Complications: Avoidance and Management

Introduction

Performing the transsphenoidal procedure requires the neurosurgeon to master a unique set of surgical techniques. While the ultimate goal rests with the hypophysis and neuraxis, the surgical approach mandates an understanding of anatomy outside the typical neurosurgical realm. Thus the potential for complication involves not only the neurological, but dental and nasal, as well.

The transsphenoidal approach was originally abandoned by Harvey Cushing’s for unacceptable mortality rates. Despite this, Oscar Hirsch and Norman Dott continued to employ the transsphenoidal route. The development of modern antibiotics, exogenous steroid replacement, and the operating microscope allowed later surgeons such as Gerard Guiot and Jules Hardy to reinvigorate the neurosurgical field with the procedure as operative mortality was lowered and pituitary function was maintained in the setting of microadenomas. As a result, the transsphenoidal procedure has become the cornerstone for the management of pituitary adenomas and related sellar lesions in modern neurosurgical practice.

As with all neurosurgical procedures, the potential complications with the procedure are wide and varied. The more common complications are generally well managed and will probably be encountered at a relatively constant rate by neurosurgeons treating pituitary lesions. But as with many neurosurgical procedures, the uncommon complications are potentially devastating and every attempt must be made to prevent such outcomes.

Nasal Complications

A clear understanding of the anatomical relationships of the midfacial region to the skull base is the best means to minimize complications related to sphenoid surgery. The midfacial region comprises the nose and its contents, the paranasal sinuses, and the nasopharynx. It is important to also understand the intricate anatomy of the clivus, the anterior skull base, and the complex nature of the neurovascular structures passing from the upper neck to the intracranial compartment.

The nasal septum consists of two layers of septal mucosa covering a scaffold of cartilage and bone. Any sublabial or transseptal approach will place these structures at risk of injury. The lateral walls of the nose comprise three turbinates shielding the openings of the paranasal sinuses and the nasofrontal duct. Further, the paranasal sinuses are located in intimate relationship to the orbit and anterior skull base. During an endoscopic or transnasal approach, these structures are placed at risk if the surgeon is unfamiliar with these structures. The range of potential complications can therefore range from minor to life threatening.

Intranasal Complications

Epistaxis is the primary early complication of any endonasal surgery. The severity may vary from relatively benign to life threatening depending on the intensity of the blood loss and the patient’s hemodynamic status. The nasal mucosas and the turbinates are very vascular structures and postoperative bleeding has been reported with a frequency of 3.4% to 8.6% in various studies.

Minor bleeding is a very common finding in transsphenoidal surgery and usually originates from a mucosal surface. Adequate preoperative vasoconstriction with local decongestants and lidocaine with epinephrine aids in preventing bleeding complications. Intraoperative bleeding is controlled with intranasal cautery or with 10 minutes of Afrin or cocaine-soaked cottonoid packing. Occasionally, nasal packing coated with Bactroban is necessary. Systemic antibiotics should be used as well if packing is necessary because several cases of toxic shock syndrome have been linked to the use of nasal packing.

Patients with an active infection, extensive polyposis, and possible bleeding diathesis are at increased risk for bleeding complications and should be identified preoperatively. Surgery should be delayed in patients with active infection for adequate treatment with antibiotics and nasal steroid sprays. Patients with extensive polyposis should undergo a course of oral steroids for 5 to 7 days preoperatively to decrease intraoperative bleeding. Patients with a history suggestive of bleeding abnormalities should undergo a prothrombin time (PT), activated partial thromboplastin time (aPTT), bleeding time, and platelet count. Any abnormalities warrant evaluation by a hematologist before surgery.

Severe hemorrhage is rare and usually occurs in patients with underlying bleeding disorders, a history of multiple sinus surgeries, or extensive polyposis. Bleeding may occur from damage to any of several arteries. The anterior ethmoid artery may be injured when approaching the anterosuperior region of the anterior ethmoid air cells. Often the lacerated artery can be identified and cauterized at the time of injury. However, the artery may retract into the orbit, leading to hematoma. The posterior ethmoidal artery is most commonly injured during the exposure of the posterior ethmoidal air cells or sphenoid sinus. Cautery is difficult in this region, and intranasal packing is usually required to stop a hemorrhage.

During the bone removal at the entrance to the sphenoid sinus, the surgeon can inadvertently injure the sphenopalatine artery at the inferolateral aspect of the anterior sphenoid sinus. This usually causes notable arterial bleeding. When identified, it may require bipolar coagulation (often necessitating angled tips) to halt the bleeding. Packing within the sphenoid sinus may also offer a means to control the bleeding if direct coagulation is unsuccessful. While some postoperative nasal bleeding is expected, if a patient develops substantial epistaxis during the postoperative period, especially if it appears arterial in origin, the patient likely requires evaluation for carotid artery injury with an arteriogram. Assuming none is found, the likely source of bleeding is the sphenopalatine artery, which can usually be easily and effectively treated with a transarterial embolization ( Figure 16-1 ).

Postoperative sinusitis ranges in its reported incidence. Neurosurgical reports have typically demonstrated rather low rates of symptomatic sinus complications (1.0 to 1.2%). Otolaryngology reports, however, suggest sinusitis may be much more common after transsphenoidal surgery, with rates ranging up to 15%.

Sinusitis may not be completely preventable, but measures can be taken to minimize the chance for its occurrence. This complication occurs if there is disruption of mucociliary flow of mucus out of the sinus cavities either from obstruction or mucosal injury leading to scarring. As a means of preventing sinusitis in the sphenoid sinus, some authorities advocate stripping of the mucosa before proceeding with the repair of the skull base defect. Once the mucosa has been meticulously removed, the surgeon may then proceed with the repair and packing of the sinus cavity with either autologous and/or alloplastic materials.

Additionally, the placement of nasal retractors usually requires and/or creates lateral displacement of the middle turbinates. This displacement will lead to the compromise of the proper drainage of the frontal, ethmoid, and maxillary sinus cavities dependent on the proper function of the hiatus semilunaris of the lateral nasal wall. Disruption of the mucosa covering the turbinates, lateral nasal wall, and/or septum may lead to the formation of postoperative synechiae, which will also impact on the proper drainage of the sinuses. To help prevent this problem, the middle turbinates are to be gently relocated to their normal anatomic position to allow for proper sinus drainage. In certain situations, it will also be important to support the turbinates in their proper position with dressings and/or alloplastic materials temporarily for a few days postoperatively to prevent lateralization.

When sinusitis is diagnosed, it typically responds to treatment with appropriate antibiotic coverage for 1 to 2 weeks.

Rarely, a patient can present postoperatively with a sphenoid sinus abscess. Though rare, an abscess requires aggressive treatment, possibly including operative débridement or drainage and intravenous antibiotics. Otolaryngology consultation would obviously be recommended.

Mucoceles arise from outflow obstruction and collection of exudates within the sphenoid sinus. These masses can eventually enlarge and erode bony structures causing potential neurological compromise. However, they are usually avoided by generous sphenoid sinus mucosal exenteration. When present, they are usually treated by either drainage or cyst wall resection.

Persistent obstruction after resolution of postoperative edema may be caused by an iatrogenic or traumatic deviation of the septum at the time of surgery. Traumatic injury to the septum at the time of the insertion of the nasal speculum during a transseptal approach may lead to a continuing deviation or disarticulation of the septal cartilage, resulting in asymmetric airflow. Any disruption of two opposing mucosal surfaces can lead to scar band and synechiae formation. Careful attention to surgical technique, especially when manipulating the middle turbinate, can decrease the incidence of synechiae formation. The placement of a spacer between the lateral nasal wall and the middle turbinate at the completion of the procedure can decrease scar formation. Telfa, Merocel, Gelfilm, and silastic have been used with success. Administration of intranasal steroids at the completion of the procedure has been recommended in the past to decrease synechiae formation, but recent work has shown little benefit. Most synechiae can be lysed under general anesthesia during a later elective surgical procedure. Occasionally, revision surgery is necessary. Synechiae are resolved by lysis and separation of the mucosal surfaces by placement of silastic splints.

One of the more common and most frustrating complications for both the patient and surgeon is a septal perforation. While not life threatening, septal perforations often cause the patient a number of aggravating symptoms including nasal crusting, pain, bleeding, and/or obstruction. Ciric noted a 4% frequency in his personal series of 638 cases. Care in handling the septal mucosa is the best deterrent for avoidance of such a complication. Typically, perforations are more likely to occur when employing an endonasal submucosal or sublabial approach rather than direct transnasal approaches through the nares. As the mucoperichondrium is elevated, tearing of the tissues can occur either unilaterally or bilaterally. The risk for a permanent septal perforation increases when bilateral tears overlap in the absence of proper intervening cartilage or bony support ( Figure 16-2 ). If a unilateral tear is encountered, it is essential to protect the contralateral mucosal flap, so that the defect is covered, preventing this complication. If a tear is encountered, the mucosa can sometimes be sutured with a direct closure or an indirect quilting stitch to minimize the perforation or to reapproximate the intact mucosal edges. The use of postoperative splinting of the septum remains controversial in the management of septal tear repair. If a perforation becomes symptomatic postoperatively, it is recommended that it be evaluated by an otolaryngologist, as the repair for these conditions is often difficult.

Fractures to the surrounding osseous anatomy can cause a variety of complications ranging from bothersome to devastating. Aggressive opening of a properly placed speculum can create a hard palate fracture or diastasis. Kern and Laws encountered a diastasis in 2 of 193 transsphenoidal cases. This usually manifests as malocclusion and may require reparative surgery. More concerning, however, is when the tips of the speculum are erroneously placed within the sphenoid sinus. As the opening pressure is applied to the lateral walls of the sphenoid ostia, the surgeon risks fracturing the cribriform plate. This can occur with a cerebrospinal fluid (CSF) leak into the sphenoid sinus, thus mandating sinus packing with possible lumbar drainage. Opening of a speculum within the sphenoid sinus also risks the rare but disastrous chance of fracturing the optic canal and causing optic nerve injury.

The blades to the speculum should never be placed within the sphenoid sinus. Additionally, the speculum should not be used as a dissecting tool whereupon forceful opening of the jaws is undertaken to enlarge the operative field. Rather, the dissection of bony structures needs to be performed under direct vision and the speculum opened to minimal or moderate resistance.

A number of cosmetic complications can occur from improper dissection techniques intranasally. The most common is a saddle nose deformity, which usually occurs after an overly aggressive removal of septal cartilage ( Figure 16-3 ). As a rule, the cartilaginous septum can be separated from its inferior and posterior bony attachments, but should not be removed. Forcing open the speculum can also lead to injury to the upper maxillary rami and consequently cosmetic disturbances to the lateral margins of the nose.

Aggressive superior dissection of the nasal mucosa can avulse the olfactory nerves and leave patients with postoperative anosmia. Again, this complication, though uncommon, is most often encountered in endonasal, submucosal approaches. Attention to the direction of dissection by using anatomical landmarks and radiographic imaging is the best avoidance as recovery is poor once the injury has occurred. Anosmia can also result from congestion of both septal mucosal flaps or accumulation of bloody serous fluid under the mucoperichondrial flaps. This may obstruct airflow to the olfactory region, producing the symptoms. Careful and thorough reapproximation of the septal flaps with a quilting suture decreases the dead space under the septal flaps, and encouraging head elevation postoperatively should alleviate some of the postsurgical congestion.

A septal hematoma is a rare complication caused by the pooling of blood between the cartilage and mucoperichondrium ( Figure 16-4 ). Since the cartilage is separated from its blood supply originating from the mucoperichondrium, avascular necrosis may occur. The cartilage can be resorbed leading to a septal perforation and potential loss of nasal dorsal support. Patients have intense pain, swelling, hematoma of the upper lip and philtrum area, and complete nasal airway obstruction. Expeditious evaluation is essential to prevent eventual nasal dorsal deformity and the formation of a septal abscess. Management consists of drainage through a mucoperichondrial incision. Needle drainage may be inadequate. After drainage, packing is placed in the nose and oral antibiotics are administered. Both nasal passages require packing to prevent shifting of the postsurgical septum. Insertion of septal splints is also useful in the postoperative management of septal hematoma, whether traumatic or postoperative.

Dental Complications

In cases in which the sublabial incision is employed, the surgeon must be cognizant of the potential injury to the vascular and nerve supply to the upper dentition. The anterior superior alveolar nerve and artery (branches of the infraorbital nerve and artery, respectively) course across the anterior wall of the maxillary sinus to the anterior alveolar process. There, branches enter the apical foramina of the incisors and canines. Anatomic and clinical reviews have demonstrated that bony resection within 3 mm or closer to the nasal floor carries a very high chance of injuring the arterial or nervous supply to dentition. This can result in numbness to the upper lip and teeth, tooth discoloration, or tooth loss. This is particularly common in patients with “vertical maxillary deficiency” in which the overall maxillary height is reduced. The distance from the nasal floor to the tooth apex is typically 9 to 12 mm in males and 6 to 10 mm in females, thus allowing for some bony resection. Injury to these neurovascular structures can also occur from electrocautery and improperly placed incisions. It is important, therefore, to make the incision in a sublabial approach at least 1 cm from the gingival margin and to use primarily sharp dissection with only occasional low current bipolar electrocautery. Avoidance of dental complications also requires the avoidance of an overly aggressive ostectomy of the piriform rim during sublabial transsphenoidal approaches. Obviously, the use of endonasal and transnasal approaches prevents this complication altogether.

Intraorbital Complications

Blindness secondary to anterior approaches to the sphenoid sinus can occur from two causes. The first cause is a rapidly expanding intraorbital hematoma, usually secondary to damage to the anterior ethmoid artery from an endoscopic approach. The anterior ethmoid artery runs along the superior portion of the medial orbital wall between the superior oblique and medial rectus muscles. If the artery is damaged, it can retract into the orbit, leading to a rapidly expanding retrobulbar hematoma. Increased orbital pressure causes a compromise of the vascular supply to the optic nerve. If not recognized and corrected rapidly, blindness can result. Additionally, an orbital hematoma can occur secondary to damage to the orbital veins lining the lamina papyracea. Hematoma accumulation is much slower, and proptosis and pupillary changes are much less common.

The second cause of blindness is damage to the optic nerve itself, which is very rare. Injuries usually occur from poor intraoperative visualization or inadequate knowledge of the optic nerve anatomy. The optic nerve is especially vulnerable to injury in several anatomic sites. The optic nerve courses in the superior lateral aspect of the sphenoid sinus. In some individuals, the bone overlying the nerve may be thin or even dehiscent. When available, preoperative CT scanning frequently reveals this finding. The most posterior and lateral posterior ethmoid cells (Onodi cells) are separated from the optic nerve by a thin layer of bone only, and damage to the nerve can also occur here.

Prevention of permanent vision loss begins before surgery with careful preoperative screening to identify patients with risk factors for orbital injury (prior nasal and sinus surgery, history of bleeding problems). A thorough review of the preoperative images enables identification of anatomic variations that may predispose to injury.

Intraoperatively, during endoscopic approaches, keeping the patient’s eyes uncovered at all times is very important. An assistant may be assigned to monitor the eye for any early signs of injury. One means to assess a breach into the orbit is to have an assistant palpate the eye as the surgeon is observing the region of the lamina papyracea endoscopically for its location as it moves back and forth for evidence of orbital fat protrusion or damage. In standard transsphenoidal approaches, the eyes are often covered with operative drapes and may be “forgotten” as the case proceeds. The eyes should be protected with lubricants administered onto the cornea. Additionally, commercial “shields” can be purchased that situate a rigid plastic barrier over the orbit so that the surgeon does not inadvertently compress the globe. With or without these shields, careful attention should be paid to prevent globe injury by not compressing the region immediately superior to the operative field.

In situations where injury to the orbit becomes apparent, either with proptosis or pupillary change, urgent attention is required. Eye massage should be started immediately to decrease intraorbital pressures and redistribute the hematoma. Mannitol, an osmotic diuretic, should be started to decrease orbital pressures. The ophthalmology service should be consulted immediately for evaluation. If the above measures do not adequately reduce orbital pressures, surgical decompression is warranted via a cantholysis and sometimes by an external ethmoidectomy.

Penetration of the lamina papyracea can lead to subcutaneous emphysema. Often, this is not noted until the patient awakens and begins to struggle or until aggressive bag-mask ventilation is begun. The air may dissect through various fascial planes involving the orbit, neck, face, or mediastinum. Treatment mainly is supportive because resolution is spontaneous. The patient should be told to avoid sneezing because this may increase the amount and duration of the emphysema. The patient should be placed on antibiotics, and all nasal packing should be removed.

Extraocular muscle damage is very uncommon but usually is permanent. The two muscles most likely to be injured during an endoscopic approach are the superior oblique and medial rectus because of their proximity to the sinuses. If injury is suspected, immediate consultation with an ophthalmologist is in order. The superior oblique muscle is less commonly injured than the medial rectus because of its location high in the orbit, lateral to the ethmoid cavity. The prognosis for recovery following superior oblique muscle injury is better than for medial rectus injury, and an observation time of 6 months is often recommended before surgical treatment to allow for adaptation. Medial rectus injury carries a poor prognosis. This may be secondary to the increased incidence of direct muscle injury in addition to scar tissue formation from lamina papyracea penetration. Most affected patients require multiple surgical treatments. Prognosis may be improved with immediate high-dose steroids and surgical treatment within 3 weeks of injury.

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