Article Text

  1. Y. J. Tsai,
  2. S. Packman
  1. CA., Los Angeles


We present a patient with developmental delay and seizures who underwent an MRI with thin sections, enabling the diagnosis of a specific brain malformation, bilateral frontoparietal polymicrogyria. The proband was a five year old boy, the first child born to non-consanguineous, healthy parents in their teens. On our exam at age 5 years, the patient was non-dysmorphic, with a neurologic exam notable for left hemiparesis and a hemiparetic gait. He uses mainly his right arm with a mature pincer grasp, which began at four years of age. Reflexes were brisker on the left than right, with an upgoing toe on the left. Family history and prenatal course were unremarkable. In the immediate post-natal period, the patient had left sided hemiparesis and was discharged with congenital hypothyroidism. He sat at 6 months, but rolled at 1 year and cruised at 2 years. At five years, he was not able to respond to commands and did not speak more than three words in a sentence. Simple partial seizures began at age three years with right arm and trunk shaking, increasing in frequency with tegretol. The patient also began having tonic-clonic activities for five minutes at three month intervals with unresponsiveness. EEG at three years showed right-sided epileptiform discharges. After tegretol was begun, an EEG at age 3.5 years revealed generalized spike wave activity. Tegretol was thought to have provoked the tonic-clonic activity. An MRI was ordered. The MRI was high resolution with thin sections, showing polymicrogyria, extensive in the right frontal, parietal, and temporal lobes. Similar findings in the left cerebral hemispheres were found. Polymicrogyria is defined as an abnormal cortical lamination and multiple small gyri. The specific finding of bilateral frontoparietal polymicrogyria (BFPP) has been mapped to chromosome 16q12-21 with a mutation in the G protein-coupled receptor GPR56 Results of mutation analyses are pending in our patient. Presentation of BFPP includes global developmental delay, seizures, and dysconjugate gaze. Our patient demonstrates the classic radiologic and clinical findings for BFPP. More than half of patients with BFPP were initially diagnosed with pachygyria or lissencephaly. A scalloped appearance of the gray-white junction on high-resolution MRI with thin sections differentiates polymicrogyria from pachygyria. We conclude that patients with developmental delay and seizures should have a high resolution brain MRI with thin sections. This enables the diagnosis and differentiation of brain malformations in the category of pachygyria, lissencephaly, and polymicrogyria, and subsequent accurate genetic testing and analysis.

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