A patient with fear of tremors in the head and environmental noise was found to have a trigeminal nerve sheath tumor, which recovered well after surgical excision. Trigeminal nerve sheath tumors account for about 0.2% to 1% of brain tumors. It can originate from any segment of the trigeminal nerve, but is more common in the Meckel’s capsule. It is a benign tumor with slow growth. According to the location, there are three types: middle cranial fossa type, posterior cranial fossa type and dumbbell type. Clinical manifestations mainly include symptoms of involvement of the trigeminal nerve itself and adjacent structures and symptoms of increased intracranial pressure. According to the location of the tumor, the clinical manifestations are as follows: 1. middle cranial fossa type: early symptoms of trigeminal nerve involvement itself are the main symptoms, and about 1/3 of them are similar to primary trigeminal neuralgia, which is a severe pain with episodes. The trigeminal nerve distribution area has more hypesthesia, but sometimes only the corneal reflex is weakened, which cannot be ignored. Motor root involvement is rare, or it may only appear in advanced stage. When the tumor involves adjacent structures, especially when the tumor develops to the cavernous sinus and supraorbital fissure, other symptoms of cerebral nerve involvement will appear, such as oculomotor disorders, diplopia, protrusion of the eye, and changes in visual acuity and visual field. The pupils are often dilated and the light reflex is blunted. The protrusion of the eyeball accounts for about 1/3 to 1/2 of the tumor, which may be caused by the compression of the cavernous sinus, affecting the reflux of the ophthalmic vein, or the direct protrusion of the tumor into the orbit through the supraorbital fissure, and there is often bruising in the fundic vein. If the tumor advances and compresses the optic nerve and optic cross, there will be primary atrophy of the optic nerve, loss of vision and visual field defects or even blindness. The symptoms of this type of intracranial pressure increase appear later and are less severe. Sometimes the tumor is as big as duck egg and has no symptoms of intracranial pressure increase. 2.Posterior cranial fossa type: The tumor mostly originates from trigeminal nerve root. The symptoms of motor root involvement are more prominent, such as weakness and atrophy of temporal and masticatory muscles. The clinical manifestation of trigeminal neuralgia is very rare, but hypesthesia can appear at an early stage, and most of the branches 1, 2 and 3 are involved at the same time, or only corneal hypesthesia may be present. If the tumor compresses the 7th and 8th cerebral nerve pairs, it may cause facial muscle twitching, peripheral facial palsy, tinnitus, hearing loss, and vestibular function is also involved. If the tumor is close to the cerebellar curtain, there are symptoms of damage to the 9th, 10th and 11th pairs of cerebral nerves. When the cerebellum is compressed, there is mostly ataxia. If the brainstem is compressed or displaced, contralateral or ipsilateral pyramidal fasciculus signs are often seen. Generally, the symptoms of increased intracranial pressure appear earlier and more obvious. 3.Dumbbell type: The tumor is located between middle cranial fossa and posterior cranial fossa, and can grow from middle cranial fossa to downward or from posterior cranial fossa to upward, and the clinical symptoms have the characteristics of the above two types.