Upper Extremity Dystonia Features in People With Spastic Cerebral Palsy

Abstract

Background and objectives: Dystonia in cerebral palsy (CP) is debilitating and common, but underdiagnosed, especially when coexistent with spasticity. With dedicated research-based assessment, dystonia is found in most people with spastic CP but is only clinically diagnosed in the minority. To begin addressing the high rates of dystonia underdiagnosis in this population, we determined the key feature experts use to assess upper extremity dystonia in people with spastic CP.

Methods: In this prospective cohort study, 3 pediatric movement disorder specialists assessed upper extremity dystonia in neurologic examination videos of people with spastic CP and isolated periventricular leukomalacia (PVL) on brain MRI (i.e., those with a brain injury pattern typical for spastic CP). Dystonia severity was rated using the 10-point Global Dystonia Severity Rating Scale, first by each expert independently and then again after consensus-building discussion. Conventional content analysis of these discussions revealed salient features ("codes") that experts used to assess upper extremity dystonia. Code frequency distributions were compared between dystonia severity categories using χ² tests.

Results: We identified 96 people with spastic CP with isolated PVL on brain MRI seen in the St. Louis Children's Hospital CP Center between 2005 and 2018. Of them, 26 people were able and willing to be recorded while doing a standardized set of upper extremity examination maneuvers (age 4-25 years; 28% nonambulatory, 77% White). When assessing their videos, experts cited the "hand" less often and "shoulder" more often with increasing dystonia severity (p < 0.005, χ² test). "Mirror movements" and the "hand open/close" examination maneuver were cited significantly more frequently in videos when experts were attempting to distinguish between no dystonia and mild dystonia (p < 0.005).

Discussion: Expert clinicians use distinct movement features to assess upper extremity dystonia in people with spastic CP and PVL. Attention to involuntary shoulder (vs hand) movements can help gauge dystonia severity. Differentiation between mirror movements and dystonia, particularly during the hand open/close examination maneuver, may help identify mild dystonia. These results can help guide upper extremity dystonia assessment in people with spastic CP, thus potentially helping mitigate dystonia underdiagnosis.

Figure 1. Expert-Cited Features of Upper Extremity Dystonia Track With Dystonia Severity

Body parts (A), actions (B), and examination maneuvers (C) were cited by experts at different frequencies for videos displaying different upper extremity dystonia severities. A: *p < 0.01 (=0.05/5), B: *p < 0.0125 (=0.05/4), C: *p < 0.017 (=0.05/3) after Bonferroni corrections for multiple comparisons, χ² tests.

Figure 2. Movement Variability and Laterality Are Not Associated With Upper Extremity Dystonia Severity

Unlike how experts assess lower extremity dystonia severity in CP, experts do not cite variability or laterality in association with different upper extremity dystonia severities. *p < 0.05, χ² tests.