Transnasal Transsphenoidal Approach for Pituitary Tumors: An ENT Perspective

Abstract

Endoscopic transnasal transsphenoidal (ETNTS) approach was first described in 1992 and is standard approach for the resection of benign pituitary adenomas. This prospective study aims in incidence and preoperative assessment of extent of the pituitary adenoma, peroperative findings of transnasal transsphenoidal excision, techniques of skull base repair, complications and its management in a tertiary centre. A prospective analysis from Jan 2017 to May 2019, of patients undergoing ETNTS approach of pituitary adenomas was made in terms of incidence in various age-groups, type of adenoma, operative findings including CSF leak, repair of the skull base defect, complications encountered and its management was done in a tertiary care centre and compared with the present literature. A total of 141 patients underwent ETNTS, with highest number of cases found in 41–50 years age-group with mean age of 42.6 years. Male: Female ratio was 1.6. Macroadenoma was in 123 patients while 18 had microadenoma, of these 63.74% were functional adenoma, highest of GH secreting, while 36.26% were non-functional. Mean surgical time was 98.4 min ± 21.2 min. Peroperative CSF leak was in 30.5% cases in various grades. Closure techniques included use of fat, multilayer techniques, Hadad’s flap and gasket technique as per the type of CSF leak. Neurological and rhinological complications were 6.38% each. This study is focused on the ENT perspective of the endoscopic transnasal trans-sphenoidal approach for pituitary adenomas. The reduced rate of morbidity and complications is encouraging. The endoscopic skull base defect closure is challenging and requires skill, meticulous approach and synchronised team work in order to achieve a favourable outcome. The incidence of CSF leak can be minimised and if encountered has to be dealt in an organised manner, thus contributing to a reduced rate of complications. The complications encountered must be foreseen and managed with a proficient approach.

Introduction

Pituitary tumors accounts for about 10–15% of all brain tumors, of which 9% are the adenomas, which are classified by its size and ability to hypersecrete the hormones [1–7]. The endoscopic nasal approach has been well established for lesions of the skull base, as it is minimally invasive. The endoscopic endonasal approach is presently being used in the patients having sellar and parasellar lesions [6, 8–13].

Initially in the early 19th century the approach to the pituitary adenoma was transcranial requiring cerebral retraction and thus increased the morbidity to the patient [6, 14]. In later period of time, Transnasal trans-sphenoidal surgery (TNTS) approach was described and was done using the microscope in 1960, it had a binocular 3-D perception but had restricted field of vision and restricted instrumentation field. With better optics in 1992, endoscope replaced the microscopes with enhanced visualisation of the field and better access to the operating site facilitating the substantial excision with a better outcome [6]. This technique had a significant role of an otorhinolaryngologist along with the neurosurgeon in scaping a pathway to the pituitary tumor. With the advent of better scope optics and high-definition camera system, it became the preferred method for the excision of the pituitary tumors as well as the repair of the skull base defect [6, 7, 15–17]. The advantages being the direct approach and visualisation of the adenomas without going through the neurovascular structures [7, 15]. However, there were intracranial and rhinological complications recorded, which are relatively less [6, 16, 18–22]. As the TNTS techniques has a steep learning curve and the technique and technology is fast evolving [6, 7, 23–25]. It is mandatory to minimise and tackle the complications encountered for a favourable outcome. Hence, this prospective study was carried out to highlight, predict and measure the surgical outcome and potential complications from an ENT point of view.

Materials and Methods

We aim to conduct a descriptive analysis of endoscopic transnasal transsphenoidal excision of pituitary tumor. Our objectives are: 1. Preoperative assessment of extent of the pituitary adenoma 2. Intraoperative findings of transnasal transsphenoidal excision 3. Techniques of skull base repair 4. Complications and its management.

A prospective study was performed in patients of pituitary adenoma who were selected for endoscopic TNTS surgical resection between Jan 2017 to May 2019. The study was carried out jointly by Department of Otorhinolaryngology Head and Neck Surgery and Department of Neuro-Surgery, at a tertiary care referral hospital. Patients having any nasal infections were treated initially and then included for TNTS surgery.

Patients undergoing TNTS surgery were evaluated and data was collected including age, gender, symptoms, visual complaints, imaging studies, per-operative findings and postoperative complications, histopathological findings as well as the surgical outcome. Radiological evaluation in all the patients was done by Magnetic resonance imaging (MRI) of the brain with contrast enhancement to analyse the tumor size and its extent using SIPAP grading system [26] as in Fig. 1. The skull base was assessed for any anomaly and nasal pathology using Computerised Tomography imaging and also as a part of preoperative planning for bony landmarks, nasal septum and sinus development [27, 28].

Fig. 1.

MRI brain for SIPAP grading of the pituitary tumors. a Confined to sella, b suprasellar and infrasellar extension, c suprasellar and parasellar extension, d infrasellar extension

Preoperative evaluation also included the Diagnostic Nasal Endoscopy to assess the nasal cavity, status of the septum, nasal pathology like polyp etc. and for planning the access to the Sphenoid sinus and Sella.

All the patients underwent Endoscopic transnasal transsphenoidal approach for the pituitary adenomas. All the surgeries were performed under General anaesthesia with oral intubation. Patient was positioned supine with head in semi-flexed, elevated up to 30 degrees and tilted towards to surgeon on the right side. Nasal cavity was decongested. A Zero-degree (0°) 4 mm rigid endoscope with light source and camera system was used while 30° and 45° scopes were used as and when required. Few cases required middle turbinectomy for the better access to the sphenoid sinus. Once the Sphenoid sinus ostium was located, it was opened and access to the floor of sella was made. Biopsy was taken from the pituitary adenoma and excision was done (Fig. 2). Final inspection was carried out using 30 degree and/or 45-degree angled scopes.

Fig. 2.

Intra-operative images of TNTS excision of pituitary adenoma. a Identification of sphenoid ostium, b sphenoid sinus opened, c pituitary adenoma exposed, d removing the adenoma with curette, e intra-operative identification of Internal Carotid Artery using doppler, f after excision of adenoma

Per operative finding was recorded in terms of grade of CSF leak, which were grade 0—no leak, grade I—Small weeping leak on Valsalva manoeuvre, grade II—Moderate leak, grade III—Large leak [29]. Closure was done using different methods deemed fit pertaining to the per operative findings. For this, vascularised Hadad’s Nasoseptal flap, tensor fascia lata (TFL), septal cartilage and fat was used as required [30–34] (Fig. 3). Also, biomaterial such as surgical, gelfoam and tisseel tissue glue were used. Nasal cavity was then packed with merocel nasal packs for 72 h with bolster dressing. Lumbar drain was required in few cases with high flow CSF leak. For initial 24 h, patient was observed in ICU and then shifted to ward.

Fig. 3.

Images of various closure techniques used in endoscopic repair. a Multilayer closure with Fat, Tensor fascia lata; b Hadad’s flap closure, c tissue glue, d after closure

Alkaline Nasal douching was advised after nasal pack removal. Post-operative complications were recorded such as persistent CSF leak, meningitis, pneumocephalocele, etc. and CT or MRI scan was done as and when required. Medical intervention was done as required. Surgical intervention was done in cases of persistent CSF leak. Follow up was done after 01 week and 01 month with nasal toileting and nasal endoscopic assessment.

Results

Data of a total 141 patients in our prospective study from Jan 2017 to May 2019, belonged to the age group of 10–74 years, with a mean age of 42.6 years. Age and gender wise distribution as given in Table 1. Maximum of 52 patients were in age-group of 41–50 years.

Table 1.

Age and gender wise distribution of number of patients

Age-group	No. of female	No. of male
1–10	1	0
11–20	0	1
21–30	8	9
31–40	15	21
41–50	19	33
51–60	10	12
61–70	1	9
71–80	0	2

There were 87 Males and 54 Females during the one year of this study with Male: Female ratio of 1.6:1.

123 patients have macroadenoma whereas the remaining 18 patients had microadenoma.

Radiological evaluation was done with contrast enhanced MRI, wherein suprasellar extension was seen in 71 patients (50%). Infrasellar extension in 31 (21.7%) patients. Parasellar extension in 22 (15.38%) patients. Anterior extension was seen in 17 (12%) patients.

Histopathological and endocrinological evaluation shows that 51 patients had functional adenoma (36.26%), whereas 90 patients had non-secretory adenomas (63.74%). Functional adenomas in our study were GH-secreting, Prolactin-secreting and ACTH-secreting adenomas as in Fig. 4.

Fig. 4.

Age-distribution of type of functional adenoma

Mean surgical time for all cases was 98.4 min with SD ± 21.2 min.

Per-operatively following the adenoma excision, CSF leak was noted in a total of 43 (30.5%) patients, however the 98 patients had no CSF leak. Of the 43 patients, 14.1% (n = 20) had grade I, 8.5% (n = 12) had grade II and 7.8% (n = 11) had grade III CSF leak. After resection of the adenoma, closure was done in graded fashion. Fat closure in 44% (n = 20) of patients with grade I CSF leak; cases with grade II CSF leak required multilayer closure using fat, TFL and other biomaterials was 33% (n = 15), wherein few cases (n = 3) with grade III CSF leak were also repaired with the multilayer technique; Hadad’s flap was used in 18% (n = 8) of patients with grade III CSF leak as shown in Fig. 5.

Fig. 5.

Pie chart showing the different closure techniques

Neurological and rhinological complications were 6.38% each are shown in Fig. 6. Postoperative CSF leak was found in an overall of 4 patients which is 2.83%. Initially these patients were managed conservatively with lumbar drain insertion. One patient had recovered but 3 of them developed meningitis, which was controlled with intravenous antibiotics as per standard protocol and later were managed surgically with closure of the defect using Hadad’s flap in 1 and septal cartilage gasket technique in 2. No recurrence of CSF leak was seen. Use of lumbar drain was discontinued in later part of the study due to increased incidence of meningitis. Pneumocephalocele with persistent CSF leak was seen in 2 patients. Nasal complication of septal hematoma was seen in 3 patients, which was managed by incision and drainage. Synechiae was in 6 patients which was removed.

Fig. 6.

Graph showing the complications

Discussion

Pituitary Adenoma, though benign, is the commonest condition of the pituitary gland causing physiological morbidity. Moreover, the treatment part of it is a learning curve for any surgeon. This study was undertaken with the aim of knowing the surgical outcome in a tertiary care facility.

This present study was conducted prospectively in total of 141 patients of the pituitary adenoma in a time period of 28 months. Maximum cases were in 41–50 years age-group. Most of the study are retrospective analysis [21, 25, 35, 36], defined age of less than 10 years (Rucia Zhan et al.) whereas all age groups were included in present study at a given period of time. Also, the present study is single centre specific study in contrast to a single centre [25], single surgeon study [37].

Introduction of better optics and endoscopes and its application in trans-nasal transsphenoidal approach for pituitary tumors has been of prime importance. Endoscopic approach has been found better than microscopic approach in terms of resection of the tumor, low surgical morbidity, improved recovery period [6, 7, 17]. Focus of this study was on the surgical outcome and complications with its management.

Comparing with the microscopic approach as mentioned in various other publications, it involves extensive septal dissection which may be frequently associated with the complications such as septal perforation, synechiae, excessive crusting of nasal cavity affecting quality of life [38, 39].

Endoscopic approach had an improved outcome and recovery in 6-8 weeks of period [6, 7].

In our series of Indian population, 36.26% (n = 33) patients had functional adenoma, whereas 63.74% (n = 58) patients had non-functional adenomas. In other series had 20% of secreting and 80% of non-secreting adenomas but overall is comparable [23, 40].

We had 80.35% of macroadenomas and 19.65% of microadenomas. Other study shows 53.33–69.1% of macroadenoma, 9.9–33.33% of giant adenoma and 13.33–21% of micro adenoma [23, 40].

Mean operating time in our study was 98.4 min (SD ± 21.2 min) which is better than time of 212.66 min [40].

In our series, postoperative complications seen were 2.83% (n = 4) of persistent CSF leak, 2.13% (n = 3) of Meningitis, 1.42% (n = 2) of pneumocephalocele with persistent CSF leak. Rhinological complications seen were septal hematoma in 2.13% (n = 3) and synechiae in 4.26% (n = 6). No other anticipated nasal or intracranial complications such as intra-ventricular haemorrhage, epistaxis, mortality was found as mentioned in several other studies [6, 13, 22, 38, 40, 41]. Complication rate was significantly less when compared [17, 40]. Graded fashion of skull base repair helps to achieve good outcome as seen in our study [6, 42].

Conclusion

In conclusion, this study was focused on the ENT perspective of the endoscopic transnasal trans-sphenoidal approach for pituitary adenomas. Considering the result of this study, in terms of reduced rate of morbidity and complications is encouraging. The endoscopic skull base defect closure is challenging and requires skill, meticulous approach and synchronised team work in order to achieve a favourable outcome. The repair of the skull base defect requires irresistible approach and all possible techniques should be pre-meditated for better results. The incidence of rhinological and intracranial complications such as CSF leak, pneumocepahalocele etc. can be minimised and if encountered has to be dealt in an organised manner, thus contributing to a reduced rate of complications. The complications encountered must be foreseen and managed with a proficient approach. With the combined effort of otorhinolaryngologists and neurosurgical team, it may establish as a gold standard method.

Funding

No funding sources.

Compliance with Ethical Standards

Conflict of interest

None declared.

Ethical Approval

This study was approved by the Institutional Ethics Committee.