Patchy abnormal signals in the left thalamic region may indicate cerebral infarction, cerebral hemorrhage, brain tumor and other diseases. 1. Cerebral infarction: Cerebral infarction is a kind of blood circulation disorder in the brain, due to ischemia and hypoxia leading to ischemic necrosis or softening of local brain tissue. Its etiology is related to atherosclerosis of large arteries, cardiogenic embolism, small artery occlusion and other factors. Left thalamus infarction can be seen in the case of left thalamus area with patchy abnormal signal. 2. Cerebral hemorrhage: patchy abnormal signal in the left thalamic region may also be caused by left thalamic hemorrhage. Cerebral hemorrhage may be caused by hypertension combined with small arteriosclerosis, cerebral arteriovenous malformation, post-infarction hemorrhage, smog disease, etc. Blood accumulates in the brain tissue and patchy abnormal signals appear. 3. Brain tumor: the patchy abnormal signal in left thalamic region is also considered to be caused by left thalamic tumor. The etiology of intracranial tumor is not yet clear, and the risk factors are related to ionizing radiation, viral infection, and neurological carcinogens and other factors. There are many reasons leading to the left thalamic area patchy abnormal signal, it is recommended that the patient go to the regular hospital for relevant examination to clarify the cause of the disease.