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| T1 pre-gad | T1 pre-gad | SPGR |
Diagnosis: Type I lissencephaly (Agyria-pachygyria complex)
Lissencephaly refers to brain that is smooth and has not developed the normal pattern of gyri and sulci. If the brain is agyric, it is completely smooth and is also known as complete lissencephaly. Pachygyria refers to gyri that are thickened and broad, and is synonymous with incomplete lissencephaly. Clinically these patients are severely developmentally delayed usually with a seizure disorder. There are five patterns of lissencephaly which are described in the 2nd ed of Pediatric Neuroimaging by Barkovich. The pattern presented here is known as type I lissencephaly or the agyria pachygyria complex. These patients are usually microcephalic and developmentally delayed as a function of the degree of lissencephaly. Many of these patients have a genetic defect at chromosome 17P. Some with agyria-pachygyria complex are described as having the Miller-Dieker syndrome. Other organ system anomalies may be noted including cardiac, renal, ear and eye abnormalities. Most patients with type I lissencephaly have a spectrum of both agyria and pachygyria. There may be regions of smooth brain while other regions demonstrate thickened cortex. White matter is usually diminished with poor differentiation between the gray and white matter. The etiology for lissencephaly is unclear. Some believe that a vascular insult is the cause; however, this is controversial. Lissencephaly has been reported in association with congenital cytomegalovirus infection. There is no differential for this case due to the characteristic appearance of lissencephaly. Of note is the deep sulcus in the right frontoparietal region which would be schizencephaly if it were connected to the ependymal lining of the lateral ventricle. Related Cases Byrd SE, Bohan TP, Osborn RE, et al. The CT and MR evaluation of lissencephaly. AJNR, Sep 1988; 9(5):p923-7.
Hayward JC, Titelbaum DS, Clancy RR, et al. Lissencephaly-pachygyria associated with congenital cytomegalovirus infection. J Child Neurol; Apr 1991; 6(2):p109-14.
