The Infant With Asymmetric Posture

History and Physical

A 15-month-old boy was brought in for difficulties using his left hand. He was born full term with no complications during pregnancy or delivery. At 5 months of age, his parents observed that his left hand remained fisted, and his thumb adducted. He had mild motor delays, walking with assistance at 15 months and favoring the use of his right hand. Language and social skills were normal. On physical examination, he exclusively used his right hand to grab objects while keeping his left hand fisted. He had left hemiparesis with hyperreflexia and upgoing plantar responses.

Diagnostic Workup

Brain MRI demonstrated right perisylvian polymicrogyria ( Fig. 13.1 ).

A set of four brain M R I scans labeled A to D presents sagittal, axial, and coronal views with asymmetrical sulcal patterns and cortical irregularity. — Fig. 13.1

Clinical Differential Diagnoses

Causes of congenital hemiparesis include perinatal large artery infarcts, small artery infarcts, and periventricular leukomalacia.

Imaging Differential Diagnoses

Polymicrogyria is a malformation of cortical development that manifests on MRI as multiple small gyri and sulci with diffuse gray-white junctional irregularity. The finding is best appreciated when comparing the affected region to normal contralateral gyri (if unilateral) or age-matched controls. Depending on the imaging plane and resolution, polymicrogyria may appear fine and small, thick and bumpy, or saw-toothed.

Antenatal infections, such as cytomegalovirus (CMV), can result in white matter injury, subependymal cysts, calcifications, ventriculomegaly, polymicrogyria, and cerebellar abnormalities depending on the timing of infection.

Schizencephaly is an early developmental insult that results in a transmantle defect from the ependymal surface of the ventricle through the pial surface of the cortex. The gray matter lining is disorganized and dysplastic, with a polymicrogyric appearance. Schizencephalic clefts are typically classified as unilateral (60%) or bilateral (40%) and as open lip (with intervening cerebrospinal fluid gap) versus closed lip ( Fig. 13.2 ).