Crossed aphasia. Functional brain imaging with PET or SPECT

Area of Science:

• Neuroscience
• Neurology
• Cognitive Science

Background:

• Crossed aphasia, a rare condition, involves language impairment due to right hemisphere lesions in right-handed individuals.
• Understanding the neurobiological underpinnings of crossed aphasia is crucial for effective diagnosis and treatment.

Observation:

• Functional brain imaging (PET/SPECT) revealed hypometabolism/hypoperfusion in the right hemisphere of patients with crossed aphasia.
• Initial stages also showed reduced metabolic activity in the left hemisphere, a phenomenon known as diaschisis.
• Follow-up imaging in one patient indicated persistent right hemisphere hypometabolism after recovery onset.

Findings:

• Computed tomography scans did not reveal any left hemisphere lesions in the studied patients.
• The study identified different types of aphasia, including global and Broca's aphasia, in the patients.
• Diaschisis, or functional depression of the anatomically intact left hemisphere, was observed acutely in all patients.

Implications:

• Findings suggest that abnormal right hemisphere dominance for language functions contributes to crossed aphasia.
• The study highlights the role of diaschisis in the acute phase of crossed aphasia.
• Understanding hemispheric language lateralization and its variations is essential for neurological research.