Automated assessment of cervical dystonia

Motor assessment of X-linked dystonia parkinsonism via machine-learning-based analysis of wearable sensor data

X-linked dystonia parkinsonism (XDP) is a neurogenetic combined movement disorder involving both parkinsonism and dystonia. Complex, overlapping phenotypes result in difficulties in clinical rating scale assessment. We performed wearable sensor-based analyses in XDP participants to quantitatively characterize disease phenomenology as a potential clinical trial endpoint. Wearable sensor data was collected from 10 symptomatic XDP patients and 3 healthy controls during a standardized examination. Disease severity was assessed with the Unified Parkinson's Disease Rating Scale Part 3 (MDS-UPDRS) and Burke-Fahn-Marsden dystonia scale (BFM). We collected sensor data during the performance of specific MDS-UPDRS/BFM upper- and lower-limb motor tasks, and derived data features suitable to estimate clinical scores using machine learning (ML). XDP patients were at varying stages of disease and clinical severity. ML-based algorithms estimated MDS-UPDRS scores (parkinsonism) and dystonia-specific data features with a high degree of accuracy. Gait spatio-temporal parameters had high discriminatory power in differentiating XDP patients with different MDS-UPDRS scores from controls, XDP freezing of gait, and dystonic/non-dystonic gait. These analyses suggest the feasibility of using wearable sensor data for deriving reliable clinical score estimates associated with both parkinsonian and dystonic features in a complex, combined movement disorder and the utility of motion sensors in quantifying clinical examination.

Hold that pose: capturing cervical dystonia's head deviation severity from video

Objective

Deviated head posture is a defining characteristic of cervical dystonia (CD). Head posture severity is typically quantified with clinical rating scales such as the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). Because clinical rating scales are inherently subjective, they are susceptible to variability that reduces their sensitivity as outcome measures. The variability could be circumvented with methods to measure CD head posture objectively. However, previously used objective methods require specialized equipment and have been limited to studies with a small number of cases. The objective of this study was to evaluate a novel software system—the Computational Motor Objective Rater (CMOR)—to quantify multi‐axis directionality and severity of head posture in CD using only conventional video camera recordings.

Methods

CMOR is based on computer vision and machine learning technology that captures 3D head angle from video. We used CMOR to quantify the axial patterns and severity of predominant head posture in a retrospective, cross‐sectional study of 185 patients with isolated CD recruited from 10 sites in the Dystonia Coalition.

Results

The predominant head posture involved more than one axis in 80.5% of patients and all three axes in 44.4%. CMOR's metrics for head posture severity correlated with severity ratings from movement disorders neurologists using both the TWSTRS‐2 and an adapted version of the Global Dystonia Rating Scale (rho = 0.59–0.68, all p <0.001).

Conclusions

CMOR's convergent validity with clinical rating scales and reliance upon only conventional video recordings supports its future potential for large scale multisite clinical trials.

Smoothness of movement in idiopathic cervical dystonia

Smoothness (i.e. non-intermittency) of movement is a clinically important property of the voluntary movement with accuracy and proper speed. Resting head position and head voluntary movements are impaired in cervical dystonia. The current work aims to evaluate if the smoothness of voluntary head rotations is reduced in this disease. Twenty-six cervical dystonia patients and 26 controls completed rightward and leftward head rotations. Patients’ movements were differentiated into “towards-dystonia” (rotation accentuated the torticollis) and “away-dystonia”. Smoothness was quantified by the angular jerk and arc length of the spectrum of angular speed (i.e. SPARC, arbitrary units). Movement amplitude (mean, 95% CI) on the horizontal plane was larger in controls (63.8°, 58.3°–69.2°) than patients when moving towards-dystonia (52.8°, 46.3°–59.4°; P = 0.006). Controls’ movements (49.4°/s, 41.9–56.9°/s) were faster than movements towards-dystonia (31.6°/s, 25.2–37.9°/s; P < 0.001) and away-dystonia (29.2°/s, 22.9–35.5°/s; P < 0.001). After taking into account the different amplitude and speed, SPARC-derived (but not jerk-derived) indices showed reduced smoothness in patients rotating away-dystonia (1.48, 1.35–1.61) compared to controls (1.88, 1.72–2.03; P < 0.001). Poor smoothness is a motor disturbance independent of movement amplitude and speed in cervical dystonia. Therefore, it should be assessed when evaluating this disease, its progression, and treatments.

Clinical and goniometric evaluation of patients with spasmodic torticollis

BACKGROUND

Patients with cervical dystonia have been evaluated prospectively by the Toronto Western Spasmodic Torticollis Rating Scale and by cervical electrogoniometry.

METHODS

Nineteen patients with cervical dystonia were studied. The Toronto Scale interobserver reliability was evaluated by two observers. An electrogoniometer was used to quantify cervical range of motion and velocity. The correlation between goniometric measurements and clinical evaluation was calculated.

FINDINGS

The interobserver reliability was excellent for the total score (r(s) = 99) and good for the disability and the pain score (r > 0.88). However, global severity scale was shown to have a moderate reliability (r = 0.63) with r ranging from 0.37 to 0.98 for the individual items. The average loss of range of motion for flexion and extension, lateral bending and rotation was 18%, 12% and 21% respectively. For the velocity of movement, the average loss was proportionately greater than for the range of motion. (41%, 43% and 52% respectively). Correlation between the severity scale and range of motion was moderate but significant (r(s) = -0.52 to -0.67). Correlation between the Toronto severity score and the sum of movement velocities was significant for flexion-extension and lateral bending velocity sums (r(s) = -0.51; r(s) = -0.61). The lateral bending and rotation velocities were significantly correlated with pain and total scores (r(s) = -0.51). No significant correlation was observed for the disability score.

INTERPRETATION

Three-dimensional electrogoniometry is helpful to quantify the velocity of neck movements and range of motion in patients with cervical dystonia.

[Kinematic evaluation of dystonic syndromes in patients treated with deep brain stimulation]

INTRODUCTION

Quantification of motor functions of patients with dystonic syndromes treated by chronic high frequency stimulation of the internal globulus pallidus is a challenge.

OBJECTIVE

Through a series of clinical examples this paper shows that kinematic analysis of movements in dystonic syndromes treated by deep brain stimulation (DBS) is a complement to clinical evaluation. In addition, it provides valuable information for early detection of improvement or impairment of movements associated with modifications of stimulation parameters.

METHOD

Thirteen dystonic patients and eleven reference subjects completed three tests (i.e., rest: lying supine; posture: standing with arms held in front (at shoulder height); and alternative movements: bimanual finger-to-nose test). These tests were recorded with an electromagnetic system quantifying movement kinematics (position) in three-dimensional space.

RESULTS

From the recorded data, several indices were developed and provided a quantitative evaluation of movements during each test. In addition, a clinical evaluation (BMFDRS) was also completed. No correlation between clinical and kinematic evaluations was found.

CONCLUSION

It is shown that kinematic analysis is a useful complement of clinical evaluation and can assist clinicians in monitoring the evolution of movements in dystonic patients treated by DBS in a simple, reliable and valid fashion.

A protocol for the assessment of 3D movements of the head in persons with cervical dystonia

OBJECTIVE

To design and test a protocol for the assessment of neck movements in patients affected by cervical dystonia by using an electromagnetic system. This approach could overcome the limits of the current assessment scales in this specific field.

BACKGROUND

Initial assessment and function recovery during treatments are diagnosed by the clinician using outcome scales which present many drawbacks in terms of easiness of use, sensitivity, and reliability.

DESIGN

A three-dimensional motion analysis system was used to record six different head movements.

METHODS

Six able-bodied subjects and 10 subjects affected by cervical dystonia participated in this study. For the different head movements three kinematic parameters (a symmetry index and two indexes related to the reduction of the range of motion) have been extracted in order to compare the performance of able-bodied and disabled persons.

RESULTS

The features selected allowed highlighting of the differences between able-bodied and disabled subjects for the degrees of freedom of the neck.

CONCLUSIONS

Using a motion analysis system, three kinematic features were extracted from head movements. They seem to allow a more objective assessment of the disability and a more appropriated strategy for the management of patients affected by cervical dystonia.