Evolution of MRI changes in Rasmussen's encephalitis.

PURPOSE

We studied the MRI findings in 16 patients with Rasmussen's encephalitis (RE), further analysed serial MRI changes in 11 of them and correlated it with clinical features.

METHODOLOGY

The diagnosis of RE was based on the European consensus statement (Brain, 128, 2005, 454). Details related to demographical, clinical, MRI observations were analysed.

RESULTS

Forty MRIs of brain of 16 patients were reviewed. Eleven patients had undergone serial brain MRIs ranging from two to five occasions. All the patients had unihemispheric focal cortical atrophy, predominantly in the perisylvian region (n = 13). Other features were white matter signal changes (n = 14), and ipsilateral caudate (n = 6) and putamen (n = 4) atrophy. Signal alterations in putamen and caudate were noted in four each. In all the 11 patients with serial MRI, there was progression of cerebral atrophy and a trend towards increase in MRI staging. The MRI signal changes remained same in five patients, resolved in three patients, differential change in two patients and increased in one patient. Diffusion-weighted imaging showed facilitated diffusion (n = 5), and MR spectroscopy showed reduced N-acetyl-aspartate and elevated lactate (n = 2).

CONCLUSIONS

Pattern recognition of MRI findings and the changes in serial MRI might serve as a surrogate marker of disease viz. unihemispheric progressive focal cortical atrophy and signal changes predominantly in the perisylvian distribution and caudate followed by putamen involvement. This might assist in understanding and monitoring of the disease progression.