Objective: To assess the central neural control of swallowing in HD patients with mild dysphagia using a multimodal imaging approach combining qualitative and quantitative swallowing assessments with functional [18F]fluorodeoxyglucose Positron Emission Tomography (FDG PET).

Background: Dysphagia is an almost inevitable symptom of HD resulting in weight loss, and aspiration pneumonia. However, the pathophysiological mechanisms underlying oropharyngeal dysphagia in HD are not well understood; moreover there is only incomplete knowledge as to which areas of the brain are involved in the disturbed swallowing process in HD.

Methods: In the pilot phase of this ongoing study, we assessed and analysed the data of 4 participants – two male patients with early stage HD (Total Function Capacity 7-13) and 2 age-matched healthy female controls. Only patients with mild dysphagia, as established by a clinical assessment, videofluoroscopy and completion of the Sydney Swallow Questionnaire and HD Dysphagia Scale, were eligible. Participants were assessed in a randomised, cross-over 2 scan paradigm of resting condition versus water swallowing at 20-second intervals both for 20 minutes prior to FDG PET scanning. Motion correction was applied to correct for involuntary movements. In order to compare the differences between patients and healthy controls, we calculated the scaled differences in activation during swallowing.

Results: Both patients displayed mild dysphagia (Penetration-Aspiration score 3). In contrast to healthy controls where major parts of the frontal cortex (left more than right) were activated while swallowing, the patients showed relative deactivation of this area compared to other brain regions. The differences between the two groups were less pronounced in other activated brain areas such as the motor cortex.

Conclusions: Early stage HD patients with mild dysphagia and healthy controls show different patterns of brain activation which may be associated with functional changes during swallowing. Frontal cortex deactivation during swallowing in early stage HD may be the result of impaired excitatory frontostriatal projections which prevents normal activation of the frontal cortex during swallowing. Thus changes in frontostriatal excitability may be one aspect of the swallowing neural network that alters swallowing function in HD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/dysphagia-in-early-stage-huntingtons-disease-hd-pilot-observations-from-a-multimodal-imaging-study/