Parinaud's syndrome - A rare presentation of clinically isolated syndrome.

We present a 26 year old Pakistani lady with first presentation of a demyelinating event, presenting as Parinaud's syndrome. The video demonstrates a convergence-retraction nystagmus on upgaze and failure of accommodation, and her brain imaging confirms a corresponding pre-tectal contrast enhancing T2 hyperintense lesion suggestive of demyelination. A review of the literature is presented.

Drusen prevalence and pigmentary changes in Caucasians aged 18-54 years.

AIMS AND PURPOSE: The aim of this study was to describe the prevalence and characteristics of drusen and pigmentary changes in a middle-aged population. METHODS: Retinal images from 500 individuals aged 18-54 years were included. The source of participants was two UK optometry practices. Retinal images were graded using the Wisconsin Age-Related Maculopathy Grading System. However, owing to the relatively young age of the population studied, a new category of drusen of smaller size (<31.5 µm) was introduced. RESULTS: Drusen were identified within the central macular grid in 91.48% of all gradable eyes and in 444 subjects. Drusen sized <31.5 µm were present in 89.7% of eyes, drusen sized >31.5 µm and <63 µm were present in 45.9% of all eyes and drusen >63 µm and <125 µm were present in only 1.7% of eyes. No eye had drusen larger or equal to 125 µm. Very few eyes (1.2%) showed pigmentary changes within the grid. Drusen load increased with increasing age, P <0.001. CONCLUSIONS: The frequency of drusen in a younger Caucasian population aged 18-54 years is high, with 91.48% of all gradable eyes having drusen. The most frequent drusen subtype was hard distinct drusen <31.5 µm. No druse greater or equal in size to 125 µm was seen. Pigmentary changes are rare.

Reliable identification of the auditory thalamus using multi-modal structural analyses.

The medial geniculate body (MGB) of the thalamus is a key component of the auditory system. It is involved in relaying and transforming auditory information to the cortex and in top-down modulation of processing in the midbrain, brainstem, and ear. Functional imaging investigations of this region in humans, however, have been limited by the difficulty of distinguishing MGB from other thalamic nuclei. Here, we introduce two methods for reliably delineating MGB anatomically in individuals based on conventional and diffusion MRI data. The first uses high-resolution proton density weighted scanning optimized for subcortical grey-white contrast. The second uses diffusion-weighted imaging and probabilistic tractography to automatically segment the medial and lateral geniculate nuclei from surrounding structures based on their distinctive patterns of connectivity to the rest of the brain. Both methods produce highly replicable results that are consistent with published atlases. Importantly, both methods rely on commonly available imaging sequences and standard hardware, a significant advantage over previously described approaches. In addition to providing useful approaches for identifying the MGB and LGN in vivo, our study offers further validation of diffusion tractography for the parcellation of grey matter regions on the basis of their connectivity patterns.

Non-invasive mapping of connections between human thalamus and cortex using diffusion imaging.

Evidence concerning anatomical connectivities in the human brain is sparse and based largely on limited post-mortem observations. Diffusion tensor imaging has previously been used to define large white-matter tracts in the living human brain, but this technique has had limited success in tracing pathways into gray matter. Here we identified specific connections between human thalamus and cortex using a novel probabilistic tractography algorithm with diffusion imaging data. Classification of thalamic gray matter based on cortical connectivity patterns revealed distinct subregions whose locations correspond to nuclei described previously in histological studies. The connections that we found between thalamus and cortex were similar to those reported for non-human primates and were reproducible between individuals. Our results provide the first quantitative demonstration of reliable inference of anatomical connectivity between human gray matter structures using diffusion data and the first connectivity-based segmentation of gray matter.