23 Weeker came for evaluation of abnormal skull shape. examination revealed fontal depression in the skull (lemon sign) and small posterior cranial fossa with concavo-convex appearance of cerebellum (banana sign). the patient had oligohydramnios. the spine looked almost normal on sagittal view, however because of inadequate liquor pocket anterior to the spine, the skin line could not be evaluated. axial scans showed divergence of laminae at 2 vertebral levels. Diagnosis of flat myelocele with small posterior cranial fossa and hypoplastic cerebellum was suggested (arnold chiari type ii malformation).
findings were confirmed on Obs MRI.
lessons learnt: 1) lemon sign and banana signs, which were the first signs in obs scans learnt ever, are really important and improve diagnostic efficacy. 2) only sagittal view is not helpful, especially when you are not able to see the skin line, especially in such flattened lesions.
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