Primary progressive aphasia (PPA) is thought to be a disorder of focal cortical degeneration which occurs as a result of lobar atrophy of dominant frontal and temporal lobe. We report a case of a 78 year old male patient presenting with progressive language affection predominantly and clinically diagnosed as PPA but magnetic resonance imaging (MRI) brain showed an unusual finding of reverse 'hot cross bun' sign in pons in T2 weighted (T2W) / diffusion weighted image (DWI)/ T2 fluid attenuated inversion recovery (FLAIR) axial views. This is the first case report of reverse 'hot cross bun' sign in a case of PPA to the best of our knowledge.
Aims
To assess retinal nerve fiber layer thickness by optical coherence tomography (OCT) in various central nervous system demyelinating diseases.
Methods and Material
A total of 40 patients were selected. There were 8 patients of multiple sclerosis, 12 patients of neuromyelitis optica spectrum disorders (NMOSD), 9 patients of optic neuritis, and 11 patients of longitudinally extensive transverse myelitis (LETM). The fast retinal nerve fiber layer (RNFL) thickness protocol was used to compute the overall average RNFL thickness for each eye. Average RNFL thickness for 360° around the optic disk, for the superior, nasal, inferior, and temporal quadrants around the optic disk as well as in the twelve 30° segments (with 3 o'clock position as nasal) were recorded.
Results
Average RNFL thicknesses were lower in NMOSD group. Superior, inferior, and temporal quadrants are the preferentially affected while 8 o'clock position RNFL was the thinnest. MS involved 8 o'clock position and temporal quadrant. Of 9 o'clock position and temporal quadrant were the thinnest in LETM. In idiopathic optic neuritis, lowest RNFL value was recorded in the nasal quadrant. In 3 o'clock position, maximum thinning was noted in idiopathic ON. At 9 o'clock position, maximum thinning was seen in LETM patients.
Conclusions
Most o'clock positions and superior, inferior, and temporal quadrants were affected in NMOSD. MS mainly involved 8 o’clock position and temporal quadrant. LETM preferentially affected 9 o’clock position and the temporal quadrant. Hence, observing the pattern of RNFL thinning with OCT in CNS demyelinating diseases can intimate the etiological cause. However, larger studies are needed further to confirm the same.
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