Botulinum toxin treatment of freezing of gait in Parkinson's disease patients as reflected in functional magnetic resonance imaging of leg movement.

BACKGROUND: Freezing of gait (FOG) is a common disabling symptom of (in) Parkinson's disease (PD). The mechanism of FOG is (in) not clearly understood. We investigated the clinical effect and changes of the activity of the sensorimotor system using repeated functional MRI (fMRI) before and after application of botulinum toxin in Parkinson's disease patients with FOG.

METHODS: We investigated 20 patients with PD, 10 with FOG and 10 without FOG. PD patients with FOG were treated with intramuscular application of botulinum toxin type A into the tensor fasciae latae muscle bilaterally. The clinical effect of treatment was assessed using FOG questionnaire, "Time up and go" test, UPDRS, Hoehn and Yahr staging, Clinical global impression scale. Activation of the sensorimotor system was studied using BOLD fMRI of the whole brain during repetitive abduction - adduction of each leg interleaved with rest. The clinical (in the FOG group) and imaging (in both groups) examination was repeated after a four-week interval.

RESULTS: In the FOG group, the FOG questionnaire has shown a decline of scores after application of botulinum toxin that suggests possible effect of botulinum toxin on freezing of gait. In fMRI results, both groups manifested reduction of the sensorimotor network activated with leg movement, however, the FOG group also showed increased activation in cerebellar vermis and nuclei, in dorsal pons and in medulla after treatment.

CONCLUSION: Alleviation of the FOG in PD patients by botulinum toxin seems to be reflected in the functional participation of the cerebellum and its projections as seen by fMRI.