Clinical question: Evaluate hygroma. Signs and symptoms: Status post Chiari decompression with hygroma now on head CT. Continuous dizziness. Nonenhanced brain MRI:Unremarkable diffusion-weighted series. Examination demonstrate postoperative changes of Chiari decompression. There is postoperative epidural fluid collection/seroma at the surgical site with subtle mass effect and without significant expansion of subarachnoid space. There is mild remaining flattening deformity of the cerebellar tonsils without detectable signal abnormality. On sagittal images this collection measures approximately 40 mm in cranial cephalad axis and 12 mm in AP axis.There is a CSF signal intensity hygroma along the left hemispheric convexity. Hygroma in the posterior fossa is also detected surrounding the cerebellar hemispheres (left greater than right). This finding demonstrate no significant change since prior head CT examination from 10-12-15. The left hemispheric convexity hygroma measures approximately 7 to 8 mm in thickness. There is resultant subtle flattening deformity of the adjacent parenchyma and subtle mass effect on the left lateral ventricle and trace rightward deviation of midline of approximately 4 mm. Hypoechoic posterior fossa measures maximum of approximately 1.5 mm thickness.There is no evidence of ventriculomegaly. There is no signal abnormality of the brain parenchyma.Nonenhanced cervical MRI:Revisualization of the above detailed postoperative changes of suboccipital craniectomy.Normal signal intensity and alignment of vertebral column.Normal signal intensity and caliber of cervical and upper most visualized thoracic cord without evidence of syrinx.No spinal stenosis or neural foraminal compromise.CSF flow study demonstrates presence of biphasic flow through the foramen magnum anterior and without detectable flow posteriorly. There is also no detectable flow through the fourth ventricle or the aqueduct.
1.Nonenhanced brain MRI demonstrate postoperative changes of suboccipital craniectomy, epidural seroma immediately posterior to the surgical site with subtle mass effect as detailed-measured about. Right hemispheric convexity hygroma measuring approximately 7 to 8 mm without significant change since prior head CT examination and with resultant 4 mm midline shift. Thin approximately 1.5 mm maximum thickness of diffuse hygroma in the posterior fossa (left greater than right) without significant mass effect.2.Unenhanced cervical MRI demonstrate Chiari decompression postop changes. Normal signal intensity and caliber of the cord. Normal appearing biphasic flow through the foramen magnum anteriorly and absence of flow posteriorly. No detectable flow through the fourth ventricle or the aqueduct.