Axonal excitability in sporadic migraine

Migraine is a common yet debilitating condition worldwide, affecting individuals, particularly women, of working age, causing significant impacts on quality of life and productivity. In this study, we set out to evaluate a group of individuals with sporadic migraine. We aimed to evaluate the effect of botulinum toxin or the novel calcitonin gene-related peptide (CGRP) erenumab. We were also able to consider studies on patients with familial hemiplegic migraine, where we were particularly looking to see if there were alterations in axonal excitability related to the gene mutations. A study has identified differences in episodic ataxia type 2, and patients with familial hemiplegic migraine type 1 (FHM1) carry mutations of the same gene CACNA1A. We sought to see if FHM1 patients had similar changes to those of episodic ataxia type 2, and whether axonal excitability allowed identification of genetically affected migraine individuals. We collected data on clinical outcomes, thermal threshold perception and sensory and motor axonal excitability parameters from the median nerve for our cohort of sporadic chronic migraine. No significant excitability changes were identified when compared to healthy controls at baseline, or after treatment. No alterations were seen when patients were divided into subgroups of erenumab or botulinum toxin treatment. We did note significant clinical improvements in patients treated with either botulinum toxin or erenumab, with some patients experiencing a large treatment response. We did not identify any significant change in thermal perception or thermal pain thresholds, before and after treatment. We were unable to recruit sufficient numbers of hemiplegic migraine patients for this study, and future work will involve further recruitment, before definite conclusions can be drawn about excitability changes in hemiplegic migraine