This study provides evidence for REM sleep without atonia diagnostic thresholds applicable in Parkinson disease-REM sleep behavior disorder (PD-RBD) patient populations with comorbid OSA that may be useful toward distinguishing PD-RBD in typical outpatient populations.

Objectives We aimed to determine whether visual and automated REM sleep without atonia (RSWA) methods could accurately diagnose idiopathic REM sleep behavior disorder (iRBD) patients with comorbid obstructive sleep apnea (OSA). Methods We visually analyzed RSWA phasic burst durations; phasic, tonic and “any” muscle activity by 3-second mini-epochs; phasic activity by 30-second (AASM rules) epochs; and automated REM atonia index (RAI) analysis in iRBD patients (n=15) and matched controls (n=30) with and without OSA. Group RSWA metrics were analyzed with regression models. Receiver operating characteristic (ROC) curves were used to determine the best diagnostic cutoff thresholds for REM sleep behavior disorder (RBD). Both split-night and full-night polysomnographic studies were analyzed. Results All mean RSWA phasic burst durations and muscle activities were higher in iRBD patients than in controls (p<0.01). Muscle activity (phasic, “any”) cutoffs for 3-second mini-epoch scorings were: submentalis (SM) (15.8%, 19.5%), anterior tibialis (AT) (29.7%, 29.7%), and combined SM/AT (39.5%, 39.5%). Tonic muscle activity cutoff was 0.70% and RAI (SM) cutoff 0.86. Phasic muscle burst duration cutoffs were SM (0.66) and AT (0.71) seconds. Combining phasic burst durations with RSWA muscle activity improved sensitivity and specificity of iRBD diagnosis. Conclusions This study provides evidence for quantitative RSWA diagnostic thresholds applicable in iRBD patients with OSA. Our findings in this study were quite similar to those seen in Parkinson's disease-REM sleep behavior disorder (PD-RBD) patients, consistent with a common mechanism and presumed underlying etiology of synucleinopathy in both groups.

The human fovea lies at the center of the retina and supports high-acuity vision. In normal visual system development, the highest acuity is correlated with both a high density of cone photoreceptors in the fovea and a magnified retinotopic representation of the fovea in the visual cortex. Both cone density and the cortical area dedicated to each degree of visual space—the latter describing cortical magnification (CM)—steadily decrease with increasing eccentricity from the fovea. In albinism, peak cone density at the fovea and visual acuity are decreased, but seem to be within normal limits in the periphery, thus providing a model to explore the correlation between retinal structure, cortical structure, and behavior. Here, we used adaptive optics scanning light ophthalmoscopy to assess retinal cone density and functional magnetic resonance imaging to measure CM in the primary visual cortex of normal controls and individuals with albinism. We find that retinotopic organization is more varied among individuals with albinism than previously appreciated. Additionally, CM outside the fovea is similar to that in controls, but also more variable. CM in albinism and controls exceeds that which might be predicted based on cone density alone, but is more accurately predicted by retinal ganglion cell density. This finding suggests that decreased foveal cone density in albinism may be partially counteracted by nonuniform connectivity between cones and their downstream signaling partners. Together, these results emphasize that central as well as retinal factors must be included to provide a complete picture of aberrant structure and function in albinism.

33Retinotopic organization is a fundamental organizational feature of visual cortex thought to 34 play a vital role in encoding spatial location. One important aspect of normal retinotopic 35 organization is the contralateral representation of the right and left hemifields in visual cortex. 36 In human albinism, the temporal retinal afferents decussate pathologically at the optic chiasm 37 resulting in partially superimposed right and left hemifield representations in each hemisphere 38 of visual cortex. Thus, albinism provides a natural model of aberrant retinotopy in which to 39 study the development and function of retinotopic maps. Previous fMRI studies in human 40 albinism suggest that the right and left hemifields are superimposed in a mirror-symmetric 41 manner such that each imaging voxel responds to two regions in visual space mirrored across 42 the vertical meridian. However, to date no group has explicitly attempted to model the 43 receptive field properties of single voxels in albinism. Here we used traditional fMRI retinotopic 44 mapping techniques in conjunction with population receptive field (pRF) modeling in subjects 45 with albinism to fit each voxel's rotating wedge timecourse in V1-V3 with both single and dual 46 pRF models. We find that most subjects with albinism (but not controls) have sizable clusters 47 of voxels with convincing dual pRFs often corresponding to regions of R-L hemifield overlap. 48However, not all dual pRFs were mirror symmetrical across the vertical meridian. These 49 asymmetric dual pRFs are not predicted by currently accepted models and suggest that 50 retinocortical miswiring in albinism may be more complicated and heterogenous than 51 previously appreciated. 52 53 54 55 56 57 4 Significance Statement: 58 In albinism, the temporal retinal afferents decussate aberrantly at the optic chiasm during 59 development causing partially superimposed right and left hemifield maps in visual cortex. The 60 currently accepted model of retinocortical miswiring in human albinism suggests that these 61 maps are superimposed in a mirror-image fashion such that single locations in visual cortex 62 should respond to two symmetric locations in opposite visual hemifields. To test this, we 63 modeled population receptive fields of individual voxels as single or dual Gaussian sensitivity 64 profiles, fitting the predicted responses to fMRI retinotopic mapping data. For the first time, our 65 results reveal dual pRFs in cortical visual areas V1-V3 in subjects with albinism. However, 66 some subjects had highly asymmetric dual pRFs, indicating that retinocortical miswiring in 67albinism is more heterogenous and complex than suggested by the "mirror symmetric" model. 68 69 70 71 Retinotopic organization is one of the most fundamental and widely-described organizational 72 principles of visual cortex. Present at every level of the visual hierarchy, the retinotopic 73 organization of visual cortex is thought to play a vital role in the brain's ability to encode visual-74 spatial location. T...

Purpose: Chiari malformation (CM) type-1 frequently causes obstructive or central sleep-disordered breathing (SDB) in both adults and children, although SDB is relatively rare as a presenting manifestation in the absence of other neurological symptoms. The definitive treatment of symptomatic CM is surgical decompression. We report a case that is, to our knowledge, a novel manifestation of central sleep apnea (CSA) due to CM type-1 with severe exacerbation and initial clinical presentation during pregnancy.Methods: Case report from tertiary care comprehensive sleep medicine center with literature review of SDB manifestations associated with CM type-1. PubMed search was conducted between January 1982 and October 2013.Results: We report a 25-year-old woman with severe CSA initially presenting during her first pregnancy that eventually proved to be caused by CM type-1. The patient was successfully treated preoperatively by adaptive servoventilation (ASV), with effective resolution of SDB following surgical decompression, and without recurrence in a subsequent pregnancy. Our literature review found that 58% of CM patients with SDB had OSA alone, 28% had CSA alone, 8 (10%) had mixed OSA/CSA, and 6 (8%) had hypoventilation. Of CM patients presenting with SDB, 50% had OSA, 42% had CSA, 8% had mixed OSA/CSA, and 10.4% had hypoventilation. We speculate that CSA may develop in CM patients in whom brainstem compression results in excessive central chemoreflex sensitivity with consequent hypocapnic CSA.Conclusion: Chiari malformation type-1 may present with a diversity of SDB manifestations, and timely recognition and surgical referral are necessary to prevent further neurological deficits. ASV therapy can effectively manage CSA caused by CM type-1, which may initially present during pregnancy.