Assessment of hand functions in patients with idiopathic cervical dystonia

Cervical dystonia (CD) is the most common form of focal dystonia characterized by involuntary contractions of the neck muscles, causing abnormal rotation of the head into specific directions. Studies report that idiopathic dystonia is a developmental disorder of the sensorimotor circuits, involving both the cortico-striatal and thalamo-cortical pathways. It is also suggested that enhanced cortical plasticity extends beyond the clinically affected region and may also be detected in the unaffected upper limbs of the patient with CD. In the present study, we aimed at exploring if patients with CD had hand motor dysfunctions. Forty patients with idiopathic CD and 40 healthy controls were included in this study. Dystonic symptoms were assessed by means of The Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). Stanford Health Assessment Questionnaire (HAQ) was used to assess functional status. Quality of life (QoL) was assessed by using the Medical Outcomes Study Short Form 36-Item Health Survey (SF 36). Grip strength was assessed by using hand dynamometers. Tip pinch, lateral pinch and chuck pinch of the hand were assessed by using a pinchmeter. Fingertip dexterity and hand coordination was assessed using Purdue Pegboard. Duruoz Hand Index (DHI) was used for the assessment of hand functions. There were no significant differences between the groups in grip and pinch strengths of hands and fingers. As to the fingertip dexterity, patients with CD had a mean Pin 1 and Pin 2 test score of 10.6 ± 2.8 and 10.8 ± 3.2 respectively and a mean assembling test score of 5.2 ± 2.0. These results were significantly worse than those of the healthy controls. As to the SF 36 sub-scores, there were significant differences between the groups in all SF 36 sub-scores (p < .001). This study indicates that patients with CD suffer a deteriorated fine motor coordination of hands without dystonic involvement of upper extremities. Furthermore, lower SF 36 scores in patients with CD suggest poorer health-related quality of life.