Autoimmune and inflammatory conditions

There are a wide variety of autoimmune conditions that affect the brain and spine. Some, like demyelinating disease, are common, but have a variety of manifestations that can appear differently. Others, such as unusual inflammatory encephalitis, are rare but it is relatively important for radiologists to know about them.

This page covers the most common autoimmune and demyelinating disease that affect the brain and spine. To review all the videos on this topic, check out the entire autoimmune/inflammatory playlist.

Demyelinating disease

CNS demyelinating disease is common, with the most common being multiple sclerosis (or MS), neuromyelitis optica (NMO), and acute disseminated encephalomyelitis (ADEM). These are all demyelinating/autoimmune conditions in which the brain loses its normal myelination. Susac syndrome is a small vessel vasculitis which can mimic demyelinating disease.

MS is the most common demyelinating disease, affecting women more than men, with 2 age distribution peaks in younger and middle age women. MS commonly presents with optic nerve or visual symptoms, affects the brain more commonly than the spine, and can result in short segment spine lesions.

Neuromyelitis optica, or NMO, is an autoimmune disease characterized by predominantly optic nerve and spine lesions. It is often associated with an antibody to aquaporin 4.

ADEM is an acute fulminant demyelinating syndrome characterized by acute onset and often many supratentorial lesions. The majority of patients recover, although some may have residual symptoms and it can even progress to death.

AHEM is a closely related variant of ADEM which is associated with hemorrhage.

Susac syndrome is a small vessel vasculitis with small vessel infarcts, most commonly in the retina, cochlea, and periventricular white matter and corpus callosum. It can frequently mimic demyelinating disease because the distribution of lesions is similar.

For more detailed information, check out the more specific videos about multiple sclerosis and pitfalls of interpretation below.

Interpreting MRI in Multiple sclerosis patients

Demyelinating disease – overview

There are complexities to interpreting MRIs in patients with suspected multiple sclerosis. You need to think about lesion location, enhancement pattern, and clinical history. In this video, Dr. Hoch reviews some of the key techniques to properly assessing these white matter lesions

Interpreting MS cases part 1

Clinical history has an important role in determining how specific imaging findings are for multiple sclerosis. Some features may suggest that a patient does not have multiple sclerosis, such as if they are the wrong age (< 20 or > 50 years old), if they have abrupt swift progression, if they have systemic symptoms such as fever or weight loss, and if they have uncommon CNS symptoms such as a movement disorder or meningitis signs. MS lesions also usually occur in some specific locations, such as in the corpus callosum, temporal lobe, periventricular white matter, and juxtacortical white matter. In this video, Dr. Hoch discusses some of the Red Flags that might suggest you are looking at a mimic or variant of MS.

Interpreting MS cases part 2

Encephalitis

Encephalitis is a condition in which the brain parenchyma becomes acutely inflamed or irritated. It can occur from infectious, autoimmune, or inflammatory causes. There are imaging features which help us distinguish them, but often it depends on clinical history, CSF results, and other testing.

Encephalitis

Masslike Inflammatory Disease

There are a few CNS inflammatory diseases which have masslike manifestations, so I’ve lumped them in here. This includes orbital inflammatory disease and sarcoidosis. These diseases often have expansile enhancement, nodules, and masses, even though they are not neoplastic processes. If you see nodular or masslike enhancement, particularly at the skull base or in the orbits, think of these diseases.

Masslike Inflammatory Disease

Spine Inflammatory Disease

A few inflammatory or demyelinating diseases affect the spine (in addition to MS, which we won’t really discuss here. These are trasnverse myelitis, which is commonly seen in a viral or post-viral setting, and sarcoidosis. Sarcoid can mimic a number of other conditions, such as tumors and lymphoma, so watch out.

Spine Inflammatory Disease

Amyloid disease

Amyloid deposition disorders can also affect the CNS. There are three main manifestations:

Cerebral amyloid angiopathy
Inflammatory amyloid
Amyloidoma

While related, these disorders have different imaging appearances that can be clues to their presence.

Amyloid related disease

Vascular processes

There are inflammatory vascular processes that can also appear in the CNS. These include Moya Moya disease/syndrome, CADASIL, and MELAS, among others. These involve an inflammatory or autoimmune component of the vessels and can both affect the vessels directly or result in a characteristic parenchymal appearance.

Inflammatory vascular processes

Summary

In summary, there are a wide range of autoimmune and inflammatory processes that can affect the brain and spine. On this page, we have reviewed some of the most common ones. Their manifestations can be highly varied, and they can be especially challenging to diagnose, often depending on other systemic factors and other conditions.