Primary dystonia (PDy) is an idiopathic neurological disorder causing involuntary muscle contraction. Its pathophysiology is believed to involve basal-ganglia (BG) dysfunction. A possible association with Obsessive-compulsive symptoms (OCS) is regarded as further evidence of BG involvement but remains controversial due to contradictory research data. We proposed to answer three questions:

1. 1. Do PDy patients have high OCS scores?

2. 2. Are OCS in PDy reactive?

3. 3. Does botulinum toxin treatment (BT) influence PDy psycopathology?

45 patients with blepharospasm, spasmodic torticollis, writer's cramp; 43 patients with hemifacial spasm, cervical spondilarthropathy, peripheral hand neuropathy; 27 healthy volunteers.

Assessment: non-structured DSM-IV based psychiatric interview; Symptom Checklist 90 Revised (SCL-90R); Yale-Brown Obsessive-Compulsive Scale (YBOCS); Unified Dystonia Rating Scale (UDRS).

PDy patients scored significantly higher than controls and healthy controls on the YBOCS (11.1 ± 7.24; 5.98 ± 4.33; 2.07 ± 0.92, both p< 0.001). Controls’ mean score was also significantly higher than healthy subjects’. Controls scored higher than PDy and healthy subjects on the SCL-90R somatization scale. BT treated PDy patients had significantly lower anxiety and somatization but higher UDRS and similar YBOCS ratings compared to untreated patients.

Higher ratings of OCS but not of depression, anxiety or somatization in PDy patients suggests a neurophysiological origin for OCS in PDy. However, diseased controls also scored higher than healthy subjects, suggesting that OCS may nevertheless be partly reactive in PDy. BT may decrease anxiety/depressive symptoms but not OCS, lending further strength to a possible neurophysiological aetiology for OCS in PDy.