EXPERIMENTAL STUDIES SUTURING TECHNIQUE AND THE INTEGRITY OF DURAL CLOSURES:AN IN VITRO STUDY Joseph F. Megyesi, M.D., Ph.D. Brain Research Laboratory, Experimental Research Unit, Division of Neurosurgery, University of Western Ontario, London, Ontario, Canada Adrianna Ranger, M.D. Brain Research Laboratory, Experimental Research Unit, Division of Neurosurgery, University of Western Ontario, London, Ontario, Canada Warren MacDonald, B.Sc., R.T. Brain Research Laboratory, Experimental Research Unit, Division of Neurosurgery, University of Western Ontario, London, Ontario, Canada Rolando F. Del Maestro, M.D., Ph.D. Brain Research Laboratory, Experimental Research Unit, Division of Neurosurgery, University of Western Ontario, London, Ontario, Canada Reprint requests: Joseph F. Megyesi, M.D., Ph.D., Division of Neurosurgery, University of Western Ontario, London Health Sciences Centre, University Campus, 339 Windermere Road, Room 10-OF1, London, Ontario, Canada N6A 5A5. Email: jmegyesi@uwo.ca Received, August 20, 2003. Accepted, March 4, 2004. OBJECTIVE: The watertight closure of the dura mater is fundamental to intracranial procedures in neurosurgery. Nevertheless, for any given operator and type of suture, it is still not certain which suturing technique affords the most watertight dural closure. We have developed a laboratory model that allows us to compare the pressures at which dural closures leak when different suturing techniques are used. METHODS: Human cadaveric dura was secured to a glass cylinder filled with colored saline. By application of force to a bag of saline attached to the cylinder, the pressure at which sutured dural incisions leak can be recorded. Using this method, we have compared the closure of 2-cm dural incisions with 3-0 silk using the following techniques (10 per group): 1) interrupted simple, 2) running simple, 3) running locked, and 4) interrupted vertical mattress. We have also compared the closure of 1-  3-cm dural windows with cadaveric dura and 3-0 silk using the same suturing techniques (10 per group). RESULTS: The pressure at which 2-cm linear dural incisions leaked was significantly higher when they were closed with the interrupted simple suturing technique (P  0.05). There was no significant difference among the different suturing techniques when they were used to close a 1-  3-cm dural window with a duraplasty. Overall, the pressures at which sutured linear dural incisions leaked were higher than the pressures at which sutured dural windows closed with duraplasties leaked. CONCLUSION: In the experimental model described, an interrupted simple suturing technique affords the most watertight dural closure for linear incisions, whereas no suturing technique proved advantageous for the closure of a duraplasty. KEY WORDS: Dura, Leak pressure, Suture Neurosurgery 55:950-955, 2004 DOI: 10.1227/01.NEU.0000138441.07112.1B www.neurosurgery-online.com A voiding postoperative cerebrospinal fluid leaks is the main goal of a water- tight dural closure. Various suturing techniques are used to close the dura mater, but it is not certain which of these techniques provides a closure that leaks less readily. We have developed an in vitro system to test the pressures at which dural incisions closed with sutures leak fluid. We have used this system to compare the closure of linear dural inci- sions using different suturing techniques and the closure of dural windows with a dura- plasty and different suturing techniques. MATERIALS AND METHODS The use of human cadaveric dura was ap- proved by the Department of Pathology at the University of Western Ontario. It was ob- tained at the time of autopsy and kept refrig- erated in saline. Experiments were conducted within 2 weeks. Measurement of Fluid Leak Pressure An apparatus was designed to determine the pressure at which sutured dura leaked fluid (Fig. 1). A glass cylinder with a 6.7-cm opening at the top and a 2-cm fluid valve at the base was secured with a clamp to a bench- top stand. An intravenous bag of saline was attached to the port at the base of the cylinder via intravenous tubing. The saline was colored with Evans blue dye for easy visualization. The intravenous tubing was Y-connected to a reservoir and, via a pressure transducer, to a chart recorder (pressure meter). The glass cyl- 950 | VOLUME 55 | NUMBER 4 | OCTOBER 2004 www.neurosurgery-online.com