The intention tremor seen in chronic progressive multiple sclerosis is
often disabling and existing treatments are of limited benefit. The p
resent pilot study was designed to assess the role of Botulinum toxin
type A (BOTOX(R)) in such cases. Five patients with the condition rece
ived 40 mouse units of toxin into the flexor and extensor compartments
of the forearm. Two of these went on to receive a further 100 mouse u
nits 2 months after the previous injection. Tremor was assessed at 0,
2 and 8 weeks post-injection using a validated clinical rating scale,
spirography and handwriting samples, and a clinician's global rating s
cale; functional capacity was measured using an activities of daily li
ving (ADL) scale adapted for use in tremor. No statistically significa
nt improvement occurred in intention tremor, although there was a tren
d toward a mild improvement in the clinician's global rating scale. Pa
tients noted an increase in their pre-existing corticospinal weakness
which proved to be dose-limiting. No change occurred in ADL scores. It
is concluded that pre-existing weakness limits the use of Botulinum t
oxin in the intention tremor seen in multiple sclerosis, but further w
ork in disabling primary and secondary cerebellar degenerations withou
t corticospinal weakness may be worthwhile.