Cortical activation in patients with functional hemispherectomy.

Area of Science:

• Neuroscience
• Neurosurgery
• Epilepsy Research

Background:

• Functional hemispherectomy is a treatment for intractable epilepsy.
• This procedure allows for studying unilateral brain activation.
• Investigating cortical activation post-hemispherectomy is crucial for understanding brain plasticity.

Purpose of the Study:

• To assess cortical activation patterns in patients after functional hemispherectomy.
• To compare brain activation in patients versus healthy subjects during passive limb movement.
• To identify brain regions involved in functional reorganization within a single hemisphere.

Main Methods:

• Positron emission tomography (PET) with 15[O]H2O was used to measure regional cerebral blood flow (rCBF).
• Six patients post-functional hemispherectomy and six healthy subjects participated.
• Passive elbow movements of the affected arm induced brain activation, analyzed using statistical parametric mapping (SPM96).

Main Results:

• Normal subjects showed contralateral sensorimotor cortex and supplementary motor area activation, plus ipsilateral inferior parietal cortex activation.
• Patients exhibited ipsilateral activation in the inferior parietal cortex, caudal sensorimotor cortex, and supplementary motor area, though weaker than in controls.
• Patients displayed additional activation in the premotor cortex, caudal sensorimotor cortex, and inferior parietal cortex of the remaining hemisphere compared to controls.

Conclusions:

• Patients show significant reorganization within the remaining hemisphere after functional hemispherectomy.
• A functional network involving the inferior parietal cortex, premotor cortex, and supplementary motor area appears key to this reorganization.
• Ipsilateral projections from these regions likely contribute to functional recovery within a single hemisphere.