Saturday, March 28, 2015

Imaging characteristics of NMO-SD esp in brain; update

Kim et al.  MRI characteristics of neuromyelitis optica spectrum disorder: an international update.Neurology 2015; 84: 1165-1173
While the findings below are not considered pathognomonic, and do not even construe the "main" elements of the disease, they can be considered imaging pearls for NMO that may help differentiate it from  MS.
1.  Up to 46 % have involvement of the area postrema, which has been postulated as the port of entry in the CNS
2.  Callosal lesions occur in NMO SD but rather than being ovoid,  perpendicular, "Dawson's fingers" as in MS, have unique characteristics.  They are more likely periependymal, following the ependymal lining; they may be edematous and heterogenous forming a "marbled pattern,"; and may involve the whole thickness of the splenium in an "arch bridge " pattern. Clinical symptoms of callosal lesions have not been well described.
3.  Lesions involving the corticospinal tracts, unilateral or bilateral, that may be contigious and longitudinally extensive may occur, curiously, since the area is not rich in aquaphorin 4 receptor.
4.  Contrast enhancement in a marginated, subtle, multiple "cloudlike" pattern may appear.
5.  Optic nerve involvement tends to be more posterior, to involve chiasm and be bilateral
6. On MRS, myo-inositol is reduced compared to NAA in MS

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