dura closure is a very important last step in the performance of the posterior fossa approach . primary dural closure is often technically difficult and requires use of substitutes either autologous materials ( fat graft , pericranium ) or dural sealant augmentation . various techniques and products are used to ensure watertight dural closure - failure of which lead to dire consequences . posterior fossa approaches are often accompanied with complications like cerebrospinal fluid ( csf ) leakage , surgical site infection , meningitis , pseudomeningocele formation and delayed hydrocephalus . treatment of csf leaks leads to profound morbidity with increased hospital stay and its cost has been estimated to be one and half times greater than uncomplicated cases . the two main techniques used in ensuring water tight dural closure in posterior fossa surgery are the use of autologous materials and dural substitutes with dural sealant augmentation . dural substitutes like bovine collagen matrix are accompanied with a rate of 50% complications , whereas in general the risk is about 22% . not only the differences in the material is described , but also the different suture techniques , which show no significant shift by comparison . sealants increase the water tightness of suture significantly with variations in water tightness capacities of different sealants . this study presents our experience with the sandwich technique of dural closure using a combination of autologous dura , dural substitute and fibrin glue . this is a retrospective technique study . in accordance to the chamber of medical doctors of north rhine westfalia , germany , no institutional review board ( irb ) the charts of patients > 18 years old ( mean age : 60.7 years ) were analyzed , which were operated in our department from 2009 - 2013 . the female to male ratio was 1.08:1 . the follow up period was 6 months ( until the second postsurgical control visit ) . after removing the pathology in the posterior fossa , dural closure follows a sandwich closure with lyophilized dura , which is sutured on the dural edges , suturing the dura as tight as possible and placement of fibrin coated watertight sealant over the dura and under the edges of the craniotomy . in a next step the bone is replaced with polymethylmethacrylate , which is fixed as shown in figure 1a - f . in almost all cases we placed bur holes on the lower edge of the transverse sinus and figure 2 shows intraoperative images of the closure method and figure 3 illustrates pre- and postoperative images . after removing the pathology in the posterior fossa , dural closure follows a sandwich closure with lyophilized dura , which is sutured on the dural edges , suturing the dura as tight as possible and placement of fibrin coated watertight sealant over the dura and under the edges of the craniotomy . in a next step the bone is replaced with polymethylmethacrylate , which is fixed as shown in figure 1a - f . in almost all cases we placed bur holes on the lower edge of the transverse sinus and figure 2 shows intraoperative images of the closure method and figure 3 illustrates pre- and postoperative images . the patients were operated on variable pathologies with the greatest number representing astro-/oligodendroglial tumors ( 110 ) , metastases ( 80 ) , meningioma ( 30 ) , glioblastoma ( 15 ) and acoustic neuroma ( 30 ) . all other pathologies were represented by numbers < 10 ( arteriovenous malformation , meningocele , cavernoma , abscess , ependymomy , medulloblastoma , lymphoma , cyst , ganglioma , teratoma , amyloid angiopathy , arnold - chiari malformation , bone tumor ) . the general health status ( risk factors like hypertonia , adipose patients , etc . ) of the individuals was not significantly different compared to the general population . only 3.8% of patients developed csf leakage and only 0.5% needed a second surgery for csf leakage closure . by csf leakage we mean a subcutaneous palpable mass , which is leaking outside the wound or not . two percent had a cerebellar bleeding with no need for re - operation and 3% had a wound infection treated with antibiotics . five patients developed a hydrocephalus and there was no significant difference between the csf leakage rate in these patients and patients without hydrocephalus although the number of patients was too small to allow a statistical comparison . there was also not a statistical difference between csf leakage and patients with extended opening of the arachnoid . there are different dural closure techniques in use ranging from meticulous primary dural closure using interrupted or continuous stitches , use of dural substitutes - autologous ( fat graft , fascia , pericranium ) and synthetic . many neurosurgeons use autologous materials or dural substitutes due to the associated lesser complication rates . complication rates following posterior fossa surgeries vary between 1 and 10% . various aspects of the surgical approach and closure technique contribute to the complication rate . csf leakages following posterior fossa surgery has remained an unsolved problem since the era of cushing and constitute a major post operative complication due to potentially life threatening sequelae and delay beginning of adjuvant therapy in oncologic cases . it occurs in 2 - 17% following posterior fossa surgery . in the present study the combination of those techniques , as it is in the sandwich technique , reduces the csf leakage complication rate to 3.8% ( only 0.5% needed a surgical revision ) which is low compared to the complication rate described in the literature . the 0.5% of patients needed a second surgery for csf leakage closure which is better compared to 3.7% in a similar study . the rest of the patients with csf leakage were managed by a lumbar drain for 5 - 7 days . the 2% of the patients had cerebellar bleeding with no need of re - operation and 3% had a wound infection treated with antibiotics to good effect . the sandwich wound closure we applied for posterior fossa surgery in our patients , correlates with a significant reduction of csf leaks compared to the literature and less need for surgical closure for the few who had csf leaks .