1Hz rTMS Preconditioned by tDCS Over the Primary Motor Cortex in Parkinson’s Disease: Absence of Effect on Arm Lift and Hand Grip Force Control

Abstract

This study investigated whether a period of low frequency rTMS preconditioned by tDCS over the primary motor cortex modulates control of grip force in Parkinson's disease. The presented results are from the same patient cohort tested in an earlier study (Gruner et al. J Neural Transm 2010: 117: 207-216). 15 patients with Parkinson's disease (mean age: 69 ± 8 years; average disease duration: 5 ± 3 years) on dopaminergic drugs performed a grasp-lift task with either hand before (baseline) and after a period of 1Hz rTMS (90% of the resting motor threshold; 900 pulses) preconditioned by sham, anodal or cathodal tDCS (1mA, 10 min) over the primary motor cortex. We found that compared with baseline, none of the grip force parameters was significantly influenced by either stimulation session and concluded that grasping is a higher order motor skill, which cannot be modulated by tDCS preconditioned 1Hz rTMS in PD.

Tolerability and Blinding of Transcranial Direct Current Stimulation in People with Parkinson’s Disease: A Critical Review

“…One study tested in both off and on dopaminergic medication [ 33 ], one tested in the off state [ 49 ], and one did not report medication status [ 52 ]. Five investigations had open-label designs [ 38 , 43 , 45 , 46 , 47 ]; seven were parallel arm, randomized, double-blind, sham-controlled designs [ 33 , 40 , 41 , 42 , 44 , 50 , 52 ]; and eight were crossover, randomized, sham-controlled designs, with six being double-blind [ 36 , 37 , 39 , 48 , 49 , 51 ] and two with unstated blinding [ 34 , 35 ]. The tDCS intensities ranged from 1 to 2.8 mA (range of current densities = 0.02 mA/cm 2 –0.12 mA/cm 2 ) and stimulation was applied for 7–30 min (mode = 20 min).…”

“…The third study did not have any unusual stimulation parameters that might explain the reported tingling and light flash experienced by one subject and the reported event might be attributed to the individual characteristics of that subject or slightly different electrode placement in that session [ 40 ]. Lastly, although the group sizes and characteristics were not identical, the possibility of at least some of the subjects being included in all three of the Hadoush et al papers is noted [ 45 , 46 , 47 ], and the results of Grüner et al [ 34 ] and Eggers et al [ 35 ] were explicitly stated to be from the same subjects.…”

“…Manenti et al [25] Active: 11, 65.5 ± 6. Most of the reviewed studies (20/36) provided qualitative tolerability reports [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] (Table 2). Most included simple statements (e.g., "no adverse events were reported by any of the [subjects]" [42]), but a few provided descriptions of the experiences of individual subjects who had more severe or unique (at least for the study) adverse effects [33,40,50]; only one study mentioned blinding integrity [33].…”

Non-invasive brain stimulation for Parkinson’s disease: Current concepts and outlook 2015

“…Cathodal tDCS interferes with beneficial effects of 1 Hz rTMS in finger tapping and pointing movements (Gruner et al, 2010), but anodal stimulation does not. Grasping cannot be modulated by tDCSprimed 1 Hz rTMS (Eggers, Gruner, Ameli, Sarfeld, & Nowak, 2012), and anodal tDCS, but not cathodal stimulation, with subsequent 1 Hz rTMS improves gait (von Papen, Fisse, Sarfeld, Fink, & Nowak, 2014). This combined approach of tDCS-priming with a subsequent rTMS protocol remains to be tested in a therapeutic trial in PD.…”

Parkinson's disease treatments: focus on transcranial direct current stimulation (tDCS)

“…Similar to Lefaucheur's comprehensive review, 8 we chose to exclude three studies that used tDCS as a priming mechanism for testing an alternative intervention, namely rTMS. [9][10][11] tDCS tDCS involves the delivery of a low-intensity current (1-2 mA) using relatively large electrodes (~2-10 cm) generally placed on the scalp. Most studies of tDCS employ a " bipolar" montage consisting of one anode and one cathode to induce an electric field that passes across the various cranial structures (skin, bone, pia, and cerebrospinal fluid) to reach the brain parenchyma.…”