Introduction
The transsphenoidal route is a direct and rapid extracerebral approach to the sellar region and therefore it is the most widely used technique for the processes involving this area. Since its introduction by Schloffer in 1907, it has been refined thanks to improvements in the instrumentation and techniques. One of the most important advances in instrumentation was the operative microscope, introduced by Hardy in 1967. This instrument, combining the benefits of magnification and coaxial illumination, seemed, at the time, to have resolved problems due to the narrowness and depth of the operating field. In reality, the tunnel-shaped cone of illumination of the microscope and the rigidity of the working canal created by the divaricator persist in limiting vision and maneuverability of this approach.
The endoscope is the latest innovation in the field of optical instrumentation; it allows the “surgeon’s eye” to penetrate the depth of the operating field and it furnishes a panoramic and/or angled view independent of the depth and width of the access route. It was Guiot in 1963 who first suggested its use in transsphenoidal surgery, but its real acceptance by neurosurgeons had to wait for it to be perfected and for further surgical technical advances. The latest transsphenoidal techniques have employed a direct endonasal approach in which the sphenoidotomy begins directly in the depth of the nasal cavity at the junction between the vomer and the septum. This route, which had been designed with microscopic surgery in mind, has been adapted to the endoscopic technique. Jankowski (1992) was the first to use endonasal endoscopy for the removal of pituitary adenomas. Subsequently, the technique has been perfected and popularized by Jho and Carrau, and Cappabianca and de Divitiis.
These authors have focused their attention on the minimal postoperative discomfort, lower complication rate, quick postoperative recovery rate, and short hospital stay permitted by this technique.
Although the previously mentioned procedures are characteristic of this type of surgery, it is necessary to mention the functional endoscopic pituitary surgery (FEPS) as well due to its efficacy.
Transsphenoidal surgery in Bologna was begun in the 1930s and has evolved, allowing the introduction of the operating microscope at the end of the 1960s. In 1998, we replaced transsphenoidal microscopic surgery with endoscopic surgery. Close collaboration with ENT surgeons, experienced in functional endoscopic nasosinusal surgery, has facilitated the changeover of technique. The change has been smooth and there has not been a single case in which there has been a return to a microsurgical approach after an endoscopic approach had been attempted.
In this chapter, we discuss our experience, reporting results and complications to provide a benchmark for the evaluation of the efficacy of endoscopic endonasal surgery and to compare it with the microscopic technique.
Indications
Indications for the FEPS are the same as for transsphenoidal microscopic surgery. Extra-arachnoidal tumors, such as adenomas, Rathke cleft cysts, and craniopharyngiomas, growing from the sella and expanding in a symmetrical fashion, are suitable for this type of surgery. When the lesion expands downward, the transsphenoidal approach allows the procedure to be carried out in the direction of growth, thus controlling the tumor. FEPS, due to its tolerability, can be used for elderly patients and for patients in poor condition. The narrowness of the surgical tunnel required by FEPS makes it ideal for children. Finally, FEPS facilitates the approach in case of relapse due to the lack of dissection of the septum, typical of the transseptal microscopic approach. Some of the “classic” contraindications to the transsphenoidal approach, such as asymmetrical tumors, conchal sphenoidal sinus, significant cavernous sinus growth, or supradiaphragmatic double-shaped tumors, are partially overcome by endoscopy and the instrumental and technical procedures used.
In case the standard transsphenoidal endoscopic route to the sella does not permit control of the lesion extending to the parasellar, suprasellar, clival regions or pterygomaxillary fossa, we use “extended approaches” such as ethmoido-pterygo-sphenoidal (EPS), the supradiaphragmatic, the transsphenoidal-transclival, and EPS with medial maxillectomy approaches. These procedures allow extracerebral control of a parasellar tumor growing in the cavernous sinus, of tumors growing in the region of the tuberculum sellae, pituitary stalk, and suprasellar and chiasmal cistern; of tumors in the clivus as far as C1; and also in the pterygomaxillary fossa.
Surgical Technique
Standard Technique
Instrumentation
The instrumentation used in the endoscopic technique is a xenon 300 watt cold light fountain source, an endoscopic video camera, and a video record. The endoscopes are zero- to 30- and 45-degree Hopkins telescopes, diameter 4 mm, length 18 mm. A clean system with pedal control is used to reduce the necessity of extracting the telescope from the nose. During the tumor removal phase, we use a mechanical holder for the endoscope and video camera to allow the surgeon to work with both hands. To permit a better distant visual control of the instrumentation, the classic bayonet-shaped instruments are substituted with straight, double-shaped, or pistol-handled instruments.
A neuronavigator, instead of fluoroscopy, is used in case of recurrence or conchal or presellar sphenoid variant, to localize the vascular structure during the approach. In parasellar lesions, the Doppler is helpful, in addition to the neuronavigator, for localizing the internal carotid artery ( ICA) .
Surgical Standard Technique
Surgery is carried out under general anesthesia using orotracheal intubation; the patient is placed in a half-sitting position with his or her head turned toward the surgeon and resting freely in the horseshoe head holder. Only in cases in which the neuronavigator is required is the head fixed in a three-pin holder (Mayfield). The oropharynx is packed with moist gauze to prevent blood and secretions from the operative site from reaching the stomach. The nose and face are cleaned with soap and aqueous solutions. The nasal mucous membranes are decongested with Xylocaine 5%. The periumbilical abdomen is routinely prepared for the harvest of a free fat graft.
The operation is generally done through both nostril. The decision of which nostril to be used to insert the endoscope hold by the holder depends on the nasal cavity anatomy, the nostril having the larger endonasal space.
The surgical procedure can be schematically divided into three stages.
- 1.
Localization of the sellar wall
- 2.
Adenomectomy
- 3.
Final exploration and closure of the surgical field
Stage I: Localization of Sellar Wall
The lateral dislocation of the middle and upper turbinate allows the localization of the sphenoethmoidal recess and the natural ostium of the sphenoid sinus ( Figure 13-1 ).
The opening of the sphenoidal sinus starts with the enlargement of the natural ostium, with a Kerrison punch or with a Stammberger punch. A semilunar incision is made in the vomer to separate the mucoperiosteum from the bone of the vomer and the natural ostium of the sphenoid sinuses. In cases of difficult exposition of the sphenoidal ostium, the entry point to the sphenoid sinus may be obtained through a direct perforation of the anterior wall at the junction of the keel of the sphenoid bone and the posterior nasal septum, approximately 1 cm above the rim of the choana and close to the septum.
The enlargement of the access to the sphenoid sinus should be wide, extending from the roof to the floor of the sphenoid vertically and exceeding the sphenoidal ostia laterally. All the intersinusal septa which reduce the vision and limit the maneuverability in front of the sella have to be removed. It is not necessary to remove the sphenoidal mucosa because with the opening of the natural ostium the risk of postoperative mucocele is very low; preserving the mucosa permits a faster postoperative stabilization of the sphenoid cavity with less incidence of sphenoidal flogosis or compromised ventilation.
The opening of the sellar floor should be as wide as possible from one cavernous sinus to the other and from the superior to the inferior intercavernous sinuses ( Figure 13-2 ).
Second Stage: Adenomectomy ( Figure 13-3 )
This stage begins with the incision of the dural membrane of the sella. With a single-blade curved microscissors, a classic cruciform incision is made or, if a histological examination is required, a rectangular window of dura is removed. It is mandatory to mobilize the tumor before any traction with curette or dissector. To prevent a premature collapse of the supradiaphragmatic cistern, it is necessary to mobilize and remove the tumor first from its inferior and lateral portion and then from its posterior and superior portion.
Final Exploration and Closure of the Surgical Field
After hemostasis is obtained using cotton packing, exploration into the surgical field with angled 30- and 45-degree optic scopes to localize and remove any remnant tumor is recommended ( Figure 13-4 ). To work into the surgical field “behind the angle,” curved instruments designed for this type of approach are required.
In the absence of CSF leaks, the surgical cavity is packed with Gelfoam; otherwise, if a CSF leak is detected or suspected, autologous fat is applied in the sellar cavity and the dural gap is closed with sphenoidal mucosa or, more securely, with a middle turbinate mucoperiosteal graft.
The sphenoid sinus is gently packed with Gelfoam and, finally, the middle turbinate is medially displaced from its normal position. Nasal packing is not routinely required except in the case where the middle turbinate was necessarily resected. We have never used the lumbar drainage.
Extended Approaches
Ethmoido-pterygo-sphenoidal endoscopic approach (EPS)
EPS is reserved for soft tumors involving the cavernous sinus without a histopathological tendency to infiltrate the vessel wall. This type of procedure permits the frontal exposition of the cavernous sinus with the possibility of direct control of the medial and lateral compartments of the cavernous sinus.
The procedure is performed by means of an ethmoidal route and a complete sphenoethmoidectomy with a wider meatotomy required. The medial portion of the posterior wall of the maxillary sinus is resected and the sphenopalatine artery is cauterized with bipolar forceps or closed with titanium hemaclips. The partial resection of the pterygoid process is carried out taking in account the degree of pneumatization of the lateral recess of the sphenoid and the need for visualization of the lateral and inferior walls of the sphenoid sinus ( Figure 13-5 ).
With the exception of a tumor exclusively located in the lateral portion of the cavernous sinus, the periosteal/dural opening is made in the sellar region and progressively enlarged following the tumor from its medial to its lateral portion ( Figures 13-6 and 13-7 ). Venous bleeding is not notable and is generally well controlled with Gelfoam and cotton packing. The tumor filled the venous plexus and, after tumor removal, progressive slow bleeding is possible.
Supradiaphragmatic Approach
The indications for this approach are strictly median extra-arachnoidal tumors not accessible through a standard approach, such as some adenomas, Rathke cleft cysts, craniopharyngiomas, and meningiomas.
The nasal phase of the surgical procedure is the same as that of the standard endoscopic endonasal technique. The approach to the planum sphenoidale and tumor removal is the same as that first described by Weiss (1987) ; removal of the posterior wall of the sphenoidal sinus is extended to the planum sphenoidale between the optic carotid recesses. The opening of the dura is carried out above and below the superior intercavernous sinus, in front of the sella, and in front of the chiasmatic cistern; the intercavernous sinus is resected after coagulation or clamping, and dura resection is extended to the diaphragma sellae. The surgical route gives straight narrow access to the region of the chiasm, the suprasellar cistern, and the pituitary stalk ( Figure 13-8 ). Generally, the expanding mass displaces the chiasm anterosuperiorly and the pituitary stalk posteriorly, and pushes the vascular structures laterally and posteriorly. Therefore, it is mandatory to preserve the arachnoidal layer, perform a centrifugal removal of the tumor, and finally, avoiding any traction, remove the remaining wall after having dissected out the adherent tissue ( Figures 13-9 and 13-10 ).
Material and methods
Between May 1998 and December 2004 at the Neurosurgical Department of Bellaria Hospital in Bologna, Italy, 490 patients underwent transnasal transsphenoidal endoscopic surgery for tumors involving the sella and parasellar regions. In this work, we reported our experience in the treatment of 460 patients with a sellar pathology, such as pituitary adenomas (418 cases), Rathke cleft cysts (32 cases), and craniopharyngiomas (10 cases). All cases of extrasellar pathology (CSF leaks, chordomas, meningiomas, etc.) and sporadic sellar pathology (metastasis, hypophysitis, etc.) were excluded from this report.
Preoperative and postoperative evaluation
All patients underwent preoperative endocrinological, neuroradiological, and neuro-ophthalmological evaluation. After an overnight fast, plasma samples were collected for the measurement of cortisol, free thyroxine (Ft 4 ), thyrotropin (TSH), corticotropin (ACTH), prolactin (PRL), growth hormone (GH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), insulin-like growth factor-I (IgF1), testosterone (in males), and estradiol (in females). A 24-hour urine collection was obtained for the measurement of urinary free cortisol (UFC).
All patients underwent radiological assessments by means of MRI and CT scans. All patients received a short-term prophylaxis with cefazolin 1 g IV during the induction and 1 g IV after 6 hours. Patients with secondary hypoadrenalism received a loading dose of a 50 to 100 mg infusion of hydrocortisone.
Our postoperative protocol consists of an endocrinological evaluation on the third day and again at 1, 3, and 6 months. MRI follow-up is performed 3 months postoperatively and then yearly, while early neuroradiological examinations by MRI or CT are carried out for specific indications. An endoscopic rhinological evaluation is carried out after 1 month postoperatively to evaluate the normalization of the nasal and sphenoid cavities. A neuro-ophthalmological control is routinely performed 3 months after surgery only in case of preoperative dysfunctions or postoperative referred visual disturbances.
Outcome analysis
We analyzed 460 patients who underwent endoscopic transnasal surgery for a sellar pathology. Three hundred and seventy-six patients were treated for the first time, while 84 had previously been treated with microscopic or endoscopic surgery with or without radiotherapy; there were 418 adenomas, 32 Rathke cleft cysts, and 10 craniopharyngiomas ( Table 13-1 ).
| Pathology | Type of Approach | Cases | Surgical Time (min) | Median Hospital Stay (days) | Intraop CSF Leak | Nasal Packing |
|---|---|---|---|---|---|---|
| Adenomas | Standard | 380 |
|
|
|
|
| EPS | 34 |
|
|
|
| |
| Supradiaphragmatic | 4% |
|
|
|
| |
| Rathke cleft cyst | Standard | 31 |
|
|
|
|
| Supradiaphragmatic | 1 | |||||
| Craniopharyngiomas | Standard | 3 |
|
|
|
|
| Supradiaphragmatic | 7 |
The mean surgical time for the standard technique was 45 minutes, and for the EPS approach 90 minutes; the longest was the supradiaphragmatic procedure, which took 120 minutes. Average intraoperative blood loss was 100 mL. In only two cases was a blood transfusion necessary. Where there were no major complications, the median hospital stay varied from 3 days for the standard procedure, without CSF leak, to 8 days for the supradiaphragmatic technique. No intraoperative or perioperative deaths were observed.
Pituitary Adenomas
Four hundred and eighteen pituitary adenomas underwent an endoscopic transsphenoidal procedure; there were 195 nonfunctioning adenomas, 223 functioning adenomas (73 PRL adenomas, 89 GH adenomas, and 3 TSH adenomas). Three hundred thirty-nine patients underwent endoscopic endonasal transsphenoidal surgery for the primary treatment of their tumor while 79 patients had recurrences after previous surgery. Twenty-two out of 79 were previously submitted at our institute for the endoscopic endonasal procedure.
Their ages varied from 7 to 89 years (median 48 years); 191 (45.5%) were male and 227 (54.5%) were female.
The most common symptoms were endocrinological alterations, which were observed in 273 patients (65.3%) while visual disturbance (monolateral or bilateral hemianopia, amaurosis, etc.) and neurological alterations were observed in 154 cases (36.8%) and 22 cases (5.2%), respectively. In 51 (12.2%) patients, the pituitary adenoma was an incidental finding, while in 32 (7.6%) patients, the clinical manifestation was pituitary apoplexy.
Three hundred and eighty-one patients with a follow-up of more than 6 months were analyzed; there were 208 functioning adenomas and 173 nonfunctioning adenomas.
We observed the complete normalization of visual alterations in 56 (36.3%) out of 154 patients and a notable improvement in 90 (58.4%). No variations in the visual field were observed in six patients (3.8%), while in two (1.2%) patients, we had worsened visual capacity.
Trigeminal neuralgia disappeared in all cases while ophthalmoplegia disappeared in 13 out of 14 patients.
Only 11 (2.8%) patients showed a new anterior pituitary insufficiency. The endocrinological alterations will be described related to the type of adenoma ( Table 13-2 ).
Related posts:
Microsurgical Approaches for Transsphenoidal Surgery
Classification, Pathobiology, Molecular Markers, and Intraoperative Pathology
Transsphenoidal Surgery for Acromegaly
Surgical Anatomy of the Sellar Region
Endoscopic Transsphenoidal Surgery: Anatomy, Instrumentation, Techniques
Transsphenoidal Resection of Craniopharyngiomas
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