Is there pain with neuropathic characteristics in patients with amyotrophic lateral sclerosis? A cross-sectional study

Background: Amyotrophic lateral sclerosis is a progressive debilitating and lethal disorder, characterized by degeneration of motor neurons that warrant palliative care. Pain is frequent in patients with amyotrophic lateral sclerosis and significantly impacts on quality of life. Aim: To describe pain and assess the prevalence of pain with neuropathic characteristics in patients with amyotrophic lateral sclerosis. Design: Cross-sectional survey from March 2009 to October 2013. Setting/participants: Amyotrophic lateral sclerosis patients underwent multidisciplinary assessment and completed questionnaires measuring the severity and impact of pain and anxiety. The Douleur Neuropathique-4 questionnaire was used to look for pain with neuropathic characteristics. Results: Of 96 clinical evaluations, 93 were usable for analysis (age at onset: 6212.5years; disease duration: 34 +/- 33months). The overall pain prevalence was 66%, with 9% experiencing pain with neuropathic characteristics. Pain was most often located in the neck and shoulders (38% of pain patients). Neck and shoulder pain was associated with neck (p=0.04) and proximal upper limb muscular weakness (p=0.02), respectively. Pain was not associated with disease duration, respiratory or nutritional parameters, but with higher anxiety scores (p=0.01). Patients with neuropathic characteristics pain did not differ significantly from patients with or without pain, except that they had higher minimal pain intensity score (p<0.05). Neuropathic characteristics pain was frequently spontaneous (rarely evoked) and described as numbness, burning, electric shock, tingling, and pins-and-needle. Conclusion: Even if amyotrophic lateral sclerosis is a disease of the motor system, pain is frequent and can rarely have neuropathic characteristics. Pain must be always sought and appropriately treated to limit quality of life impairment.