Abstract
Onabotulintoxin A (BontA) is an efficacious preventive treatment for chronic migraine, though the specific mechanism of action is still under discussion. The study aims: (1) To evaluate pain processing modifications in chronic migraine patients (CM) under single BontA administration in pericranial muscles, by means of CO2 Laser Evoked Potentials (LEPs) obtained by the stimulation of the skin over the right frontal and trapezius injection sites and hand dorsum, in a double blind placebo controlled crossover design. (2) To correlate main LEPs findings with clinical outcome after one year of BontA treatment. Twenty refractory CM patients were included in the analysis. The LEPs were recorded in basal conditions and seven days after BontA (PREEMPT protocol) and saline solution injection. The N1, N2 and P2 amplitude and latencies and N2P2 habituation index were evaluated and correlated with the percent change of headache frequency after one year of toxin treatment. After seven days of BontA treatment, a normalization of the trigeminal habituation index was observed, which was correlated with the clinical outcome after one year of BontA therapy. Patients displaying trigeminal LEPs facilitation at T0 time showed a more efficient therapeutic outcome. Neurotoxin may exert a modulating effect on trigeminal nociception, normalizing central neurotransmission.
Highlights
OnabotulintoxinA (BontA) is an efficacious preventive treatment for chronic migraine [1,2,3], though the specific mechanism of action is still under discussion [4,5]
The Laser Evoked Potentials (LEPs) performed at T0 and T1 before placebo or BontA were almost super-imposable, and statistical analysis of Student’s t-test did not report relevant differences, so we decided to consider the average values across the two recording series
Score approached the statistical significance (Pearson correlation = 0.4226, p = 0.051). We found that both (TTS), though the negative correlation between allodynia and trigeminal habituation index approached allodynia and Total Tenderness Score (TTS) influenced headache severity (Pearson correlation between allodynia and Migraine Disability Assessment (MIDAS): the statistical significance (Pearson correlation = 0.4226, p = 0.051)
Summary
OnabotulintoxinA (BontA) is an efficacious preventive treatment for chronic migraine [1,2,3], though the specific mechanism of action is still under discussion [4,5]. The neurotoxin can exert a modulating effect on central sensitization by blocking the release of CGRP and glutamate from nociceptive nerve fibers terminating in the spinal cord, suppressing the stimulation of second-order neurons and glial cells [4,9,10,11]. The observations about the low efficacy of BontA in episodic migraine compared to the good results in chronic forms [13] may suggest that the main action is exerted on the phenomena of central sensitization, which subtend the transition from sporadic to continuous headache, rather
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