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Table of Contents    
NI FEATURE: PRESIDENTIAL ORATION - COMMENTARY
Year : 2018  |  Volume : 66  |  Issue : 1  |  Page : 4-8

Changing trends in surgery for suprasellar lesions


1 Department of Neurosurgery, Mahatma Gandhi University of Medical Sciences and Technology, Sitapura, Jaipur, Rajasthan, India
2 Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India

Date of Web Publication11-Jan-2018

Correspondence Address:
Dr. Bhawani Shanker Sharma
Department of Neurosurgery and Director Neurosciences, Mahatma Gandhi University of Medical Sciences and Technology, Sitapura, Jaipur - 302 022, Rajasthan
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.222822

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How to cite this article:
Sharma BS, Sawarkar DP. Changing trends in surgery for suprasellar lesions. Neurol India 2018;66:4-8

How to cite this URL:
Sharma BS, Sawarkar DP. Changing trends in surgery for suprasellar lesions. Neurol India [serial online] 2018 [cited 2019 Jun 26];66:4-8. Available from: http://www.neurologyindia.com/text.asp?2018/66/1/4/222822






The suprasellar area is one of the most difficult regions to approach surgically because of the crowding of vital neurovascular structures in the region.[1] A diverse group of extradural or/and intradural lesions occur in this area [Table 1]. An approach that provides the shortest route, adequate access, minimal or no brain retraction, optimal visualization, multidirectional view, avoids crossing of neurovascular structures, as well as also interrupts the vascular supply of the tumor prior to its removal is preferred for surgical excision of these lesions. The conventional approaches to the suprasellar region include the pterional/fronto-lateral approach;[2],[3],[4] or, the complex skull base approaches like the bifrontal basal interhemispheric or the fronto-temporo-orbito-zygomatic approach.[5],[6],[7],[8],[9],[10],[11],[12],[13],[14],[15] The selection of the surgical approach is decided by the size, consistency, location, vascularity, the extension of the lesion as well as its relationship with neurovascular structures, and the origin or attachment of the lesion.
Table 1: Various common lesions present in the midline skull base region

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The two primary aims underlying the utilization of complex skull base approaches to remove these lesions include performing an extradural removal of bone to prevent brain retraction; and, the unroofing of foramina or canal to mobilize cranial nerves and arteries. This provides the scope for a radical deviation of the axis of the operative microscope along the base of skull, allowing for an enhanced inferior to superior trajectory, and a widened field of view of approach to the tumor.[4],[5],[6],[8],[12],[13]

The bifrontal basal interhemispheric approach (BBIA) provides a true midline exposure with better orientation, a wider operative field and the visualization of lesion from different perspectives.

[Figure 1], [Figure 2], [Figure 3].[5],[6],[9],[10],[11] With inferior angle of visualization from the skull base, the entire extent of the tumor located in the region of third ventricle, as well as the superior surface of the suprasellar tumors are visualized in a better way. Retraction of bilateral frontal lobes, and hence, the possibility of intellectual deterioration, as well as the contamination of surgical field consequent to opening of the frontal air sinus are the disadvantages of this approach.
Figure 1: Bifrontal basal interhemispheric approach (a and b) for excision of a craniopharyngioma. Intraoperative photographs showing that (c) the lamina terminalis (white arrow) is opened to gain access to the tumor (white* in d), which shows calcifications (black * in e). Gross total excision of the tumor is achieved (f)

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Figure 2: Preoperative (a) and postoperative (b) contrast enhanced MRI (sagittal view), demonstrating complete excision of a solid-cysic craniopharyngioma with preservation of normal pituitary gland

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Figure 3: Bifrontal basal interhemispheric approach adopted for a suprasellar epidermoid. (a) Intraoperative photograph showing a bicoronal flap. (b) View of the tumor after elevation of the bifrontal flap and cutting of falx after careful dissection of bilateral frontal lobes from the olfactory nerves. (c) Image showing the pituitary stalk during tumor decompression. (d) Image showing the intraoperative view of the suprasellar structures, including the basilar artery exposure, while removing final bits of the epidermoid

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The fronto-temporo-orbito-zygomatic approach (FTOZ) is the workhorse of skull base surgery.[8],[12],[13] A one- or two-piece orbito-zygomatic osteotomy [8],[12] increases the surgical field of view by up to three times compared to the conventional pterional approach.

In this era, the availability of endoscopes fulfills these aims through minimally invasive/access approaches.[16],[17],[18],[19],[20],[21],[22],[23],[24],[25],[26],[27] These approaches include:

  1. The supra-orbital key-hole approach (SOKHA) with its various modifications
  2. The extended endoscopic endonasal approach (EEEA).[15],[28],[29]


The supraorbital key-hole approach provides a greater microsurgical control and freedom in dissecting tumors from vessels or nerves, and also an enhanced exposure of the lesion lateral to the internal carotid artery (ICA) and the optic nerve (ON).[2],[5],[20] It is, therefore, the preferred approach in lesions that are adherent to neurovascular structures. There is no scope of change in the plan of the operative approach once this trajectory is adopted; therefore, a proper pre-operative planning is essential. A preoperative surface marking is performed for the skin incision, for localising the path of the supraorbital nerve and artery, the burr-hole site, to mark the extent of the craniotomy and the orientation of the Sylvian fissure. A 3-4cm skin incision is given in the upper half and lateral two-third of the eyebrow ipsilateral to the tumor. A 3 cm × 2.5 cm free bone flap is raised and the inner table and juga cerebralia (impressions of the cerebral gyri on the inner surface of the skull) are drilled. After opening the dura, the microscope and/or endoscope is used and the Sylvian fissure is opened in an antegrade fashion from medial to lateral aspect.

The SOKHA has the following advantages.[17],[18],[20] It is a minimally invasive approach utilizing a small skin incision, minimal temporalis muscle dissection, and an extremely small and low lying craniotomy along the frontal base. Shaving of hair over the head at the site of craniotomy is also avoided. There is very little brain retraction utilizing this approach. There is also minimum brain exposure minimizing the chances of injury to the normal brain. It has been determined that the standard pterional approach with a 8cm craniotomy exposes approximately 50.27 cm2 of the underlying brain, whereas the key-hole approach with a 2cm craniotomy exposes only approximately 3.14 cm2 of the brain surface.[18] This prevents an excessive exposure of the brain tissue for several hours during the performance of the surgery and prevents it from being vulnerable to injury. This approach is safe and cost-effective, and has a low morbidity. In the patient, it results in a rapid recovery, with a smooth postoperative course, shorter hospital stay and a pleasing cosmetic skull opening.[28] SOKHA is technically demanding, and hence, a gradual stepwise progression from the pterional to the minipterional to the SOKHA approach is the key to the shortening of learning curve.[17],[18],[20],[21] Also, in order to avoid morbidity during the initial phase, it should be utilized for simpler lesions like excision of an epidermoid [Figure 4].
Figure 4: Supraorbital key hole approach (SOKHA) for a suprasellar epidermoid. (a-c) A 3 × 2.5 cm supraorbital craniotomy is performed, approaching the epidermoid through the optico-carotid corridor. (d) Visualization of the pituitary stalk. (e) Endoscopic view showing the suprasellar structures after the epidermoid removal

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In aneurysm surgery utilizing the SOKHA, the dissection commences with ICA exposure, which also provides proximal control of the parent artery in case the aneurysm ruptures prematurely. The possibility of a catastrophic aneurysmal rupture and the need to undertake an emergent proximal and distal control of the parent artery harbouring the aneurysm has to be kept in mind throughout surgery.[17] Any fear of having to tackle an intra-operative rupture of the aneurysm in the narrow and confined space can be minimized by an early and wide opening of the Sylvian and the carotid cistern before tackling the neck of the aneurysm. The ICA, as well as the M1 segment of the middle cerebral artery, and both A1 segments of the anterior cerebral artery should be dissected and prepared for an appropriate proximal clipping. One must practice temporary vessel occlusion of the parent artery using temporary clips several times before reaching the aneurysm; and, the dissection in close proximity to the aneurysm should be performed with the temporary clips occluding the proximal and distal parts of the parent vessel. This minimally invasive procedure is contraindicated in acute subarachnoid haemorrhage, or in the case where a complex or giant aneurysm is present. Aneurysm surgery through a key-hole should be attempted only after one has significant experience in microscopic clipping of numerous aneurysms [Figure 5].
Figure 5: (a) An anterior communicating aneurysm seen on angiography. (b) The aneurysm has been dissected. (c and d) An aneurysm clip was then applied across the neck of the aneurysm. (e) Postoperative digital subtraction angiography shows a well-clipped aneurysm with no residual filling

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The endoscopic endonasal approach is a minimal access but equally invasive and direct approach to gain exposure of central skull base tumors.[15],[16],[19],[25],[27],[30],[31],[32],[33] It does not require brain retraction.[15],[25],[31] The endonasal approach includes the endoscopic pituitary surgery (EPS) and the extended endoscopic approach (EEA).[16],[19],[25],[27] In general, the endonasal approach provides an inferior to a superior trajectory of approach and a direct access to the third ventricle, and so is the preferred approach for accessing midline sellar/suprasellar lesions having a significant sphenoidal sinus involvement, in lesions with a significant inferior extension, or in lesions under the ipsilateral optic nerve.[25],[31]

The endoscopic pituitary surgery (EPS) [Figure 6][16] provides a panoramic wider, a close-up as well as a multi-angled view. Better illumination permits differentiation between the tumor and the normal pituitary gland and between the diaphragma sellae and the suprasellar arachnoidal membrane. It, thus, permits complete excision of the tumor with preservation of the normal pituitary gland and a lower incidence of cerebrospinal fluid (CSF) leak. There is reduced incidence of postoperative complications as well as mortality. With increasing experience in EPS, there is improvement in the endocrinal remission rate, the extent of tumor resection, the pre-operative visual deficits and the post-operative hypopituitarism (due to preservation of the normal pituitary gland). There is also reduction in the duration of surgery, the amount of mucosal trauma and the consequent postoperative discomfort, hospital stay and CSF leak.[16],[34]
Figure 6: Axial (a), sagittal (b), and coronal (c) view of magnetic resonance imaging scan of a pituitary macroadenoma. Follow-up images (d-f) showing total excision of the tumor

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The extended endoscopic approach (EEA) is an extension of the endoscopic endonasal approach (the latter is primarily used for excision of midline pituitary tumors) that is utilized for tumors extending beyond the sella. The EEA permits gaining of approximately 2 cm wide exposure of the midline skull base to obtain access to the suprasellar region [Figure 7]. This approach is facilitated by the use of neuronavigation. Reconstruction of the skull base after the tumor excision has to be planned meticulously prior to surgery. The tumor excision during the conduction of EEA requires a combination of various bimanual dissection techniques that are essentially utilized in microneurosurgery also. This includes internal debulking, capsular mobilization, extracapsular dissection of neurovascular structures and the arachnoidal membrane, as well as coagulation and shrinking of the tumor capsule prior to its removal [Figure 8].[15],[16],[22],[23],[24],[25],[30],[34]
Figure 7: Extended endoscopic endonasal surgery for a Rathke's cleft cyst. Preoperative coronal (a) and sagittal (b) MRI images showing the Rathke's cleft cyst. Intraoperative photograph (c) after removal of the cyst; (d) Postoperative axial CT scan showing the air in the sellar-suprasellar region with complete excision of the tumor

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Figure 8: Craniopharyngioma operated by the endoscopic extended endonasal approach Contrast MRI axial (a) and sagittal (b) scan showing the craniopharyngioma with the third ventricular extension. (c) The dural exposure after bone removal from the sella, tuberculum sellae and planum sphenoidale. (d) Coagulation and cutting of the anterior intercavernous sinus exposing base of the tumor (e). (f) Removal of the tumor. (g) View of the opened foramen of Monro after tumor removal. (h and i) Intraoperative image of the anterior cerebral artery complex and the basilar artery complex after tumor excision

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Selection of the surgical approach in common suprasellar lesions

  1. Pituitary tumors: The endoscopic endonasal approach (EEA) is generally preferred in tumors with cellular or cystic components, with a sphenoidal sinus/suprasellar/medial cavernous sinus extension, and in those tumors associated with CSF rhinorrhoea.[16],[25],[35] The transcranial keyhole approach is indicated in fibrous and solid tumors with significant parasellar/lateral/retrosellar multicompartmental (especially giant tumors) extension, and/or those that are adherent to neurovascular structures
  2. Craniopharyngiomas: The EEA is the preferred approach in the case of retrochiasmal midline tumors with sellar, suprasellar, or third ventricular extension.[25],[30],[31] The SOKHA is indicated in solid tumors in the presence of multicompartmental extension and/or vascular adhesions [35]
  3. Chordomas: EEA is the approach of choice [32],[33]
  4. Meningiomas (tuberculum sellae or planum sphenoidale): SOKHA is the preferred approach in larger (>30 mm) tumors with a lateral extension beyond the optic nerve and the ICA; in those tumors extending beyond the midpoint of the orbit/optic canal (present in approximately 70% of the cases);[35] and, in those cases where olfaction needs to be preserved.[25],[27] The EEA may be the preferred approach in smaller tumors with an extensive or a disproportionate brain edema
  5. Epidermoids: These tumors grow within cisterns and infiltrate along arteries. A better dissection and complete excision is possible using the SOKHA
  6. Chiasmal gliomas: The SOKHA is the preferred approach.
  7. Simple anterior circulation aneurysms: The SOKHA is the preferred approach.



  Conclusion Top


Surgical approach for the suprasellar lesions must be individualized. Skull base approaches have their own place and are reserved for large and firm lesions; in extensive lesions often with multicompartmental projections; in lesions causing encasement of the ICA or the optic nerve; in lesions invading the cavernous sinus and/or the orbit; and, in lesions with a large dural attachment and/or extensive bony changes. With the availability of stereotactic radiosurgery, a generally less aggressive approach for lesions infiltrating the lateral wall of the cavernous sinus is adopted. Awareness of the need for an early diagnostic imaging; as well as advances in the various modalities of imaging, permit an early diagnosis of these lesions when they are still of moderate size and, therefore, may be treated with minimally invasive approaches using a microcrope or an endoscope. Advances in neuronavigation and endoscopic equipment have permitted the treatment of these lesions through smaller surgical corridors, and more specifically, less traumatic approaches.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
 
 
    Tables

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