Endoscopic endonasal approach for pituitary neuroendocrine tumor

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Endoscopic transsphenoidal approach technique

The endoscopic endonasal approach (EEA) has become a widely used and effective surgical technique for treating pituitary neuroendocrine tumors. This approach involves accessing the pituitary gland through the nasal passages and sphenoid sinus, eliminating the need for external incisions and minimizing trauma to surrounding structures.

Surgical Procedure:

The surgery is performed using an endoscope, which is a thin, flexible tube with a light and camera at its tip. The endoscope is inserted through the nostrils, and the surgeon navigates through the nasal passages to reach the sphenoid sinus, where the pituitary gland is located.

Advantages:

Minimally Invasive: EEA is a minimally invasive procedure, which generally leads to reduced postoperative pain, shorter hospital stays, and quicker recovery compared to traditional open surgeries. Reduced Trauma: The approach avoids manipulation of the brain and provides direct access to the pituitary gland, minimizing trauma to surrounding structures. Visualization and Illumination:

The endoscope provides a high-definition, panoramic view of the surgical field, allowing for better visualization of the tumor and surrounding structures. Fiber-optic lights are used to illuminate the surgical area, aiding in precision during tumor removal. Tumor Removal:

Once the pituitary gland is reached, the surgeon can remove the tumor using specialized instruments. The goal is to achieve complete tumor resection while preserving normal pituitary tissue and function. Recovery and Outcome:

Patients often experience a faster recovery with less pain compared to traditional approaches. The endoscopic endonasal approach has been associated with high success rates in achieving tumor removal and improving symptoms related to pituitary dysfunction. Postoperative Care:

Postoperative care may include monitoring hormonal function, as pituitary neuroendocrine tumors often affect hormone production. Follow-up imaging studies, such as MRI, may be conducted to assess the extent of tumor removal and ensure there is no residual tumor. Multidisciplinary Approach:

Treatment of pituitary neuroendocrine tumors often involves a multidisciplinary approach, including endocrinologists, neurosurgeons, and sometimes radiation oncologists, to address hormonal imbalances and optimize patient outcomes. It's important to note that the appropriateness of the endoscopic endonasal approach depends on various factors, including the size and location of the tumor, as well as the patient's overall health. The choice of surgical approach is typically determined on a case-by-case basis after careful evaluation by a medical team.

Jankowski et al. ¹⁾ were the first to use endonasal endoscopy for the removal of pituitary neuroendocrine tumors.

The technique has subsequently been refined and popularized by Hae-Dong Jho and Carrau Inspired by an experience with endoscopic paranasal sinus surgery, an endoscope was applied in transsphenoidal pituitary surgery. This endoscopic transsphenoidal technique was used in 45 cases of pituitary neuroendocrine tumors. Using a 4 mm rigid endoscope, the pituitary neuroendocrine tumor was removed through a nostril. A zero-degree endoscope is used for micro-adenomas. A combination of a 0-degree endoscope and a 30-degree endoscope is used for macro-adenomas that have extended to the suprasellar region. Although it is early in experience with a small number of patients, the short-term surgical results have been encouraging with patients' short hospital stay and minimum morbidity. The endoscopic technique that has evolved with Jho and Carrau experience is described with two cases of pituitary neuroendocrine tumors ²⁾.

Subsequently, outcomes related to the original procedure and extended endoscopic approaches have been reported by other authors ^{3) 4) 5) 6) 7) 8) 9)}.

The introduction of the endoscope to transsphenoidal approach in pituitary surgery represents a major advancement in the field. The use of the endoscope to visualize the sella via a direct endonasal approach offers the surgeon dramatically better visualization as well as improved range of motion compared to the operating microscope. Growing evidence confirms that these improvements directly translate into better surgical resections and outcomes. Further, patient comfort and satisfaction are higher with the endonasal method compared with other transsphenoidal approaches, and it is a cost-effective technology ¹⁰⁾.

Endoscopic endonasal pituitary surgery is a feasible technique, yielding good surgical and functional outcomes, and low morbidity ¹¹⁾.

Results achieved using an endoscopic approach in pituitary neurosurgery are better than those of microneurosurgery for cavernous sinus invasion ¹²⁾.

Results in high (> 80%) rates of resection and improvement in visual function. It is not associated with high rates of major complications and is safe when performed by experienced surgeons. The preoperative Knosp grade, tumor volume, tumor diameter, hemorrhagic components on MRI, posterior extension, and sphenoid sinus invasion may allow a prediction of extent of resection and in these patients a staged operation may be required to maximize extent of resection ¹³⁾.

In conjunction with iMRI and navigation, the endoscopic technique allows increased radicality together with fewer adverse effects ¹⁴⁾.

Endoscopic endonasal surgery provides effective initial management of giant pituitary neuroendocrine tumors with favorable results compared with traditional microscopic transsphenoidal and transcranial approaches ¹⁵⁾.

555 patients underwent an EEA for removal of a pituitary neuroendocrine tumor. The mean follow up was 3.1 years (range 3 months to 9.5 years); 36 were lost to follow up. Ninety-one (17.5 %) harbored recurrent adenomas. An expanded approach to reach the supra-, para- and infra-sellar spaces was employed in 290 patients (55.9 %). Reconstruction with a nasal septal flap was used in 238 cases (65.6 %). The rate of gross total resection was 65.3 % in the 359 patients with non-functioning adenomas. The remission rates with EEA alone were 82.5 % in the 57 ACTH-secreting adenomas, 65.3 % in the 49 GH-secreting adenomas and 54.7 % in the 53 prolactinomas. Of the 237 patients presenting with visual loss, 190 (80.2 %) improved or normalized, 41 (17.3 %) remained unchanged and 4 (1.7 %) experienced transient visual deterioration due to postoperative apoplexy. In addition, no patient without preexisting visual loss suffered new visual decline. The overall post-operative Cerebrospinal fluid fistula rate was 5 % and this decreased to 2.9 % after the introduction of reconstruction with the naso-septal flap. Two patients (0.3 %) had an ICA injury.

The remission and complication rates are comparable or favorable compared with those reported in previous series of microscopic and endoscopic approaches ¹⁶⁾.

The ex vivo chicken wing model is an inexpensive and relatively realistic model to train endoscopic dissection using microsurgical techniques ¹⁷⁾.

The approach is currently under investigation for perisellar tumor surgery.

A higher resection rate is to be expected and nasal complications should be minimized.

After 218 procedures between October 2000 and September 2011, 210 patients received 218 endoscopic endonasal transsphenoidal procedures for perisellar lesions. Procedures were video recorded. The surgical technique was carefully analyzed. These cases were prospectively followed.

The standard technique was mononostril approach with 0-degree optics. 30-degree and-after availability-45-degree optics were used for assessment of radicality. On follow-up, magnetic resonance imaging revealed radical tumor resection in 94 out of 104 cases (90.3%). Recurrent tumor growth was observed in five younger patients (2.2%). There was no mortality and a low complication rate. Three patients (1.4%) complained postoperatively of nasal congestion or reduced nasal air flow; however, no complaints were considered to be severe.

In comparison with other literature reports, the results are comparable or even better with respect to surgical radicality. The very low rate of nasal complaints is particularly remarkable. The technique has been shown to be safe and successful with a high radicality and only minor complications ¹⁸⁾.

Resection of the lower half of the middle turbinate and maxillary antrostomy and harvest of a nasoseptal flap are associated with an increased radiographic incidence of mucosal thickening of the ipsilateral anterior ethmoids compared with the undissected contralateral side. When accessing the transnasal transsphenoidal corridor for skull base surgery, preservation of native anatomy is associated with a lower incidence of mucosal thickening on postoperative imaging ¹⁹⁾.

The endoscopic endonasal approach (EEA) has become a well-established and safe technique for the treatment of pituitary neuroendocrine tumor (PitNET) ^{20) 21) 22) 23) 24) 25)}

Ammirati et al. undertook a systematic review of the English literature on the results of transsphenoidal surgery, both microscopic and endoscopic from 1990 to 2011. Series with less than 10 patients were excluded. Pooled data were analyzed using meta-analysis techniques to obtain estimate of death, complication rates and extent of tumour removal. Complications evaluated included Cerebrospinal fluid fistula, meningitis, vascular complications, visual complications, diabetes insipidus, hypopituitarism and cranial nerve injury. Data were also analysed for tumour size and sex. 38 studies met the inclusion criteria yielding 24 endoscopic and 22 microscopic datasets (eight studies included both endoscopic and microscopic series). Meta-analysis of the available literature showed that the endoscopic transsphenoidal technique was associated with a higher incidence of vascular complications (p<0.0001). No difference was found between the two techniques in all other variables examined. Meta-analysis of the available literature reveals that endoscopic removal of pituitary neuroendocrine tumor, in the short term, does not seem to confer any advantages over the microscopic technique and the incidence of reported vascular complications was higher with endoscopic than with microscopic removal of pituitary neuroendocrine tumors.

They recognise the limitations of meta-analysis, but the study suggests that a multicentre, randomised, comparative effectiveness study of the microscopic and endoscopic transsphenoidal techniques may be a reasonable approach towards establishing a true valuation of these techniques ²⁶⁾.

Only 20% of patients with residual tumor developed recurrent disease over a median follow up of 23.1 months. This recurrence rate may be an important consideration in cases where gross total resection is not feasible. Preferentially operating from the right does not seem to influence the location of residual tumor ²⁷⁾.