Objective: This study aims to characterize bulbar motor impairments in patients with X-linked XDP and to identify clinical correlates for prediction of aspiration.

Background: X-linked dystonia-parkinsonism (XDP) is an inherited neurodegenerative disease endemic in Panay Island, Philippines that predominantly affects males. Initial stages are characterized by focal dystonia, which then generalizes. Seven to ten years after onset, parkinsonian symptoms emerge alongside symptoms of dystonia. Around 15 years post onset, parkinsonism predominates.  In approximately 28% of cases, dystonic symptoms initially manifest in the oromandibular and cervical area causing significant bulbar impairment.  Over the course of the disease, most persons with XDP develop bulbar dysfunction resulting in speech and swallowing impairments. The characteristics and severity of bulbar impairment in XDP is not well understood. 

Methods: Twenty-five XDP patients underwent assessments of respiratory function, speech, lip and tongue strength, diadochokinetic rates, articulation during connected speech, and swallowing function. Patient-reported measures of speech and swallowing impairment included the Communicative Participation Item Bank and the Eating Assessment Tool – 10.

Results: All participants exhibited bulbar impairment.  Sixteen subjects had evidence of aspiration. The average lip and tongue strength were both reduced with respective mean values of 9.48 ± 4.03 kPa (NV= 35 kPa) and 19 ± 11.29 kPa (NV = 63 kPa). The average pause percentage for speech sample was 34.18%. The mean scores for the following questionnaires were all abnormal: EAT-10 score of 19.28 ± 10.15 (score >/= 3 is abnormal), FOIS score of 4.88 ± 0.97 (score < 7 is abnormal), and CPIB score of 7.32 ±. 7.72 (maximum score of 30 and higher scores are more favorable). Logistic regression analysis showed that the duration of illness (p = 0.463), site of onset (p = 0.553), and phase of illness (dystonic p = 0.977, parkinsonian p = 0.829, dystonia-parkinsonian p = 0.999) did not contribute significantly to the prediction model of aspiration. The resulting model was not statistically significant, X2(4) = 4.71, p = 0.316.

Conclusions: Bulbar dysfunction in XDP results in speech and swallowing impairments characterized by decreased phonation time, decreased lip and tongue strength, decreased diadochokinetic rates, evidence of aspiration, and patient-reported speech and swallowing deficits.

References: Kreisler, A, Verpraet, AC, Veit, S, Pennel-Ployart, O, Behal, H, Duhamel, A, Destee, A. Clinical characteristics of voice, speech, and swallowing disorders in oromandibular dystonia. Journal of Speech, Language, and Hearing Research, Vol. 59, October 2016, pp. 940-949. LaPointe, LL, Murdoch, BE. Movement disorders in neurologic disease: effects on communication and swallowing. Plural Publishing, Inc., 2014, pp 123-159.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/characterizing-bulbar-dysfunction-in-x-linked-dystonia-parkinsonism-xdp-a-pilot-study/