Speech and swallowing deficits in X-Linked Dystonia-Parkinsonism.

Introduction: X-linked Dystonia-Parkinsonism (XDP) is a progressive, disabling disease characterized by the devastating impairment of bulbar function, including speech and swallowing. Despite these detrimental impacts, bulbar impairments in this population are not well characterized.

Objectives: To identify impairments in the bulbar system measured by oromotor performance in individuals with XDP relative to healthy controls. Secondarily, to detect diagnostic bulbar markers that are sensitive and specific to the initial years of XDP.

Methods: This case-control study included 25 healthy controls and 30 participants with XDP, divided into two subgroups based on the median of their disease length. Multiple clinical and instrumental oromotor tasks and measures were used to evaluate bulbar motor function.

Results: Differences were found between both the subgroups with XDP and healthy controls on almost all measures, including maximum performance tasks such as tongue strength, alternating motion rate (AMR), and sequential motion rate (SMR) (p < 0.05). Differences were found between the XDP subgroups and the control group for the percentage of pause time during the speech, a rating of speech severity, and a swallowing task (ps < 0.05). Scores on self-reported questionnaires, tongue strength, the number of repetitions produced during an AMR, percent pause, and speech severity demonstrated good sensitivity and specificity to differentiate the initial years of XDP onset from healthy controls.

Conclusions: Our findings revealed impairments across bulbar functions in participants within the first 7 years of the XDP onset. Highly sensitive and specific bulbar impairment measures were detected in instrumental and self-reported measures that are fundamental for monitoring disease.