1.Posterior bulbar optic neuritis has a rapid onset, often with rapid loss of vision in one or both eyes, but later stabilizes and improves. There is a headache when the eye is turned, but there are also those who do not have headache. Visual field changes are atypical, with a central dark spot or a paracentral dark spot, and there may be a narrowing of the peripheral visual field. The intracranial pressure is not high, the pterygoid saddle is normal, and there are no endocrine changes. There is no positive finding in angiography and CT, which is enough to differentiate from saddle area tumor. 2, skull base meningitis, adhesive arachnoiditis. These disorders often have visual field impairment, but the visual field defects are often irregular. There is no enlargement of the pterygoid saddle. Long duration of disease and history of infection, pituitary endocrine hormone measurement is normal or reduced, but no endocrine overdrive phenomenon. In contrast, in neoplastic lesions, the visual field is mostly involved first, and visual acuity is not reduced until late. Pneumoencephalography with poorly inflated cross pools. Cerebral angiography or CT can help to differentiate. Traffic hydrocephalus Traffic hydrocephalus can cause the ventricles to dilate, and the anterior part of the third ventricle also dilates to the pterygoid saddle to enlarge. Vision and visual field may be impaired, and a few patients also have endocrine symptoms, such as amenorrhea and obesity. However, there may be a history of chronic infection in the medical history, and there are sometimes increased fingerprick marks on cranial plain films. Pneumoencephalography, cerebral angiography and CT can help to differentiate. 4.Intersaddle aneurysm Aneurysm often occurs in suprasaddle and parasternal, but intersaddle aneurysm is rare. It can have bilateral temporal hemianopia, hypopituitarism and butterfly saddle enlargement, which can be easily misdiagnosed as pituitary tumor and craniopharyngioma. However, if there is sudden headache and cranial nerve palsy on one side of III, IV, VI and V1, the possibility of aneurysm should be considered. Cerebral angiography can be used to differentiate. 5.Empty saddle The onset of middle-aged, more women than men, mostly have headache vision loss, visual field disorders often irregular, sometimes have obesity, amenorrhea and other endocrine symptoms. The butterfly saddle can be slightly large or normal. The main differentiation method is pneumoencephalography, which can be seen in the saddle with gas entry, or with positive contrast contrast imaging, which can show more clearly.