CONGENITAL MALFORMATION IN NERVOUS SYSTEM ANENCEPHALY DEFINITION ANENCEPHALY

CONGENITAL MALFORMATION IN NERVOUS SYSTEM

ANENCEPHALY DEFINITION: ANENCEPHALY IS A CEPHALIC DISORDER THAT RESULTS FROM A NEURAL TUBE DEFECT THAT OCCURS WHEN THE CEPHALIC (HEAD) END OF THE NEURAL TUBE FAILS TO CLOSS, USUALLY BETWEEN THE 23 rd and 26 th DAY OF PREGNANCY, RESULTING IN THE ABSENCE OF A MAJOR PORTION OF THE BRAIN SKULL AND SCALP.

ENCEPHALOCELE DEFINITION: ENCEPHALOCELE IS A NEURAL TUBE DEFECT CHARACTERIZED BY SAC-LIKE PROTRUSIONS OF THE BRAIN AND THE MEMBRANES THAT COVER IT THROUGH OPENINGS IN THE SKULL.

MICROCEPHALY DEFINITION: MICROCEPHALY IS A TYPE OF CEPHALIC DISORDER. THIS IS A DISORDER CHARACTERIZED BY A SMALL HEAD AND MAY BE CAUSED BY A DISTURBANCE IN THE RAPID GROWING OF NERVE CELLS.

SEPTO-OPTIC DYSPLASIA DEFINITION: SEPTO-OPTIC DYSPLASIA (SOD), ALSO KNOWN AS “DE MORSIER” SYNDROME, IS A CONGENITAL MALFORMATION SYNDROME MADE MANIFEST BY HYPOPLASIA (UNDERDEVELOPMENT OF THE OPTIC NERVE AND ABSENCE OF THE SEPTUM PELLUCIDUM (A MIDLINE PART OF THE BRAIN).

MEGALENCEPHALY DEFINITION: MEGALENCEPHALY (OR MACRENCEPHALY) IS A CONDITION IN WHICH THERE IS AN ABNORMALLY LARGE BRAIN. IT IS USUALLY MALFUNCTIONING.

POLYMICROGYRIA DEFINITION: POLYMICROGYRIA (PMG) IS A DEVELOPMENTAL MALFORMATION OF THE HUMAN BRAIN CHARACTERIZED BY AN EXCESSIVE NUMBER OF SMALL CONVOLUTION (GYRI) ON THE SURFACE OF THE BRAIN. EITHER THE WHOLE SURFACE OR PARTS OF THE SURFACE CAN BE AFFECTED.

SPINA BIFIDA DEFINITION: SPINA BIFIDA IS A DEVELOPMENTAL BIRTH DEFECT CAUSED BY THE INCOMPLETE CLOSURE OF THE EMBRYONIC NEURAL TUBE.

DIASTOMATOMYELIA DEFINITION: DIASTOMATOMYELIA IS A CONGENITAL ANOMALY, OFTEN ASSOCIATED WITH SPINA BIFIDA, IN WHICH THE SPINAL CORD IS SPLIT INTO HALVES BY A BONY SPICULE OR FIBROUS BAND, EACH HALF BEING SURROUNDED BY A DURAL SAC.