We would like to thank the endocrinology unit and the operative room team for their help and support in the management of these patients. We do not have any funding source for this work nor conflict of interest.

The protocol here illustrated follows the guidelines of the human research ethics committee at the University Hospital of Lausanne.
NOTE: The procedure explained here is focused on the classical approach performed for pituitary adenomas.
1. Preoperative Protocol
<ol>
	<li>Systematically perform a pre-operative craniofacial CT-Scan and MRI, along with the endocrinological and ophthalmological assessments.</li>
</ol>
2. Positioning and Anesthesia
<ol>
	<li>Induce general anesthesia and perform orotracheal intubation.</li>
	<li>Place the patient in the supine position after general anesthesia and orotracheal intubation.</li>
	<li>Position the head in a head holder and secure the band for the magnetic neuro-navigation around the head.</li>
	<li>Raise the head of the table to 20 &#176; to improve venous drainage and slightly rotate the head about 30 &#176; towards the neurosurgeon, while performing a contralateral head tilt. 
	NOTE: The degree of extension or flexion of the patient&#39;s head depends upon the surgical target: slightly flexed (15 - 20 &#176;)17 for the sella turcica approach, neutral for anterior skull base surgery, and flexed up to 45 &#176; for lower clival lesions.</li>
	<li>Sterilize the face with an alcohol-free chlorexidine solution. Clean the nasal fossae with an antiseptic solution before wicking with cotton pads impregnated with diluted Xylocaine 1% with adrenaline (1:1,000,000). 
	NOTE: In addition to the local anesthesia and vasoconstriction, this wicking also provides a lateral retraction of the middle turbinate to enable the endoscopic approach. An adjustable holding arm may be fixed to the operating table to be used at specific phases of the surgical procedure (particularly during the sellar phase). However, some surgeons prefer not to fix the endoscope to have a more dynamic view of the surgical field. In these cases, they either leave the endoscope to the assistant to enable work with both hands or they hold the endoscope themselves.</li>
	<li>Clean the right abdominal quadrants and drape the abdomen while leaving a small window in the right peri-umbilical region as it represents a possible site of fat graft harvesting in the case of an intra-operative cerebrospinal fluid (CSF) fistula. 
	NOTE: Anesthesiologists should take special care for deep morphinic analgesia and control the mean blood pressure during the nasal phase of the procedure, to reduce the bleeding due to the rich innervation of the nasal mucosa.</li>
</ol>
3. Surgery
NOTE: The choice of the side of the nasal fossa to be used primarily is determined by the nasal anatomy (septal deviation, mega-turbinate, polyps, previous surgeries, etc.), lateral extensions of the tumor (contralateral approach to a lateral extension), and the size of the tumor (binostril approach for large tumors). In the majority of pituitary adenomas, a unilateral approach is sufficient to achieve a good exposure of the tumor and its extensions.
<ol>
	<li>Nasal phase
	<ol>
		<li>Introduce the 0 &#176; short rigid endoscope (18 cm length, 4 mm diameter) into the right nostril to identify the inferior and middle turbinates laterally and the nasal septum medially. Prefer the left nostril approach in case of septal deviations, anomalies of the turbinates, or for specific tumor extensions that are detected in pre-operative imaging.</li>
		<li>Place the endoscope tube either at the superior or inferior aspect of the nostril to provide enough space to other instruments entering the nasal cavity.</li>
		<li>Gently retract laterally the middle and superior turbinates with a blunt spatula to achieve a wide access to the ipsilateral sphenoid ostium. Take care to support the superior and middle turbinates through their entire length with the spatula to avoid fractures during the retraction maneuver.</li>
	</ol>
	</li>
	<li>Sphenoidal phase 
	<ol>
		<li>Coagulate the nasal mucosa in a vertical linear fashion for about 10-15 mm with a monopolar between the sphenoid osteum and the choana, to avoid bleeding from the nasoseptal arteries (branches of the sphenopalatine arteries running at the superior margin of the choana).</li>
		<li>Open the coagulated nasal mucosa with a blunt spatula vertically until a bony contact, corresponding to the vomer, is felt.</li>
		<li>Follow the vomer anteriorly until its junction with the nasal cartilaginous septum and push it to the left side to expose the contralateral sphenoid ostium, while taking care to remain in the submucosal plane.</li>
		<li>Expose and remove the sphenoid rostrum with bone forceps and a rongeur extending the resection from one ostium to the other. This opening of the sphenoid sinus allows exposure of the exocranial skull base surface.</li>
		<li>Gently remove the sphenoid mucosa if it interferes with the sellar opening.</li>
		<li>Remove the sphenoid septum (often multiple septa are present) with rongeurs to provide a wide exposure of the sella turcica.</li>
		<li>Carefully analyze the pre-operative magnetic resonance imaging (MRI) and/or CT scan for the number and direction of these septations; this is crucial to recognize the relevant anatomy. Some of these septations may insert directly onto the carotid prominences and therefore should be identified as important landmarks during this phase of the surgery (Figure 1, Figure 2, Figure 3, Figure 4). 
		NOTE: The CT-scan was performed using a 64-detector row-based system. Three-dimensional reconstruction was processed using a series of thin-slice data. The MRI protocol was performed on a 3-Tesla imager. The protocol included a sagittal T1-weighted gradient-echo sequence (MPRAGE) with and without contrast injection, 160 contiguous slices, 1-mm isotropic voxel, repetition time (TR) 2,300 ms, echo time (TE) 2.98 ms, field of view 256 mm as a basis for segmentation, and 3D T2 sequence.</li>
	</ol>
	</li>
	<li>Sellar phase
	<ol>
		<li>Identify the sella turcica anterior and superior to the clival recess in the midline. 
		NOTE: In large and/or invasive pituitary tumors, the sellar floor may be very thin or completely eroded. The sellar floor is limited anteriorly by the depression that corresponds to the tuberculum sellae and laterally by the carotid prominences (C3 to C5 segments) and by the optico-carotid recesses.</li>
		<li>After identification of the carotid prominences laterally, open the sellar floor with a 5-mm large bone cutter to tailor or hinge a bone flap that may be repositioned at the end of the surgery. At this point, enlarge the sellar osteotomy laterally or anteriorly with bone rongeurs, according to the surgical target. 
		NOTE: Some surgeons may prefer to open the sellar floor with a diamond drill and to enlarge the bone opening secondarily with a small bone rongeur. This procedure may be faster and it is generally used with extended approaches. However, the bone cannot be repositioned at the end of the procedure and attention should be paid to drill in the midline to avoid injuries to the carotid artery. Use neuronavigation to guide the procedure.</li>
		<li>Open the sellar dura with a micro-blade in the midline for a macroadenoma or laterally in cases of lateralized microadenomas. If needed, extend this dural opening laterally and take care to avoid any injury to the carotid arteries.</li>
		<li>Limit the risk of arachnoid breaches in the anterior recess by performing a small anterior opening of the dura and push up the dura with the suction tip to provide sufficient access to the sellar contents.</li>
		<li>Remove the tumor tissue with annular angled curettes, forceps, and suction tips.</li>
		<li>After an intra-sellar saline wash-out, use the 30 &#176; angled endoscope to inspect the intrasellar space and check for any remnant, particularly towards the cavernous sinuses.</li>
		<li>Ask for a Valsalva maneuver at the end of the resection procedure to detect a CSF leak before the closure step.</li>
	</ol>
	</li>
	<li>Closure
	<ol>
		<li>Do not place any hemostatic material within the sella if not absolutely required, to enable a more accurate interpretation of the postoperative MRI.</li>
		<li>Obtain hemostasis within the pituitary sella with patient saline irrigation and slight pressure with cotton pads.</li>
		<li>Reconstruct the durotomy with a patch of bio-absorbable artificial dural substitute that is placed extradurally and reinforce it with a thin layer of surgical adhesive (e.g., bioglue).</li>
		<li>Replace the bone flap and secure it with surgical adhesive. 
		NOTE: In cases where the sellar floor is drilled, the disarticulated rostrum or a piece of cartilage coming from the posterior part of the nasal septum may be used to close the bone defect. Other options of the use of synthetic materials (e.g., Porex plates) have also been described.</li>
		<li>Do not leave artificial material in the sphenoid sinus to avoid any chronic inflammatory reaction.</li>
		<li>Pay attention to the hemostasis of the nasal mucosa, particularly in the region of the nasoseptal branches of the sphenopalatine arteries on both sides, to prevent postoperative epistaxis.</li>
		<li>Gently replace the superior and middle turbinates in their original position with a blunt spatula.</li>
		<li>If a CSF leak has been observed during the procedure, pack the sella with a small fat graft. Do not use nasal packing unless strictly necessary.</li>
	</ol>
	</li>
</ol>
4. Postoperative management
<ol>
	<li>Provide adequate hormonal substitution in the perioperative period. Use intravenous hydrocortisone during the first 24 h (100 mg per day) and then provide an oral substitution (variable from case to case but at least 30 mg per day during the hospitalization).</li>
	<li>Twice a day, check blood and urinary osmolality and electrolytes, along with the urinary density. Monitor the urinary output constantly. Perform a hormonal check-up to evaluate the anterior pituitary function at day 4 postoperatively.</li>
	<li>Keep amoxicillin/clavulanate at 1.2 g twice a day till day 5 postoperatively. Provide standard analgesic treatment while combining acetaminophen and NSAIDS and provide tramadol for refractory pain.</li>
	<li>Constantly clean nasal fossa with saline solution to limit the risk of postoperative crostous rhinitis.</li>
	<li>Explain to the patient the importance of avoiding Valsalva maneuvers to allow a correct healing of the operative site during the first postoperative weeks.</li>
	<li>Perform an MRI in the early postoperative period only if the resection is suspected to be subtotal, if the intraoperative aspect is atypical for pituitary adenomas, or if complications are suspected. After standard procedures, perform the cerebral MRI at 3 months postoperatively.</li>
	<li>Perform a first evaluation 3 months postoperatively and organize follow-ups in collaboration with the endocrinology unit and schedule them according to the pathology and the extent of resection.</li>
</ol>

<ol>
	<li>Carrau, R. L., Jho, H. D., Ko, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transnasal-transsphenoidal+endoscopic+surgery+of+the+pituitary+gland.">Transnasal-transsphenoidal endoscopic surgery of the pituitary gland.</a> Laryngoscope. 106 (7), 914-918 (1996).</li><li>Kassam, A. B., Gardner, P., Snyderman, C., Mintz, A., Carrau, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expanded+endonasal+approach:+fully+endoscopic,+completely+transnasal+approach+to+the+middle+third+of+the+clivus,+petrous+bone,+middle+cranial+fossa,+and+infratemporal+fossa.">Expanded endonasal approach: fully endoscopic, completely transnasal approach to the middle third of the clivus, petrous bone, middle cranial fossa, and infratemporal fossa.</a> Neurosurg Focus. 19 (1), E6 (2005).</li><li>Jouanneau, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+endoscopic+endonasal+approach+to+the+Meckel's+cave+tumors:+surgical+technique+and+indications.">The endoscopic endonasal approach to the Meckel's cave tumors: surgical technique and indications.</a> World Neurosurg. 82 (6 Suppl), S155-S161 (2014).</li><li>Essayed, W. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopic+endonasal+approach+to+the+ventral+brainstem:+anatomical+feasibility+and+surgical+limitations.">Endoscopic endonasal approach to the ventral brainstem: anatomical feasibility and surgical limitations.</a> J Neurosurg. , 1-8 (2017).</li><li>Messerer, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extended+endoscopic+endonasal+approach+to+clival+and+paraclival+tumors:+Indications+and+limits.">Extended endoscopic endonasal approach to clival and paraclival tumors: Indications and limits.</a> Neurochirurgie. 62 (3), 136-145 (2016).</li><li>Rotenberg, B., Tam, S., Ryu, W. H., Duggal, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microscopic+versus+endoscopic+pituitary+surgery:+a+systematic+review.">Microscopic versus endoscopic pituitary surgery: a systematic review.</a> Laryngoscope. 120 (7), 1292-1297 (2010).</li><li>Zaidi, H. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+outcomes+between+a+less+experienced+surgeon+using+a+fully+endoscopic+technique+and+a+very+experienced+surgeon+using+a+microscopic+transsphenoidal+technique+for+pituitary+adenoma.">Comparison of outcomes between a less experienced surgeon using a fully endoscopic technique and a very experienced surgeon using a microscopic transsphenoidal technique for pituitary adenoma.</a> J Neurosurg. 124 (3), 596-604 (2016).</li><li>Juraschka, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopic+endonasal+transsphenoidal+approach+to+large+and+giant+pituitary+adenomas:+institutional+experience+and+predictors+of+extent+of+resection.">Endoscopic endonasal transsphenoidal approach to large and giant pituitary adenomas: institutional experience and predictors of extent of resection.</a> J Neurosurg. 121 (1), 75-83 (2014).</li><li>Pratheesh, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+current+role+of+transcranial+surgery+in+the+management+of+pituitary+adenomas.">The current role of transcranial surgery in the management of pituitary adenomas.</a> Pituitary. 16 (4), 419-434 (2013).</li><li>Messerer, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evidence+of+improved+surgical+outcome+following+endoscopy+for+nonfunctioning+pituitary+adenoma+removal.">Evidence of improved surgical outcome following endoscopy for nonfunctioning pituitary adenoma removal.</a> Neurosurg Focus. 30 (4), E11 (2011).</li><li>Zoli, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cavernous+sinus+invasion+by+pituitary+adenomas:+role+of+endoscopic+endonasal+surgery.">Cavernous sinus invasion by pituitary adenomas: role of endoscopic endonasal surgery.</a> J Neurosurg Sci. 60 (4), 485-494 (2016).</li><li>Hamid, O., El Fiky, L., Hassan, O., Kotb, A., El Fiky, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anatomic+Variations+of+the+Sphenoid+Sinus+and+Their+Impact+on+Trans-sphenoid+Pituitary+Surgery.">Anatomic Variations of the Sphenoid Sinus and Their Impact on Trans-sphenoid Pituitary Surgery.</a> Skull Base. 18 (1), 9-15 (2008).</li><li>Frank, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+endoscopic+extended+transsphenoidal+approach+for+craniopharyngiomas.">The endoscopic extended transsphenoidal approach for craniopharyngiomas.</a> Neurosurgery. 59 (1 Suppl 1), ONS75-ONS83 (2006).</li><li>Cossu, G., Daniel, R. T., Leviver, M., Sykiotis, G., Messerer, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pituitary+metastasis+and+the+role+of+CSF+pulsations+in+secondary+displacement+after+surgery.">Pituitary metastasis and the role of CSF pulsations in secondary displacement after surgery.</a> Journal of Neurology and Neurosurgery. 3 (2), (2016).</li><li>Tarabay, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primary+pituitary+lymphoma:+an+update+of+the+literature.">Primary pituitary lymphoma: an update of the literature.</a> J Neurooncol. 130 (3), 383-395 (2016).</li><li>Dehdashti, A. R., Karabatsou, K., Ganna, A., Witterick, I., Gentili, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expanded+endoscopic+endonasal+approach+for+treatment+of+clival+chordomas:+early+results+in+12+patients.">Expanded endoscopic endonasal approach for treatment of clival chordomas: early results in 12 patients.</a> Neurosurgery. 63 (2), 299-307 (2008).</li><li>Alfieri, A., Jho, H. D., Tschabitscher, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopic+endonasal+approach+to+the+ventral+cranio-cervical+junction:+anatomical+study.">Endoscopic endonasal approach to the ventral cranio-cervical junction: anatomical study.</a> Acta Neurochir (Wien). 144 (3), 219-225 (2002).</li><li>Trouillas, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+prognostic+clinicopathological+classification+of+pituitary+adenomas:+a+multicentric+case-control+study+of+410+patients+with+8+years+post-operative+follow-up.">A new prognostic clinicopathological classification of pituitary adenomas: a multicentric case-control study of 410 patients with 8 years post-operative follow-up.</a> Acta Neuropathol. 126 (1), 123-135 (2013).</li><li>Kuo, J. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Congress+of+Neurological+Surgeons+Systematic+Review+and+Evidence-Based+Guideline+on+Surgical+Techniques+and+Technologies+for+the+Management+of+Patients+With+Nonfunctioning+Pituitary+Adenomas.">Congress of Neurological Surgeons Systematic Review and Evidence-Based Guideline on Surgical Techniques and Technologies for the Management of Patients With Nonfunctioning Pituitary Adenomas.</a> Neurosurgery. 79 (4), E536-E538 (2016).</li><li>Lucas, J. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Congress+of+Neurological+Surgeons+Systematic+Review+and+Evidence-Based+Guideline+on+Primary+Management+of+Patients+With+Nonfunctioning+Pituitary+Adenomas.">Congress of Neurological Surgeons Systematic Review and Evidence-Based Guideline on Primary Management of Patients With Nonfunctioning Pituitary Adenomas.</a> Neurosurgery. 79 (4), E533-E535 (2016).</li><li>Teixeira, M., Souteiro, P., Carvalho, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prolactinoma+management:+predictors+of+remission+and+recurrence+after+dopamine+agonists+withdrawal.">Prolactinoma management: predictors of remission and recurrence after dopamine agonists withdrawal.</a> Pituitary. , (2017).</li><li>Cappabianca, P., de Divitiis, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopy+and+transsphenoidal+surgery.">Endoscopy and transsphenoidal surgery.</a> Neurosurgery. 54 (5), 1043-1048 (2004).</li><li>Jho, H. D., Carrau, R. L., Ko, Y., Daly, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopic+pituitary+surgery:+an+early+experience.">Endoscopic pituitary surgery: an early experience.</a> Surg Neurol. 47 (3), 213-222 (1997).</li><li>Borg, A., Kirkman, M. A., Choi, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopic+Endonasal+Anterior+Skull+Base+Surgery:+A+Systematic+Review+of+Complications+During+the+Past+65+Years.">Endoscopic Endonasal Anterior Skull Base Surgery: A Systematic Review of Complications During the Past 65 Years.</a> World Neurosurg. 95, 383-391 (2016).</li><li>Buchfelder, M., Schlaffer, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+Techniques+in+the+Surgical+Treatment+of+Acromegaly:+Applications+and+Efficacy.">Novel Techniques in the Surgical Treatment of Acromegaly: Applications and Efficacy.</a> Neuroendocrinology. 103 (1), 32-41 (2016).</li><li>Shirakawa, M., Yoshimura, S., Yamada, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effectiveness+of+Endoscopic+Endonasal+Transsphenoidal+Surgery+Using+a+Neuronavigation:+Clinical+Results+of+178+Pituitary+Adenomas.">Effectiveness of Endoscopic Endonasal Transsphenoidal Surgery Using a Neuronavigation: Clinical Results of 178 Pituitary Adenomas.</a> Journal of Neurology and Neuroscience. 7 (1:71), (2016).</li><li>Dehdashti, A. R., Ganna, A., Karabatsou, K., Gentili, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pure+endoscopic+endonasal+approach+for+pituitary+adenomas:+early+surgical+results+in+200+patients+and+comparison+with+previous+microsurgical+series.">Pure endoscopic endonasal approach for pituitary adenomas: early surgical results in 200 patients and comparison with previous microsurgical series.</a> Neurosurgery. 62 (5), 1006-1015 (2008).</li><li>Starnoni, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surgical+treatment+of+acromegaly+according+to+the+2010+remission+criteria:+systematic+review+and+meta-analysis.">Surgical treatment of acromegaly according to the 2010 remission criteria: systematic review and meta-analysis.</a> Acta Neurochir (Wien). 158 (11), 2109-2121 (2016).</li><li>Alahmadi, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+technique+on+cushing+disease+outcome+using+strict+remission+criteria.">Impact of technique on cushing disease outcome using strict remission criteria.</a> Can J Neurol Sci. 40 (3), 334-341 (2013).</li><li>Donegan, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surgical+Outcomes+of+Prolactinomas+in+Recent+Era:+Results+of+a+Heterogenous+Group.">Surgical Outcomes of Prolactinomas in Recent Era: Results of a Heterogenous Group.</a> Endocr Pract. 23 (1), 37-45 (2017).</li><li>Andereggen, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=10-year+follow-up+study+comparing+primary+medical+vs.+surgical+therapy+in+women+with+prolactinomas.">10-year follow-up study comparing primary medical vs. surgical therapy in women with prolactinomas.</a> Endocrine. 55 (1), 223-230 (2017).</li><li>Onnestam, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=National+incidence+and+prevalence+of+TSH-secreting+pituitary+adenomas+in+Sweden.">National incidence and prevalence of TSH-secreting pituitary adenomas in Sweden.</a> J Clin Endocrinol Metab. 98 (2), 626-635 (2013).</li><li>Malchiodi, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thyrotropin-secreting+pituitary+adenomas:+outcome+of+pituitary+surgery+and+irradiation.">Thyrotropin-secreting pituitary adenomas: outcome of pituitary surgery and irradiation.</a> J Clin Endocrinol Metab. 99 (6), 2069-2076 (2014).</li><li>Yamada, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinicopathological+characteristics+and+therapeutic+outcomes+in+thyrotropin-secreting+pituitary+adenomas:+a+single-center+study+of+90+cases.">Clinicopathological characteristics and therapeutic outcomes in thyrotropin-secreting pituitary adenomas: a single-center study of 90 cases.</a> J Neurosurg. 121 (6), 1462-1473 (2014).</li></ol>

No conflict of interest.

For the majority of pituitary tumors, surgery remains the first-line treatment in case of symptomatic patients19,20. Only for prolactin (PRL)-secreting adenomas, the first-line of treatment is dopamine agonists and surgery is chosen secondarily when medical treatment fails21.
Since the introduction of the endoscope in the field of skull base surgery in the early 1990&#39;s22,<s...

The introduction of endoscopic techniques to the skull base surgery has markedly improved the outcomes of skull base surgery when used in itself or as an adjunct to standard microsurgical approaches. The endoscopic endonasal approach was initially introduced to treat sellar lesions1, but during the last two decades the applications of this technique have expanded thanks to significant technological improvements and increased surgical experience. The endoscopic approach is now also used for lesions of the anterior and antero-lateral skull base through extended midline and paramedian approaches. Approaches from the anterior skull base to the odontoid are now safely performed in many specialized centers with satisfying results2,3,4,5.
In fact, the endoscope allows a direct visualization of the lesion through a natural access without crossing important neuro-vascular structures. Multiple reviews have sustained the safety and relative advantages of endoscopic procedures over traditional microscope-based approaches and affirmed that the major outcomes, such as the extent of tumor resection and the changes in hormonal levels, were not different between the two approaches. However neurological complications, operative time and hospitalization length, as well as patients&#39; postoperative discomfort, were significantly lower with the endoscopic approach6. According to a provocative publication, even a less experienced surgeon may achieve a similar outcome with a fully endoscopic technique as a very experienced surgeon using a microscopic technique in a cohort of non-functioning pituitary adenomas7.
The endoscopic endonasal trans-sphenoidal approach is actually widely recommended for sellar lesions, even in the case of cavernous sinus invasion or suprasellar extension. If the suprasellar extension is very important, a fully-endoscopic two-staged procedure may be performed, while waiting for the natural descent of the residue8. If the diaphragm is very tight (&#34;waist sign&#34;), a transcranial approach may be performed to address the suprasellar component9. Concerning the invasion of the cavernous sinus, the endoscopic technique seems to be superior to microscopic techniques for Knosp grade 2 and 3 non-functioning pituitary adenomas10, and the endoscopic endonasal inspection may help in detecting the invasion of the cavernous sinus11.
Factors which might hinder an endoscopic radical excision are: tumors extending above and lateral to the supraclinoid internal artery or the presence of &#34;kissing carotids&#34;, an asymmetric subfrontal extension, tumors reaching the foramen of Monro, or fibrous tumors invading the surrounding cerebral parenchyma9. In these complicated cases, a combined transcranial approach may be proposed to the patient. Also the pneumatization of the sphenoid sinus is an important factor in determining the feasibility of the surgery because conchal type sinuses render the endoscopic approach more challenging12.
Through their personal experience of approximately 500 endoscopic endonasal approaches for pituitary adenomas, the authors here describe the different stages of the approach for pituitary tumors. The surgery may be divided into three main steps: the nasal, the sphenoidal, and the sellar phase. They are performed through a fully endoscopic procedure. The cohort here described included patients with micro or macro-adenomas with a variable extension to the cavernous sinus, to the sphenoid sinus, or the suprasellar space. Both functioning and non-functioning adenomas were included.
A fully endoscopic procedure may be also performed for a variety of other lesions such as craniopharyngiomas, pituitary metastases, clival chordomas, or petro-clival meningiomas. However, these pathologies often required wider approaches and the description of these variants goes beyond the aim of this paper.
Indication
The procedure described here is for pituitary adenomas (functioning or non-functioning). A suprasellar extension was not a contraindication for the procedure, nor were the extension or invasion of the cavernous sinus. The pneumatization of the sphenoidal sinus and the orientation of the septa of the sphenoidal sinus were analyzed at the pre-op CT-scan. Also the orientation of the optic nerve and the internal carotid artery were important factors to plan the surgical strategy.
This surgical technique can also be useful for others tumors located in the sellar region like craniopharyngiomas13, symptomatic Rathke&#39;s cleft cysts, pituitary metastases14, or lymphomas15. Also, other lesions may be approached through the endoscopic approach, such as meningiomas of the sellar diaphragm or the sphenoidal planum, meningiomas of the petro-clival region and clival chordomas5,16, and epidermoid or dermoid cysts of the prepontine cistern. In these cases, however, a wider approach is necessary.

<table>
	<tbody>
		<tr>
			<td>The StealthStation surgical navigation system</td>
			<td>Medtronic</td>
			<td>ENT Fusion Software 9733652</td>
			<td></td>
		</tr>
		<tr>
			<td>4-mm 18cm 0&#176; rigid endoscope</td>
			<td>Karl Storz</td>
			<td>28132AA</td>
			<td></td>
		</tr>
		<tr>
			<td>4-mm 18cm 30&#176; rigid endoscope</td>
			<td>Karl Storz</td>
			<td>28132BVA</td>
			<td></td>
		</tr>
		<tr>
			<td>4-mm 18cm 45&#176; rigid endoscope</td>
			<td>Karl Storz</td>
			<td>28132FVA</td>
			<td></td>
		</tr>
		<tr>
			<td>Suction Tube</td>
			<td>Karl Storz</td>
			<td>28164XA</td>
			<td></td>
		</tr>
		<tr>
			<td>Coagulation Cannulas</td>
			<td>Karl Storz</td>
			<td>28164MXB</td>
			<td></td>
		</tr>
		<tr>
			<td>Bipolar Forceps</td>
			<td>Karl Storz</td>
			<td>28164BDB</td>
			<td></td>
		</tr>
		<tr>
			<td>Kerrison Bone Punches</td>
			<td>Karl Storz</td>
			<td>28164MKA</td>
			<td></td>
		</tr>
		<tr>
			<td>Kerrison Bone Punches</td>
			<td>Karl Storz</td>
			<td>28164MKB</td>
			<td></td>
		</tr>
		<tr>
			<td>Kerrison Bone Punches</td>
			<td>Karl Storz</td>
			<td>28164MKC</td>
			<td></td>
		</tr>
		<tr>
			<td>Ring Curettes</td>
			<td>Karl Storz</td>
			<td>28164RN</td>
			<td></td>
		</tr>
		<tr>
			<td>Ring Curettes</td>
			<td>Karl Storz</td>
			<td>28164RO</td>
			<td></td>
		</tr>
		<tr>
			<td>Ring Curettes</td>
			<td>Karl Storz</td>
			<td>28164RI</td>
			<td></td>
		</tr>
		<tr>
			<td>Ring Curettes</td>
			<td>Karl Storz</td>
			<td>28164RG</td>
			<td></td>
		</tr>
		<tr>
			<td>Ring Curettes</td>
			<td>Karl Storz</td>
			<td>28164GLL</td>
			<td></td>
		</tr>
		<tr>
			<td>Ring Curettes</td>
			<td>Karl Storz</td>
			<td>28164GLR</td>
			<td></td>
		</tr>
		<tr>
			<td>de DIVITIS-CAPPABIANCA Scalpels</td>
			<td>Karl Storz</td>
			<td>28164M</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Karl Storz</td>
			<td>28164TD</td>
			<td></td>
		</tr>
		<tr>
			<td>High-speed drill</td>
			<td>Midas Rex Medtronic</td>
			<td>1898430</td>
			<td></td>
		</tr>
		<tr>
			<td>Hemostatic agent</td>
			<td>Floseal, Baxter</td>
			<td>1503350</td>
			<td></td>
		</tr>
		<tr>
			<td>Fibrin sealant</td>
			<td>Tisseel, Baxter</td>
			<td>600065</td>
			<td></td>
		</tr>
		<tr>
			<td>CT Lightspeed</td>
			<td>GE medical systems, Milwaukee, WI, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Carestream Vue PACS</td>
			<td>Carestream Health, Rochester, NY, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>3-Tesla Siemens Tim Trio scanner</td>
			<td>Siemens AG, Erlangen, Germany</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

endoscopic endonasal trans-sphenoidal approach: minimally invasive surgery for pituitary adenomas

Endoscopic endonasal trans-sphenoidal surgery has become the gold standard for the surgical treatment of pituitary adenomas and many other pituitary lesions. Refinements in surgical techniques, technological advancements, and incorporation of neuronavigation have rendered this surgery minimally invasive. The complication rates of this surgery are very low while excellent results are consistently obtained through this approach.
This paper focuses on the step-by-step surgical approach to pituitary adenomas, which is based on personal experience, and details the results obtained with this minimally invasive surgery.

Since 2009, our pituitary program has evolved to a point where a fully endoscopic endonasal approach has been used to treat pituitary tumors with excellent postoperative results. From 2009 to 2016, the two senior surgeons (RTD and MM) operated on 473 patients with pituitary adenomas through a full endoscopic technique. The histology is detailed in Table 1: most of these cases were non-functioning pituitary adenomas (57%) (Figure 1), followed ...

Watch this Scientific Journal Video about Endoscopic Endonasal Trans-sphenoidal Approach: Minimally Invasive Surgery for Pituitary Adenomas at JoVE.com

Endoscopic Endonasal Trans-sphenoidal Approach: Minimally Invasive Surgery for Pituitary Adenomas

The aim of this paper is to describe the different steps of the endoscopic endonasal approach to the sella turcica.

Endoscopic endonasal trans-sphenoidal surgery has become the gold standard for the surgical treatment of pituitary adenomas and many other pituitary ...

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Research

JoVE Journal

Neuroscience

18.7K Views.  University Hospital of Lausanne. The aim of this paper is to describe the different steps of the endoscopic endonasal approach to the sella turcica.

Video: Endoscopic Endonasal Trans-sphenoidal Approach: Minimally Invasive Surgery for Pituitary Adenomas

Minimally-invasive Technique for Injection into Rat Optic Nerve

The rat optic nerve is a useful model for stem cell regeneration research. Direct injection into the rat optic nerve allows delivery into the central nervous system in a minimally-invasive surgery without bone removal. This technique describes an approach to visualization and direct injection of the optic nerve following minor fascial dissection from the orbital ridge, using a conjunctival traction suture to gently pull the eye down and out. Representative examples of an injected optic nerve show successful injection of dyed beads.

Direct injection into the rat optic nerve is useful for regenerative research. We demonstrate a minimally-invasive technique for direct injection into a rat optic nerve that does not involve opening the skull. Using this method, surgical complications are minimized and recovery is more rapid.

The rat optic nerve is a useful model for stem cell regeneration research. Direct injection into the rat optic nerve allows delivery into the central ...

Intramuscular Injections Along the Motor End Plates: A Minimally Invasive Approach to Shuttle Tracers Directly into Motor Neurons

Diseases affecting the integrity of spinal cord motor neurons are amongst the most debilitating neurological conditions. Over the last decades, the development of several animal models of these neuromuscular disorders has provided the scientific community with different therapeutic scenarios aimed at delaying or reversing the progression of these conditions. By taking advantage of the retrograde machinery of neurons, one of these approaches has been to target skeletal muscles in order to shuttle therapeutic genes into corresponding spinal cord motor neurons. Although once promising, the success of such gene delivery approach has been hampered by the sub-optimal number of transduced motor neurons it has so far shown to yield. Motor end plates (MEPs) are highly specialized regions on the skeletal musculature that are in direct synaptic contact to the spinal cord &#945; motor neurons. In this regard, it is important to note that, so far, the efforts to retrogradely transfer genes into motor neurons were made without reference to the location of the MEP region in the targeted muscles. Here, we describe a simple protocol 1) to reveal the exact location of the MEPs on the surface of skeletal muscles and 2) to use this information to guide the intramuscular delivery and subsequent optimal retrograde transport of retrograde tracers into motor neurons. We hope to utilize the results from these tracing experiments in further studies into investigating retrograde transport of therapeutic genes to spinal cord motor neurons through the targeting of MEPs.

The efficacy of intramuscular uptake and retrograde transport of molecules to corresponding motor neurons depends on the location of the injection sites with respect to the motor end plates (MEPs). Here, we describe how to locate MEPs on skeletal muscles to optimise retrograde transport of tracers into motor neurons.

Diseases affecting the integrity of spinal cord motor neurons are amongst the most debilitating neurological conditions. Over the last decades, the ...

Effects of Transcranial Alternating Current Stimulation on the Primary Motor Cortex by Online Combined Approach with Transcranial Magnetic Stimulation

Transcranial Alternating Current Stimulation (tACS) is a neuromodulatory technique able to act through sinusoidal electrical waveforms in a specific frequency and in turn modulate ongoing cortical oscillatory activity. This neurotool allows the establishment of a causal link between endogenous oscillatory activity and behavior. Most of the tACS studies have shown online effects of tACS. However, little is known about the underlying action mechanisms of this technique because of the AC-induced artifacts on Electroencephalography (EEG) signals. Here we show a unique approach to investigate online physiological frequency-specific effects of tACS of the primary motor cortex (M1) by using single pulse Transcranial Magnetic Stimulation (TMS) to probe cortical excitability changes. In our setup, the TMS coil is placed over the tACS electrode while Motor Evoked Potentials (MEPs) are collected to test the effects of the ongoing M1-tACS. So far, this approach has mainly been used to study the visual and motor systems. However, the current tACS-TMS setup can pave the way for future investigations of cognitive functions. Therefore, we provide a step-by-step manual and video guidelines for the procedure.

Transcranial Alternating Current Stimulation (tACS) allows the modulation of cortical excitability in a frequency-specific fashion. Here we show a unique approach which combines online tACS with single pulse Transcranial Magnetic Stimulation (TMS) in order to "probe" cortical excitability by means of Motor Evoked Potentials.

Transcranial Alternating Current Stimulation (tACS) is a neuromodulatory technique able to act through sinusoidal electrical waveforms in a specific ...

Healthy Brain-pituitary Slices for Electrophysiological Investigations of Pituitary Cells in Teleost Fish

Electrophysiological investigations of pituitary cells have been conducted in numerous vertebrate species, but very few in teleost fish. Among these, the clear majority have been performed on dissociated primary cells. To improve our understanding of how teleost pituitary cells, behave in a more biologically relevant environment, this protocol shows how to prepare viable brain-pituitary slices using the small freshwater fish medaka (Oryzias latipes). Making the brain-pituitary slices, pH and osmolality of all solutions were adjusted to values found in body fluids of freshwater fish living at 25 to 28 &#176;C. Following slice preparation, the protocol demonstrates how to conduct electrophysiological recordings using the perforated whole-cell patch-clamp technique. The patch-clamp technique is a powerful tool with unprecedented temporal resolution and sensitivity, allowing investigation of electrical properties from intact whole cells down to single ion channels. Perforated patch is unique in that it keeps the intracellular environment intact preventing regulatory elements in the cytosol from being diluted by the patch pipette electrode solution. In contrast, when performing traditional whole-cell recordings, it was observed that medaka pituitary cells quickly lose their ability to fire action potentials. Among the various perforation techniques available, this protocol demonstrates how to achieve perforation of the patched membrane using the fungicide Amphotericin B.

The article describes an optimized protocol for making viable brain-pituitary tissue slices, using the teleost fish medaka (Oryzias latipes), followed by electrophysiological recordings of pituitary cells using the patch-clamp technique with the perforated patch configuration.

Electrophysiological investigations of pituitary cells have been conducted in numerous vertebrate species, but very few in teleost fish. Among these, the ...

Minimally Invasive Endoscopic Intracerebral Hemorrhage Evacuation

Intracerebral hemorrhage (ICH) is a subtype of stroke with high mortality and poor functional outcomes, largely because there are no evidence-based treatment options for this devastating disease process. In the past decade, a number of minimally invasive surgeries have emerged to address this issue, one of which is endoscopic evacuation. Stereotactic ICH Underwater Blood Aspiration (SCUBA) is a novel endoscopic evacuation technique performed in a fluid-filled cavity using an aspiration system to provide an additional degree of freedom during the procedure. The SCUBA procedure utilizes a suction device, endoscope, and sheath and is divided into two phases. The first phase involves maximal aspiration and minimal irrigation to decrease clot burden. The second phase involves increasing irrigation for visibility, decreasing aspiration strength for targeted aspiration without disturbing the cavity wall, and cauterizing any bleeding vessels. Using the endoscope and aspiration wand, this technique aims to maximize hematoma evacuation while minimizing collateral damage to the surrounding brain. Advantages of the SCUBA technique include the use of a low-profile endoscopic sheath minimizing brain disruption and improved visualization with a fluid-filled cavity rather than an air-filled one.

This paper details the surgical protocol for minimally invasive endoscopic intracerebral hemorrhage evacuation using the SCUBA technique.

Intracerebral hemorrhage (ICH) is a subtype of stroke with high mortality and poor functional outcomes, largely because there are no evidence-based ...

A Minimally Invasive Lesion Technique for Muscles Intrinsic to the Odontophore of Aplysia californica

Aplysia californica is a model system for studying the neural control of learning and behavior. This animal has a semi-open circulatory system, making it possible to access many of its internal structures without causing any significant damage. Many manipulations can be easily performed both in vivo and in vitro, making it a highly tractable model for the analysis of behavior and neural circuitry. To better understand the functions of muscles within the feeding grasper, we have developed a technique for lesioning them without opening the main body cavity of the animal or damaging the outer layers of the feeding organ (i.e., the buccal mass). In this technique, the grasper is partially everted, allowing direct access to the musculature. This procedure allows animals to recover quickly and reliably. This has made it possible to lesion the I7 muscles and sub-radular fibers, allowing us to show that both muscles significantly contribute to the opening in vivo.

A Minimally Invasive Lesion Technique for Muscles Intrinsic to the Odontophore of Aplysia californica

Here we present a protocol for minimally invasive surgical lesioning of muscles intrinsic to the feeding apparatus of the marine mollusk Aplysia californica to understand the roles of these muscles during feeding behavior.

Aplysia californica is a model system for studying the neural control of learning and behavior. This animal has a semi-open circulatory system, making it ...

Statistical Modelling of Cortical Connectivity Using Non-invasive Electroencephalograms

Non-invasive electrophysiological recordings are useful for the evaluation of nervous system function. These techniques are inexpensive, fast, replicable, and less resource-intensive than imaging. Further, the functional data produced have excellent temporal resolution, which is not achievable with structural imaging.
Current applications of electroencephalograms (EEG) are limited by data processing methods. Standard analysis techniques using raw time series data at individual channels are very limited methods of interrogating nervous system activity. More detailed information about cortical function can be achieved by examining relationships between channels and deriving statistical models of how areas are interacting, allowing visualization of connectivity between networks.
This manuscript describes a method for deriving statistical models of cortical network activity by recording EEG in a standard manner, then examining the interelectrode coherence measures to assess relationships between the recorded areas. Higher order interactions can be further examined by assessing the covariance between the coherence pairs, producing high-dimensional &#34;maps&#34; of network interactions. These data constructs can be examined to assess cortical network function and its relationship to pathology in ways not achievable with traditional techniques.
This approach offers greater sensitivity to network level interactions than is achievable with raw time series analysis. It is, however, limited by the complexity of drawing specific mechanistic conclusions about the underlying neural populations and the high volumes of data generated, requiring more advanced statistical techniques for evaluation, including dimensionality reduction and classifier-based approaches.

Standard EEG analysis techniques offer limited insight into nervous system function. Deriving statistical models of cortical connectivity offers far greater ability to investigate underlying network dynamics. Improved functional assessment opens new possibilities for diagnosis, prognostication, and outcome prediction in nervous system diseases.

Non-invasive electrophysiological recordings are useful for the evaluation of nervous system function. These techniques are inexpensive, fast, replicable, ...

A Revised Surgical Approach to Induce Endolymphatic Hydrops in the Guinea Pig

Endolymphatic hydrops is an enlargement of scala media that is most often associated with Meniere&#39;s disease, though the pathophysiologic mechanism(s) remain unclear. In order to adequately study the attributes of endolymphatic hydrops, such as the origins of low-frequency hearing loss, a reliable model is needed. The guinea pig is a&#160;good model because it hears in the low-frequency regions that are putatively affected by endolymphatic hydrops. Previous research has demonstrated that endolymphatic hydrops can be induced surgically via intradural or extradural approaches that involve drilling on the endolymphatic duct and sac. However, whether it was possible to create an endolymphatic hydrops model using an extradural approach that avoided dangerous drilling on the endolymphatic duct and sac was unknown. The objective of this study was to demonstrate a revised extradural approach to induce experimental endolymphatic hydrops at 30 days post-operatively by obliterating the endolymphatic sac and injuring the endolymphatic duct with a fine pick. The sample size consisted of seven guinea pigs. Functional measurements of hearing were made and temporal bones were subsequently harvested for histologic analysis. The approach had a success rate of 86% in achieving endolymphatic hydrops. The risk of cerebrospinal fluid leak was minimal. No perioperative deaths or injuries to the posterior semicircular canal occurred in the sample. The presented method demonstrates a safe and reliable way to induce endolymphatic hydrops at a relatively quick time point of 30 days. The clinical implications are that the presented method provides a reliable model to further explore the origins of low-frequency hearing loss that can be associated endolymphatic hydrops.

This article demonstrates an extradural approach to obliterate the guinea pig endolymphatic sac and injure the endolymphatic duct with a fine pick in order to induce experimental endolymphatic hydrops.

Endolymphatic hydrops is an enlargement of scala media that is most often associated with Meniere&#39;s disease, though the pathophysiologic mechanism(s) ...

Adaptable Angled Stereotactic Approach for Versatile Neuroscience Techniques

Stereotactic surgery is an essential tool in the modern neuroscience lab. However, the ability to precisely and accurately target difficult-to-reach brain regions still presents a challenge, particularly when targeting brain structures along the midline. These challenges include avoiding of the superior sagittal sinus and third ventricle and the ability to consistently target selective and discrete brain nuclei. In addition, more advanced neuroscience techniques (e.g., optogenetics, fiber photometry, and two-photon imaging) rely on targeted implantation of significant hardware to the brain, and spatial limitations are a common hindrance. Presented here is a modifiable protocol for stereotactic targeting of rodent brain structures using an angled coronal approach. It can be adapted to 1) mouse or rat models, 2) various neuroscience techniques, and 3) multiple brain regions. As a representative example, it includes the calculation of stereotactic coordinates for targeting of the mouse hypothalamic ventromedial nucleus (VMN) for an optogenetic inhibition experiment. This procedure begins with the bilateral microinjection of an adeno-associated virus (AAV) encoding a light-sensitive chloride channel (SwiChR++) to a Cre-dependent mouse model, followed by the angled bilateral implantation of fiberoptic cannulae. Using this approach, findings show that activation of a subset of VMN neurons is required for intact glucose counterregulatory responses to insulin-induced hypoglycemia.

Described here is a stereotactic procedure that can target challenging and difficult-to-reach brain regions (due to spatial limitations) using an angled coronal approach. This protocol is adaptable to both mouse and rat models and can be applied to diverse neuroscientific applications, including cannula implantation and microinjections of viral constructs.

Stereotactic surgery is an essential tool in the modern neuroscience lab. However, the ability to precisely and accurately target difficult-to-reach brain ...

Role of Diffusion MRI Tractography in Endoscopic Endonasal Skull Base Surgery

Endoscopic endonasal surgery has gained a prominent role in the management of complex skull base tumors. It allows the resection of a large group of benign and malignant lesions through a natural anatomical extra-cranial pathway, represented by the nasal cavities, avoiding brain retraction and neurovascular manipulation. This is reflected by the patients' prompt clinical recovery and the low risk of permanent neurological sequelae, representing the main caveat of conventional skull base surgery. This surgery must be tailored to each specific case, considering its features and relationship with surrounding neural structures, mostly based on preoperative neuroimaging. Advanced MRI techniques, such as tractography, have been rarely adopted in skull base surgery due to technical issues: lengthy and complicated processes to generate reliable reconstructions for inclusion in the neuronavigation system. 
This paper aims to present the protocol implemented in the institution and highlights the synergistic collaboration and teamwork between neurosurgeons and the neuroimaging team (neurologists, neuroradiologists, neuropsychologists, physicists, and bioengineers) with the final goal of selecting the optimal treatment for each patient, improving the surgical results and pursuing the advancement of personalized medicine in this field.

We present a protocol to integrate diffusion MRI tractography in patient work-up to endoscopic endonasal surgery for a skull base tumor. The methods for adopting these neuroimaging studies in the pre- and intra-operative phases are described.

Endoscopic endonasal surgery has gained a prominent role in the management of complex skull base tumors. It allows the resection of a large group of ...