Botulinum toxin type B in the spastic arm: a randomized, double-blind, placebo-controlled, preliminary study.

OBJECTIVE

To determine the efficacy and safety of 2 doses of botulinum toxin type B (rimabotulinumtoxinB, BoNT/B) in spastic upper limb muscles.

DESIGN

Randomized, double-blind, placebo-controlled trial with a 3-month follow-up.

SETTING

Tertiary care center.

PARTICIPANTS

Referred sample of adult hemiparetic patients (N=24) with disabling elbow flexor overactivity after stroke or traumatic brain injury.

INTERVENTIONS: Injection of 10,000U of rimabotulinumtoxinB (fixed 2500U dose into elbow flexors; n=8), 15,000U (5000U into elbow flexors; n=8), or placebo (n=8) into overactive upper limb muscles selected as per investigator's discretion.

MAIN OUTCOME MEASURES: At 1 month postinjection, active range of elbow extension (goniometry; primary outcome); active upper limb function (Modified Frenchay Scale [MFS]); subjective global self-assessment (GSA) of arm pain, stiffness, and function; rapid alternating elbow flexion-extension movement frequency over the maximal range; elbow flexor spasticity grade and angle (Tardieu), and tone (Ashworth).

RESULTS

No adverse effects were associated with either BoNT/B dose. Both doses improved active elbow extension versus placebo (+8.3°; 95% confidence interval, 1.1°-15.5°; analysis of covariance, P=.028). The high dose of BoNT/B also improved subject-perceived stiffness (P=.005) and the composite pain, stiffness, and function GSA (P=.017), effects that persisted 3 months from injection. No MFS change was demonstrated, although subjects with a baseline MFS <70/100 seemed more likely to benefit from BoNT/B.

CONCLUSIONS

In this short-term study, BoNT/B up to 15,000U into spastic upper limb muscles, including the elbow flexors, was well tolerated and improved active elbow extension and subject-perceived stiffness.