Objective: The objective of this study was to investigate if continuous infusion of levodopa- carbidopa gel (LCIG) improves motor complications of Parkinson’s disease (PD) and reverse its associated maladaptive changes of plasticity.

Background: In PD chronic pulsatile treatment with oral levodopa causes maladaptive changes in the cortico- basal ganglia- talamo- cortical circuit, which underlie motor complications such as motor fluctuations and levodopa- induced dyskinesias. Using transcranial magnetic stimulation (TMS), these changes may be detected at the level of sensorimotor cortex and consist of an absent response to plasticity protocols even when patients are tested under dopaminergic medications.

Method: 17 patients with advanced PD with average age 72.5 and disease duration 14 years have been enrolled so far. All of them underwent TMS experiments two days before and ten amongst them six months after the introduction of LCIG. We measured motor thresholds, input/output curve, intracortical inhibition and response to intermittent theta burst stimulation (iTBS) plasticity protocol over the hemisphere corresponding to the more affected side.  Patients were in the clinically defined »on« state. Clinical assessment was performed using MDS- UPDRS part III and IV scales.

Results: There was no significant change in the UPDRS part III in the »on« state, however there was a clear trend for improvement of motor complications with LCIG (MDS-UPDRS part IV; p=0.12). While the response to iTBS was absent on oral dopaminergic medications, LCIG significantly recovered motor cortex plasticity (p=0.020) (Figure 1). There were no changes in other TMS parameters.

Conclusion: LCIG is able to restore impaired response to iTBS, in parallel with an improvement in motor complications. Continuous dopaminergic treatment may reverse maladaptive changes related to chronic pulsatile dopaminergic treatment.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/continuous-levodopa-carbidopa-gel-recovers-motor-cortex-plasticity-in-advanced-parkinsons-disease/