Complications of the Transsphenoidal Approach

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The transsphenoidal approach is safe and has a low complication rate. In fact, it is one of the safest procedures in contemporary neurosurgical practice. As determined by several retrospective cumulative series, operative mortality and major morbidity rates are 0.5% and 2.2%, respectively (6). In one of the most recent series of transsphenoidal surgeries performed for CD during the current decade, mortality and permanent morbidity rates were 0.9% and 1.8%, respectively (7).

Operative deaths, though fortunately rare, are usually the result of intracranial hemorrhage, hypothalamic damage, or meningitis related to CSF fistulas. A variety of other complications can also occur with this approach (8).

Hypothalamic Injury

Damage to the hypothalamus may result from direct surgical injury and also from hemorrhage or ischemia provoked by the procedure. Clinical manifestations of hypothalamic damage include death, coma, diabetes insipidus, memory loss, and disturbances of vegetative functions (morbid obesity, uncontrollable hunger or thirst, and disturbances in temperature regulation). Such complications are more frequent in patients with previous craniotomy or radiation (9). A gentle surgical technique and avoidance of traction on the tumor capsule and pituitary stalk will minimize the occurrence of such injuries.

Visual Damage

Damage to the optic nerves and chiasm can also occur from direct surgical trauma, hemorrhage, or ischemia. Fractures of bony structures at the base of the skull can damage optic nerves and can occur from misdirected placement and aggressive opening of transsphenoidal retractors. Many patients have preopera-tive compromise of visual function, making them more vulnerable to further damage. Assessment of the bony anatomy, careful and gentle technique, confirmation of surgical landmarks, and effective use of navigational guidance to direct the approach are important measures for avoiding these complications. Finally, at the time of sellar reconstruction, overpacking the sella can cause chiasmal compression, whereas under packing can, occasionally, lead to a secondary empty sella with the late onset of visual loss caused by chiasmatic prolapse (a single personal case and three or four further cases from previous surgery elsewhere).

Vascular Complications

Although rare, arterial injury is a well-known complication of transsphenoidal surgery and is one of the main causes of operative mortality of the procedure (1).

Mri Scan Aneurysm

Fig. 7. A traumatic aneurysm compressing the chiasm, seen on top of a GH macroadenoma in a coronal unenhanced T1 MRI scan. The surgeon had missed the midline, damaged the carotid, and abandoned the procedure. The patient survived an intercontinental flight despite arterial nasal hemmorrhage and was managed by endovascular coil occlusion of the aneurysm, transsphenoidal surgery, and radiotherapy.

Fig. 7. A traumatic aneurysm compressing the chiasm, seen on top of a GH macroadenoma in a coronal unenhanced T1 MRI scan. The surgeon had missed the midline, damaged the carotid, and abandoned the procedure. The patient survived an intercontinental flight despite arterial nasal hemmorrhage and was managed by endovascular coil occlusion of the aneurysm, transsphenoidal surgery, and radiotherapy.

Virtually every transsphenoidal series includes at least one example of arterial injury, most of which have proven fatal (Fig. 7). The intracavernous portion of the carotid artery tends to be the most vulnerable, followed by other components of the Circle of Willis. Because the tumor may be quite adherent to arterial structures, arteries may be lacerated, perforated, avulsed, or damaged such that they develop spasm or intraluminal thrombosis. Intracranial hemorrhage, thrombotic and embolic stroke, and the development of false aneurysms or carotid-cavernous fistulae are the usual sequelae of such injuries. When vascular injury is suspected, tamponade should be used to control hemorrhage and an immediate postoperative angiogram obtained. If a false aneurysm is seen, it should be obliterated by endovascular means. Again, a gentle technique devoid of aggressive traction on the tumor capsule, not deviating from the midline, and repeated assessment of bony landmarks are the most effective means of avoiding these devastating complications.

Cerebrospinal Fluid Rhinorrhea

CSF rhinorrhea and meningitis are among the more common serious complications associated with transsphenoidal surgery. It is the result of disruption of the sellar diaphragm, which is usually thinned, adherent to tumor, and susceptible to direct or traction injury. In the presence of a leak, careful closure of the sella is crucial. In the postoperative period, close observation for leaks and a high index of suspicion for possible meningitis is crucial. Postoperative leaks are usually obvious at the time the nasal packing is removed and are best managed by prompt transsphenoidal re-exploration, identification of the leak, and resealing.

Cavernous Sinus Injury

Pituitary tumors involve the cavernous sinus with some regularity. In some cases, the tumor may be adherent to the medial wall of the sinus only, whereas in other more invasive tumors, frank invasion of the sinus interstices occurs. Injury to the cavernous sinus and its contents can occur as the surgeon is stripping the tumor from the medial dura, following the tumor into the sinus, or overzealously packing sinus bleeding. The carotid artery and the sixth cranial nerve are most vulnerable to such maneuvers; the third and fourth cranial nerves are damaged less frequently.

Iatrogenic Hypopituitarism

In most instances, existing pituitary function can usually be preserved. Among microadenomas, our recent experience indicates that loss of one or more anterior pituitary functional axis occurs in approx 3% of cases (10). For macroadenomas, we have found that anterior pituitary function can be preserved in more than 95% of cases, provided that pituitary function was normal preoperatively. In contrast, patients with established preoperative endocrine deficits, partial or complete restoration of endocrine function is achieved in only 16%. Although temporary diabetes insipidus occurs in one third of all patients, it is permanent in no more than 3%.

Brainstem Injury

Damage to the brainstem may occur with a misdirected approach that violates the clivus, or more commonly, when a larger tumor erodes the clivus, exposing the underlying dura.

Nasal Complications

Generally less immediate and rarely fatal, complications relating to the nasofacial aspect of the procedure can be annoying and persist for some time after surgery. The use of too much force when spreading the retractor may result in diastasis or fracture of the hard palate or the cribriform plate, the latter being another source of CSF rhinorrhea. In the postoperative period, the mucosa of the sphenoid sinus may become infected, giving rise to a febrile sinusitis and the eventual development of a mucocele. Inadequate hemostasis in the nasal portion of the procedure may lead to superficial would hemorrhage and swelling. Careless handling of the nasal mucosa, the nasal septum, and the nasal spine may result in an external nasal deformity, which may be distressing, both cosmeti-cally and functionally. Loss of smell can also occur, presumably because of damage to nerve endings in the nasal mucosa. Finally, overaggressive enlargement of the basal pyriform aperture can damage distal branches of the alveolar nerves and/or vessels, which may devitalize or desensitize the teeth and gums of the maxilla.

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