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Bilateral neuropathologic changes in a child with hemimegalencephaly
R Jahan1, P S Mischel, J G Curran
1Department of Radiological Sciences, UCLA School of Medicine, Los Angeles, California 90095-1721, USA.
Insights
Hemimegalencephaly, a rare brain malformation, can present with bilateral cortical dysplasia, not just unilateral. This finding may explain varied outcomes in patients undergoing hemispherectomy for intractable seizures.
Area of Science:
- Neurology
- Developmental Neuroscience
- Pediatric Pathology
Background:
- Hemimegalencephaly is a congenital brain malformation characterized by unilateral enlargement of one cerebral hemisphere.
- It often presents with intractable seizures and developmental delay in infants.
- Previous understanding suggested primarily unilateral neuropathologic changes.
Observation:
- A 7-month-old girl with developmental delay and intractable seizures exhibited hemispheric asymmetry and an enlarged right cerebral hemisphere.
- Despite undergoing a right hemispherectomy due to medically refractory seizures, the patient unfortunately died from surgical complications.
- Postmortem examination revealed asymmetric right cerebral hemisphere enlargement and, microscopically, bilateral cortical dysplasia.
Findings:
- The case demonstrated severe cortical dysplasia in the enlarged right hemisphere and mild dysplasia in the left hemisphere.
- This represents the first reported instance of bilateral cortical abnormalities in a patient diagnosed with hemimegalencephaly.
- While white matter abnormalities in the contralateral hemisphere are known, bilateral cortical dysplasia is a novel observation.
Implications:
- The presence of bilateral cortical dysplasia may contribute to the variable clinical outcomes observed in hemimegalencephaly patients.
- This finding could necessitate a re-evaluation of treatment strategies and prognostic indicators for this condition.
- Further research is warranted to understand the pathogenesis and clinical significance of bilateral cortical dysplasia in hemimegalencephaly.
Abstract:
Evaluation of a 7-month-old girl with developmental delay and intractable seizures revealed hemispheric asymmetry and an enlarged right cerebral hemisphere. Because of a history of seizures refractory to medical therapy, she was admitted for right hemispherectomy, but died of complications of surgery. Postmortem brain examination revealed asymmetric enlargement of the right cerebral hemisphere but no gross abnormalities in the left hemisphere. Microscopic examination demonstrated bilateral neuropathologic changes consistent with severe cortical dysplasia in the right cerebral hemisphere and mild cortical dysplasia in the left. Although white matter abnormalities in the unaffected hemisphere have been reported in hemimegalencephaly, bilateral cortical abnormalities, not reported previously in patients with hemimegalencephaly, may account for the varied clinical outcome with medical therapy or after hemispherectomy.