Inflammatory diseases of the blood vessels, like giant-cell arteritis, polyarteritis nodosa, Churg–Strauss syndrome, granulomatosis with polyangiitis, and rheumatoid arthritis can cause arteritic AIONs (AAION). The vast majority of AIONs are nonarteritic AIONs (NAION). The most common acute optic neuropathy in patients over 50 years of age, NAION has an annual incidence of 2.3-10.2/100,000. NAION presents as a painless loss of vision, often when awakening, that occurs over hours to days. Most patients lose the lower half of their visual field (an inferior altitudinal loss), though superior altitudinal loss is also common. The pathophysiology of NAION is unknown, but it is related to poor circulation in the optic nerve head. NAION is often associated with diabetes mellitus, elevated intraocular pressure (acute glaucoma, eye surgery), high cholesterol, hypercoagulable states, a drop in blood pressure (bleeding, cardiac arrest, peri-operative esp. cardiac and spine procedures), and sleep apnea. Rarely, amiodarone, interferon-alpha, and erectile dysfunction drugs have been associated with this disease. Posterior ischemic optic neuropathy is a syndrome of sudden visual loss with optic neuropathy without initial disc swelling with subsequent development of optic atrophy. This can occur in patients who are predisposed to AAION and NAION as described above as well as those who had cardiac and spine surgery or serious episodes of hypotension. Radiation optic neuropathy (RON) is also thought to be due to ischemia of the optic nerve that occurs 3 months to 8 or more years after radiation therapy to the brain and orbit.
An obturator hernia is a rare type of hernia of the pelvic floor in which pelvic or abdominal contents protrudes through the obturator foramen. Because of differences in anatomy, it is much more common in women, especially multiparous and older women who have recently lost much weight. The diagnosis is often made intraoperatively after presenting with bowel obstruction. The Howship–Romberg sign is suggestive of an obturator hernia, exacerbated by thigh extension, medial rotation and abduction. It is characterized by lancinating pain in the medial thigh/obturator distribution, extending to the knee; caused by hernia compression of the obturator nerve. References


== External links ==