Diagnostic nerve block in prediction of outcome of botulinum toxin treatment for spastic equinovarus foot after stroke: A retrospective observational study

Objective: To evaluate the role of diagnostic nerve block in predicting the outcome of subsequent botulinum toxin type A treatment for spastic equinovarus foot due to chronic stroke.

Design: Retrospective observational study.

Patients: Fifty chronic stroke patients with spastic equinovarus foot.

Methods: Each patient was given diagnostic tibial nerve block (lidocaine 2% perineural injection) assessment followed by botulinum toxin type A inoculation into the same muscles as had been targeted by the nerve block. All patients were evaluated before diagnostic nerve block, after the nerve block, and 4 weeks after botulinum toxin injection. Outcomes were ankle dorsiflexion passive range of motion of the affected side, and calf muscle spasticity, measured with the modified Ashworth scale and the Tardieu Scale.

Results: Significant improvements were measured after diagnostic nerve block and botulinum toxin injection compared with the baseline condition. Diagnostic nerve block led to significantly greater improvements in all outcomes than botulinum toxin injection.

Conclusion: This study confirmed diagnostic nerve block as a valuable screening tool in deciding whether to treat spastic equinovarus with botulinum toxin. However, the results support the evidence that diagnostic nerve block results in a greater reduction in muscle overactivity than does botulinum toxin type A in patients with spastic equinovarus due to stroke.

Keywords: botulinum toxin; diagnosis; equinus deformity; muscle spasticity; nerve block.