Original Article
Bifrontal basal interhemispheric approach for midline suprasellar tumors: Our experience with forty‑eight patients Sumit Sinha, Amandeep Kumar, Bhawani S. Sharma Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India
Abstract Introduction: Suprasellar lesions present a surgical challenge due to their complex relationship with surrounding neurovascular structures. Of the approaches for these lesions, bifrontal basal interhemispheric approach (BBIA) gives a midline perspective of suprasellar anatomy and has certain advantages over lateral approaches. Materials and Methods: We retrospectively reviewed 48 patients with suprasellar lesions operated over 7 years via BBIA. Patient records, operation notes, radiology, and outpatient files were scrutinized to collect data. Results: During the study period 48 patients (mean age 33 years, M:F 1.5:1) were operated by this approach. The clinical features included: Visual field deficits in 33 (69%) patients, with 6 of them being blind, diabetes insipidus in 7, growth retardation in 5, and subarachnoid hemorrhage in three patients. Cranopharyngiomas (52%) and meningiomas (16.7%) were the most common pathologies. Dyselectrolytemia (18, 40%) and diabetes insipidus (15, 33%) were the most common complications. Postoperative seizures, meningitis, subdural effusion, and retraction site contusion were seen in 12 (27%), 5 (11%), 4 (9%), and 1 (2.2%) patient, respectively. Three patients died postoperatively and 19 (40%) patients required hormone replacement therapy. Amongst the patients with preoperative visual deficits, 23 (70%) had improvement in visual functions, in six (20%), there was no change and four (8.3%) patients had visual deterioration. Conclusion: BBIA provides a true midline perspective and orientation, and permits complete and safe removal of midline suprasellar lesions in majority of cases. This approach is especially useful in retrochiasmatic tumors and in residual/recurrent tumors providing virgin plane of dissection.
Address for correspondence: Dr. Bhawani S. Sharma, Department of Neurosurgery, Cardiothoracic and Neurosciences Centre, All India Institute of Medical Sciences, New Delhi, India. E‑mail: [email protected] Received : 30‑07‑2013 Review completed : 17‑08‑2013 Accepted : 18‑12‑2013
Key words: Bifrontal, basal interhemispheric approach, outcome, suprasellar tumors
Introduction Suprasellar lesions present a significant surgical challenge. Different surgical approaches used for these lesions include: Pterional, subfrontal, subtemporal, Access this article online Quick Response Code:
Website: www.neurologyindia.com PMID: *** DOI: 10.4103/0028-3886.125247
Neurology India | Nov-Dec 2013 | Vol 61 | Issue 6
transcortical, transcallosal and interhemispheric. [1,2] Due to its complexity and associated morbidity, the interhemispheric approach was previously avoided. However, with the advances in microneurosurgical techniques and with improvization in neurosurgical instruments, the interhemispheric approach can be safely used for managing lesions in the suprasellar region.[1‑6] The traditional interhemispheric approach is a complex approach with an associated risk of damage to olfactory tracts and disturbances of psychological functions postoperatively.[7] In order to reduce the risk of olfactory dysfunction and psychological disturbances as well as to better visualize the infundibulohypophyseal 581
Sinha, et al.: Bifrontal basal interhemispheric approach
axis, Shibuya et al. [6] and Shirane et al. [8] modified traditional interhemispheric approach, the fronto‑basal interhemispheric approach which combines the basal interhemispheric approach and the translamina terminalis approach. In this study, the authors present the technical aspects of the bifrontal basal interhemispheric approach (BBIA) and share their experience of 48 patients with suprasellar intradural lesions treated with this approach.
Materials and Methods This is a retrospective study conducted at a tertiary care neurosurgical centre. Patient records, operation notes, radiology, and outpatient files were scrutinized to collect the data. Between January 2006 and December 2012, we have operated 48 patients (mean age 33 years, range 3‑60 years, M:F 1.5:1) with suprasellar lesions via BBIA [Table 1]. Clinical manifestations The mean duration of symptoms was 6.6 months (range: 3‑72 months). The most common presenting complaint was headache present in 36 (85%) patients. Thirty‑three (69%) patients had visual field defects, six of them had blindness, seven patients had diabetes insipidus, five patients had growth retardation, three patients presented with subarachnoid hemorrhage, and two patients had diencephalic syndrome [Table 2]. Complete hormonal profile was done in all the patients and nine patients were found to have anterior pituitary hormonal imbalance. Operative technique All the patients underwent primary surgery and in all gross total excision of tumor was attempted. Table 1: Patient characteristics Total number of patients Age (years) Mean Range Male:Female ratio Duration of symptoms (months) Mean Range
After induction and intubation, patient was positioned supine with head fixed in mild extension (5‑10°) with a three pin fixation system. A bicoronal scalp incision [Figure 1a] was given behind the hairline and a subgaleal flap was raised followed by elevation of pericranium upto bilateral orbital rims. The pericranium was reflected anteriorly for future use to exteriorize frontal sinus. A low bifrontal craniotomy was made including the nasal part of frontal bone after making a single midline burrhole. The frontal air sinus was opened invariably and sinus mucosa was excised to prevent mucocele formation. The sinus was then packed with betadine‑soaked gelfoam and sealed with bonewax. This step was done painstakingly with great efforts, in order to prevent cerebrospinal fluid (CSF) rhinorrhea in the postoperative period. A pedicled pericranium was then used to exteriorize the sinus by suturing pericranium to dura caudal to dural suture line. The dura was opened in a transverse fashion on either side of midline [Figure 1b], as far forward as possible. The superior sagittal sinus was then ligated with a figure of eight silk suture and divided as far forward as possible and falx was divided down till the crista galli. Both the frontal lobes were retracted and olfactory tracts dissected from the frontal lobes bilaterally, till olfactory trigone [Figure 2a and b]. The inclusion of nasal part of frontal bone in craniotomy allows dissection of basal interhemispheric fissure, thereby avoiding damage to draining veins over convexity. Further gentle retraction of frontal lobe would expose chiasmatic and lamina terminalis cisterns which are opened to let CSF out, thereby making brain lax and minimizing the need of frontal lobe retraction.
48 33 (3‑60) 1.5:1 6.6 3‑72
Table 2: Clinical features
Clinical features Headache Field defects Diabetes insipidus Growth retardation SAH Dencephalic syndrome 582
Number (%) 36 (85) 30 (67) 7 (15) 5 (10) 3 (6) 2 (4)
a
b
Figure 1: (a) Diagrammatic representation of patient position and skin incision (dotted line). The head is fixed with three pin fixation in neutral position and extended at occipito-cervical joint and a bicoronal skin incision (dotted line) is made. (b) After raising subgaleal flap, perisoteum is elevated (*), single burrhole is made to elevate bone flap & bifrontal craniotomy is made (arrow). Bilateral transverse dural incisions are then made (arrow heads)
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Sinha, et al.: Bifrontal basal interhemispheric approach
a
b
c
d
e
f
Figure 2: Intraoperative photographs showing (2a) frontal lobe retraction after incision of dura and ligation & division of superior sagittal sinus (black arrow ). (2b) The olfactory tracts (arrow heads) are dissected off the frontal lobes and optic chiasm (star) is exposed. (2c) Lamina terminalis (white arrow) is opened to access the tumor (white* in 2d ) which shows calcifications (black * in 2e). Gross total excision of tumor is achieved (2f)
The tumor was then removed in a sequential manner depending upon pathology and directions of tumor extension. In case of craniopharyngiomas, tumor removal was started from carotico‑optic space, interoptic space, and the corridor lateral to carotid artery. Thereafter, lamina terminalis was opened [Figure 2c‑e] and tumor taken out piecemeal from within third ventricle. Extreme caution was taken to avoid spillage of tumor cyst fluid into subarachnoid spaces, in order to prevent chemical meningitis. The pituitary stalk is visualized during removal of posterior part of tumor [Figure 2f] and every effort was made to preserve this, by avoiding suction, CUSA or bipolar coagulation near stalk.
Results The most common pathology in this series was craniopharyngioma [Figures 3 and 4] in 25 patients (52%) followed by meningiomas in eight patients, hypothalamic and chiasmal gliomas in four patients each, while epidermoid and giant pituitary adenomas were present in three patients each [Table 3]. Among the 25 patients with craniopharyngiomas, radical resection was achieved in 22 (88%) patients, while subtotal resection was done in 3 (12%) patients. Of the 8 patients with meningiomas, total resection of was achieved in 6 patients. All the patients with epidermoid and pituitary adenomas underwent gross total resection of the lesions. In patients with hypothalamic/chiasmal gliomas, only subtotal resection was performed. Complications (a) Immediate complications The most common complications in were dyselectrolytemia and diabetes insipidus occurring Neurology India | Nov-Dec 2013 | Vol 61 | Issue 6
Table 3: The pathology of the suprasellar intradural lesions in the study
Pathology Craniopharyngioma Meningioma Hypothalamic glioma Chiasmal glioma Epidermoid Giant pituitary tumor Dermoid+colloid cyst
Number (%) 25 (52) 8 (16.7) 4 (8.3) 4 (8.3) 3 (6.2) 3 (6.2) 1 (2.1)
in 18 (40%) and 15 (33%) patients respectively. Twelve (27%) patients had seizures in postoperative period that were controlled with antiepileptic drugs. Meningitis developed in five (11%) patients. Four (9%) patients developed subdural effusion and retraction site contusion developed in one (92.2%) patient. Most complications in our series (dyselectrolytemia, seizures, meningitis, and prolonged ventilation) were transient and well controlled without any sequelae with appropriate medical management [Table 4]. Four (8.3%) patients had deterioration in vision postoperatively. All these patients also had preoperative visual deficits. None of the patients developed postoperative olfactory dysfunction. Three patients died postoperatively. The causes of death in these patients were hypothalamic dysfunction, sepsis and respiratory failure. (b) Late complications: Nineteen (40%) patients were found to have hypopituitarism and required hormonal replacement postoperatively. While, in rest of the patients, postoperative hormonal analysis was normal. High morbidity (mostly transient) can be explained by radical approach adopted by the surgeon in resecting these lesions. 583
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a
a
b
c
d
b Figure 3: Preoperative (a) and postoperative (b) contrast enhanced MRI (sagittal view), demonstrating complete excision of a solid-cysic craniopharyngioma
Table 4: Complications
Complications Morbidity Dyselectrolytemia Diabetes insipidus Seizures Prolonged ventilation/tracheostomy Meningitis Subdural effusion Pseudomeningicele Retraction contusion Mortality (causes) Hypothalamic dysfunction Sepsis Respiratory failure
Number (%) 18 (40) 15 (33) 12 (27) 6 (13) 5 (11) 4 (9) 1 (2.2) 1 (2.2) 1 (2.2) 1 (2.2) 1 (2.2)
Postoperative endocrine function Post operatively, 19 (40%) patients were found to have hypopituitarism and required hormonal replacement therapy. In rest of the patients, assessment of hypothalamo‑pituitary axis revealed normal results. Postoperative visual functions Among the 33 patients with preoperative visual deficits, 23 (70%) patients had improvement in visual functions. Overall, the visual function either remained unchanged or improved in 44 (91.7%) patients, while four (8.3%) patients had deterioration in vision. None of the patients with normal preoperative vision had visual deterioration after surgery.
Discussion Anterior interhemispheric approach has been described by various authors for treatment of suprasellar lesions.[1,2,4‑6] The advantages of this approach are that it provides a wider corridor with excellent visualization of anterior circulation, optic apparatus, and tumor within the third ventricle itself. However, there is a risk of rupture of anterior draining veins with consequent 584
Figure 4: Shows the preoperative axial CT scan at the level of sella (a) and third ventricle (b) with a large cystic craniopharyngioma. The tumor was completely removed as is evident from postoperative images (c and d)
venous infarct of supero‑medial frontal lobes bilaterally especially when combined with prolonged frontal lobe retraction. A basal interhemispheric approach has been described by Shibuya et al.[6] and Shirane et al.[8] for craniopharyngiomas and by Yasui et al. for anterior communicating artery aneurysms.[9] The advantage of this approach lies in the fact that it requires minimal brain retraction, allows preservation of arteries and veins along the medial and dorsal surfaces of frontal lobes and corpus callosum and involves less extensive dissection of interhemispheric fissure, limited only to basal part. Additionally, basal approach offers a much acute angle for a better visualization of third ventricular tumor and area behind lamina terminalis to as far behind the aqueduct and basilar apex, as opposed to standard interhemispheric or pterional approach combined with translamina terminalis approach.[6,8,10,11] As the posterosuperior part of tumor is not adherent to adjacent structures, corridor provided by basal interhemispheric approach is adequate to remove this portion of tumor without damaging third ventricular floor and veins in the region.[11‑14] The bilateral midline approaches provide a true midline perspective, better orientation under operative field, view of tumor from different angles avoiding blunt dissection and permitting complete and safe excision,[6,8,10,11] unlike the unilateral approaches (like pterional approach, subtemporal approach) for suprasellar lesions located in midline such as craniopharyngiomas, hypothalamic glioma and midline anterior circulation aneurysms. The bilateral approaches provide a wide uninterrupted view of important midline structures, such as optic chiasm, anterior communicating artery with perforators, hypothalamus and infundibulohypophyseal axis, thereby, providing a better chance to preserve these Neurology India | Nov-Dec 2013 | Vol 61 | Issue 6
Sinha, et al.: Bifrontal basal interhemispheric approach
important anatomic structures. The contralateral structures are relatively blind for unilateral approaches and important perforators on ipsilateral side prevent a safe approach. However, there are certain situations in which BBIA cannot be used. Presence of active sinusitis involving frontal sinuses is an absolute contraindication to this approach. Additionally, tumors with extension into middle cranial fossa cannot be completely removed by this approach. Although the pterional approach is familiar to the neurosurgeons, ipsilateral optic nerve obstructs vision and dissection, thereby making the removal of tumor medial to optic nerve difficult and also third ventricle is visualized obliquely through the lamina terminalis. The subfrontal approach [15,16] is another unilateral approach that has been widely used for lesions in this location due to its simplicity and also because it obviates the need to dissect open the interhemispheric fissure. However, an important drawback of this approach is its relatively narrow corridor as compared with interhemispheric approach. It is difficult to open the entire lamina terminalis with this approach, thereby requiring extreme retraction of frontal lobes. It also does not give a midline orientation of regional anatomy as described above. As tumors in suprasellar location have a close relationship with infundibulohypophyseal axis, and may even be densely adherent to infundibulum, meticulous dissection and preservation of infundibulohypophyseal axis constitutes an important aspect of surgery in this region. The fronto‑basal interhemispheric approach offers a good chance to achieve this goal as it provides a good view of infundibulohypophyseal axis. In addition, it does not require strong retraction of frontal lobes if lamina terminalis is widely exposed.[8] Shirane et al.[8] used a small craniotomy to prevent inadvertent damage
to olfactory tracts, fornix, corpus callosum, and anterior commissure. In their series of 31 patients, none of the patients developed olfactory dysfunction or psychological problems and only one patient developed transient ischemic damage to hypothalamus. When compared to classical interhemispheric approach, BBIA provides angle of visualization from base so that 3rd ventricle and superior surface of tumor are well visualized because of inferior angle, needs no coagulation of bridging veins, permits improved pituitary stalk preservation and hormonal outcome, thereby postoperative course is less stormy. Retraction of bilateral frontal lobes and contusion and contamination from opening of frontal sinuses are potential drawbacks of this approach; however, in our series only one patient (2.2%) developed frontal lobe retraction secondary to retraction. A comparison between merits and demerits of different approaches to suprasellar tumors are given in Table 5. Shirane et al.[8] achieved total resection in 71% patients with craniopharyngiomas using frontobasal interhemispheric approach. Hypothalamo‑pituitary dysfunction was observed in 81% of the patients. They reported a mortality rate of 7.1% (3/42). Similarly, Shibuya et al.[6] performed total or near total resection of craniopharyngiomas in 22 patients via BBIA. Visual deterioration was seen in two of the patients (9%). All except one of their patients required hormone replacement. There were three deaths (13.6%) in a delayed manner. Hori et al.[10] accomplished total resection in 80.4% of patients using anterior interhemispheric approach; however, the rate of postoperative hypothalamic dysfunction and dyselectrolytemia was very high. Diabetes insipidus occurred in 62.2% of patients after surgery. Visual deterioration occurred in 10.7% patients. Fahlbusch et al.[1] reported 45.7% total resection rates for craniopharyngiomas operated by pterional and anterior interhemispheric approach. The risk of visual
Table 5: Comparison between different approaches to suprasellar tumors
Approach
Exposure
Merits
Demerits
Pterional
Unilateral
Unilateral subfrontal
Unilateral
Early visualization of optic nerve and ipsilateral carotid artery; Less frontal lobe retraction; view interrupted by the perforator vessels Only unilateral frontal lobe and olfactory nerve at risk
Anterior interhemispheric Bifrontal basal interhemispheric
Bilateral/ midline Bilateral/ midline
Narrow space and angle especially in cases with prefixed chiasm; an oblique angle of vision; restricted view of contralateral structures; requires sylvian fissure dissection Frontal lobe retraction; narrow corridor and longer access to sellar‑suprasellar region; restricted view of purely midline lesions and contralateral structures; CSF leak; Olfactory nerve injury Risk of damage to anterior draining veins; requires extensive interhemispheric dissection Frontal lobe retraction; CSF leak; Olfactory nerve injury
Wide uninterrupted view of suprasellar area; A true midline perspective of suprasellar anatomy; Wide uninterrupted view of suprasellar area; A true midline perspective of suprasellar anatomy; only basal interhemispheric fissure dissected
CSF - Cerebrospinal fluid
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deterioration in their patients operated transcranially was 14.7%. Yasargil et al.[16] adopted a very aggressive approach toward craniopharyngiomas in their series of 144 patients and achieved total resection in 90% of patients. They reported a mortality rate of 16.7%. They also reported a very high incidence of postoperative hypothalamic dysfunction in 79% of patients. In the present series, radical resection was achieved in 21/25 (84%) of the patients with craniopharyngiomas. Six of the eight patients (75%) with meningiomas underwent total resection diabetes insipidus was seen in 15 (33%) patients and hormonal disturbances requiring replacement therapy were seen in 19 (40%) patients postoperatively. Visual deterioration occurred in 4 (8.3%) patients. The mortality rate was 6.2% (3/48). The extent of resection and complication rate was comparable to those reported in literature.
References 1. 2. 3.
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586
Fahlbusch R, Honegger J, Paulus W, Huk W, Buchfelder M. Surgical treatment of craniopharyngiomas: Experience with 168 patients. J Neurosurg 1999;90:237‑50. Oi S, Samii A, Samii M. Operative techniques for tumors in the third ventricle. Op Tech Neurosurg 2003;6:205‑14. Fujiwara H, Yasui N, Nathal‑Vera E, Suzuki A. Anosmia after anterior communicating artery aneurysm surgery: Comparison between the anterior interhemispheric and basal interhemispheric approaches. Neurosurgery 1996;38:325‑8. Suzuki J, Katakura R, Mori T. Interhemispheric approach through the lamina terminalis to tumors of the anterior part of the third ventricle. Surg Neurol 1984;22:157‑63. Suzuki J, Mizoi K, Yoshimoto T. Bifrontal interhemispheric approach
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to aneurysms of the anterior communicating artery. J Neurosurg 1986;64:183‑90. Shibuya M, Takayasu M, Suzuki Y, Saito K, Sugita K. Bifrontal basal interhemispheric approach to craniopharyngioma resection with or without division of the anterior communicating artery. J Neurosurg 1996;84:951‑6. Suzuki J, Yoshimoto T, Mizoi K. Preservation of the olfactory tract in bifrontal craniotomy for anterior communicating artery aneurysms, and the functional prognosis. J Neurosurg 1981;54:342‑5. Shirane R, Ching‑Chan S, Kusaka Y, Jokura H, Yoshimoto T. Surgical outcomes in 31 patients with craniopharyngiomas extending outside the suprasellar cistern: An evaluation of the frontobasal interhemispheric approach. J Neurosurg 2002;96:704‑12. Yasui N, Nathal E, Fujiwara H, Suzuki A. The basal interhemispheric approach for acute anterior communicating aneurysms. Acta Neurochir 1992;118:91‑7. Hori T, Kawamata T, Amano K, Aihara Y, Ono M, Miki N. Anterior interhemispheric approach for 100 tumors in and around third ventricle. Neurosurgery 2010;66:65‑73. Dehdashti AR, de Tribolet N. Frontobasal anterior interhemispheric translamina terminalis approach for suprasellar lesions. Neurosurgery 2005;56 (2 suppl):418‑24. King TT. Removal of intraventricular craniopharyngiomas through the lamina terminalis. Acta Neurochir (Wien) 1979;45:277‑86. Klein HJ, Rath SA. Removal of tumors in the third ventricle using the lamina terminalis approach: Three cases of isolated growth of craniopharyngiomas in the third ventricle. Childs Nerv Syst 1989;5:144‑7. Maira G, Anile C, Colosimo C, Cabezas D. Craniopharyngiomas of the third ventricle: Trans‑lamina terminalis approach. Neurosurgery 2000;47:857‑65. Samii M, Tatagiba M. Craniopharyngioma, In: Kaye AH, Laws ER Jr, editors. Brain Tumors: An Encyclopedic Approach. Edinburgh: Churchill Livingstone; 1995. p. 873‑94. Yasargil MG, Curcic M, Kis M, Siegenthaler G, Teddy PJ, Roth P. Total removal of craniopharyngiomas. Approaches and long‑term results in 144 patients. J Neurosurg 1990;73:3‑11.
How to cite this article: Sinha S, Kumar A, Sharma BS. Bifrontal basal interhemispheric approach for midline suprasellar tumors: Our experience with forty-eight patients. Neurol India 2013;61:581-6. Source of Support: Nil, Conflict of Interest: None declared.
Neurology India | Nov-Dec 2013 | Vol 61 | Issue 6
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Bifrontal basal interhemispheric approach for midline suprasellar tumors: Our experience with forty‑eight patients Sumit Sinha, Amandeep Kumar, Bhawani S. Sharma Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India
Abstract Introduction: Suprasellar lesions present a surgical challenge due to their complex relationship with surrounding neurovascular structures. Of the approaches for these lesions, bifrontal basal interhemispheric approach (BBIA) gives a midline perspective of suprasellar anatomy and has certain advantages over lateral approaches. Materials and Methods: We retrospectively reviewed 48 patients with suprasellar lesions operated over 7 years via BBIA. Patient records, operation notes, radiology, and outpatient files were scrutinized to collect data. Results: During the study period 48 patients (mean age 33 years, M:F 1.5:1) were operated by this approach. The clinical features included: Visual field deficits in 33 (69%) patients, with 6 of them being blind, diabetes insipidus in 7, growth retardation in 5, and subarachnoid hemorrhage in three patients. Cranopharyngiomas (52%) and meningiomas (16.7%) were the most common pathologies. Dyselectrolytemia (18, 40%) and diabetes insipidus (15, 33%) were the most common complications. Postoperative seizures, meningitis, subdural effusion, and retraction site contusion were seen in 12 (27%), 5 (11%), 4 (9%), and 1 (2.2%) patient, respectively. Three patients died postoperatively and 19 (40%) patients required hormone replacement therapy. Amongst the patients with preoperative visual deficits, 23 (70%) had improvement in visual functions, in six (20%), there was no change and four (8.3%) patients had visual deterioration. Conclusion: BBIA provides a true midline perspective and orientation, and permits complete and safe removal of midline suprasellar lesions in majority of cases. This approach is especially useful in retrochiasmatic tumors and in residual/recurrent tumors providing virgin plane of dissection.
Address for correspondence: Dr. Bhawani S. Sharma, Department of Neurosurgery, Cardiothoracic and Neurosciences Centre, All India Institute of Medical Sciences, New Delhi, India. E‑mail: [email protected] Received : 30‑07‑2013 Review completed : 17‑08‑2013 Accepted : 18‑12‑2013
Key words: Bifrontal, basal interhemispheric approach, outcome, suprasellar tumors
Introduction Suprasellar lesions present a significant surgical challenge. Different surgical approaches used for these lesions include: Pterional, subfrontal, subtemporal, Access this article online Quick Response Code:
Website: www.neurologyindia.com PMID: *** DOI: 10.4103/0028-3886.125247
Neurology India | Nov-Dec 2013 | Vol 61 | Issue 6
transcortical, transcallosal and interhemispheric. [1,2] Due to its complexity and associated morbidity, the interhemispheric approach was previously avoided. However, with the advances in microneurosurgical techniques and with improvization in neurosurgical instruments, the interhemispheric approach can be safely used for managing lesions in the suprasellar region.[1‑6] The traditional interhemispheric approach is a complex approach with an associated risk of damage to olfactory tracts and disturbances of psychological functions postoperatively.[7] In order to reduce the risk of olfactory dysfunction and psychological disturbances as well as to better visualize the infundibulohypophyseal 581
Sinha, et al.: Bifrontal basal interhemispheric approach
axis, Shibuya et al. [6] and Shirane et al. [8] modified traditional interhemispheric approach, the fronto‑basal interhemispheric approach which combines the basal interhemispheric approach and the translamina terminalis approach. In this study, the authors present the technical aspects of the bifrontal basal interhemispheric approach (BBIA) and share their experience of 48 patients with suprasellar intradural lesions treated with this approach.
Materials and Methods This is a retrospective study conducted at a tertiary care neurosurgical centre. Patient records, operation notes, radiology, and outpatient files were scrutinized to collect the data. Between January 2006 and December 2012, we have operated 48 patients (mean age 33 years, range 3‑60 years, M:F 1.5:1) with suprasellar lesions via BBIA [Table 1]. Clinical manifestations The mean duration of symptoms was 6.6 months (range: 3‑72 months). The most common presenting complaint was headache present in 36 (85%) patients. Thirty‑three (69%) patients had visual field defects, six of them had blindness, seven patients had diabetes insipidus, five patients had growth retardation, three patients presented with subarachnoid hemorrhage, and two patients had diencephalic syndrome [Table 2]. Complete hormonal profile was done in all the patients and nine patients were found to have anterior pituitary hormonal imbalance. Operative technique All the patients underwent primary surgery and in all gross total excision of tumor was attempted. Table 1: Patient characteristics Total number of patients Age (years) Mean Range Male:Female ratio Duration of symptoms (months) Mean Range
After induction and intubation, patient was positioned supine with head fixed in mild extension (5‑10°) with a three pin fixation system. A bicoronal scalp incision [Figure 1a] was given behind the hairline and a subgaleal flap was raised followed by elevation of pericranium upto bilateral orbital rims. The pericranium was reflected anteriorly for future use to exteriorize frontal sinus. A low bifrontal craniotomy was made including the nasal part of frontal bone after making a single midline burrhole. The frontal air sinus was opened invariably and sinus mucosa was excised to prevent mucocele formation. The sinus was then packed with betadine‑soaked gelfoam and sealed with bonewax. This step was done painstakingly with great efforts, in order to prevent cerebrospinal fluid (CSF) rhinorrhea in the postoperative period. A pedicled pericranium was then used to exteriorize the sinus by suturing pericranium to dura caudal to dural suture line. The dura was opened in a transverse fashion on either side of midline [Figure 1b], as far forward as possible. The superior sagittal sinus was then ligated with a figure of eight silk suture and divided as far forward as possible and falx was divided down till the crista galli. Both the frontal lobes were retracted and olfactory tracts dissected from the frontal lobes bilaterally, till olfactory trigone [Figure 2a and b]. The inclusion of nasal part of frontal bone in craniotomy allows dissection of basal interhemispheric fissure, thereby avoiding damage to draining veins over convexity. Further gentle retraction of frontal lobe would expose chiasmatic and lamina terminalis cisterns which are opened to let CSF out, thereby making brain lax and minimizing the need of frontal lobe retraction.
48 33 (3‑60) 1.5:1 6.6 3‑72
Table 2: Clinical features
Clinical features Headache Field defects Diabetes insipidus Growth retardation SAH Dencephalic syndrome 582
Number (%) 36 (85) 30 (67) 7 (15) 5 (10) 3 (6) 2 (4)
a
b
Figure 1: (a) Diagrammatic representation of patient position and skin incision (dotted line). The head is fixed with three pin fixation in neutral position and extended at occipito-cervical joint and a bicoronal skin incision (dotted line) is made. (b) After raising subgaleal flap, perisoteum is elevated (*), single burrhole is made to elevate bone flap & bifrontal craniotomy is made (arrow). Bilateral transverse dural incisions are then made (arrow heads)
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Sinha, et al.: Bifrontal basal interhemispheric approach
a
b
c
d
e
f
Figure 2: Intraoperative photographs showing (2a) frontal lobe retraction after incision of dura and ligation & division of superior sagittal sinus (black arrow ). (2b) The olfactory tracts (arrow heads) are dissected off the frontal lobes and optic chiasm (star) is exposed. (2c) Lamina terminalis (white arrow) is opened to access the tumor (white* in 2d ) which shows calcifications (black * in 2e). Gross total excision of tumor is achieved (2f)
The tumor was then removed in a sequential manner depending upon pathology and directions of tumor extension. In case of craniopharyngiomas, tumor removal was started from carotico‑optic space, interoptic space, and the corridor lateral to carotid artery. Thereafter, lamina terminalis was opened [Figure 2c‑e] and tumor taken out piecemeal from within third ventricle. Extreme caution was taken to avoid spillage of tumor cyst fluid into subarachnoid spaces, in order to prevent chemical meningitis. The pituitary stalk is visualized during removal of posterior part of tumor [Figure 2f] and every effort was made to preserve this, by avoiding suction, CUSA or bipolar coagulation near stalk.
Results The most common pathology in this series was craniopharyngioma [Figures 3 and 4] in 25 patients (52%) followed by meningiomas in eight patients, hypothalamic and chiasmal gliomas in four patients each, while epidermoid and giant pituitary adenomas were present in three patients each [Table 3]. Among the 25 patients with craniopharyngiomas, radical resection was achieved in 22 (88%) patients, while subtotal resection was done in 3 (12%) patients. Of the 8 patients with meningiomas, total resection of was achieved in 6 patients. All the patients with epidermoid and pituitary adenomas underwent gross total resection of the lesions. In patients with hypothalamic/chiasmal gliomas, only subtotal resection was performed. Complications (a) Immediate complications The most common complications in were dyselectrolytemia and diabetes insipidus occurring Neurology India | Nov-Dec 2013 | Vol 61 | Issue 6
Table 3: The pathology of the suprasellar intradural lesions in the study
Pathology Craniopharyngioma Meningioma Hypothalamic glioma Chiasmal glioma Epidermoid Giant pituitary tumor Dermoid+colloid cyst
Number (%) 25 (52) 8 (16.7) 4 (8.3) 4 (8.3) 3 (6.2) 3 (6.2) 1 (2.1)
in 18 (40%) and 15 (33%) patients respectively. Twelve (27%) patients had seizures in postoperative period that were controlled with antiepileptic drugs. Meningitis developed in five (11%) patients. Four (9%) patients developed subdural effusion and retraction site contusion developed in one (92.2%) patient. Most complications in our series (dyselectrolytemia, seizures, meningitis, and prolonged ventilation) were transient and well controlled without any sequelae with appropriate medical management [Table 4]. Four (8.3%) patients had deterioration in vision postoperatively. All these patients also had preoperative visual deficits. None of the patients developed postoperative olfactory dysfunction. Three patients died postoperatively. The causes of death in these patients were hypothalamic dysfunction, sepsis and respiratory failure. (b) Late complications: Nineteen (40%) patients were found to have hypopituitarism and required hormonal replacement postoperatively. While, in rest of the patients, postoperative hormonal analysis was normal. High morbidity (mostly transient) can be explained by radical approach adopted by the surgeon in resecting these lesions. 583
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a
a
b
c
d
b Figure 3: Preoperative (a) and postoperative (b) contrast enhanced MRI (sagittal view), demonstrating complete excision of a solid-cysic craniopharyngioma
Table 4: Complications
Complications Morbidity Dyselectrolytemia Diabetes insipidus Seizures Prolonged ventilation/tracheostomy Meningitis Subdural effusion Pseudomeningicele Retraction contusion Mortality (causes) Hypothalamic dysfunction Sepsis Respiratory failure
Number (%) 18 (40) 15 (33) 12 (27) 6 (13) 5 (11) 4 (9) 1 (2.2) 1 (2.2) 1 (2.2) 1 (2.2) 1 (2.2)
Postoperative endocrine function Post operatively, 19 (40%) patients were found to have hypopituitarism and required hormonal replacement therapy. In rest of the patients, assessment of hypothalamo‑pituitary axis revealed normal results. Postoperative visual functions Among the 33 patients with preoperative visual deficits, 23 (70%) patients had improvement in visual functions. Overall, the visual function either remained unchanged or improved in 44 (91.7%) patients, while four (8.3%) patients had deterioration in vision. None of the patients with normal preoperative vision had visual deterioration after surgery.
Discussion Anterior interhemispheric approach has been described by various authors for treatment of suprasellar lesions.[1,2,4‑6] The advantages of this approach are that it provides a wider corridor with excellent visualization of anterior circulation, optic apparatus, and tumor within the third ventricle itself. However, there is a risk of rupture of anterior draining veins with consequent 584
Figure 4: Shows the preoperative axial CT scan at the level of sella (a) and third ventricle (b) with a large cystic craniopharyngioma. The tumor was completely removed as is evident from postoperative images (c and d)
venous infarct of supero‑medial frontal lobes bilaterally especially when combined with prolonged frontal lobe retraction. A basal interhemispheric approach has been described by Shibuya et al.[6] and Shirane et al.[8] for craniopharyngiomas and by Yasui et al. for anterior communicating artery aneurysms.[9] The advantage of this approach lies in the fact that it requires minimal brain retraction, allows preservation of arteries and veins along the medial and dorsal surfaces of frontal lobes and corpus callosum and involves less extensive dissection of interhemispheric fissure, limited only to basal part. Additionally, basal approach offers a much acute angle for a better visualization of third ventricular tumor and area behind lamina terminalis to as far behind the aqueduct and basilar apex, as opposed to standard interhemispheric or pterional approach combined with translamina terminalis approach.[6,8,10,11] As the posterosuperior part of tumor is not adherent to adjacent structures, corridor provided by basal interhemispheric approach is adequate to remove this portion of tumor without damaging third ventricular floor and veins in the region.[11‑14] The bilateral midline approaches provide a true midline perspective, better orientation under operative field, view of tumor from different angles avoiding blunt dissection and permitting complete and safe excision,[6,8,10,11] unlike the unilateral approaches (like pterional approach, subtemporal approach) for suprasellar lesions located in midline such as craniopharyngiomas, hypothalamic glioma and midline anterior circulation aneurysms. The bilateral approaches provide a wide uninterrupted view of important midline structures, such as optic chiasm, anterior communicating artery with perforators, hypothalamus and infundibulohypophyseal axis, thereby, providing a better chance to preserve these Neurology India | Nov-Dec 2013 | Vol 61 | Issue 6
Sinha, et al.: Bifrontal basal interhemispheric approach
important anatomic structures. The contralateral structures are relatively blind for unilateral approaches and important perforators on ipsilateral side prevent a safe approach. However, there are certain situations in which BBIA cannot be used. Presence of active sinusitis involving frontal sinuses is an absolute contraindication to this approach. Additionally, tumors with extension into middle cranial fossa cannot be completely removed by this approach. Although the pterional approach is familiar to the neurosurgeons, ipsilateral optic nerve obstructs vision and dissection, thereby making the removal of tumor medial to optic nerve difficult and also third ventricle is visualized obliquely through the lamina terminalis. The subfrontal approach [15,16] is another unilateral approach that has been widely used for lesions in this location due to its simplicity and also because it obviates the need to dissect open the interhemispheric fissure. However, an important drawback of this approach is its relatively narrow corridor as compared with interhemispheric approach. It is difficult to open the entire lamina terminalis with this approach, thereby requiring extreme retraction of frontal lobes. It also does not give a midline orientation of regional anatomy as described above. As tumors in suprasellar location have a close relationship with infundibulohypophyseal axis, and may even be densely adherent to infundibulum, meticulous dissection and preservation of infundibulohypophyseal axis constitutes an important aspect of surgery in this region. The fronto‑basal interhemispheric approach offers a good chance to achieve this goal as it provides a good view of infundibulohypophyseal axis. In addition, it does not require strong retraction of frontal lobes if lamina terminalis is widely exposed.[8] Shirane et al.[8] used a small craniotomy to prevent inadvertent damage
to olfactory tracts, fornix, corpus callosum, and anterior commissure. In their series of 31 patients, none of the patients developed olfactory dysfunction or psychological problems and only one patient developed transient ischemic damage to hypothalamus. When compared to classical interhemispheric approach, BBIA provides angle of visualization from base so that 3rd ventricle and superior surface of tumor are well visualized because of inferior angle, needs no coagulation of bridging veins, permits improved pituitary stalk preservation and hormonal outcome, thereby postoperative course is less stormy. Retraction of bilateral frontal lobes and contusion and contamination from opening of frontal sinuses are potential drawbacks of this approach; however, in our series only one patient (2.2%) developed frontal lobe retraction secondary to retraction. A comparison between merits and demerits of different approaches to suprasellar tumors are given in Table 5. Shirane et al.[8] achieved total resection in 71% patients with craniopharyngiomas using frontobasal interhemispheric approach. Hypothalamo‑pituitary dysfunction was observed in 81% of the patients. They reported a mortality rate of 7.1% (3/42). Similarly, Shibuya et al.[6] performed total or near total resection of craniopharyngiomas in 22 patients via BBIA. Visual deterioration was seen in two of the patients (9%). All except one of their patients required hormone replacement. There were three deaths (13.6%) in a delayed manner. Hori et al.[10] accomplished total resection in 80.4% of patients using anterior interhemispheric approach; however, the rate of postoperative hypothalamic dysfunction and dyselectrolytemia was very high. Diabetes insipidus occurred in 62.2% of patients after surgery. Visual deterioration occurred in 10.7% patients. Fahlbusch et al.[1] reported 45.7% total resection rates for craniopharyngiomas operated by pterional and anterior interhemispheric approach. The risk of visual
Table 5: Comparison between different approaches to suprasellar tumors
Approach
Exposure
Merits
Demerits
Pterional
Unilateral
Unilateral subfrontal
Unilateral
Early visualization of optic nerve and ipsilateral carotid artery; Less frontal lobe retraction; view interrupted by the perforator vessels Only unilateral frontal lobe and olfactory nerve at risk
Anterior interhemispheric Bifrontal basal interhemispheric
Bilateral/ midline Bilateral/ midline
Narrow space and angle especially in cases with prefixed chiasm; an oblique angle of vision; restricted view of contralateral structures; requires sylvian fissure dissection Frontal lobe retraction; narrow corridor and longer access to sellar‑suprasellar region; restricted view of purely midline lesions and contralateral structures; CSF leak; Olfactory nerve injury Risk of damage to anterior draining veins; requires extensive interhemispheric dissection Frontal lobe retraction; CSF leak; Olfactory nerve injury
Wide uninterrupted view of suprasellar area; A true midline perspective of suprasellar anatomy; Wide uninterrupted view of suprasellar area; A true midline perspective of suprasellar anatomy; only basal interhemispheric fissure dissected
CSF - Cerebrospinal fluid
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deterioration in their patients operated transcranially was 14.7%. Yasargil et al.[16] adopted a very aggressive approach toward craniopharyngiomas in their series of 144 patients and achieved total resection in 90% of patients. They reported a mortality rate of 16.7%. They also reported a very high incidence of postoperative hypothalamic dysfunction in 79% of patients. In the present series, radical resection was achieved in 21/25 (84%) of the patients with craniopharyngiomas. Six of the eight patients (75%) with meningiomas underwent total resection diabetes insipidus was seen in 15 (33%) patients and hormonal disturbances requiring replacement therapy were seen in 19 (40%) patients postoperatively. Visual deterioration occurred in 4 (8.3%) patients. The mortality rate was 6.2% (3/48). The extent of resection and complication rate was comparable to those reported in literature.
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How to cite this article: Sinha S, Kumar A, Sharma BS. Bifrontal basal interhemispheric approach for midline suprasellar tumors: Our experience with forty-eight patients. Neurol India 2013;61:581-6. Source of Support: Nil, Conflict of Interest: None declared.
Neurology India | Nov-Dec 2013 | Vol 61 | Issue 6
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