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Efficacy and Tolerability of Low-dose Naltrexone for Pain Relief among Neuropathic Corneal Pain Patients

Title
Efficacy and Tolerability of Low-dose Naltrexone for Pain Relief among Neuropathic Corneal Pain Patients
Publication Type
Abstract/Poster/Letter
Research Type
Human
Reported as
Case Report/Series/Restrospective Study
Date
June 15, 2020
Authors
Gabriela Dieckmann; Mehmet Cuneyt Ozmen; Ryan Engert; Pedram Hamrah
Institution
Tufts Medical Center
Link
Abstract

PURPOSE: Neuropathic corneal pain (NCP) is a recently described ocular pain modality resulting from nerve damage and presenting with symptoms of pain or persistent unpleasant sensations, such as dryness, burning, or light sensitivity. When symptoms do not resolve with topical anesthetics, this point to a non-ocular source of pain. Low-dose naltrexone (LDN) acts as a neuromodulator with a neuroprotective effect via inhibition of microglial activation in the central nervous system and upregulation of endogenous opioid production. We aimed to assess the efficacy and tolerability of LDN for NCP.

METHODS: In a retrospective cohort study,patients diagnosed with ocular pain and the keyword “naltrexone” were identified. All patients were required to have been diagnosed with NCP and using LDN for at least 3 months. Diagnosis was based on medical history, discordance in clinical signs and symptoms, and corneal in vivo confocal microscopic findings. Patients were required to exhibit persistent ocular discomfort/pain after instillation of 0.5% proparacaine hydrochloride. Patients were excluded if they had any ocular pathology that might cause pain.

RESULTS: Thirty out of 71 identified patients were included in the final data-set based on inclusion/exclusion criteria. Mean age was 45.60±19.30 years with a white (80.00%) female (73.33%) predominance. Time between visits (duration of LDN use) was 14.87±11.25 months (range 1-36 months) and duration of NCP prior to treatment was 17.53±17.29 months (range 3-79 months). The average percent improvement was -49.22%. Sixteen patients (53.33%) had equal to or more than 50% improvement, 4 patients (13.33%) had 30-49% improvement, 5 patients (16.67%) had 1-29% improvement, and 5 patients (16.67%) did not improve. Mean Quality of life (QoL) score by the ocular pain assessment survey was 5.84±2.57 (range 1.14-9.00) at the first visit (p<0.0001). Mean QoL score improved to 3.77±2.91 (range 0-8.86) at the last visit (p=0.023). Pre-treatment comorbidities were dry eye disease (66.67%), neuropsychiatric diseases (30.61%) and auto-immune diseases (10.20%). All patients were on previous systemic medications (most common being Nortriptyline 26.7% and SSRI 16.7%).

CONCLUSIONS: LDN was effective and well tolerated as an adjunct therapy for NCP.