 There are expected postoperative changes from a Chiari decompression and revision. The neoforamen magnum is patent and the cerebellar tonsils are unchanged in position. There is residual T2 signal abnormality along the tract of a prior right frontal ventriculostomy catheter. The ventricles and sulci are normal in size. There are no intracranial masses, mass effect or midline shift. The pituitary gland is normal in size. There is no evidence for acute cerebral, brainstem or cerebellar infarction. No diffusion-weighted abnormalities are identified. There is no abnormal intracranial enhancement. A faint focus of susceptibility in the left parietal white matter is nonspecific and unchanged. Flow voids are present within the major vessels indicating patency. The paranasal sinuses and mastoid air cells are clear. There is no abnormal enhancement within the brain. There is preseptal edema and enhancement in the lateral periorbital tissue of the left eye. Additionally, there is a small focus of abnormal T2 signal behind the left globe. There is a subperiosteal collection measuring 2.2 x 1.2 x 2.6 cm (transverse by craniocaudal by AP) along the superior left orbital wall which displaces the superior rectus muscle inferiorly and flattens the superior aspect of the globe. This collection is predominately low signal on T2 weighted images and has layering high T1 signal. However, it only minimally enhances and does not restrict on diffusion-weighted imaging.
1. Left preseptal edema and enhancement is consistent with preseptal cellulitis with a small focus of post septal extension indicating orbital cellulitis.2. Left superior orbital subperiosteal collection, with mass effect on the adjacent superior rectus muscle, with internal layering high T1 signal; given location and clinical history, this could represent an abscess with internal hemorrhage. A fungal etiology should also be considered given a significant amount of T2 hypointense signal. If there is clinical concern for osseous involvement, CT of the orbits may be considered for further evaluation of the bony structures. 3. Postsurgical changes of a Chiari decompression without evidence of intracranial edema, infarct, or hemorrhage.Findings discussed via telephone by Dr Katzman with Dr Frim prior to this dictation on 1/16/2016. 