Neuropathic pain in multiple sclerosis: discrepancies between DN4 screening and neurophysiological measures

Area of Science:

• Neuroscience
• Neurology
• Pain Medicine

Background:

• Pain is a significant and debilitating symptom in multiple sclerosis (MS).
• The underlying pathophysiological mechanisms of MS-related pain are not well understood.
• Current clinical assessment often relies on subjective tools like the DN4 questionnaire.

Purpose of the Study:

• To characterize the pain phenotype in MS patients using the DN4 score.
• To investigate the relationship between the DN4 score and objective neurophysiological markers.
• To assess nociceptive and non-nociceptive pathway function using laser-evoked potentials (LEPs) and somatosensory evoked potentials (SEPs).

Main Methods:

• Fifty MS patients with pain completed clinical evaluations including DN4, pain intensity (VAS), fatigue (FSMC), anxiety/depression (HADS), and disability (EDSS).
• LEPs and SEPs were recorded following specific nerve stimulations.
• Statistical analyses included logistic regression, non-parametric comparisons, and correlation analyses to compare neurophysiological parameters between DN4 groups.

Main Results:

• A neuropathic pain phenotype (DN4 ≥4) was identified in 56% of MS patients.
• The DN4 score showed moderate correlation with pain intensity and fatigue, but weak correlation with anxiety.
• No significant association was found between DN4 status and LEPs or SEPs, indicating subjective pain burden rather than objective pathway dysfunction.

Conclusions:

• The DN4 score in MS primarily reflects subjective symptom experience, not objective sensory pathway dysfunction.
• The limited correlation with neurophysiological measures underscores the complex, multidimensional nature of pain in MS.
• LEPs and SEPs offer complementary insights, advocating for multimodal, mechanism-based pain assessment and management strategies in MS.