Inclusion Criteria:  At least a 1-year history of chronic migraine (CM), with or without aura, consistent with a diagnosis according to International Classification of Headache Disorders 3rd edition (ICHD-3 2018) and with or without acute medication as defined in the protocol. Must be currently treated with BOTOX for CM: treated with >= 2 treatment cycles in the 8 months prior to Visit 2 (Day 1). Must have 8 to 23 (inclusive) migraine days in the 28-day Screening/Baseline period (as assessed with eDiary).  Exclusion Criteria:  Use of opioid-containing products for more than 4 days for acute treatment of headache in the 3 months prior to Screening (Visit 1) or during the 28-day Screening/Baseline period. Treatment of study target muscles using acupuncture, transcutaneous electrical nerve stimulation (TENS), cranial traction, dental splints for headache, or injection of anesthetics/steroids within 4 weeks prior to Screening (Visit 1). Concurrent use of any migraine prevention treatment other than BOTOX (including use of oral gepants) in the 4 weeks prior to Visit 1 nor during the Screening/Baseline period. Current use or use within the 6 months (24 weeks) prior to Screening (Visit 1), of mAbs blocking the CGRP pathway. Concurrent use of oral gepants for acute migraine treatment in the 4 weeks prior to Visit 1 nor during the screening/baseline period.