Distribution of spasticity in both lower limbs of people affected by unilateral stroke and the muscles selected for botulinum toxin A injections

Dr Ettie Ben-shabat1, Ms Lucy Bell1, Dr Mithu Palit1

1Alfred Health – Caulfield Hospital, Caulfield, Australia

Aim: 1) To identify the muscles most frequently affected by spasticity in stroke.  2) To assess spasticity in the unaffected side. 3) To assess whether the distribution of botulinum injections (BoNT-A) matches that of spasticity.

Method:  Thirty-one adults with unilateral stroke were recruited from a single centre for this observational study.  Seven muscles of each leg were assessed for spasticity using the Modified Tardieu Scale.  The frequency of spasticity in each muscle was compared with the frequency it was injected with BoNT-A.

Results:  In the affected side spasticity often occurred both above and below the knee together (n=22, 71%) and occasionally in muscles only above (n=7, 23%) or only below (n=2, 6%) the knee.  Spasticity in the “unaffected” side was mainly in muscles below the knee (n=11, 58% below the knee only, n=7, 23% both above and below the knee).  Twenty-seven participants received BoNT-A injections.  Frequencies of injections were similar to the frequencies of spasticity for muscles below the knee (gastrocnemius, X2=1.133, p=0.287; soleus, X2=0.118, p=0.73; tibialis posterior, X2=1.442, p=0.230) but not for muscles above the knee (binomial analysis adductors p=0.042 and hamstrings p=0.000; rectus femoris, X2=41.66, p=0.000).

Significance of the findings to allied health:  Spasticity in the affected side is common in both muscles above and below the knee. Yet, BoNT-A injections are mainly administered into below knee muscles. Addressing only one group of spastic muscles with BoNT-A injections may limit the efficacy of this intervention.  Assessing spasticity in the “unaffected” side may be required due to its frequency and possible contribution to dysfunction.