Pathophysiology
Aneurysm means an outpouching of a blood vessel wall that is filled with blood. Aneurysms occur at a point of weakness in the vessel wall. This can be because of acquired disease or hereditary factors. The repeated trauma of blood flow against the vessel wall presses against the point of weakness and causes the aneurysm to enlarge. As described by the law of Young-Laplace, the increasing area increases tension against the aneurysmal walls, leading to enlargement. In addition, a combination of computational fluid dynamics and morphological indices have been proposed as reliable predictors of cerebral aneurysm rupture.Both high and low wall shear stress of flowing blood can cause aneurysm and rupture. However, the mechanism of action is still unknown. It is speculated that low shear stress causes growth and rupture of large aneurysms through inflammatory response while high shear stress causes growth and rupture of small aneurysm through mural response (response from the blood vessel wall). Other risk factors that contributes to the formation of aneurysm are: cigarette smoking, hypertension, female gender, family history of cerebral aneurysm, infection, and trauma. Damage to structural integrity of the arterial wall by shear stress causes an inflammatory response with the recruitment of T cells, macrophages, and mast cells. The inflammatory mediators are: interleukin 1 beta, interleukin 6, tumor necrosis factor alpha (TNF alpha), MMP1, MMP2, MMP9, prostaglandin E2, complement system, reactive oxygen species (ROS), and angiotensin II.
Wildervanck syndrome or cervico-oculo-acoustic syndrome comprises a triad of:
Duane syndrome
Klippel-Feil anomaly (fused cervical vertebrae)
congenital hearing lossWildervanck syndrome is a developmental disorder that may be characterized by accessory tragi. References


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