Analysis of the pain in multiple sclerosis patients

Introduction: Despite pain being a disabling symptom in patients with multiple sclerosis (MS), its prevalence and characteristics are not well established. The aim of this study is to describe the characteristics and prevalence of pain in patients with MS, and to assess the associated clinical variables and radiological findings.

Methods: We prospectively studied patients with MS. A structured questionnaire which evaluated depression symptoms, type of pain, location, intensity (defined according to a visual analogue scale (VAS) as severe (VAS 7-10), moderate (VAS 4-6) and mild (VAS 0-4), and pain therapy was recorded in patients who referred to pain at the time of interview. Protocol variables were demographic data, MS clinical forms (remitting-relapsing, progressive-secondary and progressive-primary), neurological dysfunction (defined according to EDSS scale), symptoms at onset, attack frequency, illness duration, disease modifying treatment, fatigue, spasticity, oligoclonal bands in CSF, visual evoked potentials, depression symptoms (Hamilton test) and presence of lesions in spinal cord MRI.

Results: A total of 134 MS patients were included, and MRI was performed on 105 of them. Pain was reported by 74 (55%) patients and was most frequently neuropathic, located in limbs, severe and burning/spiky. Of these 28 (38%) received therapy for their pain, based predominantly in anti-inflammatory drugs. Patients with pain had a worse functional state (EDSS score, 4.5 [3-6] vs 1.5 [1-2], p<0.001), higher number of relapses (7.13±3.4 vs 3.75±2.9, p<0.001), progressive forms of MS (86.7% vs 13.3%, p<0.001), depression (91.9% vs 8.1%, p<0.001), spinal cord involvement at onset (79.2% vs 20.8%, p=0.009), spinal cord lesions by MRI (84.3% vs 15.7%, p<0.001) and longer duration of disease (14.6±7.8 vs 8.43±5.9 months, p<0.001). In a logistic regression model, the presence of lesions in spinal cord MRI (OR 3.5 [1.5-24.5]) and higher EDSS score (OR 1.7 [1.1-2.7]) were independently associated with pain.

Conclusions: Pain is a frequent disabling symptom in MS and is associated with disability and spinal cord lesions.