Osteonecrosis is also associated with cancer, lupus, sickle cell disease, HIV infection, Gauchers disease, and Caisson disease (dysbaric osteonecrosis). The condition may also occur without any clear reason.Bisphosphonates are associated with osteonecrosis of the mandible. Prolonged, repeated exposure to high pressures (as experienced by commercial and military divers) has been linked to AVN, though the relationship is not well understood.In children, avascular osteonecrosis can have several causes. It can occur in the hip as part of Legg–Calvé–Perthes syndrome, and it can also occur as a result after malignancy treatment such as acute lymphoblastic leukemia and allotransplantation. Pathophysiology
The hematopoietic cells are most sensitive to low oxygen and are the first to die after reduction or removal of the blood supply, usually within 12 hours. Experimental evidence suggests that bone cells (osteocytes, osteoclasts, osteoblasts etc.) die within 12–48 hours, and that bone marrow fat cells die within 5 days.Upon reperfusion, repair of bone occurs in 2 phases. First, there is angiogenesis and movement of undifferentiated mesenchymal cells from adjacent living bone tissue grow into the dead marrow spaces, as well as entry of macrophages that degrade dead cellular and fat debris. Second, there is cellular differentiation of mesenchymal cells into osteoblasts or fibroblasts. Under favorable conditions, the remaining inorganic mineral volume forms a framework for establishment of new, fully functional bone tissue. Diagnosis
In the early stages, bone scintigraphy and MRI are the preferred diagnostic tools.X-ray images of avascular necrosis in the early stages usually appear normal.
Marchiafava–Bignami disease is a progressive neurological disease of alcohol use disorder, characterized by corpus callosum demyelination and necrosis and subsequent atrophy. The disease was first described in 1903 by the Italian pathologists Amico Bignami and Ettore Marchiafava in an Italian Chianti drinker. In this autopsy, Marchiafava and Bignami noticed that the middle two-thirds of the corpus callosum were necrotic. It is very difficult to diagnose and there is no specific treatment. Until 2008 only around 300 cases had been reported. If caught early enough, most patients survive. Symptoms and signs
Symptoms can include, but are not limited to lack of consciousness, aggression, seizures, depression, hemiparesis, ataxia, apraxia, coma, etc. There will also be lesions in the corpus callosum. Causes
It is classically associated with chronic alcoholism especially with red wine consumption and sometimes associated nutritional deficiencies. Alcohol use disorder can also cause thiamine deficiency, which is also observed to cause MBD. Mechanism
Individuals with MBD usually have a history of excessive alcohol consumption, but this is not always the case. The mechanism of the disease is not completely understood, but it is believed to be caused by a Vitamin B deficiency, malnutrition, or alcohol use disorder. The damage to the brain can extend into neighboring white matter and sometimes go out as far as subcortical regions. Diagnosis
Marchiafava–Bignami disease is routinely diagnosed with the use of an MRI because the majority of clinical symptoms are non-specific. Before the use of such imaging equipment, it was unable to be diagnosed until autopsy.