Double decussated ipsilateral corticospinal tract in schizencephaly

Area of Science:

• Neuroscience
• Neurology
• Developmental Neuroscience

Background:

• Schizencephaly is a rare congenital brain malformation characterized by a full-thickness cleft in the cerebral hemisphere.
• Left hemiparesis can result from schizencephaly affecting motor pathways, particularly the precentral gyrus.

Observation:

• A patient with schizencephaly impacting the right precentral gyrus presented with left hemiparesis.
• Functional magnetic resonance imaging (fMRI) and motor-evoked potential (MEP) studies were utilized for multimodal brain mapping.
• The unaffected primary motor cortex (M1) in the left hemisphere was observed to control both hands.

Findings:

• A unique corticospinal tract (CST) pathway was visualized using multimodal brain mapping.
• The CST originated from the unaffected left M1, traversed the ipsilateral internal capsule and cerebral peduncle.
• The tract exhibited a double decussation (crossing over twice) at the brainstem level before descending to the ipsilateral spinal cord.

Implications:

• This case demonstrates significant brain plasticity and reorganization following early brain injury.
• The findings highlight an unusual compensatory mechanism involving a double decussated ipsilateral corticospinal tract.
• Understanding such unique neural pathways is crucial for predicting recovery and developing targeted rehabilitation strategies in patients with congenital brain malformations.