Multiple sclerosis and spasticity: the role of anaesthetic nerve blocks on rectus femoris muscle. When should stiff knee be treated with botulinum toxin?
Alessio Baricich, Marco Battaglia, Margherita B Borg and 7 others
PMID 39101677WHAT IT FOUND
In 14 people with MS and stiff knee, a diagnostic nerve block predicted who would improve after botulinum toxin.
Those with more severe disability saw the block match toxin results across all walking tests. Those with milder disability saw the block underestimate improvement in agility tasks.
Key findings
01The diagnostic nerve block predicted which patients would show clinically significant improvements after botulinum toxin injection, with a correlation coefficient of 0.98.
02For patients with higher disability (EDSS > 3.5), the nerve block predicted improvements in walking speed, endurance, and agility. For those with lower disability (EDSS ≤ 3.5), it only predicted walking speed and endurance, missing agility gains.
03Improvements in the Timed-Up-and-Go test were significantly greater after botulinum toxin than after the nerve block, suggesting the block may underestimate functional gains in complex tasks.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study was very small (14 patients) and had no control group, so it cannot prove the treatments work better than natural variation or placebo. Patients received rehabilitation treatment alongside the injections, so it is impossible to separate the effect of the botulinum toxin from the effect of the therapy. The study used minimal clinically important difference values derived from stroke survivors, not people with multiple sclerosis, which may not be accurate for this population. The nerve block may not fully mimic the long-term effects of botulinum toxin, particularly for complex movements like the Timed-Up-and-Go test.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not assume a negative nerve block means the patient will not benefit from botulinum toxin. The block failed to predict agility improvements in patients with milder disability, and the study was too small to establish this as a reliable rule-out test.