Low-Dose Naltrexone (LDN) for Chronic Pain at a Single Institution: A Case Series.

Purpose: Low-dose naltrexone (LDN) has increased in popularity as a non-opioid medication that may decrease chronic pain symptoms. LDN is most commonly used to treat fibromyalgia, complex regional pain syndrome (CRPS), and painful diabetic neuropathy. Other studies suggest that LDN provides general symptom reduction in inflammatory conditions such as Crohn's disease and multiple sclerosis. We reviewed our experience with patients to whom we have prescribed LDN to see what types of painful conditions were most responsive to LDN in our patient population. Patients and Methods: Charts from patients who came to the Pain Center between 2014 and 2021 were reviewed. Results: Of the n = 137 patients who were prescribed LDN, 44% had no evidence of ever filling the prescription, and 4.4% of the responses were not charted. Of the remaining who took LDN (n = 70), 64% had some relief and were designated as 'Responders'. The most common pain diagnosis was neuropathic pain which, when added to the diagnosis of complex regional pain syndrome, accounted for 51% of responders to LDN. Patients who experienced greater than 50% pain relief from LDN were more likely to have the diagnosis of neuropathic pain or complex regional pain syndrome (p = 0.038, Fisher's Exact Test). There was a significant difference in the diagnosis of patients who responded to LDN. Patients with spondylosis were much less likely to respond to LDN when compared with other diagnoses (p = 0.00435, Chi-Square Test). Conclusion: Patients with all types of neuropathic pain, including CRPS, were significantly more likely to have pain relief from LDN than patients with spondylosis (p=0.018). The diagnosis of spondylosis was more often associated with a lack of response to LDN than any other diagnosis. Patients may need to have a trial of several weeks before analgesic effects are seen with LDN.