Many patients experience difficulty sitting for long (or even short) periods of time due to discomfort or pain, or because of efferent neurological or other motor symptoms, such as difficulties controlling limbs. Difficulty sitting can be problematic for patients who have trouble standing or walking for long periods, as wheelchairs are not always helpful in such cases. Causes
The root cause of the condition is not entirely clear, and it appears to have multiple causes, including iatrogenic cause from misplaced epidural steroid injection therapy when accidentally administered intrathecally (inside the dura mater, the sac enveloping the arachnoid mater), or from contrast media used in myelography prior to the development of metrizamide and other water-soluble contrast agents. Other noninfectious inflammatory processes include surgery, intrathecal hemorrhage, and the administration of anesthetics (e.g. chloroprocaine), and steroids (e.g. prednisolone, triamcinolone acetonide). A variety of other causes exist, including infectious, inflammatory, and neoplastic processes. Infectious causes include bacterial, viral, fungal, and parasitic agents. Prior spinal surgery has been documented as a cause of arachnoiditis ossificans, as well as for the adhesive form. It can also be caused by long term pressure from either a severe disc herniation or spinal stenosis. Diagnosis
For the ossificans form of the condition, unenhanced CT may better show the presence and extent of arachnoid ossifications, and is complementary to MRI, as MRI can be less specific and findings can be confused with regions of calcification or hemosiderin. Treatment
Arachnoiditis is difficult to treat and treatment is generally limited to alleviation of pain and other symptoms.
Hypocholesterolemia is the presence of abnormally low (hypo-) levels of cholesterol in the blood (-emia). A defect in the bodys production of cholesterol can lead to adverse consequences as well. Cholesterol is an essential component of mammalian cell membranes and is required to establish proper membrane permeability and fluidity. It is not clear if a lower than average cholesterol level is directly harmful; however, it is often encountered in particular illnesses. Presentation
Role in disease
With the increased use of medication to suppress cholesterol, some have expressed concern that lowering cholesterol levels excessively will itself cause disease. Specific disease entities
Demographic studies suggest that cholesterol levels form a U-shape curve when plotted against mortality; this suggests that low cholesterol is associated with increased mortality, mainly due to depression, cancer, hemorrhagic stroke, aortic dissection and respiratory diseases. It is possible that whatever causes the low cholesterol level also causes mortality, and that the low cholesterol is simply a marker of poor health.Links with depression have been supported by studies. In contrast, no evidence was found for a link with hemorrhagic stroke (although higher cholesterol levels conferred a relative protection), and neither did statin drugs worsen the risk.The Heart Protection Study found no increase in either respiratory disease or neuropsychiatric illness in a large trial population taking a statin drug. Elderly
In the elderly, low cholesterol may confer a health risk that may not be offset by the beneficial effects of cholesterol lowering. Similarly, for elderly patients admitted to hospital, low cholesterol may predict short-term mortality.