Left temporal lobe abnormal signal shadow is a descriptive term used in the cranial MRI report to suggest that the left temporal lobe signal may have a lesion such as inflammation, tumor, or vascular lesion. The presence of a left temporal lobe abnormal signal shadow on the test suggests the presence of a lesion in the patient’s left temporal lobe. Infectious encephalitis, immune-related autoimmune encephalitis, space-occupying lesions, cerebrovascular lesions, etc., may be present, and the diagnosis needs to be evaluated in conjunction with clinical symptoms, medical history, and other relevant tests. Patients with abnormal signaling in the left temporal lobe need to go to the hospital in a timely manner, follow the doctor’s instructions for further examination to determine the cause of the disease, and adopt the correct treatment according to the specific cause.