15/.Thanks for tuning in this week! Check out the articles below for more juicy details! Stay tuned for next week's #tweetorial.

14/.Takeaways: . 1. The BBB is a highly-specialized "organ" that serves to ensure a homeostatic environment for the CNS, free of toxins as well as tightly regulate influx/efflux of substances. 2. BBB dysfunction plays a part in several neurological diseases' pathogenesis

13/.In brain tumors, VEGF and TGF-B secreted by the tumors have been shown to downregulate tight junction proteins (specifically claudin-1 and claudin-5). Induction of expression of MMP, and displacement of endfoot processes are also implicated.

12/.In Alzheimer's, amyloid-beta accumulation on vessels induces vascular degeneration through production of ROS, leading to BBB disruption. AD also causes increased INF-1B release, thereby downregulating tight junction proteins. Check out this article:

11/.In multiple sclerosis, NO and other cytokines (INF, TNF, IL-3) are released by activated macrophages and leads to hypertrophy of cerebral blood vessels and reduced expression of TJ molecules, interfering with BBB integrity. Read this article for more:

10/.In the case of stroke, hypoxia–ischemia involves a cascade of events in which cytokines, VEGF, and NO are released, leading to BBB dysfunction; astrocytes appear to play a protective role. Check out this article for more:

9/ .BBB dysfunction has been reported in many disease states, including: .- stroke.- Alzheimer disease.- multiple sclerosis.- epilepsy.- brain tumors.In pathologic conditions, several vasoactive agents, cytokines, and chemical mediators are released that increase BBB permeability.

8/ .The tightness of the BBB precludes entrance of most drugs via passive transcytosis, except for substances with high lipid solubility. This can potentially impact methods of drug delivery and, thereby, drug development. Be sure to check out for more:

7/ .Areas of the brain that lack a BBB:. - Pituitary gland.- Median eminence.- Area postrema.- Preoptic recess.- Paraphysis.- Pineal gland.- Endothelium of choroid plexus

6/.Circumventricular organs (CVOs) are structures located in the midline of the ventricular system and lack the BBB. Tight junctions are discontinuous in these areas, allowing for entry of molecules, commonly for hormonal control.

5/.The tight junctions between endothelial cells are responsible for the barrier function and include occludin and other proteins, which function to act as a barrier but are also required for the formation of such junctions. Remember that not all areas of the brain have a BBB.

4/.Within capillaries, endothelial cells line the interior vessels forming extensive tight junctions. Astrocyte endfoot processes also play a role in development of these tight junctions. The intact BBB impedes the influx of most blood-borne substances from entering the brain.

@MedTweetorials @umkcIM 3/.In order to understand its function, what is the BBB comprised of exactly?.

@MedTweetorials @umkcIM 2/.Before getting into its implication in disease pathogenesis, how does the BBB work normally? The BBB is a highly-specialized system that protects the brain parenchyma from toxins/infections and overall maintains a stable, homeostatic environment.

1/ .It’s time for another #neurology #tweetorial! This week’s topic: blood-brain barrier! BBB is a term thrown around often and even the source of some jokes, though do we understand how it functions to serve the CNS? #NeuroTwitter #MedTwitter #MedEd .@MedTweetorials @umkcIM.

12/.Takeaways: . 1. Don't be fooled by an NIHSS of 0; PC strokes are 3x more likely to be missed than AC strokes. 2. HiNTS exam is helpful in distinguishing central and peripheral vertigo. 3. POST-NIHSS can help identify PC stroke patients at risk of poor outcome vs. NIHSS alone.

11/.POST-NIHSS can be a helpful tool in identifying patients, particularly with low standard NIHSS with posterior circulation stroke, who may have higher likelihood of poor outcome and would benefit from reperfusion therapies. Image Source:

10/.POST-NIHSS was calculated by adding to the baseline NIHSS:.- 3 points for gait/truncal ataxia.- 4 points for dysphagia.- 5 points for abnormal cough

9/.POST-NIHSS is a newer tool with a few additional components added to the standard NIHSS assessment that has shown higher prognostic accuracy in posterior circulation strokes.

8/.Test of skew is performed by covering one eye and then, on uncover, seeing if the opposite eye corrects with a vertical saccade. Presence of vertical skew (such as in Figure 3b below) is suggestive of central pathology. Image Source: