29 - A Rare Case of Polymicrogyria with Polygenic Underlinings in an 81-year-old Female Cadaver

Poster Board Number: 29
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Co-authors:

Andrey Frolov - Center for Anatomical Science and Education, Department of Surgery - Saint Louis University School of Medicine; Miguel Guzman - Department of Pathology - Saint Louis University School of Medicine; John Martin - Center for Anatomical Science and Education, Department of Surgery - Saint Louis University School of Medicine

Abstract Body : Polymicrogyria (PMG) describes a spectrum of cortical malformations that have a common feature of an irregular cortical surface with multiple small gyri and an abnormal sulcal and gyral pattern. The cortical distribution varies significantly with unilateral and bilateral forms, with the perisylvian cortex being the most affected area. Histological features display abnormalities in cortical structure and lamination and as a result PMG has been regarded as a defect in neuronal migration. Clinical features vary with the most common including epilepsy, intellectual disabilities, language, and motor deficits. The severity of the clinical features depends on the extent of the regions involved with bilateral PMG being most severe. PMG is typically associated with syndromes that contain multiple congenital anomalies and intellectual disabilities and has a heterogeneous etiology with both environmental and genetic causes. Due to its variable presentations and etiologies more information regarding the anatomical and genetic profiles of individuals with PMG is needed for better understanding of the molecular mechanisms governing this disorder and its link to other neurological diseases.

An 81-year-old female cadaver was received through the Saint Louis University (SLU) Gift Body Program. Reported medical history included polymicrogyria, intellectual disability, static encephalopathy, cerebral palsy, aphasia, ptyalism, and edentia. External examination revealed small body height of 155 cm, protruding tongue, pot belly, and normal extremities with 10 fingers and toes. The head circumference was small with a measurement of 50.15 cm. MRI showed bilateral PMG limited to the frontal lobes with small gyri, abnormal gyrial patterns and an irregular grey-white interface. Gross inspection of the brain confirmed bilateral frontal PMG. Coronal sections showed small cortical folds and shallow sulci over the frontal lobes sparing the temporal, parietal and occipital lobes. Subcortical structures were normally present, and the lateral ventricles showed mild to moderate enlargement. The cortex of the right frontal lobe showed a stippled grey-white matter boundary in the anterior cingulate gyrus, extending posteriorly in the superior and inferior frontal gyri. H&E-stained sections revealed fusion of the molecular layers between adjacent sulci with leptomeningeal tissue and vessels. The whole exome sequencing of cadaveric DNA on the Next Generation Sequencing platform indicated multiple rare and pathological genetic variants.

Conclusion: The current study provides important insights into the molecular basis of brain cortical malformations and associated neurological disorders.