Clinical Analysis Of Middle Cranial Fossa Epidural Epidermoid Cysts

Objective Intracranial epidermoid cyst are believed to originate from embryonic rests of ectodermal remnants.They are mostly found in cerebellopontine angle,fourth ventricle and sellar region.Epidermoid cysts originating from the epidural of middle cranial fossa and extending to adjacent structures such as infratemporal fossa,pterygopalatine fossa and cavernous sinus are extremely rare.Due to its low incidence,most of the relevant literature reports are case reports,people have insufficient understanding of the disease,and the preoperative misdiagnosis rate is high.Total resection is often considered the preferred treatment because it offers a cure.However,due to the deep location of the epidermoid cyst located in the epidural area of the middle cranial fossa and the important neurovascular structures around it,it is difficult for surgical exposure,and there is no standard surgical approach to choose from.Surgery of middle cranial fossa epidural epidermoid cysts involves many disciplines and is challenging for surgeons.This study reports the cases of middle cranial fossa epidural epidermoid cysts treated in our hospital in recent years,combined with the relevant literature at home and abroad,analyzed and summarized the clinical characteristics of middle cranial fossa epidural epidermoid cysts and discussed its surgical treatment strategy.Methods This paper reports the cases of middle cranial fossa epidural epidermoid cysts treated by neurosurgery in Cancer Hospital of Chinese Academy of Medical Sciences from 2015 to 2020,and reviewed the cases of middle cranial fossa epidural epidermoid cysts reported in the literature at home and abroad in past 10 years.The relevant clinical data were collected,the clinical characteristics of middle cranial fossa epidural epidermoid cysts were analyzed and summarized,and its individual surgical treatment strategy was discussed.Results A total of 31 cases were analyzed,including 23 patients from literature search and 8 patients from our hospital.There were 16 males and 15 females,aged from 11 to71 years old,with an average of 42.5 years old.The patients showed varying degrees of headache in 13 cases,decreased vision in 5 cases,the Ⅲ,Ⅳ and Ⅵ cranial nerve dysfunction in 9 cases,the Ⅴ cranial nerve dysfunction in 14 cases,the Ⅶ cranial nerve dysfunction in 2 cases,the Ⅷ cranial nerve dysfunction in 3 cases,cerebrospinal fluid leakage in 1 case,cerebrospinal fluid leakage in 1 case and oral mass with pain in 1 case.Among the 31 patients,13 cases underwent CT examination: low density in 11 cases,isodensity in 1 case,high density in 2 cases;enhanced CT in 3 cases: slightly enhancement in 2 cases,non-enhancement in 1 case;bone compression destruction in 7 cases,and CTA examination in 1 case,no vascular distribution was found in the tumor.Among the 31 patients,MRI was performed in 27 cases: T1 sequence in 25 cases: low signal in 16 cases,mixed signal in 7 cases,high signal in 2 cases;T2 sequence in 24 cases: low signal in 2cases,mixed signal in 2 cases,high signal in 20 cases;DWI sequence in 15 cases: high signal in 15 cases,enhanced MRI in 20 cases: partly enhancement in 12 cases,no enhancement in 8 cases,magnetic resonance spectroscopy in 1 case,Flair sequence in 1case.Among the 31 patients,craniotomy was performed in 25 cases,including middle cranial fossa epidural approach in 22 cases;endoscopic surgery was performed in 6 cases,including transnasal approach and sublabial transmaxillary approach.Of the 31 tumors,total resection was performed in 19 cases and subtotal resection in 10 cases.Postoperative pathological examinations indicated epidermoid cysts in all cases.The preoperative symptoms were improved in 26 cases and not improved in 2 cases.Among the 31 patients,23 cases had no postoperative complications and 3 cases had complications.Except for 5cases with lack of information,all cases were followed up for 3-105 months,with an average time of 6.5 months.During the follow-up,the quality of life of the patients was good,and the average KPS score was 80.Tumor recurrence occurred in 4 patients during the follow-up period,of which 3 cases were surgically resected.Conclusions Middle cranial fossa epidural epidermoid cysts are rare and often present with the symptoms of headache and cranial nerve paralysis.The lesion generally appears as a parasellar epidural low density mass on CT scan,the surrounding bone shows compressive changes.The lesion does not enhanced after injection of contrast agents,and shows hyperintense on DWI sequence.The treatment of choice is surgical removal of the tumor for patients with obvious clinical symptoms,and the appropriate surgical approach is chosen according to the location of the cyst.The cyst and capsule should be removed as much as possible on the premise of protecting the integrity of neurological function,so as to reduce the possibility of recurrence.Repeated surgery will be considered if cyst recurrence is found.