Purpose Patients with Alzheimer’s Disease (AD) exhibit decreased retinal blood flow and vessel density (VD). However, it is not known whether these changes are also present in individuals with early AD (eAD) or amnestic type mild cognitive impairment (aMCI), an enriched pre-AD population with a higher risk for progressing to dementia. We performed a prospective case-control clinical study to investigate whether optical coherence tomography angiography (OCTA) parameters in the macula and disc are altered in those with aMCI and eAD. Methods This is a single center study of 32 participants. Individuals with aMCI/eAD (n = 16) were 1:1 matched to cognitively normal controls (n = 16). We evaluated OCTA images of the parafoveal superficial capillary plexus (SCP) and two vascular layers in the peripapillary region, the radial peripapillary capillary (RPC) and superficial vascular complex (SVC). Outcome vascular and structural parameters included VD, vessel length density (VLD), adjusted flow index (AFI) and structural retinal nerve fiber layer (RNFL) thickness. We compared these parameters between the two groups and examined the correlation between OCTA parameters and cognitive performance on the Montreal Cognitive Assessment (MoCA). Results Cognitively impaired participants demonstrated statistically significant decrease in parafoveal SCP VD and AFI as compared to controls, but no statistically significant difference in peripapillary parameters. Furthermore, we found a significant positive correlation between MoCA scores for the entire study cohort and both the parafoveal SCP VD and peripapillary RPC VLD. Conclusion OCTA shows significant decline in parafoveal flow and VD in individuals with early cognitive impairment related to AD, suggesting that these parameters could have potential utility as early disease biomarkers. In contrast, the presence of larger vascular channels in the peripapillary region may have obscured subtle capillary changes in that region. Overall, the correlation between vascular OCTA parameters and cognitive performance supports further OCTA studies in this population.

IntroductionRetinal structural changes in subjects with mild cognitive impairment (MCI) remain a subject of controversy.MethodsWe investigated the correlation between optical coherence tomography (OCT) of the retinal sublayers, including the retinal nerve fiber layer (RNFL), and cognitive function in subjects with amnestic MCI and compared the OCT findings with matched controls. We also performed a meta-analysis of the world literature using a random-effects model.ResultsWe found no statistically significant differences in OCT between amnestic MCI (aMCI) and controls. In aMCI subjects, we found an inverse relationship between RNFL thickness and two cognitive tests (delayed story recall and a word-list learning test and the word-list test). The meta-analysis revealed a statistically significant decrease in RNFL thickness in MCI subjects.DiscussionThe inverse relationship between cognitive testing and RNFL thickness suggests that retinal involvement may include paradoxically increased thickness of the RNFL, which could suggest gliotic reactive changes.

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Pneumocephalus is defined as air in the cranial cavity. It typically occurs after trauma, surgical procedures, intracranial infections, or related to a tumor. Spontaneous pneumocephalus is very rare, with less than 30 reported cases, but prompt identification and management remain important for neuro-intensivists.[1-2] CASE PRESENTATION: 79 year-old man with remote bilateral carotid endarterectomies presented with 10 days of progressing severe headache, new right-sided tinnitus and ear fullness. He denied recent head trauma, valsalva maneuver, constipation, excessive coughing or other provoking causes. His exam was without focal deficits. Otoscopic exam was normal. His bloodwork was unrevealing. Initial head Computer Tomography (CT) showed intracranial air (Figure 1A-B). He was managed with conservative measures initially, however several hours later he became abruptly altered without change in pupillary size. Repeat CT demonstrated worsening pneumocephalus (Figure 1C-D) involving the bilateral subarachnoid spaces, right temporal lobe intraparenchymal tissue, and entire ventricular system. Bony dehiscences of the right tegmen mastoideum were suspected. He underwent right middle fossa craniotomy with repair of multiple tegmen defects which gradually improved the pneumocephalus.

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