Clinical question: Evaluate CSF flow. Signs and symptoms: Left ear pain, status post foramen magnum to the atrial shunt. Nonenhanced brain MRI:Diffusion weighted images are severely compromised due to extensive metallic artifact. The images and the artifact demonstrate no abnormalities.Examination demonstrates extensive postoperative changes of Chiari decompression without appreciable change since prior study. There is prolapse of the cerebellum into the expanded thecal sac and neo foramen magnum similar to prior exam without visible CSF signal. A stent is noted extending from the fourth ventricle posteriorly and abutting the craniectomy site similar to prior exam.There is interval increased size of the fourth ventricle superiorly and extending into distal aqueduct with resultant elevation of the quadrigeminal plate posteriorly. It measures at approximately 11.5 x 14 mm in transaxial dimensions compared to prior study measurement of approximately 7 mm in transaxial. There is however no evidence of supratentorial ventriculomegaly. The normal size of supratentorial ventricles remain stable since prior study and with maintained midline. Cerebral cortex and cortical sulci and the supratentorial CSF spaces remain within normal and stable since prior exam. Signal void the major intracranial arterial branches are identified. The signal intensity of intracranial venous sinuses appear normal.Unremarkable images through the orbits, paranasal sinuses and mastoid air cells.CSF flow study:Demonstrate presence of biphasic flow anteriorly through the foramen magnum however significantly compromised at the level of the dens and with suggestion of interval worsening since prior. There is no detectable flow posteriorly through the foramen magnum.Previously noted flow through the fourth ventricle is significantly less conspicuous compared to prior exam.Nonenhanced cervical MRI:Stable postoperative changes of Chiari decompression as detailed in MRI of brain is again identified.A non-expansile syrinx involving the entire cervical cord demonstrate no interval change since prior exam. Straightening of cervical lordosis similar to prior study.Nonenhanced thoracic MRI:There is revisualization of a mildly expansile syrinx of the thoracic cord superiorly contiguous with syrinx of cervical cord and inferiorly terminating at T10 level similar to prior exam. The most expansile component of syrinx extends from approximately T2 inferiorly to T5 level and measuring maximum of 4.5-mm in transverse axis at T2 level similar to prior exam.There is normal signal intensity and anatomical alignment the vertebral column similar to prior study. No spinal stenosis or neural foraminal compromise is detected at any level.
1.Nonenhanced brain MRI demonstrate interval increased size of the superior aspect of the fourth ventricle and the distal aqueduct with resultant mass-effect and superior displacement of the quadrigeminal plate as detailed/measured. Stable exam otherwise and with revisualization of extensive Chiari decompression postoperative changes detailed above. CSF flow study demonstrate diminished flow through the foramen magnum anteriorly compared to prior exam and significantly less conspicuous flow through the fourth ventricle and the aqueduct since prior study.2.Nonenhanced MRI of the cervical spine demonstrate no evidence of an acute or new finding since prior study. Stable non-expansile syrinx involving the entire cervical cord since prior exam.3.Nonenhanced MRI of the thoracic spine demonstrate no evidence of an acute or new finding since prior study. Stable mildly expansile syrinx of thoracic cord extending from cervical spine inferiorly to T10 level similar to prior exam.