Sensory tricks in focal dystonia and hemifacial spasm

Sensory tricks are sensory, often but not exclusively tactile, stimuli usually in the body part affected by the movement disorder that produce a meaningful alleviation of dystonia. The frequency and clinical features of sensory tricks in different types of dystonia are poorly studied in the literature. There is no information regarding the presence of a similar phenomenon in HFS.

We enrolled consecutive patients who had the diagnosis of HFS (26) or the following types of dystonia: cervical dystonia (CD; 21); blepharospasm (BS; 20); and writer's cramp (WC; 10). Patients underwent a structured interview to assess the following items related to sensory trick: presence, type and effectiveness. Statistical analysis used the Verisimilitude Reason test and the significance level was set at 5%.

Sensory trick was more frequent in the CD group (81%) when compared with HFS (38.5%; P=0.004) and WC (20%; P=0.001), but there was no statistical difference from the frequency in BS patients (55%; P=0.078). The most common sensory tricks were facial massage (60%) in HFS; to touch the head with the hands (35.3% in CD); to touch the upper eyelid with the index finger and thumb (81.8%) in BS; and to touch the hand with the contralateral hand (100%) in WC.

Sensory tricks are common in all types of focal dystonia herein studied, although they are more frequent in CD. Patients with HFS also often display improvement of the movement disorder with tactile stimulation.