Ipsilateral motor pathway without contralateral motor pathway in a stroke patient

Area of Science:

• Neuroscience
• Neurology
• Medical Imaging

Background:

• Stroke often leads to motor deficits by damaging the corticospinal tract.
• The ipsilateral motor pathway is a proposed mechanism for motor recovery after stroke.
• Understanding these pathways is crucial for rehabilitation strategies.

Observation:

• A 53-year-old patient with a right middle cerebral artery infarct presented with left hemiparesis.
• Functional MRI (fMRI) revealed activation of the unaffected (left) sensorimotor cortex during movements of both hands.
• Diffusion tensor tractography (DTT) showed a disrupted right corticospinal tract with Wallerian degeneration.

Findings:

• The patient's left hand motor function showed slow recovery, enabling antigravity movements.
• fMRI indicated that only the left primary sensorimotor cortex was active for both left and right hand movements.
• DTT confirmed the integrity of the left corticospinal tract but degeneration of the right tract.

Implications:

• This case suggests that the ipsilateral motor pathway from the unaffected motor cortex can compensate for a damaged contralateral pathway.
• Motor function recovery in this patient appeared to be solely mediated by this ipsilateral pathway.
• Findings highlight the brain's plasticity and potential for motor reorganization after stroke, offering insights for therapeutic interventions.