1 Unit of Cranio-Maxillofacial Surgery (Head." Dr Giulio Cantz~), Istituto Nazionale per lo Studio e la Cura dei Tumori Via Venezian 1, 20133 Milano, Italy; 2Second Division of Neurosurgery, Istituto Nazionale Neurologico "C. Besta' Via Celoria, 20133 Milano, Italy
Ketcham et al. (1963; 1966; 1973) popularized the craniofacial approach for turnouts of the paranasal sinuses involving the anterior skull base. Their pioneer experience fostered the work of many others, leading to surgical removal of tumours with intra- cranial extension. Many technical advances were gradually introduced but without changing the basic concept of block resection. An unnatural commu- nication between intra- and extracranial spaces is the result of such operations, irrespective of the techni- que used. The repair of a skull base defect has been the object of vigorous discussions, and many varia- tions have been proposed, some very simple and others very complicated. The reasons advanced by those who support sophisticated repairs are as follows: to supply adequate structural support for the intracranial content, thereby preventing brain herniation; to avoid intracranial infection; to dimi- nish the risk of CSF leakage; and to avoid pneumo- cephalus.
Ketcham et al. (1963) did not repair the skull base; they used only a split-thickness skin graft placed on the dura. They had many complications but never experienced brain herniation (Ketcham et al., 1966). Some authors who performed the surgery feared the possibility of such a complication, but none reported it, even those who used Ketcham's simple technique (Schramm et al., 1979; Panje et al., 1989; Freije et al., 1992; Morita et al., 1993). The risk of brain hernia- tion has been described by many authors (Johns et al., 1981; Stiernberg et al., 1987; Price et al., 1988; Roux et al., 1991; Freije et al., 1992). Complex and imag- inative reconstructions have been proposed. Edgerton and Snyder (1965) used a pedicled scalp flap rotated into the skull base; after 3 weeks the hair-bearing part of the flap was returned to its original site, leaving the deep layer of the flap on the dura; the tissue was then
skin-grafted. Westbury and Wilson (1975), Terz et al. (1980) and Ousterhout and Tessier (1981) used frontal skin flaps based on the temporal artery. Large frontal scars resulted with such reconstructions. Schaefer et al. (1986) described a galea-pericranial flap based on the superficial temporal and supraorbital arteries. Jackson et al. (1985) recommended a galea-pericra- nial flap simpler than that previously used by Schramm et al. (1979), which was pedicled anteriorly, others followed this type of reconstruction (Curioni et al., 1990; Snyderman et al., 1990; Shah et al., 1992). Schuller et al. (1984) and Schaefer et al. (1986) stressed the necessity of structural support (iliac bone or rib) of the pericranial or galea-pericranial flap as prophylaxis against brain herniation. Finally, Roux et al. (1991) described, with the same purpose, an augmentation of the skull base by a coral plate.
We also repaired cranial base defects by a pericra- nial flap and a methacrylate or calvarial bone plate in our first cases.
The purpose of this paper is to review the literature and to demonstrate our own experience of 168 anterior craniofacial resections in our attempt to determine valid conclusions on skull base reconstruc- tion.
PATIENTS AND METHODS
Between 1987 and 1997, 168 patients underwent an anterior craniofacial resection at the Istituto Nazio- nale per lo Studio e la Cura dei Tumori of Milan. Main patient characteristics and tumour distribution are summarized in Tables 1 and 2. The ethmoid sinus was always involved, and was the probable site of origin of the tumour in the majority of the patients. A total of 106 patients had tumour vegetations in the nasal cavity. The maxillary sinus was partially involved in 47 cases. The posterior wall of the maxillary sinus, the
228
Skull base reconstruction after anterior craniofacial resection 229
Table 1 - Anterior craniofacial resection: main patient characteristics
No. %
No. of patients 168 Sex
Male 116 69 Female 52 31
Age (years), mean 53.4, median 56.0, range 24~7.9
Any pretreatment No 90 53 Yes 78 47
Table 2 - Anterior craniofacial resection: main patient characteristics
pterygoid plate and the infratemporal fossa were involved in 14 patients. Three of those 14 cases had erosion of the greater wing of the sphenoid with invasion of the middle cranial fossa. In 4 patients, the tumour eroded the hard palate. The sphenoid sinus was involved in 16 cases. In 30 patients the tumour infiltrated the outer layer of the dura of the anterior fossa, and in 10 cases there were intradural neoplastic vegetations. In these cases we performed a resection of the dura. Three patients had frontal lobe infiltra- tion, requiring brain resection (Fig. 1). Eight patients had nasal or canthal skin infiltration. Erosion of the medial orbital wall was present in 6 cases. Twenty patients had anterior orbital involvement (Fig. 2) (in these cases the periorbita was resected, without requiring orbital clearance to achieve radical clear- ance. Twenty-two patients, however, presented with orbital apex involvement (Fig. 3): 19 of them under- went exenteration of the orbit.
In 6 cases we did not achieve macroscopically radical clearance and in 16 specimens the pathologist found tumour cells in the margins of the resection.
Surgical technique
The surgical technique has changed substantially since 1990. In the first 30 cases, the frontal craniotomy was wide and high above the frontal sinuses, which implied considerable retraction of the frontal lobes for anterior skull base resection. The cranial base was reconstructed with a pericranial flap and a methacrylate or calvarial bone plate (12 and 2
Fig. 1 - CT image of a malignant tumour involving the ethmoid, eroding the cribriform plate and infiltrating the frontal lobes.
Fig. 2 - CT image of a tumour invading the anterior orbit.
cases, respectively). The dural defect was repaired by a cadaveric dura patch.
The technique was subsequently simplified. Now a coronal skin and galeal incision is chosen which is asymmetric, with posterior deviation on one side, allowing the use of the temporal muscle to repair the orbit or the maxillary cavity and palate. Skin and galea are raised and a rectangular, anteriorly pedicled pericranial flap is prepared (Fig. 4). The frontal craniotomy measures 7 x 3 cm and is performed by an oscillating saw and chisel, without burr holes (Fig. 5). Its inferior edge is 1 cm above the orbital roofs, thus sparing supraorbital vessels and nerves.
After removal of the bone flap, the residual part of the posterior wall of the frontal sinuses is resected to widen the operative field. With minimal retraction of the frontal lobes, the crista galli is reached quickly and the anterior sleeves of the olfactory nerves are
230 Journal of Cranio-Maxillofacial Surgery
Fig. 3 - CT image of a tumour involving the orbital apex.
F i g . 4 - Skin and galea are raised and a rectangular anteriorly pedicled pericranial flap is prepared (arrows).
divided. Here the dura is opened which results in a CSF leak. In this way, the brain slackens, achieving the same purpose of a spinal catheter (which is not used). The decision to proceed by an extradural or intradural route depends on the intracranial exten- sion of the tumour. It is invariably possible to reach the sphenoid roof and expose it as for the anterior clinoid processes. In cases of extradural resections, small dural tears are sutured. If the dura is resected, the resultant defect is repaired with a free pericranial graft (Fig. 6). The closure of the dura must be meticulous and watertight. Lateral osteotomies of the skull base are tailored to the size of the neoplasm, whereas anterior osteotomy is always conducted through the floor of frontal sinus and the posterior osteotomy through the roof of the sphenoidal sinus. The medial third of the orbital roof is resected almost always, at least in one side, to allow removal of the lamina papyracea and the medial periorbita (Fig. 6).
In the second type of the operation, the skin incisions are tailored to tumour involvement of the maxillary sinus and orbit. When the turnout involves the maxillary sinus, the orbit and the infratemporal fossa an infratemporal approach is used (Janecka and Sekhar, 1993). This approach may be extended to the middle cranial fossa removing the greater sphenoidal wing. With appropriate osteotomies, the specimen is freed and removed with a 'push and pull' manoeuvre, before performing frozen sections of the margins.
Our current skull base reconstruction is straight- forward; Six small holes are made on the bone edges, two in the residual sphenoid roof and four laterally in the orbital roofs (Fig. 7). The pericranial flap is brought into the cranium and sutured using these holes (Figs 8 and 9). No bone or alloplastic material is used for augmentation. The residual part of the posterior wall of the frontal sinuses is removed from the craniotomy segment and is then fastened with sutures (Fig. 10). A drain is placed along the inferior craniotomy line to evacuate blood, secretions and residual intracranial air, then the galea and skin are closed appropriately. When an orbital clearance or a
F i g . 5 - Frontal craniotomy performed with an oscillating saw, without burr holes.
F i g . 6 - Repair of the dural defect with a pericranial graft after an intradural resection. The right orbital fat after resection of the lamina papyracea is evident (arrow).
Skull base reconstruction after anterior craniofacial resection 231
- w w - - ~
Fig. 7 - Schematic drawing of anterior skull base after the resection with the six holes.
Fig. 9 The pericranial flap is brought into the cranial defect and fixed with 4~6 sutures to close the cranial base defect.
B O
FI~
Fig. 8 Schematic drawing showing the pericranial flap between the inferior edge of the frontal craniotomy and the residual sphenoid roof.
total maxillectomy is performed, the temporal muscle (20 cases) or a free flap (4 cases) is used for coverage.
The nasal cavity is packed with fibrin mesh form, a double-balloon catheter and gauze. The usual oper- ating time for anterior craniofacial resection is approximately 3 hours.
R E S U L T S
Major complications are reported in Table 3. There were 8 postoperative deaths, 6 in the first 30 patients and 2 in the following 138. (Three cases of infective meningitis, 1 subarachnoid haemorrhage, 1 extradur- al haematoma, 1 haemorrhage in the brain stem, and 1 myocardial infarction. The eighth patient, who was
Fig. 10 The craniotomy bone is replaced and sutured.
Table 3 - Anterior craniofacial resections: major complications
Postoperative death 8 Tension pneumocephalus 12 CSF leak 16 Delayed recovery of neurologic status 3 Gastric haemorrhage 2 Colonic perforation 1 Diabetes insipidus 2 Wound infection 4 Necrosis of the craniotomy bone 1
operated on for a tumour compressing the frontal lobe, never awoke from coma and died 18 days post- operatively). It is noteworthy that there was a marked difference in mortality between the two parts of the series, and that the infectious complications all occurred in the first part. All the CSF leaks recovered spontaneously. Segmentation of the craniotomized bone occurred in only 1 case.
A sagittal MR image and a photograph of a patient 5years after an anterior craniofacial resection are shown in Figs 11 and 12.
Overall and disease-free survival of our patients with appropriate follow-up has already been pub- lished (Cant~ et al. 1999).
232 Journal of Cranio-Maxillofacial Surgery
Other considerations are secondary and unnecessary reconstruction may lead to dangerous complications.
There are four reasons regularly quoted for complex skull base reconstructions:
Fig. 11 - A sagittal MR image of a patient after an anterior skull base resection.
Fig. 12 Photograph of a patient 5 years after an anterior craniofacial resection.
DISCUSSION
The authors who performed anterior craniofacial resection were aware violating a dogma of neurosur- gery namely complete asepsis of the operative field. Such awareness of this basic rule motivated them to try to separate the intracranial and extracranial spaces as much as possible.
Fre~/e et al. (1992) stated that: Although craniofacial resection is now an accepted
treatment, no universally accepted repair method has yet emerged. Different repairs are reported in various sized series, each repair being chosen for individual reasons.
Our own experience suggests that sophisticated reconstructions are not necessary. The crucially important element we are confronted within cranio- facial resection is the dura. It is the true barrier which may be violated but must be reconstructed perfectly.
1. To support the brain and avoid herniation. In a standard anterior craniofacial resection for an ethmoidal tumour, the skull base defect may measure between 3 and 5 cm. Following dural closure, CSF leakage ceases and the brain again occupies the available space, the dura becomes adapted to the orbital roofs and prevents brain herniation. We believe that the brain needs no other support than a thorough dural repair. Freije et al. (1992) also end their review by stating that brain herniation does not seem to be a problem.
2. To avoid intracranial sepsis. Although a herm- etic seal at the skull base is not usually feasi- ble, we believe that multilayered reconstruction may promote formation of abscesses that are difficult to drain. Moreover, augmentation with alloplastic material or non-vascularized bone may also be a source of infection. Avoidance requires good antibiotic treatment, continuous and abundant intraoperative irrigation of the intracranial field, disinfection of the nasal area with appropriate solutions and, of course, meticulous closure of the dura. Such patients should also be barrier nursed in separate rooms. Since adopting such precautions, we have had only one case of meningitis, which quickly recovered with a suitable antibiotic therapy.
3. To prevent CSF leak. We also disagree on this point with other authors. We feel that it is the meticulous dural seal that avoids a CSF leak, not multilayered skull base reconstruction which only serves to delay its appearance by which time the antibiotics may have been stopped. In our experience, CSF leaks occurred within 2-4 days after surgery, and all recovered spontaneously.
4. To avoid pneumocephalus. This complication has been reported by most authors, including those using simple (Ketcham et al,, 1966; Fre~/e et al., 1992) or many layered reconstructions (Shah et al., 1992). Kraus et al. (1994) aban- doned reconstructions with the pericranial flap for galea pericranial reconstruction, with a decrease in complications, including pneumo- cephalus. However, they reported 66 pericranial flap cases and only 6 galea-pericranium cases. The use of a pericranial pedicled flap, did not always preclude this complication (Price et al., 1988; Arbit et al., 1991; Riehtsmeier et al., 1992; Wanamaker et al., 1995; Deschler et al., 1996). A pressure gradient is necessary for air access into the cranial cavity. Increased sinonasal tract air pressure may occur when a patient blows his nose, or air may enter during attempts to remove nasal crusts. Other causes include coughing, sneezing and straining. A valve mechanism may
Skull base reconstruction after anterior craniofacial resection 233
operate to trap in t racrania l air under pressure. P rompt diagnosis is impor t an t to allow drainage with a t ranscutaneous catheter (Arbit et al., 1991; Wanarnaker et al., 1995). Our patients with pneumocepha lus recovered after such a t reatment .
Some authors have suggested a prophylact ic t racheostomy. We performed this in 10 patients, but even so one pa t ient developed pneumocephalus . We consequent ly no longer use t racheostomy, which is also u n p o p u l a r with patients.
After what we have poin ted out, one might conclude that, after an anter ior craniofacial resection, no skull base recons t ruc t ion is necessary to avoid bra in hernia t ion, in t racrania l infections, CSF leakage and pneumocephalus . However, in agreement with m a n y authors (Johns et al., 1981; Stiernberg et al., 1987; Price et al., 1988; Sundaresan and Shah, 1988; Blacklock et al., 1989), we believe that the pericranial flap should be used. It is no t necessary to suppor t the bra in to avoid hern ia t ion as it is the best tissue to foster growth of a new mucosa on the vaul t of the large cavity result ing from resection. F r o m this po in t of view, according to our experience, it is better than Ke tcham ' s split-thickness skin graft on the dura. It is also useless to place the graft on the inferior face of the pericranial or ga lea-per icrania l flap, as proposed by other authors (Van Tuyl and Gussack, 1991; Shah et al., 1992). In our pat ients a new mucosa covered the nasal face of the pericranial flap within one month .
C O N C L U S I O N S
Ante r io r skull base resection is a sufficiently compli- cated opera t ion per se and requires simplification. Crania l base reconst ruct ion therefore should be simplified and in our experience, the pedicled pericranial flap is the best tissue, since it is easy to prepare, is thin, adaptable and viable.
A n y augmen ta t ion with bone or alloplastic mate- rials is unnecessary.
Only in resections extending to the orbit, maxi l lary sinus, in f ra tempora l or middle cranial fossa is it necessary to fill the large cavity with the tempora l muscle or a free flap.
Acknowledgements
This work was partially supported by AIRC (Associazione Italiana per la Ricerca sul Cancro). The authors thank B. Johnston for editing the manuscript.
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Giulio Cantli Istituto Nazionale Tumori Via Venezian 1 20133 Milano Italy
