Some cases will be eligible, but not all. The NICE guidance states:

Botulinum toxin type A is recommended as an option for the prophylaxis of headaches in adults with chronic migraine (defined as headaches on at least 15 days per month of which at least 8 days are with migraine):

• that has not responded to at least three prior pharmacological prophylaxis therapies and
• whose condition is appropriately managed for medication overuse.

In addition, availability of the service varies regionally.