient and the doctors who manage it. The only plus point is that it is episodic in nature. However, with any recurrence you are pretty much starting again at the bottom, up titrating the neuromodulators (carbamazepine, oxcarbazepine, gabapentin, baclofen etc.) to very high doses to bring the pain under control.
TN presenting without a known etiologic factor is termed as classic or “idiopathic”, whereas secondary cases are due to well-defined causative factors such as space-occupying lesions or multiple sclerosis (MS) – from Franzini et al 2021 (see below for the abstract)
There are a few surgical approaches available for TN, and in my opinion they are more efficacious than tablets alone. They range from glycerol injection to the trigeminal ganglion, gamma knife radiosurgery to microvascular decompression. There is no clear evidence as to which strategy is best, but most seem to work unless there is clear compression of the trigeminal nerve root by a blood vessel (in which instance, most surgeons pick the microvascular decompression route). The seniority of the surgeon and experience also colours procedure selection, as well as procedure availability (i.e. gamma knife is currently only available at Queen Square in London). I have found when faced with MS very few surgeons favour microvascular decompression.
With this in mind, the latest study using Gamma knife comes from Italy comprising of 29 MS patients, a group from Italy retrospectively reviewed their outcomes for surgery between 2015 and 2019. For the first treatment, an average dose of 85 Gy (mean 83.4 Gy, range 74 to 88 Gy) irradiation was used. For repeat procedures, an average dose of 73.5 Gy (mean 74.25 Gy, range 70 to 80 Gy) was used. For all treatments, the median beam on time was 51.3 minutes (mean 51.4 minutes, range 31.8 to 97.2 minutes).
Pain reduction was achieved in 28 patients on average within 14 days (average 26.5 days, range 1-150 days). Successful response was maintained at 1, 3, and 5 years post-operatively in 70%, 57%, and 57%, respectively. Repeat procedures seem to help for recurrent pain; of the 4 who underwent repeat procedure there was benefit in all 4. In terms of side effects 12 out 29 experienced some degree of facial numbness. It must be born in mind that in a number of these cases neuromodulators were still needed but this was at a lower dose than previously needed.
World Neurosurg. 2021 Feb 25;S1878-8750(21)00267-9. doi: 10.1016/j.wneu.2021.02.074. Online ahead of print.
Gamma Knife radiosurgery for the treatment of trigeminal neuralgia in patients with multiple sclerosis: A single-center retrospective study and literature review
Objective: Trigeminal neuralgia (TN) in patients with multiple sclerosis (MS) is a challenging condition to manage that is treated with Gamma Knife radiosurgery (GKRS). The aim of this report is to assess the safety, efficacy, and durability of GKRS for the treatment of TN in patients with MS. Our findings are compared with those of the existing literature and discussed.
Methods: We retrospectively reviewed all patients at our institution who underwent GKRS for the treatment of TN secondary to MS and had one or more years of follow-up. Pre-operative and post-operative pain intensities and facial numbness were evaluated with the Barrow Neurological Institute (BNI) scores. Durability of successful pain relief was statistically evaluated with Kaplan-Meier analysis. The prognostic role of perioperative factors was investigated and analyzed using Cox proportional hazards regression.
Results: There were 29 patients with MS-TN who underwent GKRS at our institution. Two patients underwent bilateral treatment. Four patients underwent repeat GKRS for pain recurrence. The median period of follow-up assessment was 33 months. Rates of reasonable pain reduction at 1, 3, and 5 years were 70%, 57%, and 57% respectively. All patients who underwent repeat GKRS had durable pain reduction. No prognostic factor for successful pain reduction was found.
Conclusions: Our study shows that GKRS for the treatment of TN secondary to MS is a safe and effective procedure in controlling pain in the short term, but often fails to provide long-term pain control. GKRS can be safely repeated to prolong the time of pain reduction.