Thrombocytopenia is a condition characterized by abnormally low levels of platelets, also known as thrombocytes, in the blood. It is the most common coagulation disorder among intensive care patients and is seen in 20% of medical patients and a third of surgical patients.A normal human platelet count ranges from 150,000 to 450,000 platelets per microliter of blood. Values outside this range do not necessarily indicate disease. One common definition of thrombocytopenia requiring emergency treatment is a platelet count below 50,000 per microliter. Thrombocytopenia can be contrasted with the conditions associated with an abnormally high level of platelets in the blood: thrombocythemia (when the cause is unknown), and thrombocytosis (when the cause is known). Signs and symptoms
Thrombocytopenia usually has no symptoms and is picked up on a routine complete blood count. Some individuals with thrombocytopenia may experience external bleeding such as nosebleeds, or bleeding gums. Some women may have heavier or longer periods or breakthrough bleeding. Bruising, particularly purpura in the forearms and petechiae in the feet, legs, and mucous membranes, may be caused by spontaneous bleeding under the skin.Eliciting a full medical history is vital to ensure the low platelet count is not secondary to another disorder. Ensuring that the other blood cell types, such as red blood cells and white blood cells are not also suppressed, is also important. Painless, round, and pinpoint (1 to 3 mm in diameter) petechiae usually appear and fade, and sometimes group to form ecchymoses.
Poorer outcomes are associated with unresponsiveness to steroid therapy, unusually severe neurological symptoms, or sudden onset. Children tend to have more favorable outcomes than adults, and cases presenting without fevers tend to have poorer outcomes. The latter effect may be due to either protective effects of fever, or that diagnosis and treatment is sought more rapidly when fever is present. ADEM can progress to MS. It will be considered MS if some lesions appear in different times and brain areas

Motor deficits
Residual motor deficits are estimated to remain in about 8 to 30% of cases, the range in severity from mild clumsiness to ataxia and hemiparesis. Neurocognitive
Patients with demyelinating illnesses, such as MS, have shown cognitive deficits even when there is minimal physical disability. Research suggests that similar effects are seen after ADEM, but that the deficits are less severe than those seen in MS. A study of six children with ADEM (mean age at presentation 7.7 years) were tested for a range of neurocognitive tests after an average of 3.5 years of recovery. All six children performed in the normal range on most tests, including verbal IQ and performance IQ, but performed at least one standard deviation below age norms in at least one cognitive domain, such as complex attention (one child), short-term memory (one child) and internalizing behaviour/affect (two children). Group means for each cognitive domain were all within one standard deviation of age norms, demonstrating that, as a group, they were normal.