Spatiotemporal characteristics of the pharyngeal event-related potential in healthy subjects and older patients with oropharyngeal dysfunction

Abstract

Background

Oropharyngeal dysphagia (OD) is a highly prevalent symptom in older people. Appropriate oropharyngeal sensory feedback is essential for safe and efficient swallowing. However, pharyngeal sensitivity decreases with advancing age and could play a fundamental role in the physiopathology of swallowing dysfunction associated with aging. We aimed to characterize pharyngeal sensitivity and cortical response to a pharyngeal electrical stimulus in healthy volunteers (HV) and older patients with and without OD.

Methods

Eight young HV, eight older HV without OD, and 14 older patients with OD were studied by electroencephalography through 32 scalp electrodes. Pharyngeal event-related potentials (ERP) were assessed following electrical stimulation of the pharynx. Sensory and tolerance thresholds to the electrical stimulus and latency, amplitude, and scalp current density of each ERP component were analyzed and compared. An ERP source localization study was also performed using the sLORETA software.

Key Results

Older participants (with and without OD) presented an increased sensory threshold to pharyngeal electrical stimulation (10.2 ± 1.7 mA and 11.5 ± 1.9 mA respectively), compared with young HV (6.0 ± 1.2 mA). The cortical activation of older HV in response to pharyngeal electrical stimulus was reduced compared with young HV (N2 amplitude: 0.22 ± 0.79 vs −3.10 ± 0.59, P<.05). Older patients with OD also presented disturbances to the pharyngo-cortical connection together with disrupted pattern of cortical activation.

Conclusions and Inferences

Older people present a decline in pharyngeal sensory function, more severe in older patients with OD. This sensory impairment might be a critical pathophysiological element and a potential target for treatment of swallowing dysfunction in older patients.

Appropriate oropharyngeal sensory feedback is essential for safe and efficient swallowing. Non-dysphagic older patients present impaired cortical activation compared with young healthy volunteers in response to pharyngeal electrical stimulus. Older patients with dysphagia also present disturbances in the pharyngo-cortical connection together with a disrupted pattern of cortical activation. Swallowing therapy in older people with dysphagia should include strategies aiming to stimulate the pharyngeal sensory afferents to promote recovery of the swallowing function.

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