Microscopic Transsphenoidal Resection of Pituitary Adenomas With Conchal Sphenoid Sinus: a Report of Three Cases

Object The present study aimed to investigate the methodology and characteristic of the microscopic transsphenoidal resection of pituitary adenomas with a conchal sphenoid sinus. Method Three patients with sellar tumor and non-pneumatized sphenoid sinuses received microscopic transsphenoidal surgery with help of neuronavigation system. Result The three conchal spenoid sinuses were accessed safely, total resction was achieved and no serious complication occurred. we found that pituitary tumors with conchal sphenoid sinus was more smaller and soft. Conclusion the presence of a conchal sphenoid sinus is not an absolute contraindication for employing the microscopic transsphenoidal route in the resction of pituitary adenomas with help of neuronavigation.


Introduction
The microscopic transsphenoidal route is considered the standard procedure for cure pituitary adenoms, which represent at least 10% of all intracranial tumors [i]. Transsphenoidal route needs pass through the sphenoid sinus to reach the sella. According to the commonly used classi cation system proposed by Hammer & Radberg (1961), the pneumatization of the SS is divided into three types: conchal, presellar, and sellar [ii]. The conchal nonpneumatized sphenoid was always considered to be a contraindication to the transsphenoid approach to the sella. It usually makes this approach less favorable [iii]. The presence of a conchal sphenoid sinus is typically considered to be one of the contraindications for the use of transsphenoidal route due to the di culties of intraoperative localization and exposure of the sellar oor[iv] -[v]- [vi] . The current study presents three cases of resection of sellar tumors with conchal sphenoid sinus via the microscopic transsphenoidal surgery. Written informed consent was obtained from the patient's family and the patient for all three cases.

Case 1 History and clinical examination
35-year-old female, unfortunately falling at home, head hitting the oor, unbearable headache arise after injury, she was been transported urgently to the local hospital, the brain CT scan was performed quickly, found a lesion in the sellar area without intracranial hemorrhage; 4 months later for further examination and treatment she went to our department. Nervous system examination found no obvious signs of neurological de cits.
Neuroimaging and serum hormones MR scan revealed a lesion in the sellar cavity with a concal sphenoid sinus, tumor with height of 1.5cm, enhanced scan showed a uniform homogeneous enhancement. Serum hormone test found no signi cant abnormal increase in hormones, all hormones indicators are in the normal range gure1 A-B .
Treatment we also applied Microscopic transsphenoidal surgery on this patient with the help of neuronavigation system gure1C . The position of patient was supine during procedure of surgery. The incision was in the middle of nasal septum. Using nasal dilator make a surgical corridor between mucosa and bone of septum. It's intermittently employing baton of navigation to nd hole of sphenoid sinus accurately, then we gradually drill a tunnel, the diameter was about 1.6cm, through concal shpenoid sinus to the sellar oor. When the dura of sellar oor was full exposure, we found that dura was lack of blood supply, then the dura was cut off in X-shaped without bleeding of intercavernous sinuses. The tumor tissue that is in solid, intermediate stiffness form and lack blood supply was owed out through the dura incision. After

Case 2
History and clinical examination 25-year-old male patient presented to our hospital's department of Cardiology with chest tightness and asthma for more than 2 months. They consider that this patient may have acromegaly because he has a rough face. The brain MRI examination found the sellar region had a turmor of pituitary, Then he was turned to our department for further treatment. Neurological examination: In addition to special facial changes, the patient also exists oily and thickly skin, sweating, enlargement of heart, heart rate 110 beats/min, lower extremity with moderate edema.

Neuroimaging and serum hormones
The MR image found that a lesions occupied in the seller region, with height 18mm, enhanced scaning show that tumor was moderately enhanced; skull bone was unevenly thickening, patched enhancement signal was broadly showed in the diploe of skull bone, the signal is not Uniform. Sphenoid sinus area was full of bone signals, been considered a non-pneumatolytic sphenoid sinus Figure2 A-B . Serum GH level was higher than 40 ng / ml, PRL level was equaled 343.99 ng / ml (reference range 2.1-17.7 ng / ml), IGF-1 was 392 ng / ml (reference range 116-358 ng / ml), Other hormone levels were no obvious abnormalities.

Treatment
Under the guidance of neuro-navigation, we applied microscopic transsphenoidal surgery to resect the pituitary adenomas. Bilateral nasal of this patient were stenosis and the right stenosis was more signi cant. Removed the bilateral middle turbinate, left nasal septum before the left side of the incision.
Under the guidance of the navigation, and gradually removed the skull base. Finally reached the saddle, exposure of the dura of sella, when the dura was incised by mini knife, we found that the tumor tissue , soft, milky white, blood supplying not rich, ow out from inner sella; as the tumor stopped ow the incision of dura was enlarged by scissors, then the residual tumor was removed totally.

Discussion
The presence of a conchal sphenoid sinus is typically considered to be one of the contraindications for the use of transsphenoidal route due to the di culties of intraoperative localization and exposure of the sellar oor. With advances of the application of microscopy and the application of neural navigation technology, we are able to safely carry out transsphenoidal resection of pituitary adenomas with conchal sphenoid sinus. Compared with the non conchal sphnoid sinus pituitary adenoma, the channel of the transsphenoidal surgery will be smaller, the operation space will be limited, it is more di cult that the surgical instrument be operating in this narrow corridor. We consider that surgical resection of pituitary adenoma with conchal sphnoid sinus under microscope have more advantages than endoscopic transsphnoidal surgery due to microscope surgery need less surgical instruments than endocopic surgery. the distance of the internal carotid artery of the cavernous segment should be carefully measured preoperatively, which determines the size of corridor of TSS surgery[i], which is the adverse aspect to exsect pituitary lesion with conchal sphnoid sinus; during the procedure of drilling conchal sphnoid sinus we should be intermittently apply the probe of neuronavigation to con rm the distance of carotid arteries and to adjust the direction of surgery path to prevent injury the internal carotid arteries accidentally.
But in these four patients of pituitary adenoma with conchal sphnoid sinus, we found, during TSS procedure, that sphenoid boney tissue is relatively loose and easy to drill away, hemostasis of bone surface is not di cult, the sellar oor dura mater is smooth, few vessel, easy to open, Except one case which have very small intercavernous sinus is not caused a signi cant impact to operation, which may be due to bilateral cavernous sinus blood circulate through a large number of cancellous bone communication instead of the intercavernous sinus of sellar dura, so poor blood supply through sellar dura, bleeding was signi cantly reduced more rather than those with pneumatized well sphenoid sinus. Loose bone within the sinusoids is easy to drill, bleeding could be stop immediately by the heat and bone meal, when necessary, bone wax can also be used to stop bone bleeding easily. At the same time, we found that the size of pituitary adenoma with conchal sphnoid sinus are smaller, the average diameter is about 1.9cm, and the tissue of tumor is soft easy removal, and lesions are without rich blood supply, less bleeding. These nds need further research because there are exist same papers already published about that some pituitary adenoma with conchal sphnoid sinus have larger diameter [ii]. Therefore, we believe that pituitary adenoma with conchal sphnoid sinus can relatively safe be resected by transsphenoidal surgery with aid of the neuronavigation and achieve satisfactory therapeutic effect, this type PA is no longer a contraindication to transsphenoidal surgery.
To study the anatomy of sphenoid sinus we will nd that sphenoid sinus can be divided into conchal type, saddle type, and saddle according to the degree of pneumatolysis; There is study show that the degree of pneumatization of sphenoid sinus play an important role to safely carry out TS surgery, suggest that the circumstance of sphenoid sinus should be full evaluated preoperatively [iii]. Our experience is not only must carry on the MRI scaning preoperatively, also must carry on the thin layer CT scanning of saddle area that would give us more information to comprehensively understand degree of pneumatolysis of sphenoid sinus, and to know the relationship between the internal carotid artery and sphenoid sinus. Conchal type of sphenoid sinus occurrence rate is very low, Song Tao team found that the incidence of sphenoid sinus of nonpneumatized is 6% in Chinese population [iv], that is consistent with our center study found. Conchal type of pituitary adenoma is a taboo for transsphenoidal surgery in the past, this is due to the thickening of the sphenoid sinus bone cause obstacles to surgery corridor, making the surgeon lost and increasing the risk to injury the internal carotid artery; The application of neuronavigation can better solve this problem, with the aid of neuronavigation improve the success rate of surgery; reduce the rate of complication of operation [v]. In addition, because the bone structure of sphenoid sinus and skull base those structure scanning by MRI is less clear than CT scanning and Studies have shown that error of navigation registration base on CT image is smaller than MRI, we choose CT's neuronavigation, the accuracy is reliable. we are not machinery in accordance with the instruction of the navigation, but we should combin with the experience of surgeons and the observation of sella anatomy, at the same time, to judge the right direction of surgery.
In this study we think pituitary adenomas with conchal sphenoid sinus, the surgery corridor is narrow, so microscopic resection with the aid of neuronavigation has more certain advantages than endoscopic TSS. microscopic surgery use the surgical instruments less than endoscope TTS, so the microscopic TTS are easier to operate, less time needed for surgery; endoscopic observation Angle more wide than microscope[vi], but we found that this type of pituitary adenomas tumors are smaller, no obvious intercavernous sinus, don't need more viewing Angle in resection of pituitary adenoma with conchal sphenoid sinus. although neural endoscopic resection of pituitary adenoma surgery is more and more widely applied, according to our experience, microscopic transsphenoid surgery applying to conchal type of pituitary adenoma has some advantages. at the same time we found that between pituitary adenomas with conchal sphenoid siuns and other type pituitary adenomas exist certain differences, such as anatomical differences, tumor biological behavior characteristics and so on, it remains to be further research.
[ Conclusion the presence of a conchal sphenoid sinus is not an absolute contraindication for employing the microscopic transsphenoidal route in the resction of pituitary adenomas with help of neuronavigation.
Pituitary adenomas with conchal sphenoid sinus, the surgery corridor is narrow, microscopic resection with the aid of neuronavigation may has more certain advantages than endoscopic TSS.  Figure 1 The preoperative MR imaging and intraoperative picture of Case one: A~B, Preoperative MR image showed that saddle area occupied by the pituitary adenomas with concal sphenoid sinus. C, Neuronavigation guided the surgical direction. D, Postoperative MR images revealed complete tumor resection. E, Open the anterior wall of sphenoid sinus after exposure of ossi cation of the sphenoid sinus. F, Open the sellar oor display dural thick, no obvious intercavernous sinus. G, Soft tumor texture, less blood supply. H, The medial wall of cavernous sinus was revealed after tumor resection.

Figure 2
Preoperative and postoperative MR imaging of Case two and Case three: A-B: case 2 preoperative axial and sagittal magnetic resonance imaging, found a lesion in the saddle area, the maximum diameter of tumor was 18mm, sphenoid sinus calci cation, and visible skull brous hyperplasia. C-D: Case 2 postoperative 2 months review of magnetic resonance imaging, there had a bony surgical pathway in the sphenoid sinus, no tumor recurrence. E-F: case 3 preoperative coronal and sagittal magnetic resonance imaging, found a microadenomas on the right side of the pituitary fossa, with conchal sphenoid sinus. G-H: Case 3 postoperative MR image after surgery of 4.5 months showed no tumor recurrence.