M. AMOR, S. MAJDOUB, B. BEN SALAH, M. DHIFALLAH, H. ZAGHOUANI, T. RZIGA, H. AMARA, D. BAKIR, C. KRAIEM Radiology service, University Hospital Farhat Hached Sousse, Tunisia MR IMAGING OF PACHYGYRIA: A CASE REPORT AND LITERATURE REVIEW PED11

OBJECTIVES MRI manifestations of pachygyria are presented with a review of the pathological features of the disorder and an evaluation of the diagnostic value of imaging modalities.

MATERIALS AND METHODS We reported a case of pachygyria brain in a 1 month- old girl with recurrent convulsive seizures and axial hypotonia. Transfontanellar sound and brain MRI using axial FLAIR, diffusion,T2-weighted and coronal, sagittal T1- weighted, and MPR 3D sequences with multiplanar reformations was performed.

RESULTS Transfontanellar ultrasound showed signs of leukodystrophy. MR imaging demonstrate patterns of pachygyria, including: Smooth and markedly thickened cortex Broad, widespread flat gyri with shallow sulci Vertically- oriented and shallow Sylvian fissures and the white matter is reduced in proportion (figure 1, 2, 3 and 4)

Figura 1: axial FLAIR sequences

Figure 2: axial T2-weighed sequences

RESULTS Absence of leukodytrophy, areas of myelination in the cerebellum, pons, posterior limb of the internal capsule and thalamus with high signal on FLAIR-weighted MR images (figure 1) Mega cisterna magna (figure 3)

Figure 3: sagittal T1-weighnedFigure 4: coronal T1-weighned

DISCUSSION Advances in neuroimaging techniques have resulted in an increasing recognition of the cortical lesions as the etiology of a number of epilepsies that were previously defined as cryptogenic. Agyria-pachygyria is a disease of neuronal migration characterized by the total or partial absence of sulci and a thickened cortical mantle.

DISCUSSION In many cases, agyria and pachygyria coexist in the same patient. They represent degrees of the same fundamental disorders in cell migration and cortical organization. More and more patients have been documented as agyria-pachygyria since the advent of CT scan and MRI. Although some of these disorders have a genetic basis, the cause of the migrational arrest is still unknown.

DISCUSSION Pachygyria is considered the less severe form and exhibits a broader spectrum of clinical features than agyria. It is a rare developmental disorder resulting from the abnormal migration of neurons in the developing brain and nervous system. the gyri are relatively few are are usually broad and flat. The condition is also known as "incomplete lissencephaly". It is a milder variant of lissencephaly, and part of the lissencephaly spectrum of disorders.

DISCUSSION MRI is commonly used for diagnosis. It provides a high contrast image for better delineation of white and gray matter. Pachygyria shows on an MRI as thickened cerebral cortices with few and large gyri and incomplete development of Sylvian fissures. The prognosis for children with pachygyria varies depending on the degree of brain abnormality and subsequent neurological signs and symptoms.

CONCLUSION Pachygyria is a neuronal migration disorder characterized by reduced and broad cerebral gyri. The regions of the brain with pachygyria have an abnormally thick cortex that lacks normal folding and has deficient layering the onset and severity depending on the severity of the cortical malformation. Infantile spasms are common in affected children, as is intractable epilepsy. Neuroblast migration disorders are better known, mainly due to high resolution MRI techniques that by the quality of multiplanar study and a better differentiation between gray and white matter, allow a more precise diagnosis.