Temporal bone bulge is a symptom of arachnoid cyst. Arachnoid cysts are a type of benign brain cysts. There is an arachnoid-like cyst wall and cerebrospinal fluid-like cyst fluid. So, how should temporal bone bulge be diagnosed? The following are diagnostic methods for temporal bone augmentation: 1. History Ask about intracranial hypertension and neurological symptoms, pay attention to the presence of epilepsy seizures, and learn about the situation before, during, and after epilepsy seizures. 2.Physical examination Pay attention to check for positive neurological signs and check for bony bulges or cranial defects on the top of the head. 3.Cranial X-ray plain film Positive findings ① Bony hyperplasia of the local inner plate of the skull of the tumor, and bony protrusion may be seen when both inner and outer plates are hyperplastic, and a few may have cranial plate destruction. If the tumor is rich in blood supply, thickened and tortuous vascular pressure traces can be seen leading to the area of osteophytes or destruction. ③Cranial changes of increased intracranial pressure. ④Sometimes calcification of tumor and displacement of calcified pineal gland can be seen. 4.Cerebral angiography is mainly used to understand the source of blood supply of the tumor and the relationship between it and the surrounding important blood vessels. CT scan and MRI scan can determine the location and size of tumor, and most of them can make qualitative diagnosis. MRI shows that most of the tumors are iso-signal and significantly enhanced after enhancement.