To describe our results with botulinum toxin type A injection for headache in carefully selected patients, and to present the rationale behind this therapy.

Tertiary referral centre.

This article describes a case series of 10 consecutive patients with frontally localised headache, whose pain worsened when pressure was applied at the orbital rim near the supratrochlear nerve. The patients received a local anaesthetic nerve block with Xylocaine 2 per cent at this site. If this reduced the pain, they were then offered treatment with botulinum toxin.

Injection with 12.5 IU of botulinum toxin A into the corrugator supercilii muscle on both sides (a total of 25 IU).

Pain severity scoring by the patients, ranging from zero (no pain) to 10 (severe pain) on a verbal scale.

Following injection, all patients had less pain for approximately two months. This treatment did not appear to have lasting side effects.

Xylocaine injection is a good predictor of the effectiveness of botulinum toxin injection into the corrugator muscle as treatment of frontally localised headache. We hypothesise that this pain is caused by entrapment of the supratrochlearis nerve in the corrugator muscle. Furthermore, we found botulinum toxin injection to be a safe and effective means of achieving pain relief in this patient group.