Article

Although important for dosing and dilution, there are few data
describing botulinum toxin (BT) movement in human muscle. OBJECTIVE: To better
understand BT movement within human muscle. DESIGN:
Proof-of-concept study with
descriptive case series. SETTING: Outpatient academic practice. PARTICIPANTS:
Five subjects with stroke who were BT naive with a mean age of 60.4 +/- 14 years
and time poststroke of 4.6 +/- 3.7 years. METHODS: Three standardized injections
were given to the lateral gastrocnemius muscle (LGM):
2 contained 25 units (U) of
onabotulinumtoxinA (Botox) in 0.25 mL of saline solution and the third 0.25 mL of
saline solution only. The tibialis anterior muscle (TAM) was not injected in any
subject. A leg magnetic resonance image was obtained at baseline, 2 months, and 3
months later with a 3.0 Tesla Siemens scanner. Three muscles, the LGM, lateral
soleus muscle (LSM), and TAM, were manually outlined on the T2 mapping sequence
at each time point. A histogram of T2 relaxation times (T2-RT) for all voxels at
baseline was used to calculate a mean and standard deviation (SD) T2-RT for each
muscle. Botulinum toxin muscle effect (BTME) at 2 months and 3 months was defined
as a subject- and muscle-specific T2-RT voxel threshold >/=3 SD above the
baseline mean at or near BT injection sites. MAIN OUTCOME MEASURES: BTME volume
for each leg magnetic resonance imaging slice at 3 time points and 3 muscles for
all subjects. RESULTS: One subject missed the 3-month scan, leaving 18 potential
observations of BTME. Little to no BTME effect was seen in the noninjected TAM. A
BTME was detected in the LGM in 13 of 18 possible observations, and no effect was
detected in 5 observations. Possible BTME effect was seen in the LSM in 3
subjects due to either diffusion through fascia or needle misplacement. Volume of
BTME, as defined here, appeared to be substantially greater than the 0.25-mL
injection volume. CONCLUSIONS: This descriptive case series is among the first
attempts to quantify BTME within human muscle. Our findings are preliminary and
are limited by a few inconsistencies. However, we conclude that use of magnetic
resonance imaging to detect the volume of BTME is feasible and may assist
researchers in modeling the spread and diffusion of BT within human muscle. LEVEL
OF EVIDENCE: IV.
CI - Copyright (c) 2017 American Academy of Physical Medicine and Rehabilitation.
Published by Elsevier Inc. All rights reserved.

Langue : ANGLAIS