Selective blocks of the motor nerve branches to the soleus and tibialis posterior muscles in the management of the spastic equinovarus foot.

Objective: To identify the location of the motor nerve branches to the soleus and tibialis posterior muscles in relation to anatomic surface landmarks for selective motor nerve blocks in the management of the spastic equinovarus foot.

Design: Descriptive study by computed tomography (CT) scan of 12 hemiplegic legs.

Setting: Spasticity group at a university hospital.

Participants: Twelve patients with hemiplegia (6 men, 6 women) with spastic equinovarus foot.

Intervention: Three-dimensional location of the motor nerve branches to the soleus and tibialis posterior muscles with CT scan, followed by selective motor branch blocks with anesthetics.

Main Outcome Measures: Vertical, horizontal, and deep coordinates determined by CT scan in relation to anatomic surface landmarks (upper extremity of the fibula and vertical metallic element). Soleus and tibialis posterior spasticity (Ashworth Scale), soleus H-wave maximum (Hmax)/M-wave maximum (Mmax) ratio, and sensory testing before and after the blocks.

Results: The mean coordinates +/- standard deviation for the soleus motor branch were 10+/-5 mm (vertical), 17+/-9 mm (horizontal), and 30+/-4 mm (deep); for the tibialis posterior motor branch they were 45+/-6mm (vertical), 17+/-8mm (horizontal), and 47+/-4 mm (deep). Spasticity and Hmax/Mmax ratio decreased after the blocks, confirming their efficiency. No subjects experienced additional sensory deficit.

Conclusion: Our study determined the location of the motor nerve branches to the soleus and tibialis posterior muscles in relation to anatomic surface landmarks for selective motor branch blocks and neurolytic procedures. These coordinates allow us to perform selective motor blocks without CT scan.