Porencephalic and Cystic Encephalomalacia Changes Mimicking Arachnoid Cyst on MRI: An Important Diagnostic Pitfall in Children with Static Motor Deficits

Advisor in Pediatrics and Pediatric Psychiatry, and Expert Trainer, Baghdad Medical City and the National Training and Development Center Baghdad, Iraq

*Corresponding Author: Aamir Jalal Al-Mosawi, Advisor in Pediatrics and Pediatric Psychiatry, and Expert Trainer, Baghdad Medical City and the National Training and Development Center Baghdad, Iraq, E-mail: [email protected]

Received Date: April 23, 2026
Published Date: July 30, 2026

Citation: Al-Mosawi AJ. (2026). Porencephalic and Cystic Encephalomalacia Changes Mimicking Arachnoid Cyst on MRI: An Important Diagnostic Pitfall in Children with Static Motor Deficits. Mathews J Case Rep. 11(3):232.

Copyright: Al-Mosawi AJ. © (2026).

ABSTRACT

Background: CSF-containing intracranial spaces on Magnetic Resonance Imaging (MRI) are frequently labelled as arachnoid cysts, sometimes without careful assessment of mass effect or parenchymal loss. Porencephalic and cystic encephalomalacic changes secondary to perinatal brain injury may closely mimic arachnoid cysts, leading to misdiagnosis and unnecessary neurosurgical referrals.

Patients and Methods: We report a 5-year-old girl with long-standing static spastic left hemiparesis and gait abnormality. Brain MRI demonstrated focal CSF-filled cavities with adjacent parenchymal volume loss and ex-vacuo ventricular dilatation. These findings were initially suspected to represent an arachnoid cyst. Parents consents and the appropriate approval by the ethics committee have been ensured.

Results: Detailed imaging analysis revealed features inconsistent with a true arachnoid cyst and strongly suggestive of porencephalic / cystic encephalomalacic change due to a remote perinatal ischemic insult.

Conclusion: Recognizing porencephalic and encephalomalacic changes is essential to avoid misdiagnosis, unnecessary surgical consideration, and parental anxiety. Clinical–radiological correlation remains fundamental in pediatric neuroimaging.

Keywords: Porencephaly, Cystic Encephalomalacia, Arachnoid Cyst, Cerebral Palsy, Perinatal Brain Injury, MRI Pitfall