1. Clinical data: The patient, male, 38 years old, was admitted to the hospital for 70 days with recurrent nasal discharge of clear liquid from the nostrils after a fall with 10 days of mental confusion. Physical examination: loss of sense of smell, 1m index of visual acuity in front of the left eye, limited eye abduction, and temporal hemianopsia. Brain CT and skull base thin 3D reconstruction CT showed: large amount of air accumulation in the farce, frontal bone fracture, anterior skull base pterygoid and sieve bone fracture, partial pterygoid plateau absence, herniation of brain tissue into about 3×3cm2, and compression of the left optic nerve. A coronal incision was made, the flap was carefully separated, the intact periosteum and fascia were preserved, three pieces of crushed depressed bone were removed by drilling and sawing the bone, the anterior skull base dura was carefully separated under the microscope, the cockle was bitten off and gradually reached the edge of the defective dural fissure, the fracture line and small fracture fragments were visible in the sieve plate of the pterygoid bone, the defective dura of the pterygoid plateau and part of the brain tissue were herniated into the pterygoid sinus, its posterior edge was difficult to separate, the right frontal dura was cut, the frontal lobe was elevated and gradually reached The herniated brain tissue was excised, the posterior edge of the herniated opening was found, the posterior edge of the herniated opening was continued to be separated to 1 cm after the herniated opening, the bilateral temporalis fascia was taken, the defective dura was first repaired under the dura and adhered with biologic adhesive, and then the dural defect was found 1 cm after the epidural, repaired with fascia and fixed with the same biologic adhesive, saline was injected from the dural incision at this time, and the original leak was observed No fluid leakage, suture the dura, lay the fascia periosteum on the anterior skull base, posteriorly reach 0.5cm of the posterior edge of the original defect, adhere it with bioadhesive, fix the fascia periosteum around the same bioadhesive, fix the original fragmented bone piece with titanium joint piece and reset it after forming, then fix it with the titanium nail around the skull, place the drainage tube outside the dura to close the skull. Postoperatively, the patient was awake, no fluid flow from the nostrils, no intracranial infection was seen, the sense of smell was not restored, and the visual acuity reached the index of 6 meters in front of the eyes. 2, discussion: meningeal brain bulge is the cranial contents of the skull through the skull base bone defects or weak areas herniated to the nasal cavity formed by the cystic structure communicating with the cerebrospinal fluid circulation, the main body of the bulge is located in the nasal cavity of the meningeal brain bulge is collectively referred to as nasal meningeal brain bulge. Nasal meningoencephalic bulge is divided into fontanelle type and skull base type, fontanelle type more to the outside of the nose, easier to make an early diagnosis, intranasal type is a type of skull base, cranial defects are located in the sieve bone sieve plate, bulging site at the top of the nasal cavity, more hidden, patients can be a long time or even a lifetime without symptoms, some scholars call the skull base hidden malformation. (1) Diagnosis of cerebrospinal fluid rhinorrhea: The diagnosis of cerebrospinal fluid rhinorrhea is sometimes difficult and requires a detailed medical history, a history of trauma, the presence of cystic masses in the nasal cavity in the past, and the presence of nasal outflow of clear water-like nasal discharge. Nasal outflow is monitored quantitatively by sugar; cranial CT examination, especially the current 3D CT reconstruction can clearly detect the bone defect or destruction at the skull base. In addition, Beta-2 transferrin test of nasal secretion has greater significance in differential diagnosis. (2) Causes of cerebrospinal fluid rhinorrhea: The causes of cerebrospinal fluid rhinorrhea can be broadly divided into congenital and acquired, including traumatic, post-surgical, and neoplastic cerebrospinal fluid rhinorrhea, of which traumatic is more common. The causes of traumatic cerebrospinal fluid nasal leakage are not only related to trauma, but also related to the anatomical structure of the middle of the anterior skull base, where the olfactory nerve exits the skull and the membrane structure is complex. （Conservative treatment includes absolute bed rest, reduction of intracranial pressure and prevention of infection, while surgical treatment includes nasal endoscopic surgery and transcranial repair. In case of meningeal brain bulge, it should be returned as far as possible, and those that are impossible to be returned should be removed. If the area of meningeal defect is small or the meninges are ruptured, close sutures are given first, and then the frontal bone periosteum or temporalis fascia is used to cover the rupture. Note that the posterior edge must exceed the defect, and the perimeter of the covering periosteum or fascia can be sutured to the meninges or adhered to the meninges with biologic adhesive. In cases of cerebrospinal fluid nasal leakage and meningeal brain expansion, there is a skull base bone defect. If the diameter of the bone defect is less than 3 cm, the skull base defect can be repaired without considering the repair of the skull base bone, and the anterior skull base defect can be repaired with a cap-like tendon flap; if the diameter of the skull base bone defect is greater than 3 cm, the repair of the skull base bone defect should be considered. The special feature of this case is the intraoperative finding of congenital craniosynostosis combined with meningoencephalic bulge, the fissure is about 2 cm, congenital craniosynostosis or meningoencephalic bulge is a rare disease, which is caused by the herniation of brain contents to the outside of the skull through the unfused bone suture during the embryonic period or by the increase of intracranial pressure in the fetus during delivery, and the skull base type meningoencephalic bulge is even rarer. According to the literature, the incidence of meningoencephalic bulges is 1 in 10,000 newborns, with 71% in the occipital lobe, 10% in the parietal lobe, 10% in the nasopharynx, and 9% in the frontal lobe. Simple craniosynostosis generally does not require special treatment, when combined with bulging need to surgically remove the bulging capsule, restore the contents of the bulging brain tissue, repair the different levels of the fissure, restore its bony skull base anatomy, so that it again has the support of protective functions, but this patient did not appear before the injury cerebrospinal fluid leakage and neurological symptoms, but after the external effect, the dura, arachnoid membrane is stretched to rupture caused by cerebrospinal fluid leakage However, congenital craniosynostosis is more likely to cause cerebrospinal fluid leakage due to the lack of normal anatomy at the base of the skull when subjected to external forces. In addition to repairing the traumatic fracture, the surgery should be performed to restore the normal anatomical structure of the skull base by rehabilitating the enlarged brain tissue or removing it as much as possible, so that the success rate of the surgery is higher and the recovery is more satisfactory!