Chronic Pain after Non-traumatic, Non-compressive Myelopathy: Characteristics and Predictors for Neuropathic pain

Abstract

Introduction: Chronic pain is one of the most common and serious consequences of myelopathy. The aim of this study was to survey chronic pain experience in a neurology out-patient clinic and to determine potential predictors for neuropathic pain after non-traumatic, non-compressive(NTNC) myelopathy.

Methods: We analyzed54 patients with a history of NTNC myelopathy at the neurology out-patient clinic. All patients completed questionnaires on pain severity, descriptors and impact on quality of life (QOL) and underwent neurologic examination with bedside sensory testing. The Short Form McGill Pain Questionnaire (SF-MPQ) and the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) were used to assess pain. Neuropathic pain was diagnosed by LANSS score of 12 or more. Health-related QOL was evaluated by the Short Form 36-item (SF-36) health survey, while Hospital Anxiety and Depression Scale (HADS) and Patient Global Impression of Change (PGIC) were utilized to evaluate emotion and response to treatment for pain, respectively.

Results: Out of 54 patients, 48 reported pain; of these, 41 (85.4%) reported the initiation of pain during the first 3 months of myelopathy onset. The median (min-max) pain duration and SF-MPQ score was 41 (3.4-166) months and 10 (1-34), respectively. Thirty five (72.9%) patients reported continuous pain throughout the day. The most common pain descriptions were exhausting, gnawing and heavy. In total, 16 (33.3%) patients experienced neuropathic pain. Mean age was statistically significantly lower in patients with neuropathic pain than in patients with non-neuropathic pain (39.1 ± 12.5 vs. 49.8 ± 9.3, P = 0.002). A binary logistic regression revealed that onset age under 40, non-idiopathic etiologysuch as neuromyelitis optica, multiple sclerosis were independent predictors of the occurrence of neuropathic pain. Both SF-MPQ and LANSS scores were significantly correlated with SF-36 scores, adjusted by age, sex, presence of diabetes mellitus, and current EDSS scores (r = –0.624, P< 0.0001 for SF-MPQ; r = -0.357, P = 0.017 for LANSS). Patients who showed clinical improvement (PGIC scores >2) with treatment were female, non-idiopathic etiology or lengthy lesion (> 3 vertebral segments). But the presence of diabetes was related to a poor treatment response.

Conclusion: Chronic pain is one of annoying complications in patients with NTNC myelopathy and also affects their quality of life. Onset age and etiology of myelopathyare important factors in the development of neuropathic pain in NTNC myelopathy. Pain relief research is expected to improve health-related QOL in these patients.