1, History: The definition of old cerebral infarction requires patients to have a clear history of cerebral infarction. In the past, one case was diagnosed as cerebral infarction and recovered naturally after treatment. By understanding and confirming the individual's course of disease, we can determine whether it conforms to the old cerebral infarction.

2. Imaging examination: it plays an important role in confirming the old (stable) state. Imaging techniques such as head CT or MRI can show that the ischemic center is completely bad, no new lesions are formed, and the surrounding tissues have compensation mechanism, which is helpful for doctors to judge whether the injury belongs to or not.

3. Brain protein content: eliminating the purity and characteristics of changes and abnormal phenomena caused by other reasons will lead to aggregation and eventually generate clots, which will help eliminate brain diseases caused by other reasons.