Step manifestations and sensitivity changes in Gilles de la Tourette syndrome

Abstract

Nasal and temporal step-like visual field defects are seen in people exhibiting Tourette syndrome (TS). These field defects are found to be associated with change in the sensitivity level of the local visual field area when compared to identical areas in the second eye. The sensitivity level of the visual field area is found to change for step manifestations in the majority of visual fields. In particular, the majority of steps situated outside 30° eccentricity from fixation are found to have more sensitivity compared to normal identical areas in the fellow eye. Similarly, steps located within 10° eccentricity from fixation are found to be associated with reduced sensitivity compared to more normal identical areas in the fellow eye.

In view of these findings, knowledge about plasma dopamine level in TS and the different effects of dopamine on rod and cone systems, a possible dopaminergic mechanism is suggested as the pathogenesis of step-like field defects.

Key Words:

• Gilles de la Tourette syndrome
• visual fields
• perimetry
• nasal and temporal steps
• Neuro-Ophthalmology