Identification of direct connections between the dura and the brain.

The arachnoid barrier delineates the border between the central nervous system and dura mater. Although the arachnoid barrier creates a partition, communication between the central nervous system and the dura mater is crucial for waste clearance and immune surveillance1,2. How the arachnoid barrier balances separation and communication is poorly understood. Here, using transcriptomic data, we developed transgenic mice to examine specific anatomical structures that function as routes across the arachnoid barrier. Bridging veins create discontinuities where they cross the arachnoid barrier, forming structures that we termed arachnoid cuff exit (ACE) points. The openings that ACE points create allow the exchange of fluids and molecules between the subarachnoid space and the dura, enabling the drainage of cerebrospinal fluid and limited entry of molecules from the dura to the subarachnoid space. In healthy human volunteers, magnetic resonance imaging tracers transit along bridging veins in a similar manner to access the subarachnoid space. Notably, in neuroinflammatory conditions such as experimental autoimmune encephalomyelitis, ACE points also enable cellular trafficking, representing a route for immune cells to directly enter the subarachnoid space from the dura mater. Collectively, our results indicate that ACE points are a critical part of the anatomy of neuroimmune communication in both mice and humans that link the central nervous system with the dura and its immunological diversity and waste clearance systems.

Dilataçäo dos espaços de Virchow-Robin em pacientes com migrânea / Dilatation of Virchow-Robin spaces in patients with migraine

Os espaços de Virchow-Robin (EVR) säo invaginaçöes do espaço subpial, formando uma bainha de revestimento tubular contendo um vaso, que separa o espaço subaracnóide do subpial. A ressonância magnética (RM) é o único método de imagem capaz de avaliar este detalhe anatômico. Nós estudamos a possível associaçäo entre EVR dilatados e migrânea. Avaliamos 70 pacientes com idade compreendida entre 13 e 54 anos (média 36,5 anos), com diagnóstico clínico de migrânea e comparamos com grupo controle com igual número de pacientes com idade compreendida entre 14 e 64 anos (média de 42 anos), sem antecedentes de cefaléia. Observamos aumento dos EVR em 28 casos (40 por cento) dos pacientes com migrânea. No grupo controle tal achado foi encontrado em apenas 5 casos (7,1 por cento). Alertamos, ainda, sobre a importância na detecçäo e reconhecimento dos EVR, bem como o seu diagnóstico diferencial com infartos lacunares e cistos da fissura coroidea