Unfavourable results in skull base surgery.

Treatment of skull base tumors involves multiple specialities. The lesions are usually advanced and the treatment is often associated with unfavorable results, which may be functional and/or aesthetic. Here we have done an analysis for the complications and unfavorable results of 546 cases treated surgically by a single craniofacial surgeon over a period of 14 years. The major morbidity ranges from death to permanent impairment of vital organ functions (brain, eye, nose), infections, tissue losses, flap failures, treatment associated complications, psychosocial issues, and aesthesis besides others. This article is aimed at bringing forth these unfavorable results and how to avoid them.

INTRODUCTION

Skull base surgery is a subspecialty at the interface of various surgical specialties which include craniofacial surgery, neurosurgery, ENT surgery, head and neck surgery, maxillofacial surgery, reconstructive surgery and which works in tandem with the other branches including medical oncology, radiation therapy, ophthalmology and, prosthetics. The anatomy of this area is complex, the surgery is difficult, pathology is varied, treatment needs intensive perioperative care and also needs coordination with various subspecialties for complete care, thus making this a very challenging area to treat. Surgery is generally the mainstay of treatment in this area. Surgical treatment of any major tumor in this area would leave a major or minor deficit, which may or may not be possible to correct with surgery at the same time or later. The treatment has evolved from being with only radiation to surgery with complete removal, use of local tissues and then free flaps for reconstruction and now to endoscopic approach. All procedures have various complications and unfavorable results.[1-15]

COMPLICATIONS

Complications in skull base surgery are related to major multispecialty surgery. Also there are specific problems and complications related to disease subsets and procedures in this area which is at the interface of previously labelled “no man's land.” Certain outcomes are unavoidable but major complications are by and large avoidable.[4-79111214] Doing these procedures in a multidisciplinary team and at a regular frequency of at least once in 2 weeks can help in decreasing the rate of unfavorable results and complications.

The approach to all these tumors has been that of a multidisciplinary team. We present our experiences of those cases wherein surgery has always been a part of the treatment. There have been cases which have been treated successfully or otherwise in which surgery has not been done and these are not included. Our experience comes from dealing with 546 cases of skull base tumors over a period of 14 years from 1999 to 2012. We present an overview of complications and unfavorable results that we have come across, how we have tried to prevent these, deal with those that have already occurred, also mentioning the limitations in managing these.

DEATH

These are long procedures and can involve major work with the intracranial lesion or a large shift of tissues from vital area. Death is unacceptable and procedures which would involve removal of large areas and have a high chance of peroperative mortality are always avoided. These include lesions that involve the internal carotid artery in the infratemporal fossa or in the base of the middle fossa or the paracavernous regions. Also lesions that would involve a large part of the brain are avoided.[7911121415]

Death can be due to excessive bleed and infections. Excessive intracranial haemorrhage can be due to bleeding from the intracranial sinuses or carotids. These can be anticipated and are treated by the neurosurgeon peroperative. It requires a very close monitoring of the various parameters, especially in prolonged surgeries.

We have not had any peroperative death. There have been three deaths in the perioperative periods. Two of these have been due to myocardial infarction on the 5th and the 12th POD, respectively. The patients were 63 and 72 years old, respectively. The third patient died due to meningitis secondary to CSF leak. This patient had a post radiotherapy salvage surgery for SCC of the ethmoid, orbit and maxilla.

INFECTION

Infection may be intracranial (meningitis), or of the cranial bones or soft tissues. The basic tenet of reconstruction remains as to how to prevent infection. It is mandatory to have a good vascular barrier of the cranial base which can avoid any communication of the aero digestive tract with the intracranial contents.[16] For this purpose local, regional or free flaps are used as the case may be. Our mainstay of reconstructions has been the galeofrontalis pericranial flap which is used to seal the skull base in the midline and the paramedian area[16-21] [Figure 1]. Temporalis muscle has also been used very widely by us in cases wherever possible, specifically in the anterolateral skull base area [Figure 2]. In some cases we have used free tissue transfer (free flaps) for reconstruction of the skull base to avoid the CSF leaks. In one patient we have used a skin graft to cover the dura in the anterior skull base. Fibrin glue, fascia lata and fat have been used endoscopically in small tumors of the cribriform area.

Figure 1

Galeofrontalis myofascial flap being positioned into the anterior skull base

Figure 2

Galeofrontalis flap and Temporalis flap have been raised for use in anterior and anterolateral skull base

We have had CSF leaks leading to meningitis in 2 patients. These 2 were among our first 100 patients. Both the cases were post radiation and in both of them galeofrontalis flap had not been used. One of the patients died with fulminant infection and the other required an open surgery and galeal flap. Thereafter, we have not seen any case with meningitis. In the initial 144 patients a lumbar CSF drain was used in all patients for 2-3 days. Thereafter, we have not used this routinely.

Hematoma can also lead to infection and so it is mandatory that while the wounds are being closed, haemostasis is achieved.

Osteomyelitis requires debridement of the bone and may involve removal of the whole frontal bone, segments of orbit or the bone grafts that have been placed.[15] We find that wherever we have used the galeofrontalis flap there has been a high incidence of skin changes if the patient has been radiated postoperative [Figure 3]. We have had frontal bone osteoradionecrosis in 12 patients. These have been treated with debridement and advancement of the scalp flap. None of the patients have received secondary reconstruction of the bone defects.

Figure 3

Post radiation osteoradionecrosis of the frontal bone in a patient where galeofrontalis flap has been used

Minor infections are treated with antibiotics. We have been using injectable antibiotics for 7 days. The patients are restricted to supine position in bed for first 3 days and then are gradually allowed to sit up and made ambulatory in 7 days. The average stay in hospital is 14 days after surgery.

HEMORRHAGE

Uncontrolled bleeding and hematoma can lead to death, infection, and intracranial complications due to brain shift.

We have found that the mean operating time has decreased from about 8 h for the first 20 cases to about 4 h to the last 20 cases. Along with this there has been a decrease in the mean operative blood loss. Initially, we were transfusing 4 units of packed red blood cells (PRBC) which has come down to 1.4 in the last 20 open cases.

With endoscopic resections, the rate of transfusion and the operating time has gone up and we attribute this to the learning curve.

The main measures to decrease bleeding are hypotensive anaesthesia, use of a good coagulation and cutting tool, use of tumescence at the time of incision, routine attention to bleeding, and haemostasis during surgery.

Central nervous system complications

These are due to direct injury to the brain, prolonged brain retraction, meningitis, intradural, and extradural hematoma or infections.

Brain damage

Irrelevant talking secondary to retraction and brain oedema has been transient and seen in a few cases but we have not come across any permanent behavioral anomaly in any patient. Permanent damage may also result from major brain involvement.[2223]

Cerebro-spinal fluid leak

It has not been possible to monitor patients for a minor transient Cerebro-spinal fluid (CSF) leak through the skull base. We believe there would be a transient leak for some time which would seal on its own in many cases. There have been two patients with meningitis and we attribute this to the improper closure of the basal defect. One patient has had an open closure of the defect with a galeal pericranial flap as a secondary procedure. The other patient succumbed to the infection.

The galeofrontalis myofascial flap has been our workhorse wherever available. Its use has completely stopped the incidence of further central defect leaks.[1519] Excessive use of this flap has also led to an increase in the incidence of radiation damage to the bone and skin in the frontal area which takes about 9-12 months to settle down or may require the bone to be debrided as mentioned earlier.[3]

Nerve injuries

Olfactory nerve injuries and anosmia are anticipated in all lesions that involve the anterior cranial base which are treated by an open approach. This happens in all ethmoidal tumors and those which need stripping of the dura from the cribriform plate [Figure 4].

Figure 4

Ethmoidal tumour: Lesion extending to the anterior clinoid process

Blindness has been reported with tumors that are close to the optic nerve. Damage could also be due to radiation injury to the cornea or the optic nerve.[391012] Of the post-radiation patients that have come for regular follow-up, we had 17 patients with radiation keratitis leading to blindness [Figure 5]. In addition, we have seen blindness (complete visual loss) in the affected eye in 12 cases.

Figure 5

Radiation keratitis, vertical dystopia, and enophthalmos in a patient operated for fibrosarcoma in the sphenoid wing

Sensory nerve deficiency related to the supraorbital and supratochlear nerve which may be injured at the time of lifting the coronal flap is unacceptable. So also is the injury to branches of the facial nerve while lifting the coronal flap. We have not encountered these problems unless the tumor is involving the areas from where the nerve passes.

EYE COMPLICATIONS

Blindness

This has been discussed before and is related to radiation keratitis and to radiation optic neuritis. Radiation keratitis can be prevented with proper planning; however, it is not possible to avoid this in all cases.

Vertical dystopia

Patients who have had malignant tumors and where the orbital floor has been removed during surgery are at a high risk of having vertical dystopia [Figure 5]. Immediate reconstruction using free bone grafts is not recommended as a majority of these cases are bound to receive post-operative radiation therapy. Although widely used for trauma, we have no experience of immediate reconstruction of floor with titanium mesh or non-vascular bone grafts in malignant cases. In cases where the microvascular rectus abdominis is used for reconstruction of the defect, the dystopia is still persistent. Temporalis muscle can be used to reconstruct the floor of the orbit (it is used as a hammock). The dystopia can be significantly reduced in some patients using this muscle, but perhaps not completely eliminated.

Diplopia

This is found in patients who have significant dystopia or in whom more than two extraocular muscles are removed. As a protocol, in cases where we have to remove more than two muscles in one eye, we explain to the patient to go in for exenteration of the eyeball as the rehabilitation for diplopia is extremely difficult in these cases. Also these patients are at a very high risk of radiation injury and blindness postoperative.

Canthal drift

The patients needing excision of the medial canthal area and the bone around it develop a canthal drift. This can be minimized to some extent by procedures which bring the canthus together. This is not always possible in all cases and reconstruction is dependent on an individual case defect.

Nasolacrimal duct block and epiphora

This is prevented by using the stents that pass from the sac into the nose and leaving this in situ for a period of 6-12 weeks, although we may do this procedure secondarily as well.

Ectropion and entropion

These occur due to the soft tissue and or bone loss in the floor or the roof.

TISSUE LOSS

Bone loss

Bone loss is due to removal of the disease and the affected bone. This involves the maxilla, orbit, frontal bone, and temporal bone according to the pathology. We have not reconstructed bone defects in the maxilla or the skull base primarily using bone in any malignant tumor. Delayed reconstruction has been done for maxilla and nasal bones.

As discussed before, patients have had necrosis of the frontal bones which has been treated with debridement and flap. Secondary reconstruction has not been done in any of these patients.

Soft tissue loss

Concomitant with the bone loss there has been varying amounts of soft tissue loss depending on the extent of the disease and its excision. Reconstruction is done using local tissues if feasible, the mainstay being temporalis muscle flap, or using microvascular free flaps, in which the rectus abdominis has been the workhorse [Figures 6 and 7].

Figure 6

SCC of the right maxilla, orbit and ethmoids after resection

Figure 7

SCC of the right maxilla, orbit and ethmoids after resection and VRAM free flap

Free flaps give a better cosmesis than the local flaps, but require a microvascular facility.

Teeth loss

This happens in patients where part of maxilla is removed. This can be replaced with dentures and prosthesis which may be osteointegrated to the reconstructed bone.

Flap failures

Free flaps have been instrumental in increasing the limits of resection in skull base surgery.[24-30] In our series we have not seen any complete failures with the local flaps (temporalis or galeofrontalis). In some cases with the temporalis, there might have been marginal loss resulting in junctional fistulae in the palatal area or the medial canthal area. Of the 64 free flaps we have had 2 flap failures, one in a critical area in the central skull base, where we had to do a skin graft for salvage [Figure 8].

Figure 8

Free VRAM flap loss and salvage with a galeofrontalis flap and STG

COMPLICATIONS SECONDARY TO ENDOSCOPIC SURGERY

Endoscopic skull base surgery has been increasing in the last decade. Initially, this was limited to the central lesions and in early cases only. Now the limits of endonasal skull base surgery have expanded.

There are unfavorable results which are inherent to the procedure and the learning curve. We have used endoscopic surgery in only selected cases (14) which have either benign or early malignant lesions which need a limited resection.

Endoscopic procedures may have to be turned to open surgeries in cases where the resection is not completely possible with the endoscope[31] or in case there is a major bleed which cannot be controlled.

Incomplete removal may be seen after the endoscopic surgery if one does not have access to image guidance.

COMPLEX PROBLEMS

Major tissue loss

These are complex defects in the midface and the skull base area and are difficult to reconstruct.[24] They always leave behind an aesthetic and variable functional defect. The aim is to reconstruct the function and then minimize the aesthetic deformity. In major bone and soft tissue loss which involves the midface this may not be possible especially when the patient is in for concomitant therapy as well.[242829] The defect can be filled up with a soft tissue flap only with a plan to reconstruct at a later date. Many of these patients have poor long term prognosis of the disease and delayed reconstruction has very rarely been requested in our experience.

Radiation issues

Immediate injury secondary to radiation involves the radionecrosis of the bone flaps as mentioned before. Also injury to the eye is a problem. Delayed radiation effects are especially seen in growing children. We do not have enough long term follow-up of the children whom we have treated with surgery and radiation both.

Recurrence and residual disease

Improper analysis and diagnosis may lead to a resection which is not complete (R0). This can lead to a residual disease which is not amenable to further surgery in majority of the cases. The best chance that you have in operating these patients is at the time of primary surgery and also if prior radiation or chemotherapy have not been given. Preradiated lesions have led to more incidence of complication, inadequate and incomplete resections and a poorer survival.

OTHER PROBLEMS

There are various quality of life issues that need to be looked into when treating and analyzing the outcomes of these patients.[31-34]

GROWTH ISSUES SECONDARY TO RADIATON AND SURGERY

This happens in patients who have been radiated in the skull base area and the maxilla. These are very difficult and complex to correct and we have no experience in treating such cases.

Psychosocial

There is a major disfigurement in many of these surgeries which involve the removal of the eye and the maxilla. There may be loss of teeth also. Some of the defects are not possible to reconstruct to give an aesthetically pleasing result in the primary surgery. These patients have a psychological effect and need counseling. Many of these patients become recluse and decrease their social contacts. Some of them stop working and may not be accepted even by the immediate family. These issues need to be addressed by a psychologist and a social worker.

Non reconstructable issues

We have seen some procedures with very major excisions where reconstruction has been a problem. Special to these is a group of patients where we have done a bilateral maxillectomy with a unilateral orbit exenteration. This gives a cruzonoid look to the patient. There is no support between the skull base and the tongue. Soft tissue flaps are inadequate and bone reconstruction has not been possible. The patient has an acceptable functional result whereby they are able to eat and speak but the aesthetic acceptance has been a major issue [Figures 9 and 10].

Figure 9

Operated adenoid cystic carcinoma of bilateral maxilla, nasal cavity and ethmoids excised and reconstructed with bilateral temporalis flaps. Patient has adequate speech but with a cruzonoid look

Figure 10

Operated adenoid cystic carcinoma of bilateral maxilla, nasal cavity and ethmoids excised and reconstructed with bilateral temporalis flaps. Patient has adequate speech but with a cruzonoid look

Palliative issues

Some of these tumors present very late. Definite treatment is not possible in these patients and they are referred for palliative care.[34-40] Pain is a major issue in non-operable tumors. Some tumors have come back more aggressively after excision. Special to these are malignant melanoma. These have a very poor outcome. The 4 patients with melanoma that we have operated in the paranasal sinus and skull base, have all recurred within 6 months. All have had very major involvement of the midface and skull base after excision. As a protocol now, we have stopped operating on the mucosal melanoma of the midface and the skull base.

Also we have seen very gross recurrence in patients with rodent ulcer (presented after 8 years of surgery with a negative margin). Some of these are not excisable further [Figure 11]. The limits of excision are in involvement of both the optic nerves, involvement of the brain parenchyma, involvement of ICA and distant metastasis. These patients are subjected to palliative care (chemotherapy, radiation, or pain care)

Figure 11

Advanced recurrent BCC of the midface and anterior skull base for palliation

CONCLUSIONS

This is a complex area to treat. There are many limitations of the surgery. There are limitations to the procedures that can be done and what can be treated. Various complications are fatal and can be avoided with proper care. The priority should primarily be to have a safe outcome and then to retain functionality and have an acceptable aesthetic result.