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Year : 2020  |  Volume : 68  |  Issue : 3  |  Page : 579--580

Endoscopic Transnasal Transsphenoidal Pituitary Surgery in Acromegaly: Anatomical Variations and Surgical Considerations

N Jayashankar 
 Department of Otorhinolaryngology and Skull Base Surgery, Nanavati Superspeciality Hospital, Mumbai, Maharashtra, India

Correspondence Address:
Dr. N Jayashankar
Department of Otorhinolaryngology and Skull Base Surgery, Nanavati Superspeciality Hospital, Mumbai - 400 056, Maharashtra
India




How to cite this article:
Jayashankar N. Endoscopic Transnasal Transsphenoidal Pituitary Surgery in Acromegaly: Anatomical Variations and Surgical Considerations.Neurol India 2020;68:579-580


How to cite this URL:
Jayashankar N. Endoscopic Transnasal Transsphenoidal Pituitary Surgery in Acromegaly: Anatomical Variations and Surgical Considerations. Neurol India [serial online] 2020 [cited 2020 Sep 28 ];68:579-580
Available from: http://www.neurologyindia.com/text.asp?2020/68/3/579/289017


Full Text



The article by Rajagopal et al.[1] has very well documented the position of the sphenoid ostium in acromegalic subjects as compared to subjects with nonfunctioning pituitary adenomas. It also documents changes seen in the diameter of the cavernous segment of internal carotid artery and reduction in the intercarotid distance in acromegalic subjects, again comparing these changes with subjects having nonfunctioning pituitary adenomas.

Endoscopic transnasal pituitary surgery has been universally accepted as the most commonly used approach for excision of pituitary tumors. It, therefore, is very important to understand the anatomical changes in the nasal cavities and sinuses of acromegalic subjects before embarking on surgery for the same. In the nasal cavity, pathological changes include very edematous and enlarged inferior and middle turbinates or infrequently nasal polyps. During endoscopic transsphenoidal surgery, the inferior turbinates and posterior end of the middle turbinates are fractured laterally to improve the space in the nasal cavity toward the sphenoethmoidal recess and help in creating a rescue flap. Edematous and engorged turbinates in acromegalic subjects would require additional local decongestion and may still ooze during this step of surgery. The turbinate bones are usually stiffer and may require additional force to fracture them laterally. Nasal polyps in these subjects, if present, can be excised with a microdebrider and surgery can then proceed with better visualization of the anatomy.

The sphenoid ostium identification in acromegalic subjects is a bit more challenging due to the slightly superior and lateral position as described in the article by Rajagopal et al.[1] It could also be obscured by edematous redundant mucosa. Hence, a good study of the preoperative computed tomography scan to determine the position of the ostium and the floor of the sphenoid is of paramount importance. In addition, as described in the article, the ostium is located closer to the sphenopalatine foramen than in subjects with nonfunctioning pituitary adenomas. The clinical significance of this is to prevent damage to the vascular pedicle of the rescue flap or the Hadad-Bassagasteguy nasoseptal flap on aggressive widening of the sphenoid ostium without understanding the anatomical variation of the position of the ostium. The increase in levels of growth hormone causes the bones to be thicker than normal. This correlates with an increase in thickness of the rostrum of sphenoid which may require to be drilled to visualize the floor of the sphenoid sinus.

The sphenoid sinus is usually larger than in normal subjects and there are usually increased and thick septations in the sphenoid sinus.[2] The sphenoid septations in the majority of normal subjects are inserted on the internal carotid artery [3] or the optic nerves. These sphenoid septations need to be preoperatively studied on scans, especially in acromegalic subjects and care is taken to drill them down rather than use rongeurs or punches. The sphenoid sinus mucosa when stripped tends to ooze more due to edema and vascular congestion. This is controlled with use of warm saline irrigation, gelfoam/surgicel and pressure with cottonoids or merocel pieces. Acromegalic adenomas have a propensity for inferior spread and so tumor extension in the infrasellar or clival areas are often noted. Besides, due to bone remodeling, the bone over the tumor is usually thickened and needs to be drilled unlike in other nonfunctioning adenomas where the bone over the tumor is thinned out to variable extents. Subjects with long-standing acromegaly have been found to have an increased caliber of the internal carotid artery and the intercarotid distance is usually decreased.[4],[5],[6] This can infrequently result in having “kissing carotids.” Growth hormone tumors have been implicated in causing damage to vascular endothelium and could potentially result in easy damage to the internal carotid artery during surgery. Acromegaly has also been associated with increased incidence of intracranial aneurysms [7] and the surgeon must be aware of the remote possibility of an aneurysm of the internal carotid artery. It is crucial to bear this in mind when operating acromegalic subjects to avoid a catastrophe. Hence, some surgeons advocate additional preoperative magnetic resonance angiogram for evaluation of the same in acromegalic subjects with intracranial aneurysms noticed on magnetic resonance imaging.

In conclusion, a thorough understanding of the anatomical changes in acromegalic subjects is required in order to safely and effectively perform endoscopic transnasal transsphenoidal surgery for growth hormone-secreting pituitary adenomas.

References

1Rajagopal N, Thakar S, Hegde V, Aryan S, Hegde AS. Morphometric Alterations of the Sphenoid Ostium and other Landmarks in Acromegaly: Anatomical Considerations and Implications in Endoscopic Pituitary Surgery. Neurol India 2020;68:573-8.
2Carrabba G, Locatelli M, Mattei L, Guastella C, Mantovani G, Rampini P, et al. Transphenoidal surgery in acromegalic patients: Anatomical considerations and potential pitfalls. Acta Neurochir 2013;155:125-30. discussion 130.
3Fernandez-Miranda JC, Prevedello DM, Madhok R, Morera V, Barges-Coll J, Reineman K, et al. Sphenoid Septations and Their Relationship With Internal Carotid Arteries: Anatomical and Radiological Study. Laryngoscope 2009;119:1893-6.
4Ebner FH, Kuerschner V, Dietz K, Bueltmann E, Naegele T, Honegger J. Reduced intercarotid artery distance in acromegaly: Pathophysiologic considerations and implications for transsphenoidal surgery. Surg Neurol 2009;72:456-60. discussion 460.
5Mascarella MA, Forghani R, Di Maio S, Sirhan D, Zeitouni A, Mohr G, et al. Indicators of a reduced intercarotid artery distance in patients undergoing endoscopic transsphenoidal surgery. J Neurol Surg B Skull Base 2015;76:195-201.
6Manara R, Gabrieli J, Citton V, Ceccato F, Rizzati S, Bommarito G, et al. Intracranial internal carotid artery changes in acromegaly: A quantitative magnetic resonance angiography study. Pituitary 2014;17:414-22.
7Manara R, Maffei P, Citton V, Rizzati S, Bommarito G, Ermani M, et al. Increased rate of intracranial saccular aneurysms in acromegaly: An MR angiography study and review of the literature. J Clin Endocrinol Metab 2011;96:1292-300.