dr report says :cervical spine- there is some loss of normal cervical lorosis.no focal cord abnormality. no significant disc protusion. no thecal or nerve root compression at any level. normal marrow signal. there is an incidental note of a cytic well defined abnormality in the posterior fossa measuring 4x 3.7 x 2.6 cms it is centred in the quadrigeminal plate cistern and has same signal characteristic of csf. no calification or obvious mural nodule seen in the unenhanced study. the cystic abnormality is causing significant mass effect on the surrounding structures and also dialation of the third ventricale and both lateral ventricles. no other significantt abnormality.