Left frontal lobe soft foci means old lesions, which may be caused by cerebral infarction in the frontal lobe or cerebral hemorrhage in the frontal lobe, resulting in necrosis of brain tissues and brain cells of the patient, and after a long period of time, the necrotic brain cells will be liquefied and form cystic structure, which is the same density as that of the cerebrospinal fluid. On CT or MRI, it can be observed that the left frontal lobe has previous old softening foci. In this case, it is necessary to address the cause of the patient’s disease, prevent the recurrence of cerebral infarction or cerebral hemorrhage, and avoid the formation of multiple cerebral infarcts in the patient. Patients should take a low-salt, low-fat diet in daily life, quit smoking, limit alcohol, and actively and effectively prevent the risk factors of cerebral hemorrhage and cerebral infarction, for example, if cerebral infarction is caused by cerebral infarction, the patient should take oral aspirin to resist platelet aggregation, and strictly control the risk factors of blood pressure, lipids, and blood glucose.