Do Optic Canal Dimensions Measured on CT Influence the Degree of Papilloedema and Visual Dysfunction in Idiopathic Intracranial Hypertension?

A recent study found that increased optic canal area on magnetic resonance imaging was associated with worse papilloedema in idiopathic intracranial hypertension (IIH). We repeated this study using more accurate computerized tomography derived measurements. Optic canal dimensions were measured from 42 IIH patients and 24 controls.  These were compared with papilloedema grade.  There was no correlation between any of the optic canal measurements and papilloedema grade and no significant difference in optic canal measurements between patients and controls. Our results cast doubt on the existing literature regarding the association between optic canal size and the degree of papilloedema in IIH. CT delineates bony anatomy more accurately than MRI and our CT-derived optic canal measurements cast doubt on the existing literature regarding the association between optic canal size and the degree of Papilloedema in IIH.

Brain-injured Survivors of Monochorionic Twin Pregnancies Complicated by Single Intrauterine Death: MR Findings in a Multicenter Study.

Purpose To describe and classify the range of brain injuries present at prenatal, in-utero magnetic resonance (MR) imaging in co-twin survivors of monochorionic (MC) twin pregnancies complicated by single intrauterine death (SIUD). Materials and Methods This retrospective, observational study from six tertiary fetal medicine centers that perform tertiary-level prenatal in-utero MR studies reviewed cases in which prenatal in-utero MR imaging had shown a brain injury in a surviving co-twin of a twin pregnancy with a MC component complicated by SIUD. Results Forty-two surviving MC twins were described. The primary distinction of brain abnormalities was into nonfocal and focal lesions. The nonfocal lesions included periventricular leukomalacia (group 1; two fetuses), generalized encephalomalacia (group 2; nine fetuses), posterior encephalomalacia (group 3; seven fetuses), and bilateral parasagittal and perisylvian injury (group 4; three fetuses). The focal lesions included nonhemorrhagic lesions (group 5; 14 fetuses) and hemorrhagic lesions (group 6; seven fetuses). Focal brain lesions were more likely to be found in the surviving MC pregnancies complicated by twin-twin transfusion syndrome (TTTS) (odds ratio, 2.4; 95% confidence interval: 1.3, 18.5; P = .01) and in fetuses that underwent an obstetric intervention (odds ratio, 2.8; 95% confidence interval: 1.8, 23.6; P = .006). Conclusion Brain injury of the surviving co-twin after SIUD in MC pregnancies is usually of ischemic origin and spares the brainstem and cerebellum. Focal brain lesions are more frequent in pregnancies complicated by TTTS or in those where an intervention has been performed.

Multiple sclerosis update: use of MRI for early diagnosis, disease monitoring and assessment of treatment related complications.

MRI has long been established as the most sensitive in vivo technique for detecting multiple sclerosis (MS) lesions. The 2010 revisions of the McDonald Criteria have simplified imaging criteria, such that a diagnosis of MS can be made on a single contrast-enhanced MRI scan in the appropriate clinical context. New disease-modifying therapies have proven effective in reducing relapse rate and severity. Several of these therapies, most particularly natalizumab, but also dimethyl fumarate and fingolimod, have been associated with progressive multifocal leukoencephalopathy (PML). PML-immune reconstitution inflammatory syndrome (IRIS) has been recognized in patients following cessation of natalizumab owing to PML, and discontinuation for other reasons can lead to the phenomenon of rebound MS. These complications often provide a diagnostic dilemma and have implications for imaging surveillance of patients. We demonstrate how the updated McDonald Criteria aid the diagnosis of MS and describe the imaging characteristics of conditions such as PML and PML-IRIS in the context of MS. Potential imaging surveillance protocols are considered for the diagnosis and assessment of complications. We will explain how changes in MS treatment are leading to new imaging demands in order to monitor patients for disease progression and treatment-related complications.