Motor Innervation of the Corrugator Supercilii Muscle in Relation to Orbital Landmarks: Guidelines for Surgical Denervation

Selective denervation of the corrugator supercilii muscle for the treatment of idiopatic trigeminal neuralgia purely paroxysmal distributed in the supraorbital and suprathrochlear dermatomes

Introduction

Idiopatic trigeminal neuralgia purely paroxysmal (ITNp) distributed in the supraorbital and suprathrochlear dermatomes (SSd), refractory to conventional treatments have been linked to the hyperactivity of the corrugator supercilii muscle (CSM). In these patients, the inactivation of the CSM via botulinum toxin type A (BTA) injections has been proven to be safe and effective in reducing migraine burden. The main limitation of BTA is the need of repetitive injections and relative high costs. Based on the study of the motor innervation of the CSM, we describe here an alternative approach to improve these type of migraines, based on a minimally invasive denervation of the CSM.

Materials and methods

Motor innervation and feasibility of selective CSM denervation was first studied on fresh frozen cadavers. Once the technique was safely established, 15 patients were enrolled. To be considered eligible, patients had to meet the following criteria: positive response to BTA treatment, migraine disability assessment score > 24, > 15 migraine days/month, no occipital/temporal trigger points and plausible reasons to discontinue BTA treatment. Pre- and post- operative migraine headache index (MHI) were compared, and complications were classified following the Clavien-Dindo classification (CDC).

Results

Fifteen patients (9 females and 6 males) underwent the described surgical procedure. The mean age was 41 ± 10 years. Migraine headache episodes decreased from 24 ± 4 day/month to 2 ± 2 (p < 0.001) The MHI decreased from 208 ± 35 to 10 ± 11 (p < 0.001). One patient (7%) had a grade I complication according to the CDC. No patient needed a second operative procedure.

Conclusions

Our findings suggest that the selective CSM denervation represents a safe and minimally invasive approach to improve ITNp distributed in the SSd associated with CSM hyperactivation.

Trial registration

The data collection was conducted as a retrospective quality assessment study and all procedures were performed in accordance with the ethical standards of the national research committee and the 1964 Helsinki Declaration and its later amendments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-021-01218-6.