Objective: To analyze the efficacy of botulinum toxin (BoNT) in cases of pisa syndrome (PS) associated with Parkinson’s disease (PD) targeting paraspinal muscles ipsilateral to the trunk flexion side.

Background: PS, defined as a ≥10° lateral trunk flexion reverted by lying position or passive mobilization, is a frequent complication of PD. Two small trials provided initial evidence of BoNT efficacy in patients with PD-associated PS. In a previous pilot study, we obtained a high rate of success by a multimodal approach where BoNT target was determined by electromyographic evidence of hyperactivity in specific axial muscles.

Method: Ten PD patients with PS (mean angle 18.6±7.3°) were treated with ultrasound- and electromyography-guided BoNT injections in longissimus-thoracic (50U) and iliocostalis-lumborum (50U) at the flexion side (T0). The primary endpoint was the number of patients improving the lateral trunk flexion (LTF) angle >5° (responders) 1 month after BoNT (T1). Secondary endpoints were: improvement of PS-associated pain, as per the visual-analog scale (VAS), and residual effect of BoNT after 4 months (T2).

Results: There were 40% of responders at T1 (39.4±10 days after treatment); 30% showed minimal improvements, 10% did not show any significant change, and 10% worsened. The average LTF improved by 19.4% (3.2±8°) in the entire group, and by 48.8% (10.2±1.2°) in the responders’ group. The VAS scores improved by 53.6% (1.7±1.9). Seven patients received the 4-month follow-up (T2 – 136.1±35.3 days after treatment). Four of them showed further improvement of LTF when compared to T1, and LTF at 4 months showed a sustained 19.2% improvement compared to T0 (4.9±11.2°). The VAS score worsened compared to T1 and even T0, with a 36.7% higher VAS score than before treatment (1.2±2.8).

Conclusion: 1) BoNT is effective for PS, but patients might require differential muscle targeting, according to the different patterns of muscle hyperactivity; 2) BoNT may have a long-lasting effect on LTF, but not on the associated back pain. This finding supports the hypothesis of PS being related to altered sensorimotor integration. In fact, BoNT effect wears-off after 3-4 months, while the LTF improvement may last longer due to the interruption of maladaptive proprioceptive feedback.

References: Artusi CA, Bortolani S, Merola A, Zibetti M, Busso M, De Mercanti S, Arnoffi P, Martinetto S, Gaidolfi E, Veltri A, Barbero P, Lopiano L. Botulinum toxin for Pisa syndrome: An MRI-, ultrasound- and electromyography-guided pilot study. Parkinsonism Relat Disord. 2019 May;62:231-235.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/refining-knowledge-on-the-treatment-of-pisa-syndrome-with-botulinum-toxin/