Lower urinary tract dysfunction (LUTD) is common in parkinsonian syndromes (PS) and requires special treatment due to limitations in the use of certain drugs and the progression of the disease. Tibial nerve stimulation by Transcutaneous Electrical Nerve Stimulation (TENS) is a simple, well-tolerated treatment with proven effectiveness in LUTD. The aim of our study was to evaluate the efficacy on urinary symptoms in patients with a parkinsonian syndrome.

A prospective, double-blind, multicenter, randomized study to compare the effects of TENS 20 minutes a day for 3 months with sham stimulation using the 3-month Patient Global Impression of Improvement (PGI-I) score in adults with PS and LUTD for whom conventional treatments had failed. The secondary endpoints studied were 3-month changes in PGI-S (Severity), Urinary Symptom Profile (USP), Qualiveen questionnaire, voiding diary (VD), post-void residue and the rate of complications.

Between 2015 and 2020, 100 patients with a mean age of 68.6 ± 8.4 years were randomized and included in the intention to treat analysis population (ITT). Among them were 71 men and 85 patients with idiopathic Parkinson’s disease. Initially, the PGI-S was moderate to severe (score of 3-4) in 80 patients: 38 (83%) in the TENS group and 42 (82%) in the sham group. After 3 months of treatment, 68 patients felt an improvement (PGI-I 1-3): 30 (64%) in the TENS group and 38 (72%) in the sham-stimulation group (p=0.399). There was no statistically significant difference between the 2 groups regardless of the endpoint considered.

In this study, tibial neuromodulation by TENS improved urinary symptoms in parkinsonian syndrome (64% of the patients), but with no significant difference from the sham stimulation (72% of the patients). The placebo effect is well known in the treatment of LUTD and has been for many years. In 1991, in a study of the efficacy of oxybutynin versus placebo in overactive bladder with a non-neurological cause, Thuroff et al. reported that oxybutynin improved symptomatology in 43% of the cases (1). The extent of the placebo effect depends on many factors, including the underlying pathology. The placebo effect is more pronounced in case of pain, depression, or IPD (2). Therefore, in patients with IPD, a positive response to placebo is obtained in over 50% of patients. This effect is even more pronounced in case of invasive treatment or advanced disease. It correlates with dopaminergic activation in the striatum (3). Therefore, the high level of the placebo effect in our study is probably related to the study population.

The effect of tibial neuromodulation by TENS on urinary disorders in patients with parkinsonian syndrome after 3 months of stimulation was not significantly different from the placebo effect obtained with sham stimulation.

Thüroff, Joachim W., Björn Bunke, Arno Ebner, Peter Faber, Patrick De Geeter, Josef Hannappel, Helmut Heidler, et al. 1991. « Randomized, Double-Blind, Multicenter Trial on Treatment of Frequency, Urgency and Incontinence Related to Detrusor Hyperactivity: Oxybutynin versus Propantheline versus Placebo ». Journal of Urology 145 (4): 813-16.
De La Fuente-Fernández, Raúl, Michael Schulzer, et A Jon Stoessl. 2002. « The Placebo Effect in Neurological Disorders ». The Lancet Neurology 1 (2): 85-91.
Quattrone, Aldo, Gaetano Barbagallo, Antonio Cerasa, et A. Jon Stoessl. 2018. « Neurobiology of Placebo Effect in Parkinson’s Disease: What We Have Learned and Where We Are Going ». Movement Disorders 33 (8): 1213-27.