Lateral trunk flexion in Parkinson’s disease: EMG features disclose two different underlying pathophysiological mechanisms

Abstract

Pisa Syndrome is clinically defined as the sustained lateral bending of the trunk worsened by a prolonged sitting position or by walking. Pisa syndrome, also termed lateral trunk flexion (LTF), has been rarely reported in patients affected by Parkinson's disease (PD) and, therefore, the pathophysiology has been poorly investigated. In some cases, the hyperactivity of paravertebral muscles contralateral to the leaning side has been interpreted as a sign of dystonia; however, it is well known that paravertebral muscles flex the trunk ipsilaterally. We systematically explored the pattern of muscular activation underlying the lateral flexion of trunk in 10 PD patients (mean disease duration: 9.2 ± 3.0 years) presenting LTF for 3.6 ± 2.1 years. EMG performed during stance and during left and right lateral trunk flexion showed a continuous ipsilateral muscular hyperactivity in three patients, while in the remaining ones there was no ipsilateral activity during standing and a tonic contraction of paravertebral muscles contralateral to the leaning side. In conclusion, this EMG study investigating the synergies of paravertebral muscles during dynamic conditions detected two different patterns with a typical dystonic activation in only a minority of cases. Possible pathophysiologic mechanisms and treatment approaches are discussed.

Mood and behavioural effects of subthalamic stimulation in Parkinson's disease

“…Electromyographic (EMG) recording of paraspinal muscles failed to show any pattern of denervation or myopathy, 36,72,73 except in 2 of 26 patients in one study. 7 Very few imaging studies have been performed on the paraspinal muscles.…”

“…An early study using lumbar computed tomography scan showed atrophy of the lumbar paraspinal muscles with fatty degeneration, which was more pronounced on the side affected by deviation. 72 More recently, a magnetic resonance imaging study showed bilateral paraspinal lumbar muscle atrophy that was unrelated to the side affected by the deviation, and more pronounced in hypoactive muscles as shown by EMG recordings. 73 Although these data are difficult to interpret, they do not support the notion that musculoskeltal mechanisms play a primary role in Pisa syndrome.…”

“…7,36 However, other studies have found contradictory patterns of EMG activity: hyperactivity of paraspinal muscles ipsilateral to the leaning side versus tonic hyperactivity contralateral to the side affected by deviation. 72,73 Methodological issues (muscles examined, recording protocol) make it difficult to compare EMG studies and might account for the discrepancies in the results. In addition, clinical characteristics (disease duration, Pisa syndrome duration, pharmacological treatment) also may influence the pattern of muscle hyperactivity.…”

Insidious onset of Pisa syndrome after rasagiline therapy in a patient with Parkinson’s disease

“…1a). The patient underwent conventional EMG recordings in the paravertebral muscles at the thoracic-lumbar level T12-L1 (longissimus thoracis muscle) [2]. Recordings, that were performed with the patient in stance position and during voluntary right and left lateral trunk flexion, showed a pattern of a co-contraction of agonist and antagonist muscles compatible with dystonia of paraspinal muscles (Fig.…”

Pisa syndrome in Parkinson's disease: diagnostic and management challenges

“…33,34 Most of the clinical studies have also shown that patients lean away from the most affected side, which is consistent with animal studies. [35][36][37] However, few investigators failed to replicate this finding. 28,30,31 Another observation pointing to the involvement of central dopaminergic system is that PS can occur as a motor complication of PD.…”