Dharambir S. Sethi
INTRODUCTION
Surgical treatment for pituitary tumors has undergone a major paradigm shift to minimally invasive techniques. In the past 15 years, the endonasal endoscopic approach for pituitary tumors has gained acceptance and is now established as a safe and effective approach. Following tumor removal with a 0-degree endoscope, intrasellar endoscopic examination with angled endoscopes allows for better visualization of residual tumor enabling a more complete tumor extirpation. For a successful outcome in the surgical treatment of pituitary tumors, complete tumor resection is important for maximal decompression of the optic chiasm and to minimize recurrence. Complete removal is particularly important for secretory tumors for long-term reversal of endocrinopathy.
In the past 16 years, the combined rhinology–neurosurgical team in our institution has operated on more than 700 pituitary tumors. We had previously reported on our endoscopic endonasal approach to the sella and the “four-handed surgical technique.” Our technique involves a sphenoidotomy that is limited by the superior turbinates on either side. The middle turbinates are not resected. About 1 cm of the posterior nasal septum is resected to facilitate instrumentation through both nostrils. A vascularized nasal septal flap pedicled on the sphenopalatine artery is not routinely elevated though we preserve the sphenopalatine artery at least on one side (usually the left) so that if a vascularized nasoseptal flap is required, it may be elevated after the removal of the tumor. Our approach is aimed at maximally preserving the nasal anatomy using minimally invasive techniques.
HISTORY
A detailed history and physical examination is essential. As most patients present with visual or endocrinologic symptoms, these should be thoroughly investigated. Some patients may be asymptomatic when the pituitary lesion is discovered on a routine magnetic resonance (MR) scan for headaches. Acute headache occurs in pituitary apoplexy, and a chronic headache may result from hydrocephalus. Periorbital headache may signify compression or invasion of the cavernous sinus. Ophthalmologic disturbances include visual deficit, homonymous hemianopia, or complete bitemporal hemianopia to blindness. Diplopia may result due to involvement of the abducent and oculomotor nerves when the tumor invades the cavernous sinus. Endocrinologic symptoms may result from pituitary insufficiency or pituitary hyperfunction. Pituitary insufficiency may be associated with both large and small tumors. Pituitary hyperfunction may lead to several hypersecretory states. Acromegaly patients present with characteristic symptoms. They have characteristic coarse facial features that include enlargement of hands, feet, facial bones, and jaw. Patients with Cushing's disease also have characteristic features that include facial plethora, supraclavicular adipose tissue deposition, posterior cervical adipose tissue, acne, hirsutism, thin skin, ecchymosis, and violaceous striae. These patients usually experience weight gain, fatigue, irritability, depression, and loss of memory.
PHYSICAL EXAMINATION
Physical examination includes a complete evaluation of the head and neck region including neurologic assessment. The stigmata of pituitary hyperfunction (acromegaly, Cushing's disease) may be present. If ophthalmologic symptoms are present, a complete ophthalmologic examination should be performed by an ophthalmologist. Nasal endoscopy is important to assess the nasal airway for surgical planning and to rule out coexistent pathology such as sinusitis or nasal polyposis.
INDICATIONS
Surgery for pituitary tumors has proven to be an effective treatment for both endocrine active and nonfunctioning pituitary adenomas. Indications for surgery include all nonsecreting and most secreting pituitary tumors except for prolactinomas, which are usually well controlled by medical therapy with dopamine antagonist. Indications for surgery also include failure of or resistance to medical management or intolerable side effects of medical therapy.
Nonsecretory tumors may vary in size, expanding the sella and extending along the paths of least resistance, laterally into the cavernous sinuses and superiorly into the suprasellar cistern and anteriorly into the sphenoid sinus. Some nonsecretory tumors may have very large suprasellar extension. These tumors are best managed surgically with a combined endonasal and transcranial approach either in the same sitting or as staged operations. Most secretory tumors, presenting with features of acromegaly and Cushing disease, are an indication for surgery. For prolactin-secreting tumors, surgery is considered for those who do not respond to medical therapy, for patients who are unable to tolerate medical treatment, or for tumors that are predominantly cystic. Pituitary apoplexy may require emergency surgery as these patients usually present with sudden and rapid deterioration of vision.
CONTRAINDICATIONS
A recent review of the literature has compared the different modalities of treatment for pituitary tumors. The review confirms that the endoscopic technique compares favorably with other modalities of treatment in terms of tumor debulking, optic nerve decompression, and hormonal control. However, some patients are not suited to the endoscopic technique. Patients who are not suitable for a general anesthetic procedure may be treated with radiation or medical therapy in the case of functional tumors. The main (relative) contraindication for the endoscopic approach to pituitary surgery is the presence of extensive intracranial growth. This is highlighted by a tumor with a small sellar component, as resection of it is less likely to lead to significant descent of the tumor into the surgical field. In such patients, the surgeons must be willing to undertake wide resection of the skull base with reconstruction in order to achieve adequate access. Another relative contraindication is in the treatment of prolactinomas. In most cases, these tumors can be managed medically in the absence of immediate threat to vision, providing that the dopaminergic side effects of treatment are tolerated by the patient.
PREOPERATIVE PLANNING
All patients scheduled for pituitary surgery are required to undergo radiologic evaluation, endocrine assessment, and visual field tests pre- and postoperatively. A preoperative nasal endoscopic examination by the otolaryngologist is part of routine preoperative assessment. We in our institution, have developed a “Pituitary Surgery Pathway” for patients undergoing this operation. After initial investigations and referrals, patients are reviewed in a multidisciplinary Pituitary Clinic composed of otolaryngologists, neurosurgeons, and ophthalmologists. This is to ensure strict perioperative participation by different specialists involved in the patient's management.
Imaging Studies
Magnetic resonance imaging (MRI) of the pituitary gland is the preferred imaging modality. Fine-cut MRI scanning of the pituitary region with sagittal and coronal reconstruction is the gold standard for pituitary tumors. Computed tomographic (CT) scans of the nose, paranasal sinuses, and sella turcica should be routinely done as not only are these useful in studying the bony anatomy but calcified lesions such as craniopharyngiomas may be more easily identified on CT. MRI scan of the pituitary fossa provides useful information about the location, size, and boundaries of the tumor, as well as its relationship to adjoining structures. The extent to which neurovascular structures in the cavernous sinus are encased by the tumor must be carefully assessed. Although encasement is not a contraindication to this approach, the surgeon must judge his or her ability to safely dissect the tumor off of the carotid artery and should keep in mind the possibility of radiosurgery and fractionated radiation to control the growth of residual unresectable tumor. In some cases, what appears to be tumor encasement of a vessel on preoperative MRI scan turns out to represent a vessel coursing along the capsule of the tumor that can be separated by an excellent arachnoid plane.
Visual Field Testing
All patients undergo preoperative visual field testing. Progressive deterioration of visual fields is often the principle neurologic criterion upon which surgical management decisions are based. Humphrey and Goldmann visual field evaluations are useful even if there appears to be no contact between the optic pathway and the pituitary mass. This is because field defects may reflect previous impingement, potential vascular shunting, or displacement of the chiasm following decompression. Detection and quantification of visual pathology in the preoperative setting is important for prognostic information as well as medicolegal documentation.
Endocrine Evaluation
A preoperative endocrine evaluation is routine. The perioperative endocrine management of a patient undergoing pituitary surgery may vary depending on the size of the pituitary lesion, the type of the lesion, the surgical approach (transsphenoidal, craniotomy), and the preoperative endocrine function.
Otolaryngology Assessment
Preoperative nasal endoscopic examination to exclude active rhinosinusitis is undertaken by the otolaryngologist. It is essential to treat infections of the nasal cavity and paranasal sinuses and ensure the surgical field is without infection prior to commencing the pituitary surgery. Perioperative prophylactic antibiotics are routinely used. In addition, preoperative nasal endoscopy provides useful information of the nasal anatomy such as hypertrophy of the turbinates, concha bullosa, or a gross septal deviation that may necessitate a septoplasty for access to the sphenoid sinus.
Endoscopic Camera Setup
The Digital Endoscopic Video Camera System (Karl Storz) is placed at the cephalic end of the table to enable both surgeons to view surgery on the LCD video monitor. The otolaryngologist stands on the right side of the operating table and neurosurgeon on the left side. Video documentation of the surgical procedure is routinely done on a digital recording device.
SURGICAL TECHNIQUE (VIDEO 2.1)
More than 700 patients have undergone endoscopic pituitary surgery at our institution since 1994. In most cases, an exclusively endoscopic approach to the sella was used. Our surgical technique is demonstrated in the accompanying minimally edited operative video.
Patient 1: This 50-year-old female from a neighboring country presented with headaches and bitemporal hemianopia. MRI scans revealed a large sellar lesion extending to the suprasellar cistern (Figs. 2.1 and 2.2). Following preoperative evaluation, an endoscopic removal of the pituitary tumor was carried out using the surgical technique described as follows.
FIGURE 2.1 T1-weighted gadolinium-enhanced MRI sequence in coronal view of patient 1 revealed a large pituitary macroadenoma.
FIGURE 2.2 T1-weighted gadolinium-enhanced MRI sequence in sagittal view of patient 1 revealed a large pituitary macroadenoma.
1.The nasal cavity is decongested by placing two Neuro Patties soaked in 4% cocaine on each side about 20 minutes prior to induction of anesthesia. The patient is placed under general anesthesia in the supine position. Antibiotics, glucocorticoids, and antihistamines are administered. We routinely use cefazolin (2 g, intravenous), dexamethasone (10 mg, intravenous) and diphenylhydramine (50 mg, intravenous). Oral endotracheal intubation is used, and a pack is placed in the pharynx. The endotracheal tube is anchored on the left angle of the mouth to keep the chest free as manipulation of the endoscope over the chest may occasionally dislodge the endotracheal tube. A Foley catheter is routinely inserted into the bladder to monitor urinary output intra- and postoperatively. The patient's head is supine and turned slightly to the right. The head is elevated by about 30 degrees above the heart to facilitate venous drainage. Antiseptic solution (such as a 5% povidine–iodine solution) is applied to the nose and mouth, and the area is draped with sterile towels and Steri-Drape. The lower abdomen is prepared and draped to obtain adipose tissue for grafting if necessary.
2.The Neuro Patties that had been placed in the nasal cavity earlier are removed and discarded. The nasal cavity is once again decongested with topical application of cocaine. Sterile Neuro Patties soaked in 4% cocaine are placed endoscopically in the sphenoethmoid recess bilaterally. Allowing about 10 minutes for decongestion, the Neuro Patties are removed and the sphenoethmoid recess is infiltrated bilaterally with 1% lidocaine with 1:80,000 epinephrine. A gauge 21 spinal needle is used for infiltration of the anterior wall of the sphenoid, sphenopalatine foramen, and the posterior aspect of the nasal septum.
3.After the nose has been adequately decongested, an endoscopic examination is performed using a 0-degree or 30-degree endoscope. The ostia of the sphenoid sinus are identified bilaterally.
4.Surgery is started on the side where the sphenoid ostium is better visualized. In most cases, we start on the right side. The microdebrider with a 4-mm bit and a serrated outer shaft is used to debride the mucosa in the sphenoethmoid recess around the ostium of the sphenoid sinus taking care not to traumatize the mucosa on the superior turbinates. The serrated blade of the microdebrider is directed medially and the outer sheath laterally protecting the mucosa of the superior turbinate. The sphenoid ostium is widened inferiorly and medially down to the floor of the sphenoid sinus. Care is taken to avoid the septal branch of the sphenopalatine artery (SPA) by not going too far inferolaterally. A 2-mm up or down biting Kerrison rongeur is used to extend the sphenoidotomy. Mucosa is debrided from the posterior aspect of the vomer and the sphenoid rostrum. The sphenoidotomy is extended to the contralateral side by dislocating the attachment of the vomer from the sphenoid rostrum. The ostium of the sphenoid sinus on the contralateral side is identified, and the sphenoidotomy is extended as far as the contralateral superior turbinate (Fig. 2.3). The sphenoid rostrum is removed with strong septal forceps. A wide sphenoidotomy that extends superiorly to the roof of the sphenoid, inferiorly to the floor of the sphenoid sinus, and laterally to the superior turbinate on either side is fashioned.
5.About 1 cm of the posterior aspect of the vomer is removed with a reverse cutting forceps to facilitate the introduction of instruments from both nostrils. A panoramic view of the sphenoid sinus is obtained. The removal of part of the posterior nasal septum provides the ability to use both hands by two surgeons enabling introduction of up to four separate instruments, two through each nostril. The access to the sphenoid sinus is complete (Fig. 2.4). From this point onwards, the neurosurgeon and otolaryngologist work as a team. The otolaryngologist manually manipulates the endoscope and assists the neurosurgeon in removal of the tumor.
6.The sphenoid sinus is next examined with 0-degree, 30-degree, and 70-degree, 4-mm endoscopes, and important anatomical landmarks within are noted. Of particular importance are the structures on the lateral wall. The carotid prominence, optic prominence, and opticocarotid recess can be well identified when the sphenoid sinus is well pneumatized (Fig. 2.5). On the lateral recess of a well-pneumatized sphenoid sinus, the second branch of the trigeminal nerve (V2) and the vidian canal may be identified superolaterally and inferomedially, respectively.
On the posterior wall, the tuberculum sella, the anterior wall of the sella, and the clival recess are identified. The location of the intersinus septa, if any, is noted. Caution is exercised in not stripping the sphenoid mucosa as this may result in considerable bleeding. Once a panoramic view of the entire sphenoid sinus and the surgical landmarks is obtained, the access to the sella turcica is complete. The major landmarks for proper identification of the sellar floor are the planum sphenoidale above, clivus below, and carotid prominences bilaterally. Neuronavigation, if available, is used to confirm the landmarks (Fig. 2.6).
7.Once the sellar floor has been identified, the mucosa over the floor of the sella is cauterized with bipolar diathermy to expose underlying bone. The thickness of the floor of the sella is assessed by gentle palpation with an instrument such as a ball probe. By direct visualization and tactile feedback, the thinnest part of the sellar floor is identified and gently fractured at the point of least resistance. A plane is developed between the dura and floor of the sella with a right-angle hook. A 1-mm Kerrison punch or a curette is used to delicately remove the floor of the sella exposing dura. Boundaries of removal of the sellar floor are the planum sphenoidale superiorly, clivus inferiorly, and the carotid prominence laterally (Fig. 2.7).
8.Bipolar diathermy is used for hemostasis over the dura before incising it. The incision is made using a sickle knife or a scalpel with a retractable blade or a pair of 45-degree-angle alligator scissors.
9.A biopsy of the tumor tissue is taken. Once we have sufficient tumor tissue for a histologic examination, the tumor is removed using a combination of blunt ring curettes and pituitary forceps. The otolaryngologist and neurosurgeon work in tandem at this point. While one surgeon removes the tumor, the other provides continuous suction enabling rapid removal. A systematic approach in removing the tumor is useful. We start to remove tumor from the floor, work on the lateral extent next, and finally remove the suprasellar component if any. Often the tumor decompresses rapidly in areas where it is cystic or gelatinous. The diaphragma may descend rapidly in this region, giving the impression that the tumor has been completely removed, whereas pockets of tumor where the tumor was more semisolid or adherent to the diaphragma may be left behind. Therefore, it is useful to attempt to control the descent of the diaphragma by systematic removal of the tumor. When the diaphragma descends unequally, there may be a pocket of tumor left behind. A careful inspection of such pockets is done by gentle retraction of the arachnoid by one surgeon to enable visualization while the other removes any residual tumor.
10.Once the tumor has been removed, a 4-mm-angled endoscope (30-degree, 45-degree, or 70-degree) is used to view the cavity of the sella and suprasellar cistern to ensure absence of residual tumor (Fig. 2.8). Lateral visualization with angled endoscopes enables exploration of the medial wall of the cavernous sinus.
11.Once the tumor has been completely removed, minor oozing from the sella is controlled by packing it with Neuro Patties providing a tamponade for about 5 minutes. Upon removal of the Neuro Patties, the sella is once again examined endoscopically and any localized oozing is controlled with placement of Surgicel (Johnson & Johnson, New Brunswick, NJ) over the area. In the situation where oozing from the sella persists despite the above measures, it may controlled by application of thrombin-infused gelatin matrix (FloSeal; Baxter International Inc., Deerfield, IL).
12.Once the surgery is concluded, nasal hemostasis is ensured. Any minor mucosal oozing or bleeding from the septal branch of the sphenopalatine artery is controlled with bipolar diathermy.
13.The cavity of the sella is lined by a thin film of Surgicel. Repair of the defect in the sella is not routine. A thin film of Surgicel is placed over the defect.
14.To facilitate postoperative healing of the mucosa, we ensure that the bone of the sphenoid rostrum is not exposed and is adequately covered with mucosa. Eight-centimeter nasal Merocels (Medtronic Xomed Surgical Products, Jacksonville, FL) are placed in the nasal cavity on either side and hydrated with saline to expand. These are removed after 24 hours.
FIGURE 2.3 Bilateral sphenoidotomy (black asterisk).
FIGURE 2.4 Wide midline sphenoidotomy limited laterally by the superior turbinates (white asterisk) providing access to the sella (s). Other structures visible are the planum sphenoidale (p), tuberculum sella (ts), clivus (c), and the paraclival carotid arteries (a).
FIGURE 2.5 View of the structures within the sphenoid sinus with 30-degree endoscope. Structures of note are the left optic nerve (on), left opticocarotid recess (asterisk), and the insertion of the accessory intrasphenoid septum onto the left paraclival carotid artery (arrow).
FIGURE 2.6 Endoscopic image showing the interior of the sphenoid sinus with perspective of the bony sellar floor (s) bulging into the sphenoid sinus. Adjunctive neuronavigation is also demonstrated where the position of the tip of the probe is displayed in sagittal, coronal, and axial T1-weighted magnetic resonance images.
FIGURE 2.7 The anterior wall and the floor of the sella have been removed to expose the underlying dura (asterisk); tuberculum sella (ts).
FIGURE 2.8 The arachnoid (asterisk) is identified after the tumor has been removed. Arrow points to the suprasellar extension.
There was no leakage of cerebrospinal fluid (CSF) in the above patient. The total operative time was 57 minutes and blood loss about 150 mL. Three-month-interval postoperative MRI scans showed the tumor had been completely removed (Figs. 2.9 and 2.10)
FIGURE 2.9 Three-month-interval T1-weighted gadolinium-enhanced coronal MRI sequence of patient 1 showing that the tumor has been completely removed.
FIGURE 2.10 Three-month-interval T1-weighted gadolinium-enhanced sagittal MRI sequence of patient 1 showing that the tumor has been completely removed.
Another case demonstrating a different sellar pathology is presented to demonstrate the surgical technique and results.
Patient 2: A 49-year-old Caucasian male presented with headaches and diplopia of 2 weeks' duration. MRI scan revealed a uniformly enhancing mass within the sella extending into the suprasellar cistern, compressing and elevating the optic chiasm (Fig. 2.11A and B). Figure 2.12 showed bilateral sphenoidotomies created in the midline. Figure 2.13 provides a view of the floor of the sella. Note that the midline intersinus septum inserting on the floor of the sella has been removed. Figure 2.14 shows the anterior wall of the sella being removed. Figure 2.15 demonstrates the tumor being removed from the arachnoid using the two-hand technique. Figure 2.16 depicts the intrasellar view of the membranous arachnoid (black asterisk). There was a minor CSF leak in this patient that was repaired using a plug of adipose tissue and a pedicled nasoseptal flap. Figure 2.17 is the intraoperative view with neuronavigation probe within the sella. The MRI scans (Fig. 2.18A and B) 2 years postoperative show postsurgical changes.
FIGURE 2.11 A and B: T2-weighted MRI reveals a uniformly enhancing mass in the sella with suprasellar extension into the suprasellar cistern compressing and elevating the optic chiasm.
FIGURE 2.12 Endoscopic view of bilateral sphenoidotomies done in the midline.
FIGURE 2.13 View of the floor of the sella after a wide sphenoidotomy has been created in the midline.
FIGURE 2.14 The floor of the sella is being removed to expose the dura.
FIGURE 2.15 Tumor is being dissected off of the arachnoid using the two-hand technique.
FIGURE 2.16 Intraoperative endoscopic view of the descended diaphragm. Note the membranous arachnoid (black asterisk).
FIGURE 2.17 Image of neuronavigation with the probe on the right cavernous carotid artery.
FIGURE 2.18 A and B:Three-month interval postoperative MRI. Arrow points to the pedicled nasoseptal flap.
POSTOPERATIVE MANAGEMENT
Once the surgery is complete, the patient is extubated and brought to the recovery room where the patient's vital signs are monitored. For the next 24 hours, the patient is monitored in the neurosurgical intensive care unit, particularly for diabetes insipidus and for deterioration of vision. A fasting morning cortisol level is obtained on the morning of the 2nd postoperative day, and cortisol replacement is initiated only if the level is abnormally low. Nasal packing is removed on the first postoperative day. If no lumbar drain has been placed, patients ambulate on the 2nd postoperative day and may be discharged on the 3rd postoperative day or as soon as they are ambulating and eating well. During the postoperative period, the patient is monitored for any CSF leak, or symptoms and signs of meningitis or any hemorrhage. Antibiotics and analgesics are routinely prescribed. The patient is examined following the removal of the packs. Any blood clots in the nasal cavity are aspirated under endoscopic guidance.
The first office visit is scheduled 1 week following the surgery. After application of topical 4% cocaine, blood clots are endoscopically removed from the nasal cavity and sphenoid sinus. The sella is carefully examined for any bleeding or CSF leakage. The patient is seen on a weekly basis by the otolaryngologist for the first 3 weeks and then every 3 weeks for the next two appointments. Healing usually takes about 3 to 6 weeks and is hastened by endoscopic removal of crusts. Further appointments are scheduled as necessary. Postoperative follow-up is also provided by the endocrinologist, ophthalmologist, and neurosurgeon.
COMPLICATIONS
It is imperative that the operating surgeon is familiar with the complications that can take place and is prepared to handle these complications. Table 2.1 lists complications that the surgeon must anticipate.
Table 2.1 Complications of Endoscopic Pituitary Surgery
The most common intraoperative complication is CSF leak. The usual cause of CSF rhinorrhea is trauma to the diaphragma resulting from instruments such as curettes, forceps, or suctions. The diaphragma is often very thin and susceptible to trauma so that extreme caution must be exercised when removing tumor from this delicate structure. It is also important to remember that anterior to the infundibulum, the superior aspect of the gland is related directly to the arachnoid and pia, and the subarachnoid space here extends below the diaphragm and may be inadvertently breached while removing tumor. When a CSF leak is identified intraoperatively, the intrasellar defect should be identified. Precautions should be taken not to make it worse or larger, and surgery should be completed by working around it. At the conclusion of the surgery the defect should be repaired with intrasellar placement of abdominal adipose tissue and fibrin matrix (Tisseel; Baxter, Deerfield, IL). In some cases, the CSF leak may be due to minor “weeping” from the arachnoid when the vertical component of the cruciate incision is extended superiorly. In these patients, the “weeping” defect is repaired with a small amount of adipose tissue placed on the defect and fixing it with fibrin matrix (Tisseel; Baxter, Deerfield, IL).
Intraoperative bleeding may result from inadequate nasal decongestion prior to surgery, trauma to the sphenopalantine artery (SPA), inadvertent stripping of sphenoid mucosa, cavernous sinus trauma, intercavernous sinus injury, or trauma to the cavernous part of the internal carotid artery. Decongesting the nasal mucosa preoperatively and intraoperatively, the use of bipolar diathermy on the tumor capsule and the dura prior to incising it, and taking the precaution of not stripping the sphenoid mucosa are the key points in reducing intraoperative bleeding. Tumor tissue tends to bleed. Quick removal of tumor ensures early hemostasis. If bleeding continues from the sellar cavity, endoscopic examination with a 30-degree telescope is particularly useful in identifying the bleeding point or residual tumor. The bleeding point can then be controlled with tamponade, bipolar diathermy, or a thin layer of Surgicel. Bleeding of the cavernous sinus should be suspected when venous blood fills the surgical field. It can be repaired with Surgicel, fibrin matrix, or application of FloSeal (Baxter, Deerfield, IL).
Perhaps the most feared complication is trauma to the cavernous carotid artery. Bleeding from the carotid artery should be suspected if the surgeon is working laterally. Tamponade by promptly packing the nose and the sinus cavity is the initial measure to be taken. Meanwhile, the patient's condition is assessed. Replacement of blood loss should be expedient. At the same time, arrangements are made for angiography and test occlusion. If the packing is sufficient to stop the bleeding and the patient passes the occlusion test, the internal carotid artery may be occluded with a balloon. However, if the patient fails the occlusion test, a bypass procedure is necessary prior to occluding the internal carotid artery. If the packing is unable to stop the bleeding, emergent measures such as occlusion of the internal carotid artery in the neck or a craniotomy may need to be undertaken.
Significant postoperative hemorrhage may be due to oozing from the nasal mucosa at the site of the sphenoidotomy or active bleeding from one of the branches of the sphenopalatine artery. Profuse bleeding that is difficult to control should alert the surgeon to the possibility of intracranial vascular trauma that warrants an angiogram.
Transient or permanent worsening of vision may occur as a result of intrasellar hematoma or direct damage to the optic nerve. Intrasellar hematoma should be suspected when the patient complains of deteriorating vision after surgery. Emergent CT scan of the brain and immediate surgical evacuation of the hematoma must be carried out if intrasellar hematoma is suspected.
In our series, the incidence of postoperative CSF leak was low and in most cases the CSF leak was identified and managed intraoperatively. If CSF leak presents in the postoperative period and endoscopic examination suggests that there may be a breach in the arachnoid, formal identification and closure of the defect and repair of the sella may be necessary. An alternative is to undergo a trial of bed rest with a lumbar drain, but it should be noted that a prolonged duration of CSF leak is associated with meningitis.
RESULTS
Endoscopic surgery for the treatment of pituitary adenomas has become the new standard of care. Comparison of endoscopic and microscopic techniques have demonstrated the benefits of endoscopic surgery, especially for macroadenomas. The enhanced visualization of the endoscope enables more complete dissection with a higher gross total resection rate. With functional tumors, endoscopic techniques offer comparable rates of hormonal remission and tumor control but with less perioperative morbidity.
PEARLS
· The sphenoid ostium lies just above the sphenoethmoid recess, approximately 1.5 cm above the choana. The shape and size of the sphenoid ostia may vary, but their location is almost constant. In some circumstances, the ostium is covered by a supreme turbinate, which can be gently retracted laterally or resected if necessary. Rarely, in the situation where the sphenoid ostium cannot be identified, entry into the sphenoid sinus can be gained using a blunt instrument or suction tip to exert controlled pressure to the anterior wall at the point of least resistance.
· If the sphenoid rostrum is very thick, it may be necessary to use a diamond burr and drill the sphenoid rostrum for access.
· The extent of removal of the sellar floor varies depending on the size and location of pathology, but a generous removal that extends laterally as far as the carotid arteries is recommended.
· The type of incision made over the dura may vary depending on surgeon's preference, type and size of the tumor, and exposure necessary to remove the tumor. The incision may be vertical, horizontal, cruciate, diagonal, or made in the shape of a flap reflected inferiorly. Care is taken not to extend the vertical segment of the incision too far superiorly, so as not to encounter the subarachnoid space or the anterior intercavernous venous sinus. Lateral extent of the horizontal incision is limited by the cavernous sinus on both sides, and great caution must be exercised to avoid the carotid artery in the far lateral corners of the exposure. Incising the dura on the diagonal from corner to corner provides a wider opening than a cruciate incision. The upper leaf of dura may be further incised in the midline if exposure over the top of the gland is needed.
· In the event that a CSF leak is recognized intraoperatively, the defect is plugged with a pad of abdominal adipose tissue sandwiched between Surgicel squares and sealed with fibrin matrix (Tisseel; Baxter, Deerfield, IL).
· A wide sphenoidotomy bounded by planum sphenoidale superiorly, the floor of the sphenoid sinus inferiorly, and the superior turbinates laterally provides adequate access to the sphenoid sinus for removal of most pituitary tumors that do not extend laterally to encase the cavernous sinus.
· The septal branch of the sphenopalatine artery may be preserved by elevating a mucoperiosteal flap from the sphenoid rostrum. We always preserve at least one artery, usually on the left side, should a vascularized nasoseptal flap be required to repair an intraoperative CSF leak or in the postoperative period.
· In cases requiring a nasoseptal flap, the sphenoid rostrum must be adequately prepared with a high-speed irrigating drill to allow the flap and the pedicle to be applied onto the cavity without tenting or twisting. The cavity is then packed with bismuth iodoform paraffin pack to allow the flap to adhere to the surface of the cavity.
· Wide removal of the anterior wall of the sella and a large dural opening facilitate access and removal of the tumor.
· Capsular dissection of the tumor from the arachnoid may be necessary for complete tumor removal.
PITFALLS
· The surgeon should have adequate experience with endoscopic sinus surgery.
· A clear understanding of the endoscopic anatomy of the sella and the surrounding region is essential.
· The surgeon should be able to manage injury to the cavernous carotid artery.
· Endoscopic technique may not be suitable for large invasive tumors where the surgery may have to be combined with an open approach.
· While extending the sphenoidotomy inferiorly, brisk bleeding may result if the septal branch of the sphenopalatine artery is encountered. This may be controlled by cauterizing the vessel with bipolar diathermy. In the rare situation where bleeding cannot be controlled, it may be necessary to expose and ligate the sphenopalatine artery at the sphenopalatine foramen, which is located in the superior meatus just posterior to the middle turbinate. Most endoscopic sinus surgeons are familiar with the technique.
· If the accessory septa in the sphenoid sinus have to be removed, extreme caution should be exercised, as these often terminate on the carotid canal or the optic canal. It is safer to use Tru-Cut instruments to remove these septa. Injudicious avulsion of the septa with non–Tru-Cut instruments may cause fracture of the thin bone overlying the cavernous sinus or the optic nerve with resultant hematoma, intractable bleeding, or even blindness.
· It is extremely important to be gentle while working on the lateral aspect of the sella, as the medial layer of the cavernous sinus can be extremely thin. Arterial bleeding has been reported due to carotid artery injury but may also arise from a tear of an arterial branch of the carotid, such as the inferior hypophyseal artery or by avulsion of a small capsular artery from the carotid artery. Blunt curettes should be used, as the arachnoid can be extremely thin and CSF leakage may result even with gentle manipulation.
INSTRUMENTS TO HAVE AVAILABLE
General Setup
· Endoscopes: 0, 30, 70 degrees
· Microdebrider (Medtronic straight shot) and console (Medtronic Integrated Power Console)
· Endoscrub sheath, with irrigation tubing
· Sinus instrument tray, including Freer elevator, Blakesley Forceps (straight and 45 degrees), and Tru-Cut forceps (straight and 45 degrees) and ball probe
· Long bayonet bipolar forceps
· Two suction devices
Sphenoidotomy
· Straight sphenoid sinus mushroom-shaped punch
· Kerrison rongeurs: 1 and 2 mm, up-biting and down-biting
· 2-mm osteotome and mallet
· Extended-length skull base burrs:
o Medtronic 4-mm straight cutting burr
o Medtronic 5-mm, 15-degree angled diamond burr
Septotomy
· Back-biting forceps
Pituitary Access
· Canal knife/disc elevator
· Retractable blade scalpel
Pituitary Resection
· Endoscopic pituitary tray including
o Rhoton dissectors No. 3, 5
o Curette dissectors, large and small
o Storz curved curette
SUGGESTED READING
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