Article

The pathophysiology of adductor spasmodic dysphonia (AdSD), like
other focal dystonias, is largely unknown.
The purposes of this study
were to determine (a) cortical excitability differences between AdSD, muscle
tension dysphonia (MTD), and healthy controls; (b) distribution of potential
differences in cranial or skeletal muscle; and (c) if cortical excitability
measures assist in the differential diagnosis of AdSD and MTD. METHODS: Ten
participants with adductor spasmodic dysphonia, 8 with muscle tension dysphonia,
and 10 healthy controls received single and paired pulse transcranial magnetic
stimulation (TMS) to the primary motor cortex contralateral to tested muscles,
first dorsal interosseus (FDI), and masseter. We tested the hypothesis that
cortical excitability measures in AdSD would be significantly different from
those in MTD and healthy controls. In addition, we hypothesized that there would
be a correlation between cortical excitability measures and clinical voice
severity in AdSD. RESULTS: Cortical silent period duration in masseter and FDI
was significantly shorter in AdSD than MTD and healthy controls. Other measures
failed to demonstrate differences. CONCLUSION:
There are differences in cortical
excitability between AdSD, MTD, and healthy controls.
These differences in the
cortical measure of both the FDI and masseter muscles in AdSD suggest widespread
dysfunction of the GABAB mechanism may be a pathophysiologic feature of AdSD,
similar to other forms of focal dystonia. Further exploration of the use of TMS
to assist in the differential diagnosis of AdSD and MTD is warranted.
CI - (c) The Author(s) 2015.

Langue : ANGLAIS