Imaging CNS autoimmune and inflammatory disease
This is the sixth and final 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 intracranial vasculopathies, including central nervous system (CNS) vasculitis, Moya Moya disease, CADASIL, and MELAS. These vasculopathies can have a similar imaging appearance.
CNS vasculitis is a process affecting the vessels which supply the brain with blood/oxygen. This can be a primary CNS process or can be associated with other systemic vasculopathies, such as lupus. The imaging manifestations are unexpected infarcts that are out of proportion for age and other causes of infarct. On vascular imaging, you will see areas of narrowing followed by areas of dilation or normal caliber, almost like beads on a string. While this can be caused by atherosclerotic disease, usually it will be out of proportion for age.
Vessel wall imaging
Vessel wall imaging is a specialized technique to look for inflammation in the walls of intracranial vessels. This consists of specialized sequences that suppress both fat and flow so you can see enhancement in the walls. On vessel wall imaging, vasculitis tends to enhance circumferentially while atherosclerotic disease enhancement is more eccentric. This is a useful advanced technique.
Moya Moya disease
Moya moya disease is a primary obliterative angiopathy which primarily occurs in young Asian women. In this disease, the large vessels of the circle of Willis, namely the middle cerebral artery, are obliterated and replaced with a number of abnormal collateral vessesl. This leads to a characteristic “puff of smoke” appearance on angiography. Patients may present with multiple strokes or hemorrhage and can be treated with ECA/ICA bypass. There are other causes of a moya moya like appearance, as it can happen with anything that causes chronic obliterative angiopathy, like sickle cell disease. However, although the terms are used interchangeably, this is really a moya moya syndrome, not the primary disease..
CADASIL, or cerebral autosomal dominant arteriopathy with subcortical infarcts and leukencephalopathy, is a genetic condition associated with the NOTCH3 gene abnormality. These patients have small and middle vessel abnormalities which manifest as a number of subcortical strokes and white matter abnormality in the bilateral temporal lobes. If you see abnormal subcortical temporal white matter, think about CADASIL.
MELAS, or mitochondrial encephalopathy with lactic acidosis and stroke-like symptoms, is a similar syndrome where you get stroke-like episodes often preferentially involving the temporal and parietal lobes. They can often improve with time, but it can mimic other vasculopathies and strokes.
Summary and Conclusion
There are a number of vasculopathies which can affect the brain, with the most common being CNS vasculitis and moya moya disease or syndrome. CADASIL and MELAS can also have a similar appearance. This is the last lecture in this series. Please be sure to check out the other lectures in this series.
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.