Imaging CNS autoimmune and inflammatory disease

Masslike inflammatory disease

This is the third lecture in a case based review of imaging of the brain and spine for autoimmune and inflammatory conditions. We will cover the MRI findings of some of the common conditions and some potential pitfalls and mimics.

This lecture covers two masslike inflammatory diseases which can occur in the orbit and brain. These don’t really fit well into other categories with the exception that they are more likely to have a mass and adjacent expansion.

Orbital inflammatory disease

Orbital inflammatory disease is an infiltrative disease most often seen in the orbit and anterior skull base. It is characterized by masslike replacement of the orbital contents, sometimes with extension in the orbits. It is often T2 intermediate to dark and has avid enhancement. Many cases are associated with IgG4 abnormalities, while other cases are purely idiopathic. This disease was previously called orbital pseudotumor, but it is more exact now to call it IgG4 orbital disease or idiopathic orbital inflammation. The differential diagnosis for this appearance includes metastatic disease, lymphoma, and sarcoidosis.

Sarcoidosis

Sarcoid can also affect the brain, orbits, and spine, and when it does is referred to as neurosarcoidosis. The most common manifestation is leptomeningeal enhancement, but it can be accompanied by parenchymal nodules. It preferentially affects the basal cisterns and skull base. When you have a basilar meningitis, the differential includes metastatic disease (leptomeningeal carcinomatosis), unusual infections (such as fungi, tuberculosis, and other atypical organisms), and sarcoidosis, as was the case here.

Summary and Conclusion

In summary, when you have nodular masslike enhancement centered in the skull base or orbits, there is a pretty limited differential diagnosis. The inflammatory differential includes sarcoidosis and orbital inflammatory disease. Other things such as metastatic disease and atypical infections are also considerations.

The level of this lecture is appropriate for radiology residents, radiology fellows, and trainees in other specialties, such as neurology, who have an interest in neuroradiology or may see patients with CNS demyelinating or inflammatory conditions.

  Other videos on the autoimmune and demyelinating playlist are found here

Imaging CNS autoimmune and inflammatory disease

Encephalitis

This is the second lecture in a case based review of imaging of the brain and spine for autoimmune and inflammatory conditions. We will cover the MRI findings of some of the common conditions and some potential pitfalls and mimics.

This second lecture covers causes of encephalitis, including inflammatory and autoimmune etiology. This section also covers infectious encephalitis, which is the most common mimic.

Limbic encephalitis

Limbic encephalitis is an immune mediated encephalitis often associated with neoplasm and a variety of circulating antibodies. It most commonly is manifested as bilateral (asymmetric or symmetric) temporal lobe FLAIR/T2 abnormalities. Enhancement is variable but less common than seen in herpes encephalitis.

Chronic limbic encephalitis

Over time, chronic limbic encephalitis can result in temporal lobe sclerosis and atrophy. Volumetric analysis of the brain and temporal lobes may be useful in highlighting the differences over time.

Lupus encephalitis

Lupus is a systemic autoimmune condition which can be associated with intracranial findings, including encephalitis, vasculitis, and posterior reversible encephalopathy syndrome (PRES). Vessel imaging may be normal, as it tends to affect the small vessels of the brain.

Viral encephalitis

Viral encephalitis has a nonspecific imaging appearance with patchy white matter FLAIR/T2 abnormalities, often involving the temporal lobes. There are a number of causes of viral encephalitis, including herpes, west nile virus, St. Louis encephalitis, and others.

Herpes encephalitis

Herpes encephalitis is the most dreaded of the encephalitis causes because it has high morbidity and mortality. Compared to nonspecific viral and inflammatory encephalitis, it tends to have more enhancement and more DWI abnormality. Patients suspected of having herpes encephalitis should be started empirically on treatment immediately to improve the prognosis.

Summary and Conclusion

The level of this lecture is appropriate for radiology residents, radiology fellows, and trainees in other specialties, such as neurology, who have an interest in neuroradiology or may see patients with CNS demyelinating or inflammatory conditions.

  Other videos on the autoimmune and demyelinating playlist are found here