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Attention deficit hyperactivity disorder; Other names: Formerly: Attention deficit disorder (ADD), hyperkinetic disorder (HD) [1]: ADHD arises from maldevelopment in brain regions such as the prefrontal cortex, basal ganglia and anterior cingulate cortex, which regulate the executive functions necessary for human self-regulation.
The most frequent cause of the syndrome is brain damage to the frontal lobe. Brain damage leading to the dysexecutive pattern of symptoms can result from physical trauma such as a blow to the head or a stroke [6] or other internal trauma. It is important to note that frontal lobe damage is not the only cause of the syndrome.
After the oxygen is removed, blood reaches venules and later veins which will take it back to the heart and lungs. [10] A cerebral AVM causes blood to be shunted directly from arteries to veins because the capillary bed is lacking, causing a disrupted circulation. [10] [11] The overall annual incidence of haemorrhage from a ruptured AVM is 2-4% ...
The pathophysiology of cranial venous outflow obstruction involves the disruption of normal venous drainage from the brain. Cerebral veins play a crucial role in draining brain interstitial fluid (ISF), and their significance has been linked in various neurological conditions. [1] It can be caused by extrinsic or intrinsic anomalies. [7]
Hypofrontality is a symptom of numerous neurological diseases defined as reduced utilization of glucose and blood flow in the prefrontal cortex. Hypofrontality can be difficult to detect under resting conditions, but under cognitive challenges, it has been seen to correlate with memory deficits along with executive function deficits.
Thus, while Parkinson's disease, a neurodegenerative condition, causes executive dysfunction, a disorder such as ADHD is a classification given to a set of subjectively-determined symptoms implicating executive dysfunction – models from the 1990s and 2000s indicate that such clinical symptoms are caused by executive dysfunction.
Emissary veins have an important role in selective cooling of the head. They also serve as routes where infections are carried into the cranial cavity from the extracranial veins to the intracranial veins. There are several types of emissary veins including the posterior condyloid, mastoid, occipital and parietal emissary veins. [1]
Symptoms of AVMs vary according to their location. Most neurological AVMs produce few to no symptoms.Often the malformation is discovered as part of an autopsy or during treatment of an unrelated disorder (an "incidental finding"); in rare cases, its expansion or a micro-bleed from an AVM in the brain can cause epilepsy, neurological deficit, or pain.