Use of low-dose naltrexone in the management of post-traumatic trigeminal neuropathic pain: a retrospective case series.

Introduction: Dentists provide treatment of anatomical structures innervated by the trigeminal system such as the teeth, gingiva etc., which can be subject to injury even following routine and well performed dental procedures. As a result, the dental clinician is often presented with patients with neuropathic pain or unusual sensory distortions. In addition, the dental clinician treats patients following facial and oral trauma which may result in chronic pain. Therefore, recognition of posttraumatic trigeminal neuropathic pain (PTTNP) and its management must be considered essential for the dental clinician. Painful neuropathies, including PTTNP, can present as a debilitating form of neuropathic pain that often defies treatment normally effective for other types of somatic pain disorders. Treatment of PTTNP typically involves the use of various classes of medications including antiseizure medications (AEDs) and tricyclic antidepressants (TCAs)1. Many patients suffering with PTTNP may have contraindications for these medications due to comorbidities, occupational responsibilities, or medication side effects. An alternative to AEDs and TCAs is the use of low-dose naltrexone (LDN)2.

Methods: This study is a retrospective extended case series of patients with PTTNP. The records of twenty-one patients diagnosed with painful post-traumatic trigeminal neuropathic pain at the Center for Temporomandibular Disorders and Orofacial Pain of the Rutgers School of Dental Medicine. They met the criteria of PTTNP according to the ICOP and were prescribed LDN. Though a total of twenty-one patients were included, twelve with all the data present were included into the final analysis. The sex distribution was equal with 6 females and 6 males, with a combined average age of 59.33 ± 13.96 years.

Results: LDN significantly reduced the patients' report of pain using a Visual Analogue Scale (VAS) 0-10 subjective pain ratings at the follow-up visits compared to the initial VAS. Interestingly, the small group of patients who used LDN in combination with Serotonin Norepinephrine Reuptake Inhibitors (SNRI), demonstrated a lower average VAS score at the first follow-up visit, compared to those who took LDN with other medications. There were no significant side effects reported by the patients. No adverse effects of LDN therapy were reported. Side effects of the medication are rare and as reported the literature, include mild abdominal distress or vivid dreams. None were reported among this group of subjects. Based on our retrospective extended case series, LDN appears to be a safe and effective medication for use in chronic PTTNP. These results, highlight the need for future studies to elucidate LDN's analgesic mechanism of actions and to decisively demonstrate the analgesic effect of LDN in larger cohorts using randomized, double blinded, placebo controlled clinical studies.