Change in the second exteroceptive suppression period of the temporalis muscle during erenumab treatment

Comparative studies on the second exteroceptive suppression period (ES2) of the masseter or temporalis muscle in migraineurs and controls have provided conflicting results. As the interneurons responsible for ES2 are probably close to the trigeminal nucleus caudalis and receive afferents also from the anti-nociceptive system, the study of ES2 could provide information on neural circuits involved in migraine pathophysiology. The aim of this observational, pilot study was to assess whether erenumab treatment may affect the exteroceptive suppression reflex of the temporalis muscle activity in migraineurs. The exteroceptive suppression reflex of the temporalis muscle activity was previously studied in a small case series of three chronic female migraineurs and after 4 months of beneficial erenumab treatment, administered according to current clinical indications. There was a statistically significant decrease in ES2 latency ( p -value 0.039) and duration ( p -value 0.030) after treatment. The change observed in the temporalis ES2 during erenumab treatment indicates that ES2 may play some kind of role as a neurophysiological marker and that this monoclonal antibody can modulate the brainstem circuits involved in migraine pathophysiology, at least indirectly. Further studies are required to confirm this intriguing hypothesis.