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Surgical removal of retrochiasmatic craniopharyngiomas with transpetrosal approach
Surgical Removal of Retrochiasmatic Craniopharyngiomas with Transpetrosal Approach Kenji Ohata, MD, Toshihiro Takami, MD, Takeo Goto, MD, and Mitsuhiro Hara, MD
Although there is general agreement that surgery is the preferred treatment for craniopharyngiomas, the extent of resection and optimal approach are still debated. Since 1973 our institute has used the transpetrosal approach to remove cerebellopontine angle and clivus tumors. We also prefer this approach for the removal of retrochiasmatic craniopharyngiomas. The principal advantage of the transpetrosal approach is that it allows the hypothalamus, the wall of the third ventricle, and the inferior surface of the optic chiasm to be visualized directly during surgery. Between 1980 and 2002, 28 patients with retrochiasmatic craniopharyngiomas underwent a combined anterior and posterior transpetrosal approach with a partial labyrinthectomy. The mean follow-up was 13.6 years (range, 0.8-23 years). Total removal of the tumor was confirmed in 25 (89%) cases. Preoperatively, patients had a visual disturbance, which improved in 10 cases, worsened 3 cases, and was unchanged in 1 case. This approach is useful for the aggressive surgical treatment of retrochiasmatic craniopharyngiomas. Copyright 2003, Elsevier Science (USA). All rights reserved.
istologically, craniopharyngiomas are benign tumors that originate from remnants of Rathke’s pouch. Radical removal of the tumor is the treatment of choice to cure the patient.1-4 However, important structures such as the optic chiasm, hypothalamus, circle of Willis, and limbic system, including the mammillary bodies and fornix, can be adjacent to the tumor. Because of these anatomical relationships, total extirpation of tumor is difficult. Many different surgical approaches, such as the pterional, subfrontal, transcallosal, transsphenoidal, translamina-terminalis, interhemispheric, single or combined, have been used in the treatment of craniopharyngiomas. However, the optimal method for removing these tumor has yet to be defined.1-8 At our institution, craniopharyngiomas growing posterior to the optic chiasm and compressing the third ventricle superiorly have been treated via approaches based on the transpetrosal approach.9 This article reviews the operative technique underlying the transpetrosal approach and our surgical outcomes.
H
From the Department of Neurosurgery, Osaka City University Graduate School of Medicine, Osaka, Japan. Address reprint requests to Kenji Ohata, MD, Department of Neurosurgery, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka 545-8585, Japan; E-mail: kohata@ med.osaka-cu.ac.jp. Copyright 2003, Elsevier Science (USA). All rights reserved. 1092-440X/03/0604-0004$35.00/0 doi:10.1016/S1092-440X(03)00050-1
200
Clinical Materials and Methods Patient Population Between 1980 and 2002, 28 patients with retrochiasmatic craniopharyngiomas underwent the transpetrosal approach. There were 16 men and 12 women (mean age, 33 years; ranged 6 to 64 years). In 24 cases, the transpetrosal approach was used as the first operation. In the remaining 4 cases, it was used to remove recurrent or residual tumors. The mean follow-up period for 27 cases was 13.6 years (range, 0.8-23 years). Fourteen patients presented with preoperative visual deficits.
Surgical Technique Patients with retrochiasmatic craniopharyngiomas were approached via a combined anterior and posterior transpetrosal approach with drilling of the petrosal bone and a partial labyrinthectomy to preserve hearing. Position and Skin Incision. The patient was placed in the lateral park-bench position. The temporal region was positioned horizontal to the floor. The upper thoracic and cervical spine was flexed downward, and the head side of the operating table was elevated about 35 degrees. The skin incision began at the anterior wall of the tragus, 5 mm posterior to the superficial temporal artery and crossing the midline about 4 cm. An additional posterotemporal extension of the incision was made beginning at the previous incision 1.5 cm above the uppermost part of the ear cartilage down to about 2-cm medial to the tip of the mastoid process. The temporal muscle was separated subperiosteally from the temporal squama, zygomatic arch, and mastoid process. The suboccipital muscles and upper part of the insertion of the sternocleidomastoid muscle were also elevated subperiosteally (Fig 1B). Care was taken to preserve the insertion of the sternocleidomastoid muscle on the inferior portion of the mastoid process for the later splitting mastoidotomy. Craniotomy. After the standard temporo-occipito-suboccipital craniotomy (Fig 1B) was performed, the outer table of the mastoid process was split to preserve the insertion of the sternocleidomastoid muscle on the inferior portion of the mastoid process intact. This maneuver was easily accomplished with a reciprocating saw. The sigmoid sinus was carefully exposed down to its short horizontal segment. Extent of Petrosectomy. A retractor was used to protect the sigmoid sinus, and the petrosectomy was performed. The mastoid antrum was opened, and the posterior and anterior semicircular canals were partially drilled. The endolymphatic sac, relatively white compared with the surrounding dura mater, was identified on the posterior surface of the petrous bone
Operative Techniques in Neurosurgery, Vol 6, No 4 (December), 2003: pp 200-204
Fig 1. Diagrams demonstrating the surgical procedure. (A) Skin incision, (B) location of burr holes and the extent of the craniotomy, (C) petrosectomy with partial labyrinthectomy, (D) dural incision, (E) tentoriotomy, (F) view of suprasellar region. IC; internal carotid artery, III; oculomotor nerve, IV, trochlear nerve, SS; sigmoid sinus, TT; transverse sinus, V: trigeminal nerve, Reprinted with permission.11
where the dura mater was still attached (Fig 1C). The petrosal ridge was removed up to the level of the internal auditory meatus. Usually the anterior and posterior semicircular canals were drilled to gain a wider exposure of the suprasellar region. The medial petrous ridge is resected over the internal auditory meatus. If the tumor extended infratentorially, an anterior petrosectomy was also performed. Dural Incision and Tentoriotomy. The petrosal dura was opened, leaving 5-mm dural fringes on the anterior margin of the sigmoid sinus and on the inferior margin of the superior petrosal sinus. The subtemporal dural incision was extended as far anterior as possible. Its medial extent coursed along the posterior margin of the gasserian ganglion (Fig 1D). The superior petrosal sinus was transected immediately posterior to the trigeminal nerve. The tentorium was divided from the point of the transection of the superior petrosal sinus to its hiatus immediately behind the dural entrance of the trochlear nerve (Fig 1E). If a large dural sinus extended from the cavernous sinus to the point of transection, the stump of the petrous vein on the cavernous side was ligated with suture. Observation of the Supratentorial Region. When the arachnoid membrane was cut superiorly to the trochlear nerve, the nerve was pulled inferolaterally because the arachnoid membrane adhered to the trochlear nerve. Retraction of the temporal lobe allowed the posterior communicating artery running parallel to the oculomotor nerve to be identified (Fig 1F). In the TRANSPETROSAL APPROACH
case shown, tumor was observed medial to the trochlear and oculomotor nerves and posterior communicating artery. Tumor Removal. First, the tumor was decompressed internally through the spaces above or below the oculomotor nerve. This strategy made it possible to remove tumor safely because the inferior surface of the chiasm, pituitary stalk, ipsilateral side of the anterior cerebral artery, and posteromedial side of both carotid arteries could be visualized directly. When tumor extended into the third ventricle, the superior wall of the enlarged third ventricle was also visible. The dissector could be inserted in the wall of the third ventricle parallel to the interface of the tumor and hypothalamus. Closure. After the tumor was removed, the dural defect was closed watertight, and abdominal fat tissue was inserted epidurally. The temporo-occipito-suboccipital bone flap, outer table of the mastoid process, and zygomatic arch were replaced and fixated with titanium miniplates.
Results In 8 cases, the tumor extended posterosuperiorly compressing the midbrain, and the lateral margin of the middle skull base obscured the tumor-diencephalon interface. Therefore, the root of the zygoma and the lateral two-thirds of the mandibular fossa were transected to improve visualization.10 Complete tumor resection was confirmed in 25 cases (89%)
201
Fig 2. MRI of illustrative case. Preoperative T1-weighted coronal (A) and sagittal (B) MRIs after contrast enhancement show a homogenously enhanced mass in the retrochiasmatic region. The tumor extended into the third ventricle. T1weighted coronal (C) and sagittal (D) MRIs after contrast enhancement obtained 6 months after surgery confirms total resection of the tumor.
by postoperative magnetic resonance imaging (MRI). Of the 14 patients with a preoperative visual disturbance, 10 improved, 3 worsened, and 1 was unchanged. Hydrocephalus was detected radiographically in 9 patients, and 3 patients required shunts before or after definitive surgery.
Illustrative Case A 59-year-old female sought treatment for complaints of gait disturbance, excessive thirst, and polyuria. Neurological examination on admission showed no deficits. MRI revealed a suprasellar solid mass extending into the third ventricle (Fig 2A,B). Exploration was made via a combined anterior and posterior transpetrosal approach. After a tentoriotomy (Fig 3A), the tumor was visible medial to the oculomotor nerve (Fig 3B). The postero-inferior portion of the tumor between the oculomotor and trigeminal nerves was resected first. The retrochiasmatic portion was then exposed between the oculomotor nerve and posterior communicating artery (Fig 3C). The tumor, hard in consistency, was removed completely, and the pituitary stalk was identified and preserved (Fig 3D). Postoperative MRI confirmed complete removal of the tumor (Fig 2C,D).
Discussion The entry trajectory of the transpetrosal transtentorial approach is about 2 to 3 cm lower than that of the usual subtemporal approach. Therefore, the posterior surface of the chiasm, superiorly displaced hypothalamus, and contralateral vessels and nerves can be dissected under direct visual control. The
202
superior pole of the tumor and the wall of the third ventricle can be dissected under direct microscopic vision with minimal retraction of the temporal lobe.9 This surgical procedure for resecting retrochiasmatic craniopharyngiomas was first reported by Hakuba and followed by Ohata and co-workers.9,11 The pterional approach, which has been used to remove craniopharyngiomas for many years, has limited application for lesions in or about the third ventricle.12 Yasargil and Teddy suggested that craniopharyngiomas extending upward from the infundibulum of the third ventricle to the foramen of Monro could not be completely removed using only a frontobasal (pterional) approach, even after the lamina terminalis was opened.13 With the pure transcallosal-transforaminal approach, the anterosuperior portions of the tumor under the chiasm and lamina terminalis may not be visible. From this anatomical perspective, Yasargil and co-workers prefer a combined pterionaltranscallosal approach for extraventricular and intraventricular types of tumor causing hydrocephalus.8 Samii reported that even large craniopharyngiomas in the retrochiasmatic region at the level of the third ventricle could be approached via a subfrontal route by opening the lamina terminalis without increasing the rate of complications.5 A bifrontal anterior interhemispheric approach has several disadvantages. First, it often requires dividing the draining veins from the frontal lobe to the superior sagittal sinus. However, dividing these draining veins and retracting the frontal lobe increase the risk of postoperative contusional hemorrhage. Second, the anterior communicating artery often limits lateral exposure of large retrochiasmatic tumors. Several authors have OHATA ET AL
Fig 3. Intraoperative photographs showing surgical steps of combined anterior and posterior transpetrosal approach. (A) The temporal lobe (Tem) was retracted superiorly, and the cerebellum (Cer) was retracted posteriorly with the sigmoid sinus. A tentoriotomy (Tent) was performed to the hiatus behind the dural entrance of the trochlear nerve (IV). (B) Postero-inferior portion of the tumor (T) was visible between the oculomotor nerve (III) and trigeminal nerve (V). (C) After the postero-inferior portion of the tumor was removed its suprasellar portion between the oculomotor nerve and posterior communicating artery (P.Com) was removed. The optic nerve (II) was visible anterior to the internal carotid artery (IC). (D) The tumor was totally removed inferior and superior to the oculomotor nerve. The inferior surface of the optic chiasm was well visualized (asterisk).
reported the efficacy of dividing the anterior communicating artery in the anterior interhemispheric approach to provide a much wider operating space without significant complications.6,7 However, patients often have anomalous anatomy and variations around the anterior communicating artery. Therefore, it is not always divided safely with no complications. Third, the portion of the sella turcica inferior to the surface of the optic chiasm cannot be visualized in this approach. The transpetrosal approach provides an excellent exposure of the tumor and related structures such as the inferior surface of the optic chiasm, hypothalamus, and pituitary stalk directly from the posterolateral side. Because the dissector can be inserted in parallel toward the upper part of tumor, the risk of hypothalamic damage might be less than with bilateral median approaches. However, this approach also has disadvantages. In some cases, transient oculomotor nerve palsy is unavoidable. Although craniopharyngiomas are histologically benign tumors, they are associated with high recurrence rates even after total resection.3,6,8,14-16 Reducing the recurrence rate is a signifTRANSPETROSAL APPROACH
icant issue in the treatment of craniopharyngiomas. A wider exposure may be needed to expose the tumor and surrounding structures to achieve complete resection. The transpetrosal approach can be a useful method to achieve a radical resection of retrochiasmatic craniopharyngiomas.
References 1. Apuzzo MLJ, Chikovani OK, Gott PS, et al: Transcallosal, interfornicial approach for lesions affecting the third ventricle: Surgical considerations and consequences. Neurosurgery 10:547-554, 1982 2. Long DM, Chou SN: Transcallosal removal of craniopharyngiomas within the third ventricle. J Neurosurg 39:563-567, 1973 3. Matson DD, Crieger JF: Management of craniopharyngioma in childhood. J Neurosurg 30:377-390, 1969 4. Patterson RH, Danylevich A: Surgical removal of craniopharyngiomas by a transcranial approach through the lamina terminalis and sphenoid sinus. Neurosurgery 7:111-117, 1980 5. Samii M, Samii A: Surgical management of craniopharyngiomas, in Schmidek HH, Sweet WH (eds): Operative Neurosurgical Techniques, ed 3. Philadelphia: WB Saunders, 1995, pp 357-370
203
6. Shibuya M, Takayasu M, Suzuki Y, et al: Bifrontal basal interhemispheric approach to craniopharyngioma resection with or without division of the anterior communicating artery. J Neurosurg 84:951956, 1996 7. Suzuki J, Katakura R, Mori T: Interhemispheric approach through the lamina terminalis to tumors of the anterior part of the third ventricle. Surg Neurol 22:157-163, 1994 8. Yasargil MG, Curcic M, Kis M, et al: Total removal of craniopharyngiomas. J Neurosurg 73:3-11, 1990 9. Hakuba A, Nishimura S, Inoue Y: Transpetrosal-transtentorial approach and its application in the therapy of retrochiasmatic craniopharyngiomas. Surg Neurol 24:405-415, 1985 10. Ohata K, Baba M: Otico-condylar approach, in Hakuba A (ed): Surgical Anatomy of the Skull Base. Tokyo, Miwa Shoten, 1996, pp 48-53 11. Ohata K, Baba M: Presigmoidal transpetrosal approach, in Hakuba A
204
12.
13.
14.
15. 16.
(eds): Surgical Anatomy of the Skull Base. Tokyo: Miwa Shoten, 1996, p 115 Tindall GT, Tindall SC: Pterional approach, in Apuzzo MLJ (ed): Surgery of the Third Ventricle. Baltimore, Williams & Wilkins, 1987, pp 440-461 Yasargil MG, Teddy PJ: Combined approaches, in Apuzzo MLJ (ed): Surgery of the Third Ventricle. Baltimore, Williams & Wilkins, 1987, pp 462-475 Hoffman HJ, Silva MD, Humphreys RP, et al: Aggressive surgical management of craniopharyngiomas in children. J Neurosug 76:4752, 1992 Sweet WH: Recurrent craniopharyngiomas: Therapeutic alternatives. Clin Neurosurg 27:206-229, 1980 Symon L, Sprich W: Radical excision of craniopharyngioma: Results in 20 patients. J Neurosurg 62:174-181, 1985
OHATA ET AL
Although there is general agreement that surgery is the preferred treatment for craniopharyngiomas, the extent of resection and optimal approach are still debated. Since 1973 our institute has used the transpetrosal approach to remove cerebellopontine angle and clivus tumors. We also prefer this approach for the removal of retrochiasmatic craniopharyngiomas. The principal advantage of the transpetrosal approach is that it allows the hypothalamus, the wall of the third ventricle, and the inferior surface of the optic chiasm to be visualized directly during surgery. Between 1980 and 2002, 28 patients with retrochiasmatic craniopharyngiomas underwent a combined anterior and posterior transpetrosal approach with a partial labyrinthectomy. The mean follow-up was 13.6 years (range, 0.8-23 years). Total removal of the tumor was confirmed in 25 (89%) cases. Preoperatively, patients had a visual disturbance, which improved in 10 cases, worsened 3 cases, and was unchanged in 1 case. This approach is useful for the aggressive surgical treatment of retrochiasmatic craniopharyngiomas. Copyright 2003, Elsevier Science (USA). All rights reserved.
istologically, craniopharyngiomas are benign tumors that originate from remnants of Rathke’s pouch. Radical removal of the tumor is the treatment of choice to cure the patient.1-4 However, important structures such as the optic chiasm, hypothalamus, circle of Willis, and limbic system, including the mammillary bodies and fornix, can be adjacent to the tumor. Because of these anatomical relationships, total extirpation of tumor is difficult. Many different surgical approaches, such as the pterional, subfrontal, transcallosal, transsphenoidal, translamina-terminalis, interhemispheric, single or combined, have been used in the treatment of craniopharyngiomas. However, the optimal method for removing these tumor has yet to be defined.1-8 At our institution, craniopharyngiomas growing posterior to the optic chiasm and compressing the third ventricle superiorly have been treated via approaches based on the transpetrosal approach.9 This article reviews the operative technique underlying the transpetrosal approach and our surgical outcomes.
H
From the Department of Neurosurgery, Osaka City University Graduate School of Medicine, Osaka, Japan. Address reprint requests to Kenji Ohata, MD, Department of Neurosurgery, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka 545-8585, Japan; E-mail: kohata@ med.osaka-cu.ac.jp. Copyright 2003, Elsevier Science (USA). All rights reserved. 1092-440X/03/0604-0004$35.00/0 doi:10.1016/S1092-440X(03)00050-1
200
Clinical Materials and Methods Patient Population Between 1980 and 2002, 28 patients with retrochiasmatic craniopharyngiomas underwent the transpetrosal approach. There were 16 men and 12 women (mean age, 33 years; ranged 6 to 64 years). In 24 cases, the transpetrosal approach was used as the first operation. In the remaining 4 cases, it was used to remove recurrent or residual tumors. The mean follow-up period for 27 cases was 13.6 years (range, 0.8-23 years). Fourteen patients presented with preoperative visual deficits.
Surgical Technique Patients with retrochiasmatic craniopharyngiomas were approached via a combined anterior and posterior transpetrosal approach with drilling of the petrosal bone and a partial labyrinthectomy to preserve hearing. Position and Skin Incision. The patient was placed in the lateral park-bench position. The temporal region was positioned horizontal to the floor. The upper thoracic and cervical spine was flexed downward, and the head side of the operating table was elevated about 35 degrees. The skin incision began at the anterior wall of the tragus, 5 mm posterior to the superficial temporal artery and crossing the midline about 4 cm. An additional posterotemporal extension of the incision was made beginning at the previous incision 1.5 cm above the uppermost part of the ear cartilage down to about 2-cm medial to the tip of the mastoid process. The temporal muscle was separated subperiosteally from the temporal squama, zygomatic arch, and mastoid process. The suboccipital muscles and upper part of the insertion of the sternocleidomastoid muscle were also elevated subperiosteally (Fig 1B). Care was taken to preserve the insertion of the sternocleidomastoid muscle on the inferior portion of the mastoid process for the later splitting mastoidotomy. Craniotomy. After the standard temporo-occipito-suboccipital craniotomy (Fig 1B) was performed, the outer table of the mastoid process was split to preserve the insertion of the sternocleidomastoid muscle on the inferior portion of the mastoid process intact. This maneuver was easily accomplished with a reciprocating saw. The sigmoid sinus was carefully exposed down to its short horizontal segment. Extent of Petrosectomy. A retractor was used to protect the sigmoid sinus, and the petrosectomy was performed. The mastoid antrum was opened, and the posterior and anterior semicircular canals were partially drilled. The endolymphatic sac, relatively white compared with the surrounding dura mater, was identified on the posterior surface of the petrous bone
Operative Techniques in Neurosurgery, Vol 6, No 4 (December), 2003: pp 200-204
Fig 1. Diagrams demonstrating the surgical procedure. (A) Skin incision, (B) location of burr holes and the extent of the craniotomy, (C) petrosectomy with partial labyrinthectomy, (D) dural incision, (E) tentoriotomy, (F) view of suprasellar region. IC; internal carotid artery, III; oculomotor nerve, IV, trochlear nerve, SS; sigmoid sinus, TT; transverse sinus, V: trigeminal nerve, Reprinted with permission.11
where the dura mater was still attached (Fig 1C). The petrosal ridge was removed up to the level of the internal auditory meatus. Usually the anterior and posterior semicircular canals were drilled to gain a wider exposure of the suprasellar region. The medial petrous ridge is resected over the internal auditory meatus. If the tumor extended infratentorially, an anterior petrosectomy was also performed. Dural Incision and Tentoriotomy. The petrosal dura was opened, leaving 5-mm dural fringes on the anterior margin of the sigmoid sinus and on the inferior margin of the superior petrosal sinus. The subtemporal dural incision was extended as far anterior as possible. Its medial extent coursed along the posterior margin of the gasserian ganglion (Fig 1D). The superior petrosal sinus was transected immediately posterior to the trigeminal nerve. The tentorium was divided from the point of the transection of the superior petrosal sinus to its hiatus immediately behind the dural entrance of the trochlear nerve (Fig 1E). If a large dural sinus extended from the cavernous sinus to the point of transection, the stump of the petrous vein on the cavernous side was ligated with suture. Observation of the Supratentorial Region. When the arachnoid membrane was cut superiorly to the trochlear nerve, the nerve was pulled inferolaterally because the arachnoid membrane adhered to the trochlear nerve. Retraction of the temporal lobe allowed the posterior communicating artery running parallel to the oculomotor nerve to be identified (Fig 1F). In the TRANSPETROSAL APPROACH
case shown, tumor was observed medial to the trochlear and oculomotor nerves and posterior communicating artery. Tumor Removal. First, the tumor was decompressed internally through the spaces above or below the oculomotor nerve. This strategy made it possible to remove tumor safely because the inferior surface of the chiasm, pituitary stalk, ipsilateral side of the anterior cerebral artery, and posteromedial side of both carotid arteries could be visualized directly. When tumor extended into the third ventricle, the superior wall of the enlarged third ventricle was also visible. The dissector could be inserted in the wall of the third ventricle parallel to the interface of the tumor and hypothalamus. Closure. After the tumor was removed, the dural defect was closed watertight, and abdominal fat tissue was inserted epidurally. The temporo-occipito-suboccipital bone flap, outer table of the mastoid process, and zygomatic arch were replaced and fixated with titanium miniplates.
Results In 8 cases, the tumor extended posterosuperiorly compressing the midbrain, and the lateral margin of the middle skull base obscured the tumor-diencephalon interface. Therefore, the root of the zygoma and the lateral two-thirds of the mandibular fossa were transected to improve visualization.10 Complete tumor resection was confirmed in 25 cases (89%)
201
Fig 2. MRI of illustrative case. Preoperative T1-weighted coronal (A) and sagittal (B) MRIs after contrast enhancement show a homogenously enhanced mass in the retrochiasmatic region. The tumor extended into the third ventricle. T1weighted coronal (C) and sagittal (D) MRIs after contrast enhancement obtained 6 months after surgery confirms total resection of the tumor.
by postoperative magnetic resonance imaging (MRI). Of the 14 patients with a preoperative visual disturbance, 10 improved, 3 worsened, and 1 was unchanged. Hydrocephalus was detected radiographically in 9 patients, and 3 patients required shunts before or after definitive surgery.
Illustrative Case A 59-year-old female sought treatment for complaints of gait disturbance, excessive thirst, and polyuria. Neurological examination on admission showed no deficits. MRI revealed a suprasellar solid mass extending into the third ventricle (Fig 2A,B). Exploration was made via a combined anterior and posterior transpetrosal approach. After a tentoriotomy (Fig 3A), the tumor was visible medial to the oculomotor nerve (Fig 3B). The postero-inferior portion of the tumor between the oculomotor and trigeminal nerves was resected first. The retrochiasmatic portion was then exposed between the oculomotor nerve and posterior communicating artery (Fig 3C). The tumor, hard in consistency, was removed completely, and the pituitary stalk was identified and preserved (Fig 3D). Postoperative MRI confirmed complete removal of the tumor (Fig 2C,D).
Discussion The entry trajectory of the transpetrosal transtentorial approach is about 2 to 3 cm lower than that of the usual subtemporal approach. Therefore, the posterior surface of the chiasm, superiorly displaced hypothalamus, and contralateral vessels and nerves can be dissected under direct visual control. The
202
superior pole of the tumor and the wall of the third ventricle can be dissected under direct microscopic vision with minimal retraction of the temporal lobe.9 This surgical procedure for resecting retrochiasmatic craniopharyngiomas was first reported by Hakuba and followed by Ohata and co-workers.9,11 The pterional approach, which has been used to remove craniopharyngiomas for many years, has limited application for lesions in or about the third ventricle.12 Yasargil and Teddy suggested that craniopharyngiomas extending upward from the infundibulum of the third ventricle to the foramen of Monro could not be completely removed using only a frontobasal (pterional) approach, even after the lamina terminalis was opened.13 With the pure transcallosal-transforaminal approach, the anterosuperior portions of the tumor under the chiasm and lamina terminalis may not be visible. From this anatomical perspective, Yasargil and co-workers prefer a combined pterionaltranscallosal approach for extraventricular and intraventricular types of tumor causing hydrocephalus.8 Samii reported that even large craniopharyngiomas in the retrochiasmatic region at the level of the third ventricle could be approached via a subfrontal route by opening the lamina terminalis without increasing the rate of complications.5 A bifrontal anterior interhemispheric approach has several disadvantages. First, it often requires dividing the draining veins from the frontal lobe to the superior sagittal sinus. However, dividing these draining veins and retracting the frontal lobe increase the risk of postoperative contusional hemorrhage. Second, the anterior communicating artery often limits lateral exposure of large retrochiasmatic tumors. Several authors have OHATA ET AL
Fig 3. Intraoperative photographs showing surgical steps of combined anterior and posterior transpetrosal approach. (A) The temporal lobe (Tem) was retracted superiorly, and the cerebellum (Cer) was retracted posteriorly with the sigmoid sinus. A tentoriotomy (Tent) was performed to the hiatus behind the dural entrance of the trochlear nerve (IV). (B) Postero-inferior portion of the tumor (T) was visible between the oculomotor nerve (III) and trigeminal nerve (V). (C) After the postero-inferior portion of the tumor was removed its suprasellar portion between the oculomotor nerve and posterior communicating artery (P.Com) was removed. The optic nerve (II) was visible anterior to the internal carotid artery (IC). (D) The tumor was totally removed inferior and superior to the oculomotor nerve. The inferior surface of the optic chiasm was well visualized (asterisk).
reported the efficacy of dividing the anterior communicating artery in the anterior interhemispheric approach to provide a much wider operating space without significant complications.6,7 However, patients often have anomalous anatomy and variations around the anterior communicating artery. Therefore, it is not always divided safely with no complications. Third, the portion of the sella turcica inferior to the surface of the optic chiasm cannot be visualized in this approach. The transpetrosal approach provides an excellent exposure of the tumor and related structures such as the inferior surface of the optic chiasm, hypothalamus, and pituitary stalk directly from the posterolateral side. Because the dissector can be inserted in parallel toward the upper part of tumor, the risk of hypothalamic damage might be less than with bilateral median approaches. However, this approach also has disadvantages. In some cases, transient oculomotor nerve palsy is unavoidable. Although craniopharyngiomas are histologically benign tumors, they are associated with high recurrence rates even after total resection.3,6,8,14-16 Reducing the recurrence rate is a signifTRANSPETROSAL APPROACH
icant issue in the treatment of craniopharyngiomas. A wider exposure may be needed to expose the tumor and surrounding structures to achieve complete resection. The transpetrosal approach can be a useful method to achieve a radical resection of retrochiasmatic craniopharyngiomas.
References 1. Apuzzo MLJ, Chikovani OK, Gott PS, et al: Transcallosal, interfornicial approach for lesions affecting the third ventricle: Surgical considerations and consequences. Neurosurgery 10:547-554, 1982 2. Long DM, Chou SN: Transcallosal removal of craniopharyngiomas within the third ventricle. J Neurosurg 39:563-567, 1973 3. Matson DD, Crieger JF: Management of craniopharyngioma in childhood. J Neurosurg 30:377-390, 1969 4. Patterson RH, Danylevich A: Surgical removal of craniopharyngiomas by a transcranial approach through the lamina terminalis and sphenoid sinus. Neurosurgery 7:111-117, 1980 5. Samii M, Samii A: Surgical management of craniopharyngiomas, in Schmidek HH, Sweet WH (eds): Operative Neurosurgical Techniques, ed 3. Philadelphia: WB Saunders, 1995, pp 357-370
203
6. Shibuya M, Takayasu M, Suzuki Y, et al: Bifrontal basal interhemispheric approach to craniopharyngioma resection with or without division of the anterior communicating artery. J Neurosurg 84:951956, 1996 7. Suzuki J, Katakura R, Mori T: Interhemispheric approach through the lamina terminalis to tumors of the anterior part of the third ventricle. Surg Neurol 22:157-163, 1994 8. Yasargil MG, Curcic M, Kis M, et al: Total removal of craniopharyngiomas. J Neurosurg 73:3-11, 1990 9. Hakuba A, Nishimura S, Inoue Y: Transpetrosal-transtentorial approach and its application in the therapy of retrochiasmatic craniopharyngiomas. Surg Neurol 24:405-415, 1985 10. Ohata K, Baba M: Otico-condylar approach, in Hakuba A (ed): Surgical Anatomy of the Skull Base. Tokyo, Miwa Shoten, 1996, pp 48-53 11. Ohata K, Baba M: Presigmoidal transpetrosal approach, in Hakuba A
204
12.
13.
14.
15. 16.
(eds): Surgical Anatomy of the Skull Base. Tokyo: Miwa Shoten, 1996, p 115 Tindall GT, Tindall SC: Pterional approach, in Apuzzo MLJ (ed): Surgery of the Third Ventricle. Baltimore, Williams & Wilkins, 1987, pp 440-461 Yasargil MG, Teddy PJ: Combined approaches, in Apuzzo MLJ (ed): Surgery of the Third Ventricle. Baltimore, Williams & Wilkins, 1987, pp 462-475 Hoffman HJ, Silva MD, Humphreys RP, et al: Aggressive surgical management of craniopharyngiomas in children. J Neurosug 76:4752, 1992 Sweet WH: Recurrent craniopharyngiomas: Therapeutic alternatives. Clin Neurosurg 27:206-229, 1980 Symon L, Sprich W: Radical excision of craniopharyngioma: Results in 20 patients. J Neurosurg 62:174-181, 1985
OHATA ET AL