Pisa syndrome in Parkinson's disease: electromyographic quantification of paraspinal and non-paraspinal muscle activity

Abstract

Patients with Parkinson's disease (PD) and Pisa syndrome (PS) may present tonic dystonic or compensatory (i.e. acting against gravity) hyperactivity in the paraspinal and non-paraspinal muscles. Electromyographic (EMG) activity was measured in nine patients with PD and PS, three with PD without PS, and five healthy controls. Fine-wire intramuscular electrodes were inserted bilaterally into the iliocostalis lumborum (ICL), iliocostalis thoracis (ICT), gluteus medius (GM), and external oblique (EO) muscles. The root mean square (RMS) of the EMG signal was calculated and normalized for each muscle. In stance condition, side-to-side muscle activity comparisons showed a higher RMS only for the contralateral ICL in PD patients with PS (p=0.028). Moreover, with increasing degrees of lateral flexion, the activity of the EO and the ICL muscles progressively increased and decreased, respectively. The present data suggest that contralateral paraspinal muscle activity plays a crucial compensatory role and can be dysfunctional in PD patients with PS.

Figure 1

A: case 5 with 50° of PS, pattern I (subtype II). He shows left (arrow) and right (dotted arrow) ICL hypertrophy. The intensity of contralateral ICL activation is reduced when compared with the right side, which indicates a possible impairment of the paraspinal compensatory mechanism. B: case 4 with 42° of PS, pattern II. He shows left (arrow) and right (dotted arrow) ICL hypertrophy. The intensity of contralateral ICL activation is increased when compared with the right side, which indicates possible integrity of the paraspinal compensatory mechanism. In both these PS patients there is hyperactivity of EO, right side.

Figure 2

A= Correlation between the degree of trunk flexion and RMS of the contralateral ICL and the ipsilateral EO muscles in the right PS patients. B and C= Correlation between degree of trunk flexion and RMS of the contralateral ICL and the ipsilateral EO muscle in four young healthy controls (mean value) simulating PS from 0 to 25 degrees (B) and from 25 to 55 degrees (C).