Session Time: 1:45pm-3:15pm
Location: Les Muses Terrace, Level 3
Objective: To check whether measures of motor cortex excitability and plasticity are associated with clinical response to dopaminergic treatment in Parkinson’s disease (PD) patients.
Background: Primary motor cortex (M1) shows number of impairments in excitability and plasticity in PD. There has been scarce attempts to check whether there is a link between impaired neurophysiological measures and response to dopaminergic medication.
Method: Measures of M1 excitability [short latency intracortical inhibition (SICI), intracortical facilitation (ICF), and short-latency inhibition (SAI)], and plasticity [relative increase in size of motor evoked potentials (MEP) elicited by transcranial magnetic stimulation (TMS) immediately after and 30 minutes after paired associative stimulation (PAS) protocol] from the worst affected hand were collected in a group of 22 PD patients (Hoehn & Yahr stage range 1 – 4). They were correlated with the scores on a standard clinical scale, motor section of the Unified Parkinson’s Disease Scale (UPDRS) – total scores as well as lateralised UPDRS and bradykinesia scores for the worst affected hand. Patients were tested off medication, after an overnight withdrawal, (neurophysiological and clinical measures) and on medication, following usual morning dose (clinical measures).
Results: Measures of M1 plasticity off-medication did not correlate with medication induced changes in UPDRS motor scores and two derived scores, lateralised UPDRS and bradykinesia scores (for the worst affected side). Same was with ICF and SAI. However, there was a significant correlation between off-medication SICI and changes in lateralised UPDRS and bradykinesia scores (Spearman R=0.515, p=0.014, and R=0.419, p=0.05, respectively) – larger on-off differences (i.e. medication induced improvement) were associated with worse off-medication SICI.
Conclusion: Patients with more impaired intracoritical inhibition seems to benefit more from dopaminergic treatment than patients whose intracortical inhibition is closer to normal. Different levels of intracortical inhibition may point towards different subtypes of PD.
To cite this abstract in AMA style:SR. Filipović, A. Kačar, S. Milanović, M. Ljubisavljević, VS. Kostić. Impaired intracortical inhibition predicts response to medication in Parkinson’s disease patients [abstract]. Mov Disord. 2019; 34 (suppl 2). https://www.mdsabstracts.org/abstract/impaired-intracortical-inhibition-predicts-response-to-medication-in-parkinsons-disease-patients/. Accessed December 6, 2023.
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MDS Abstracts - https://www.mdsabstracts.org/abstract/impaired-intracortical-inhibition-predicts-response-to-medication-in-parkinsons-disease-patients/