Botulinum toxin dilution and endplate targeting in spasticity: a double-blind controlled study.
OBJECTIVE
To determine the effects of botulinum neurotoxin type A (BTX-A) dilution and endplate-targeting in spastic elbow flexors.


METHODS
Double blind randomized controlled trial; 4-month follow-up after a 160-unit injection of BTX-A into spastic biceps brachii (4 sites). Randomization into: group 1: 100 mouse units (MU)/mL dilution, 0.4cc/site, 4-quadrant injection; group 2: 100MU/mL dilution, 0.4cc/site, 4 sites along endplate band; group 3: 20MU/mL dilution, 2cc/site, 4-quadrant injection (n=7 per group).


METHODS
Institutional tertiary care ambulatory clinic.


METHODS
Referred sample of 21 adults with spastic hemiparesis. No participant withdrew due to adverse effects.


METHODS
A 160-unit injection of BTX-A of different dilutions and locations into biceps brachii.


METHODS
Primary: agonist and antagonist (cocontraction) mean rectified voltage (MRV) of elbow flexors/extensors during maximal isometric flexion/extension; secondary: maximal voluntary power of elbow flexion/extension; spasticity angle and grade in elbow flexors/extensors (Tardieu Scale); active range of elbow extension/flexion.


RESULTS
BTX-A injection overall reduced agonist flexor MRV (-47.5%, P<0.0001), antagonist flexor MRV (-12%, P=.037), antagonist extensor MRV (-19%, P<.01), flexion maximal voluntary power (-33%, P<.001), elbow flexor spasticity angle (-30%, P<.001) and grade (-17%, P=.03), and increased extension maximal voluntary power (24%, P=.037) and active range of elbow extension (5.5%, 8 degrees , P=.002). Agonist and antagonist flexor MRV reductions in group 3 (-81% and -31%) were greater than in groups 1 and 2, whereas increase in active range of elbow extension was greater in group 2 (10%) than in groups 1 and 3 (P<.05, analysis of covariance [ANCOVA]). Elbow flexor spasticity was significantly reduced in groups 2 and 3 only (P<.05, ANCOVA).


CONCLUSIONS
In spastic biceps, high-volume or endplate-targeted BTX-A injections achieve greater neuromuscular blockade, cocontraction and spasticity reduction, and active range of elbow extension improvement, than low volume, nontargeted injections.
Gracies
Jean-Michel
JM
Department of Neurology, Mount Sinai Medical Center, New York, NY, USA. jean-michel.gracies@hmn.aphp.fr
Lugassy
Mara
M
Weisz
Donald J
DJ
Vecchio
Michele
M
Flanagan
Steve
S
Simpson
David M
DM
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009045:Motor Endplate / Q000187:drug effects*; D009128:Muscle Spasticity / Q000534:rehabilitation*; D009498:Neurotoxins / Q000008:administration & dosage / Q000627:therapeutic use*; D010291:Paresis / Q000534:rehabilitation*; D016059:Range of Motion, Articular
D009498:Neurotoxins; D019274:Botulinum Toxins, Type A