:Acta

Acta Neurochir (Wien) (1992) 1I9:174-175

Ncurochirurgica 9 Springer-Verlag 1992 Printed in Austria

Repair of Skull Base Dural Defects: the Dura Sandwich Technical Note A. Ammar Department of Neurosurgery, King Fahd UniversityHospital, King Faisal University,Dammam, Saudi Arabia

Summary A techniquefor skull base dural defectrepair is presented, using two layers of periosteumand biological(Tisseelglue), one on either side of the defect. The method is reliable and relativelysimple,and was used to repair a recurrent skull base encephalocoelewith great success. The method has application in the reconstruction of any dural defect,whether congenital, traumatic or surgical. Keywords: Dural defect; encephalocoele;skull base surgery; reconstruction.

proach to increase visualization and hence reliability. By opening the dura and effecting both an intra- and extradural repair a dual advantage is obtained, that of increased visualization of the defect, combined with added strength to prevent recurrence, particularly where a large bony defect is present. The use of this technique was prompted in an infant for recurrence of a skull base encephalocoele, which had previously been repaired by using an extradural layer of periosteum.

Introduction Commonly, skull base dural defects, as a result of encephalocoele, trauma or following total removal of meningioma, are repaired using an extradural free flap, such as periosteum I, fascia lata 4, or a vascularized muscolocutaneous flap 2, which is stitched in place. A great deal of expertise is required to effect a succesful repair, particularly in postero-medial defects of the anterior cranial fossa extending posterior to the anterior-clinoid process, as the irregularity of the skull base can cause slipping of the graft unless it is well secured, and the defect is difficult to both visualize and reach in this area. Biological glue (Tisseel); Tissucol Duo S,'Immuno Comp.) has been successfully utilized in conjunction with an extradural covering material. Symon 4 advocates the use of fascia lata reinforced by split skin grafts, and states that the use of Tissel may be useful where suturing is difficult, either because of inaccessibility or where the dura holds sutures very poorly, i.e. the basal dura. Some surgeons 1, 3 recommend an intradural ap-

Operative Technique After routine intracranial exposure of the skull base, and the surgical treatment of the causative pathology, alternating intra- and extradural retraction should be applied until the defect can be clearly observed from both the intra- and extradural surfaces. Two periosteal flaps, each slightly larger in size than the defect, should be harvested from the skull approximating the bone flap. Ensuring that the defect remains clearly visualized, the dural retraction should be removed to allow intradural access to the site. One of the periosteal flaps is applied to the intradural surface of the defect. Biological glue (Tisseel) is applied to one surface of the remaining periosteal flap, which is, in turn, applied to the extradural surface of the defect, the glue in contact with the dura and exposed portion of the intradural periosteal flap. By applying mild pressure, the flaps become adherent, and a leak-proof seal is affected (Fig. 1).

A. Ammar: Repair of Skull Base Dural Defects: the Dura Sandwich

Fig. 1. Closure of the dural defect utilising two layers of pericranium, one either side of the dura (arrow heads)

175 wich) approach still has the extra advantage of increased strength. Contrary to Tissucol D u o S ( I m m u n o Comp.), which is approved in several European Countries, the use of Tisseel in smoe countries, notably U.S.A., has not yet been approved by the relevant licensing authorities. O f no biological tissue glue is available the technique would be equally as effective, although less simple, if the two grafts were secured by suturing to the dura. Although this technique has only been performed once, it lends itself to the repair of all dural defects that require grafting, be they congential, traumatic or surgical, due to the relative ease of the operation combined with the increased strength and reliability of the graft.

References Discussion The advantages of this technique over the previously used technique of applying only an extradural graft are several. 1) Vision to the operative site is vastly improved by the intradural approach. 2) The seal is completely reliable, since the two layers of periosteum become adherent, in effect causing a plug in the defect. 3) The enhanced strength afforded by two layers ofperiosteum reduces the risk of recurrence of the defect in the form of CSF leak or herniation. Whilst it is suggested that an intradural approach is preferable to an extradural one, because of enhanced visualization and consequent increased reliability of the repair, (1) the double (sand-

1. Dagi TF, George ED (1988) The management of cerebrospinal fluid leaks. In: Schmiedek HH, Sweet WH (eds) Operative neurosurgical techniques, Vol 1. Grune and Stratton, Orlando, pp 5769 2. Jones NF (1987) Methods of cranial base reconstruction. In: Sekhar LN, Schramm VL (eds) Tumours of the cranial base, diagnosis and treatment. Futura, Mount Kisco, pp 233-243 3. Spetzler RF: Comment on: Hubbard JL, McDonald TJ, Pearson BW etal (1985) Spontaneous cerebrospinal fluid rhinorrhea: Evolving concepts in diagnosis and surgical management based on the Mayo Clinic experience from 1970 through 1981. Neurology 16:314-320 4. SymonL (1990) Aspectsofthe managementof skull base tumours. Clin Neurosurg 36:48-69 Correspondence and Reprints: Dr. A. Ammar, P.O. Box 40040, A1 Khobar, Saudi Arabia.