Objective: The objective of the study is to find the key factors driving dystonia patients at risk to develop SD. 

Background: Status Dystonicus (SD) is defined as a severe, life threatening condition considered the endpoint severity in various dystonias. However, consensus diagnostic criteria and characteristics of dystonia patients evolving towards SD are lacking.

Methods: Out of 328 dystonia patients recruited for deep brain stimulation (DBS), forty patients developed during disease progression, SD. SD patients have been compared with a control group including forty dystonia patients (age, gender, aetiology matched) who did not exhibit during follow-up SD. More than 270 variables have been recorded and compared for the two groups. The Mann-Whitney statistical test was used to compare quantitative variables. MRI scans were analysed in the two groups using SPM 12 for voxel based morphometry. 

Results: Age at onset (p=0,006), age at worsening with functional disability (p=0,045), symptom distribution at onset (p<0,0001), associated neurological and systemic features (p=0,019), axial tone at onset (p<0,0001), gait disability at onset (p=0,04) represented some of the core variables supporting major differences between the SD and the control group.

Pharmacological treatment was significantly higher in the group of SD versus the control group previous and after the SD episodes, with a frequent use of benzodiazepines in the SD group. White matter abnormalities (p=0,02) are significantly more frequent in the SD group. VBM demonstrated significantly superior grey matter volume in the group of controls (p= 0.006), with significant differences distributed over the premotor, supplementary motor area, anterior cingulate cortex, anterior cerebellum and the posterior globus pallidus.

Conclusions: We documented a pattern « at risk to develop SD » in patients with dystonia. Early disease onset, generalized symptoms at onset with early disability, decreased axial muscle tone were associated with the occurrence of SD. Specific cortical, subcortical and cerebellar atrophy were associated features.

 Distinct pathophysiological background could support SD in patients with dystonia, with underlying morphological abnormalities spread over the motor network,  correlated with early tone and movement disorders.  To our best knowledge, this is the first cohort study documenting clinical and radiological characteristics of patients with dystonia at risk to develop SD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/towards-a-reappraisal-of-status-dystonicus-a-cohort-study/