Although pharmacological therapy is the primary treatment modality for trigeminal neuralgia associated pain, ineffective analgesia and dose limiting side effects often prompt patients to seek alternative pharmacological solutions such as interventional nerve blockade.
The international guidelines on TN treatment recommend carbamazepine and oxcarbazepine as first line treatment based on clinical studies.
Other drugs used to treat TN have not been investigated to the same extent but some smaller studies showed promising results using pregabalin , lamotrigine , baclofen and gabapentin. In the international guidelines it is stated that “if any of these sodium-channel blockers (carbamazepine or oxcarbazepine, edt.) are ineffective, referral for a surgical consultation would be a reasonable next step” . However, the guidelines also state that “considering the relatively narrow mechanism of action of the available drugs (carbamazepine, edt.), combination treatments might be useful” .
Based on the clinical experience of Heinskou et al they agree with the international treatment guidelines although find that referral for neurosurgery after failed monotherapy may be too hasty and in general try out a combination treatment before referral to surgery. Unfortunately, the scientific support for combination treatment is sparse and there are no published studies directly comparing monotherapy with polytherapy.
They suggest that follow up on medical treatment should remain in the hands of experts until the condition is stable and the patient is familiar with the program of titrating up and tapering of medication according to the level of pain and side effects. They suggest that 2 years of follow up is appropriate, but this depends on the resources of the clinic and the health care system 1).
Microvascular decompression is a first-line neurosurgical approach for classical TN with neurovascular conflict, but can show clinical relapse despite proper decompression. Second-line destructive techniques like radiofrequency thermocoagulation have become reluctantly used due to their potential for irreversible side effects. Subcutaneous peripheral nerve field stimulation (sPNFS) is a minimally invasive neuromodulatory technique which has been shown to be effective for chronic localised pain conditions.
The most frequently used surgical management of trigeminal neuralgia is Microvascular decompression (MVD), followed closely by stereotactic radiosurgery (SRS). Percutaneous stereotactic rhizotomy (PSR) , despite being the most cost-effective, is by far the least utilized treatment modality 2).
Radiosurgery is a well-established treatment modality for medically refractory trigeminal neuralgia. The exact mechanism of pain relief after radiosurgery is not clearly understood. Histopathology examination of the trigeminal nerve in humans after radiosurgery is rarely performed and has produced controversial results.
There is evidence of histological damage of the trigeminal nerve fibers after radiosurgery therapy. Whether or not the presence and degree of nerve damage correlate with the degree of clinical benefit and side effects are not revealed and need to be explored in future studies 3).
The results suggest that stereotactic radiosurgery with linear accelerators could constitute an effective and safe therapeutic alternative for drug-resistant trigeminal neuralgia. However, existing studies leave important doubts as to optimal treatment doses or the therapeutic target, long-term recurrence, and do not help identify which subgroups of patients could most benefit from this technique 4).