Short-Latency Afferent Inhibition Correlates with Stage of Disease in Parkinson's Patients.

Abstract

BACKGROUND:

Sensory-motor decoupling at the cortical level involving cholinergic circuitry has also been reported in Parkinson's Disease (PD). Short-latency afferent inhibition (SAI) is a transcranial magnetic stimulation (TMS) paradigm that has been used previously to probe cortical cholinergic circuits in well-characterised subgroups of patients with PD. In the current study, we compared SAI in a cohort of PD patients at various stages of disease and explored correlations between SAI and various clinical measures of disease severity.

METHODS:

The modified Hoehn and Yahr (H&Y) scale was used to stage disease in 22 patients with PD. Motor and cognitive function were assessed using the MDS-UPDRS (Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale) part III and MoCA (Montreal Cognitive Assessment) score, respectively. Objective gait assessment was performed using an electronic walkway (GAITRite®). SAI was measured as the average percentage inhibition of test motor-evoked potentials (MEPs) conditioned by electrical stimulation of the contralateral median nerve at the wrist.

RESULTS:

SAI was significantly reduced in patients with advanced PD (H&Y stage 3) compared to early PD patients (H&Y stage 1) on pairwise comparison. The visuospatial executive function and orientation domains of cognition demonstrated significant negative associations with SAI.

CONCLUSION:

Cortical sensory-motor integration is progressively diminished as disease progresses. The observation that a reduction in SAI is associated with a reduction in cognitive function possibly reflects the progressive involvement of cortical cholinergic circuits in PD with increasing motor stage. Future longitudinal studies are necessary to confirm this preliminary result.

• Authors: Supriyo Choudhury, Ummatul Siddique, Simin Rahman, Yogesh Kumar, Sattwika Banerjee, Mark R Baker, Stuart N Baker, Hrishikesh Kumar
• Journal: The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques (Can J Neurol Sci) Vol. 50 Issue 4 Pg. 579-583 (07 2023) ISSN: 0317-1671 [Print] England
• PMID: 35684949 (Publication Type: Journal Article)

Chemical References

• Cholinergic Agents

Topics

• Humans
• Neural Inhibition (physiology)
• Parkinson Disease
• Evoked Potentials, Motor (physiology)
• Wrist
• Cholinergic Agents