Asymptomatic Motor Cortex Displacement due to a Giant Arachnoid Cyst

Abstract

Cerebral lesions are held to induce plastic changes of the brain. Less well established, however, is how much space-occupying brain lesions may only displace functional representations. In a 66-year-old man we show, by means of functional magnetic resonance imaging and transcranial magnetic stimulation, a profound displacement of the motor cortex due to a large asymptomatic arachnoid cyst. Thus, the chronically compressed brain is capable of sustaining normal brain function without utilizing the potential of cortical plasticity.

Keywords:

• Arachnoid cyst
• Functional MRI
• Motor activation
• Motor cortex displacement
• TMS

Acknowledgments

The authors thank E. Raedisch for expert assistance with the acquisition of the MRI scans.