Does sex influence the natural history of idiopathic adult-onset dystonia?

BACKGROUND: Several earlier studies showed a female predominance in idiopathic adult-onset dystonia (IAOD) affecting the craniocervical area and a male preponderance in limb dystonia. However, sex-related differences may result from bias inherent to study design. Moreover, information is lacking on whether sex-related differences exist in expressing other dystonia-associated features and dystonia spread. OBJECTIVE: To provide accurate information on the relationship between sex differences, motor phenomenology, dystonia-associated features and the natural history of IAOD. METHODS: Data of 1701 patients with IAOD from the Italian Dystonia Registry were analysed. RESULTS: Women predominated over men in blepharospasm, oromandibular, laryngeal and cervical dystonia; the sex ratio was reversed in task-specific upper limb dystonia; and no clear sex difference emerged in non-task-specific upper limb dystonia and lower limb dystonia. This pattern was present at disease onset and the last examination. Women and men did not significantly differ for several dystonia-associated features and tendency to spread. In women and men, the absolute number of individuals who developed dystonia tended to increase from 20 to 60 years and then declined. However, when we stratified by site of dystonia onset, different patterns of female-to-male ratio over time could be observed in the various forms of dystonia. CONCLUSIONS: Our findings provide novel evidence on sex as a key mediator of IAOD phenotype at disease onset. Age-related sexual dimorphism may result from the varying exposures to specific age-related and sex-related environmental risk factors interacting in a complex manner with biological factors such as hormonal sex factors.

Does thyroid diseases contribute to the natural history of idiopathic adult-onset dystonia? Data from the Italian Dystonia Registry.

A few earlier observations and recent controlled studies pointed to the possible contribution of thyroid diseases in idiopathic adult-onset dystonia (IAOD). The aim of this study was to investigate the association between thyroid status and clinical characteristics of IAOD, focusing on dystonia localization, spread, and associated features such as tremors and sensory tricks. Patients were identified from those included in the Italian Dystonia Registry, a multicentre dataset of patients with adult-onset dystonia. The study population included 1518 IAOD patients. Patients with hypothyroidism and hyperthyroidism were compared with those without any thyroid disease. In the 1518 IAOD patients, 167 patients (11%; 95% CI 9.5-12.6%) were diagnosed with hypothyroidism and 42 (2.8%; 95% CI 1.99-3.74) with hyperthyroidism. The three groups were comparable in age at dystonia onset, but there were more women than men in the groups with thyroid disease. Analysing the anatomical distribution of dystonia, more patients with blepharospasm were present in the hyperthyroidism group, but the difference did not reach statistical significance after the Bonferroni correction. The remaining dystonia-affected body sites were similarly distributed in the three groups, as did dystonia-associated features and spread. Our findings provided novel information indicating that the high rate of thyroid diseases is not specific for any specific dystonia subpopulation and does not appear to influence the natural history of the disease.

Longitudinal assessment of blepharospasm severity in patients with long disease duration.

INTRODUCTION: Blepharospasm (BSP) represents one of the most common idiopathic adult-onset dystonia. A few longitudinal observations indicated progression and worsening of BSP severity within 16 years of onset. Information is lacking about the trend of BSP severity in the later stages of the disease. METHODS: The study comprised 15 women and 3 men that underwent a standardized video protocol at two time points: 14 ± 9 years after BSP onset and 11 ± 2 years later. BSP severity was rated by the Blepharospasm Severity Rating Scale (BSRS). Two independent observers reviewed 36 videos in a pseudo-randomized order, yielding satisfactory agreement. RESULTS: Mean total severity score was 7.6 ± 3.9 years at baseline, 6.4 ± 2.5 at the last examination (p = 0.14). The last video examination showed a stable BSRS score in 14/18 patients, while the score of 4 patients decreased by two points or more, due to disappearance (n.3) or reduction (n.1) of prolonged spasms with complete rim closure. Over the long term, the BoNT dosage increased in those who improved, but remained stable in the other patients. On follow-up examination, dystonia spread to the lower face or neck in two new patients. No significant correlations emerged between disease duration and BSP severity. The presence of sensory trick significantly correlated with disease duration but not with BSP severity. DISCUSSION: This study provides novel information on the long-term prognosis in patients with idiopathic BSP, showing that severity of BSP may not worsen in the later stages of the disease.