Article

Tactile temporal discrimination in patients with blepharospasm.

Dipartimento di Scienze Neurologiche e della Visione, Sez. Neurologia Riabilitativa, Universitè di Verona, Via Casorati 43, 37131 Verona, Italy.
Journal of neurology, neurosurgery, and psychiatry (impact factor: 4.87). 08/2008; 79(7):796-8. DOI:10.1136/jnnp.2007.131524 pp.796-8
Source: PubMed

ABSTRACT Blepharospasm is an adult-onset focal dystonia that causes involuntary blinking and eyelid spasms. Studies have shown the presence of sensory deficits associated with dystonia.
To rule out any confounding effect of muscle spasms on sensory performance in affected and unaffected body regions of patients with blepharospasm and with hemifacial spasm.
Participants (19 patients with blepharospasm, 19 patients with hemifacial spasm and 19 control subjects) were asked to discriminate between two stimuli that were either simultaneous or sequential (temporal discrimination threshold, TDT). Pairs of tactile stimuli were delivered with increasing or decreasing inter-stimulus intervals from 0 to 400 ms (in 10-ms steps) to the hands or on the skin over the orbicularis oculi muscle.
Tactile stimuli elicited similar TDTs in control subjects and patients with hemifacial spasm, but significantly higher TDTs in patients with blepharospasm, regardless of whether stimuli were applied to the orbicularis muscle or the hand.
As TDT was abnormal in unaffected body regions of patients with blepharospasm, and patients with hemifacial spasm processed tactile stimuli normally, TDT deficits in blepharospasm depend on central rather than peripheral factors. This study further supports the link between focal dystonia and impaired temporal processing of somatosensory inputs.

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Keywords

10-ms steps
 
19 control subjects
 
adult-onset focal dystonia
 
Blepharospasm
 
causes involuntary blinking
 
decreasing inter-stimulus intervals
 
eyelid spasms
 
focal dystonia
 
muscle spasms
 
orbicularis muscle
 
orbicularis oculi muscle
 
peripheral factors
 
sensory deficits
 
somatosensory inputs
 
tactile stimuli
 
Tactile stimuli elicited similar TDTs
 
TDT deficits
 
temporal discrimination threshold
 
temporal processing
 
unaffected body regions