Back to List
Botulinum Toxin Injections for Headache
Case History Submitted by: Randolph W. Evans, M.D.
Expert Opinion by: Andrew Blumenfeld, M.D.
Posted October 2003
Botulinum toxin injections for migraine? It seemed crazy to many
when first suggested by otolaryngologist William Binder. In 1992,
he noted that migraineurs who received injections for wrinkles
reported an improvement in their headaches, and additional evidence
for efficacy has accumulated since. Serendipity strikes again!
In patients who have migraine with aura, botulinum toxin type A therapy
frequently produces improvement in head pain, but the aura remains
unchanged. This may be related to the mechanism of action of
botulinum toxin type A in migraine, wherein the drug is hypothesized
to affect the trigeminal nerve predominantly. Triptan responsiveness
often improves following botulinum toxin type A treatment, but
patients with allodynia will continue to have a poor response to
triptans. It would be interesting to study the effects of botulinum
toxin type A on allodynia in patients with migraine.
Although patients improve after one treatment, repeated treatments
produce even greater clinical efficacy, particularly with respect
to changes in Migraine Disability Assessment (MIDAS) scores. Three
treatments of botulinum toxin type A over a 9-month period should
be considered adequate to determine whether the patient will or
will not be a responder to botulinum toxin therapy. To insure
appropriate expectations, patients should be advised about the
progressive efficacy of repeated treatments. Each successive
treatment may involve higher doses and varied combinations of
fixed-site and follow-the-pain approaches.
Botulinum toxin type A therapy may be effective in the management
of chronic daily headache. The technique of injection involves a
fixed-site approach for migrainous headaches, as for the first case,
with the addition of a follow-the-pain approach for headaches with
tension-type features. Follow-the-pain injection sites include the
frontalis, temporalis, occipitalis, trapezius, splenius capitus,
suboccipital, and cervical paraspinal muscles. Injection sites are
identified by history ("Where does it hurt when you have a headache?
" and "Show me with your hands where the pain is."), and by
examination of the cervical-shoulder girdle and temporomandibular
musculature. The doses injected in the cervical-shoulder girdle
muscles are kept low, so as to prevent any possible weakness.
For all types of headache, the dose of botulinum toxin type A is in
the range of 50 to 100 units. The technique of delivering small
doses at multiple sites reduces the occurrence of side effects and
controls head pain effectively. To achieve this, a dilution of 4
mL of normal saline to 100 units of botulinum toxin type A is used.
The dose at each site is 2.5 (0.1cc) to 5 units (0.2 cc). The
injections are administered intramuscularly to limit discomfort
and side effects imported by soft tissue diffusion. Intradermal
injections may produce a similar clinical improvement but tend to
be more uncomfortable. Owing to the potential risk of antibody
development, botulinum toxin type A treatments should not be
repeated more frequently than every 3 months.