Clinical question: Arachnoid cyst, reason for seizures. Signs and symptoms: Headaches, seizures. Nonenhanced brain MRI:Negative diffusion weighted series.Examination demonstrates a CSF signal intensity extra-axial cyst (arachnoid cyst) in left high convexity posterior frontal region along the inner table of skull. The finding measures maximum 29 x 24 and transaxial dimensions and 41 x 19 on coronal T2-weighted series. There is resultant mass effect and buckling of the adjacent cortex without detectable T2 or FLAIR signal abnormality of parenchymal. The overlying calvarium is unremarkable. The ventricular system remains within normal size and with maintained midline.The anatomical morphology of the brain is otherwise within normal limits and normal signal intensity on all MRI sequences. Cortical sulci, ventricular system and CSF spaces are within normal for patient's stated age. Signal void of major intracranial arterial branches are identified.Unremarkable images through the orbits.Unremarkable calvarium and soft tissues of the scalp.All paranasal sinuses and bilateral mastoid air cells and middle ear cavities demonstrate normal pneumatization signal pattern.
1.No acute intracranial process and negative diffusion weighted series.2.Left posterior frontal high convexity arachnoid cyst measuring 29 x 14 mm (transaxial) and 41 x 19 mm (coronal T2) with regional mass effect and no detectable signal abnormality of adjacent parenchyma.3.Unremarkable nonenhanced brain MRI otherwise.