Data from a randomised controlled trial (RCT), which have been published in Frontiers in Neurology, support the use of neuromodulation with transcranial direct current stimulation (tDCS) as an add-on to neurorehabilitation in the treatment of Parkinson’s disease patients affected by Pisa syndrome.
Based on these findings, the study’s authors—Roberto De Icco (University of Pavia, Pavia, Italy) and colleagues—conclude that tDCS “may represent a therapeutic alternative” in this patient population, owing to the fact it is a non-invasive, well-tolerated, easily repeatable, and low-cost, technique.
The authors begin by noting that Pisa syndrome, a pathological lateral flexion of the trunk, is a frequent postural complication of Parkinson’s disease that responds poorly to antiparkinsonian drugs, and improvements achieved with neurorehabilitation tend to fade in six months or less.
They also state that tDCS has shown promising results in improving specific symptoms in different movement disorders. De Icco and colleagues further note that several previous case series suggest deep brain stimulation (DBS) may exert positive effects over Pisa syndrome—but the invasiveness of this therapeutic approach, and a lack of specifically designed and well-powered trials, have limited its application in clinical practice.
As such, they conducted an RCT aimed at evaluating the role of bi-hemispheric tDCS as an add-on to a standardised hospital rehabilitation programme for Pisa syndrome management. According to a central pathophysiological hypothesis, an imbalance in the dopaminergic outflow between basal ganglia of the two hemispheres may play a crucial role in the development of Pisa syndrome. The authors state that a bi-hemispheric tDCS approach was designed with the aim of re-equilibrating the imbalance between left and right basal ganglia.
Their study included 28 patients with Parkinson’s disease and Pisa syndrome. Twenty-one of these patients were men, and the average age across the cohort was 72.9 years. Each underwent a four-week intensive neurorehabilitation treatment and randomisation to receive either tDCS (n=13) for five daily sessions with bi-hemispheric stimulation over the primary motor cortex, or sham stimulation (n=15) with the same duration and cadence.
At baseline, end of rehabilitation, and six months, patients were evaluated with both trunk kinematic analysis and clinical scales—including Unified Parkinson’s Disease Rating Scale (UPDRS-III), functional independence measure (FIM), and Numerical Pain Rating Scale (NPRS) for lumbar pain.
Detailing their results, De Icco and colleagues report that, compared to the sham group, the tDCS group achieved a more pronounced improvement in the following variables:
- Overall trunk posture (p=0.014) during upright standing position
- Lateral trunk inclination (p=0.013) during upright standing position
- Total active range of motion (ROM) of the trunk (p=0.012)
- FIM score (p=0.048)
- Lumbar pain intensity (p=0.017)
“The improvement achieved in our tDCS group is consistent with previous data reporting a reduction between 30 and 50% of lateral trunk inclination, and a comparable increase of ROM of trunk bending at the end of a rehabilitation programme,” the authors write.
“The new and inspiring aspect of our present findings is that the addition of tDCS to neurorehabilitation induced a more persistent improvement in trunk posture. This result has a great clinical significance, because the persistence of the improvement is one of the critical issues in the management of Pisa syndrome in Parkinson’s disease. In this frame, it is tempting to hypothesise that the observed benefit may possibly be further extended over time when considering the possibility of repeating tDCS stimulation in the ambulatory setting in association with a tailored physical exercise programme at home.”
Detailing limitations of their study, they add that the small sample size involved “does not allow us to infer definitive conclusions” and claim that, despite adopting a bi-hemispheric approach, they cannot exclude the possibility that other stimulation paradigms might induce comparable or even better results—for instance, a longer duration of tDCS therapy within the hospital setting.
“Despite these limitations, this study warrants further trials on larger cohorts, in order to confirm our findings,” they conclude.