Is the Outcome of Diagnostic Nerve Block Related to Spastic Muscle Echo Intensity? A Retrospective Observational Study on Patients with Spastic Equinovarus Foot.
Mirko Filippetti, Rita Di Censo, Valentina Varalta and 4 others
PMID 35266004WHAT IT FOUND
Patients with spastic equinovarus foot who had higher muscle echo intensity on ultrasound showed a reduced response to diagnostic nerve blocks.
This suggests that increased fibrosis or fatty infiltration in the muscle limits the effectiveness of temporary nerve blockade.
Key findings
01Higher spastic calf muscle echo intensity was significantly associated with a reduced clinical response to selective dorsal nerve block.
02Ultrasound echo intensity was inversely associated with baseline spasticity measures (MAS, Tardieu Scale) before the block.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
The study design was retrospective, meaning data was collected from existing charts rather than prospectively, which limits control over variables. The sample size was small (48 patients). Patients were not standardized regarding their specific aetiologies (stroke, MS, etc.), which may have influenced muscle structure. The study used the standard Heckmatt scale rather than the modified version, and ultrasound images were not stored for re-evaluation. No neurophysiological evaluation (e.g., EMG) was performed to confirm the status of the spastic muscles. Data on active range of motion and non-affected limbs were not collected.
Declared interests
The authors have no conflicts of interest to declare.
The easy way to misread this
Do not conclude that high echo intensity causes the poor response to nerve blocks. This is an observational study showing an association. It is possible that the underlying muscle pathology (fibrosis/fat) is simply more severe in these patients, making them less responsive to any intervention, not just nerve blocks.