LAUSR

STUDY DESIGN Retrospective case series. OBJECTIVE Anterior sacral meningocele (ASM) is a rare disorder. We reviewed 11 cases of congenital ASM and classified them into three types based on the anatomy and relationship between the cyst and sacral nerve roots. SUMMARY OF BACKGROUND DATA The cohort with ASM is relatively large; the classification is novel and has not been previously reported. METHODS Eleven consecutive patients with ASM who underwent surgery between February 2014 and January 2019 were retrospectively analyzed. They included four males and seven females. The dorsal transsacral approach was adopted in all cases. The follow-up time was at least three months. RESULTS We attempted to classify ASM into three types. Of the 11 cases, six were Caudal Type, two were Para-neural Type, and three were Nerve-root Type. The meningocele was ligated after exploring no nerve involvement, in Type I and II. For Type III, the herniating sac and involved nerve roots were ligated when the nerve roots were indicated as non-functional on neurophysiological monitoring; otherwise, the sacral nerve roots were protected and imbricated on the residual sac like a hand-in-glove, and sutured to reconstruct the nerves sleeve. Eight cases were accompanied by tethered cord syndrome (TCS); spinal cord detethering was done with one-stage operation. Ten patients' presenting symptoms improved at 3-6 months follow-up; notably, constipation significantly improved. Only one case accompanied by an epidermoid cyst had a second laparoscopic surgery by a general surgeon. CONCLUSION Aim of surgical treatment is to obliterate the communication between the subarachnoid space and herniated sac, detether the spinal cord, and resect the congenital tumor. The new classification helps to recognize the relationship between the meningocele and sacral nerve roots, and subsequently adopt different surgical strategies. We consider the dorsal transsacral approach relatively feasible, safe, and with lower complication. LEVEL OF EVIDENCE 4.