Mechanisms of pain in multiple sclerosis: A combined clinical and neurophysiological study
Truini A et al. – The data underline the clinical importance of pain in multiple sclerosis and indicate that a more severe disease is associated with a higher risk of developing neuropathic pain. The prevalence of pain that the authors found, which was lower than that reported in previous studies, may reflect the lesser disease severity in the patients. Neurophysiological data show that whereas ongoing extremity pain is associated with spinothalamic pathway damage, Lhermitte’s phenomenon is related to damage of non–nociceptive pathways. These findings may be useful in designing a new therapeutic approach to neuropathic pain related to multiple sclerosis.Methods
- A total of 302 consecutive patients with multiple sclerosis were screened for neuropathic pain by clinical examination and the DN4 tool.
- In patients selected for having ongoing extremity pain or Lhermitte’s phenomenon, the authors recorded somatosensory evoked potentials, mediated by Aβ non-nociceptive fibres, and laser evoked potentials, mediated by Aδ nociceptive fibres.
- Of the 302 patients, 92 had pain (30%), and 42 (14%) neuropathic pain.
- Patients with neuropathic pain had more severe multiple sclerosis, as assessed by the expanded disability severity score, than those without pain.
- Whereas, in patients with ongoing neuropathic pain, laser evoked potentials were more frequently abnormal than somatosensory evoked potentials, they found the opposite in patients with Lhermitte’s phenomenon.