经扩大迷路进路巨大听神经瘤摘除术
作者：吴皓 吕春雷 马超武 张速勤 周水淼 李兆基
单位：第二军医大学长海医院耳鼻咽 喉科，上海 200433
关键词：听神经瘤；扩大迷路进路；微创手术
第二军医大学学报001206 [摘要] 目的：探讨通过扩大的迷路进路 切除巨大听神经瘤的手术方法和手术效果。方法：扩大迷路进路的要 点是，充分暴露乙状窦及其后方硬脑膜、岩上窦、颅中窝硬脑膜，暴露并下压颈静脉球，内 听道周围骨质270°以上切除。肿瘤切除应从前下极处开始，以早期暴露脑干及脑干表面面 神经，随后即可从内侧向外侧解剖面神经。术中均使用面神经监护仪，术后均复查CT和MRI 。结果：18例直径在3 cm以上的听神经瘤(平均直径4.2 cm)，均能 手术全切，脑组织无明显损伤，2例术后一过性脑脊液漏自愈，无颅内感染；面神经解剖及 功能保存14例，其中8例面神经功能1～2级(44%)，6例面神经功能3～4级(33%)，4例面神 经中断者均为术前已有重度面瘫或已中断；16例术后1～3月恢复工作，2例恢复生活自理。[ HT5W〗结论：经扩大迷路进路既能达到全切巨大听神经瘤的目的，同时具有损 伤小、面神经保存率高的优点。
, 百拇医药
[中图分类号] R 739.6105; R 764.93 [文献标识码 ] A
Removal of large acoustic neuromas by enlarged translabyrinthine approach
WU Hao Lü Chun-Lei MA Chao-Wu ZHANG Su-Qin ZHOU Shui-Miao LI Zhao-Ji
(Department of Otolaryngology, Changhai Hospital, Second Military Medical Uni versity, Shanghai 200433, China)
[ABSTRACT] Objective: To investigate the surgical methods and outcomes of the enlarged translabyrinthine approach in the removal of large ac ousti c neuromas. Methods: A large mastoidectomy involved complete exp osure of the sigmoid sinus, the dura behind the sinus for at least 1 cm, the sup erior petrosal sinus and the middle fossa dura. The jugular bulb was exposed and pressed downwards if necessary. The internal auditory meatus was skeletonized a nd uncovered for at least 270°. The debulking of the tumor began inside the ant erior and inferior poles in order to find the brainstem and the facial nerve roo t as early as possible, and then the dissection of the nerve was done medially t o laterally. Intraoperative facial nerve monitoring and postoperative CT and MR I were done in all cases. Results: Total removal was achieved in a ll 18 patients with tumors larger than 3 cm (mean size: 4.2 cm). There were no d eaths or other complications such as intracranial infection and persistent cereb rospinal fluid leakage. There were no obvious cerebral sequelae. The facial nerv e was preserved both anatomically and functionally in 14 cases, with Grade Ⅰ or Ⅱ in 8 cases, Grade Ⅲ or Ⅳ in 6 cases. Nerve interruption occurred in 4 pati ents who all had severe facial palsy or nerve interruption before operation. Six teen patients resumed work within 1-3 months. Conclusion: Total removal of large acoustic neuroma could be acomplished via the translabyrin thine approach, with good preservation of facial nerve function and minimum inci dence of morbidity.
, 百拇医药
[KEY WORDS] acoustic neuroma; operative surgery; translabyrinthine ap proach; facial nerve
[Article Code] 0258-879X(2000)12-1116-04
The aim of large acoustic neuroma surgery is to achieve a total removal of t he tumor with low postoperative morbidity, mainly including minimal cerebral seq uelae and optimal facial nerve function. Although the choice of surgical approac hes remains controversial, the translabyrinthine procedure has been described a s the most viable option for removal of large tumors with some modified techniqu es [1, 2]. The following is our report on enlarged transla byrinthine removal of large acoustic neuromas in 18 cases and the outcomes thus achieved.
, 百拇医药
1 MATERIALS AND METHODS
1.1 Clinical data
This study included 18 patients (8 men and 10 women) surgically treated for larg e acoustic neuromas via the enlarged translabyrinthine approach at our dep artmen t between March 1999 and March 2000, whose age ranged from 20 to 74 years, with a mean of 53.1 years. The tumor related history ranged from 6 months to 20 years . Seventeen patients had sporadic acoustic neuromas, and one had bilateral acous tic neuroma. Two patients who had undergone gamma unit treatment 2 and 4 years b efore presented continuous tumor growth. Three patients had recurrence after sub occipital removal of the tumors. The primary symptoms included progressive heari ng loss in 14 cases, sudden hearing loss in 2 , facial palsy in one and facial a naesthesia in one. The main preoperative symptoms included high intracranial pre ssure in 12 cases, profound hearing loss in 14, severe hearing loss in 4, facial anaesthesia in 14, facial neuralgia in one, facial palsy in 4 (grade 4 in one c ase, grade 5 in 2 and grade 6 in one), and ataxia in 11. Two patients who prese nted chronic suppurative otitis media were operated on via a two stage proce dure. Subtotal temporal bone resection was performed to eradicate all active inf ections. Tumor removal was successfully done after two weeks.
, 百拇医药
Preoperative CT scan and MRI were undertaken in all cases. CT scan of the tempor al bone demonstrated enlargement of the internal auditory meatus in all cases, p neumatic mastoid in 15 cases, sclerotic mastoid in 3 cases, and chronic suppura tive otitis media in 2 cases. Fifteen patients were found to have a normal jugul ar bulb, and 3 a high jugular bulb. The mean size of the tumors was 4.2 cm (rang e from 3.0 to 5.7 cm) on MRI . The brainstem was compressed or displaced wit h various degrees. The fourth ventricle was displaced in 11 cases and disappeare d in 7 cases. While mild hydrocephalus occurred in 5 cases, and severe hydrocep halus developed in 2 cases. Widespread cerebellum scars were found in 3 patients who had previously received suboccipital removal procedures and in one who had received gam ma unit treatment. One patient who was diagnosed as having neurofibromatosis typ e Ⅱ presented bilateral acoustic neuromas, meningiomas of the right parietal l obe and lateral ventricle, and multiple neurofibromas of other regions.
, http://www.100md.com
The facial nerve monitoring (NIM2, XOMED) was used to locate and dissect the fac ial nerve. Facial nerve function of each patient was assessed clinically before surgery and 1-3 months postoperatively using the House-Brackmann facial nerve outcome scale (grade 1 to 6). Postoperative CT scans and MRI were undertaken i n all cases.
1.2 Surgical techniques
The aim of enlarged translabyrinthine approach is to achieve a wide operative fi eld by sufficient temporal bone dissection. Briefly, large mastoidectomy involve s complete exposure of the sigmoid sinus, the dura behind the sinus for 1-2 cm and the middle fossa dura. The mastoid segment of the facial nerve is carefully skel etonized to obtain an anterior limit of the dissection. All the bone is removed from the sinodural angle in order to expose the superior petrosal sinus. After t he labyrinthectomy, the internal auditory meatus (IAM) is skeletonized and uncov ered. It is still necessary to drill the superior and inferior walls of the meat u s. The drilling of the superior walls is carried out between IAM and the superio r petrosal sinus, and that of the inferior wall exposes the jugular bulb. If the jugular bulb is highly placed, it may be necessary to displace it, downwards. Th e dura is incised in U shape based posteriorly. Usually in large tumors, there i s no cerebrospinal fluid (CSF) escape after the dural incision, so a dissector m ust run along the lower pole of tumor to reach the arachnoid of the cisterna mag na which is then breached allowing CSF to flow out. Only at this moment does the approach begin to enlarge and allow to remove even a giant tumor. It is also at this step that the lower cranial nerves and the antero-inferior cerebellar a rtery (AICA) are exposed and dissected from the tumor.
, 百拇医药
Tumor removal begins with separating the facial nerve from the root of the tumor in the IAM. The adhesions and the vestibulofacial anastomoses are cut sharply a fter electrical testing of the facial nerve. The debulking of the tumour begins inside the anterior and inferior poles in order to find the brainstem as early a s possible and separate the facial nerve more easily in the CPA. When the inferi or pole is sufficiently debulked, one can find the facial nerve on the brainstem and then the dissection of the nerve is done medially to laterally. At the site s of strong adhesions, we also use a hydro-dissection technique with a spinal a nesthesia needle to find the plane of dissection. Ringer's solution is infiltrat ed between the nerves and the tumor, so that the arachnoid plane is enlarged and the adhesion is softened, and cutting the adhesions will not tear the nerve fib ers.
, 百拇医药
2 RESULTS
Total removal was achieved in all cases. There was no death during the follow-u p period. Two patients had a postoperative CSF leakage in whom lumbar drainage o r surgical revision was required. There was no postoperative meningitis. The ave rage operative time was 5.5 h with a mean blood loss of 300 ml. The facial n erve was anatomically preserved in 14 cases with a postoperative facial function grade Ⅰ in 5 cases, grade Ⅱ in 3, grade Ⅲ in 2 and grade Ⅳ in 4. The facial nerves were interrupted in two patients in whom facial palsy occurred preoperat ively. They underwent immediate repair by hypoglossal-facial anastomosis. One p atient had preoperative facial nerve interruption due to the previous suboccipit al removal procedure. Except the one with preoperative facial nerve interruptio n, the excellent rate of facial function (grade Ⅰ and Ⅱ) was 44% and the accep tion rate (grade Ⅰ to Ⅳ) was 77%. There was no residual tumor as revealed by f ollow-up imaging studies. The brainstem and the fourth ventricle recovered to i ts normal place with no evident cerebral damage (Fig 1A and B). Sixteen patients were discharged between 10 and 14 days postoperatively and returned to work wit hin 3 months. One patient with bilateral acoustic neuromas were transferred to the neurosurgi cal department for parietal meningioma resection due to persistent high intrac ranial pressure 1 month after operation. Another patient had tracheotomy bec ause of postoperative pneumonia. Severe adhesion between tumor and facial ne rve was found in two patients who underwent previous gamma unit treatment.
, 百拇医药
Fig 1 Pre-and post-operative MRI of
an acoustic neuroma patient
A: The brainstem was compressed and displaced before operation;
B: The tumor was totally removed and the brainstem was recovered.
The facial function was grade 1
3 DISCUSSION
Surgical removal is the viable option for the management of acoustic neuromas in most cases. The priorities in acoustic neuroma surgery are first, preservation of life, second, maintenance of the facial nerve function, and third, preservat ion of socially useful hearing of the tumor ear. Three basic approaches are av ailable in the management of acoustic neuroma, that is, the translabyrinthine ap proach, the suboccipital approach and the middle fossa approach. Each procedure has certain advantages and disadvantages in terms of surgical exposure, the capa bility of preserving cranial nerve function, and postoperative morbidity. The ad vantage of the middle fossa approach is the possibility of hearing reservaton. But manipulation within the cerebellopontine angel (CPA) with this approach is v e ry difficult. It is indicated for those small tumors, particularly intracanalicu lar tumors, with a useful preoperative hearing. The hearing preservation is poss ible postoperatively. The advantage of suboccipital approach is that it provides a relatively panoramic exposure of the posterior fossa from the tentorium to th e jugular foramen. In selected cases, it affords the possibility of hearing pres ervation. The need for cerebellar retraction is a disadvantage of the suboccipit al approach. Location of the facial nerve is relatively difficult. The translaby rinthine approach is the most direct route to the CPA region. When compared with the suboccipital approach, the translabyrinthine approach has markedly lower mo rbidity. The surgeon could identify and manipulate the facial nerve at the later al end of the internal auditory meatus at the earliest possible time. The main d isadvantage of the translabyrinthine approach is the need to sacrifice hearing i n the surgical ear. It is usually suggested that this approach is indicated for those small to medium tumors with no serviceable hearing.
, http://www.100md.com
The enlarged translabyrinthine approach is a modification of the classical trans labyrinthine approach designed to maximize the extent of the exposure of the CPA by resecting the bony structure. It is different from those combined approaches in which it doesn't increase the degree of brain damage. Several famous otoneur osurgical centers have reported their experieces in resecting large acoustic ne uromas via this approach[1,3-5]. Hitselberger[2] reported that he had never found a tumor that was too large to be taken out through this appr oach.
, http://www.100md.com
Some have argued that the translabyrinthine approach should sacrifice residual h earing of the surgical ear. In fact, hearing preservation is closely related to tumor size and preoperative speech discrimination level[6,7]. Useful hea ring can seldom be preserved in cases with acoustic neuromas larger than 3 cm. B es ides, hearing preservation attempts can increase the possibility of residual tum or and facial paralysis. Some authors have suggested that hearing conservation s urgery was only suitable for tumors smaller than 2 cm with a preoperative speech discrimination higher than 70%[8].
, 百拇医药
REFERENCES
[1] Desgeorges M, Sterkers JM. Surgery of large neurinomas of the acoustic nerve performed only by the translabyrinthine approach. Apropos of 50 cases[J]. Neurochirurgie, 1984, 30(6): 355-364.
[2] Hitselberger WE. Neurosurgical techniques in acoustic tumor surgery. In: Brackmann DE, Shelton C, Arriage MA, eds. Otologic surgery[M]. Philadelphi a: Saunders, 1994. 617-618.
[3] Naguib MB, Saleh E, Cokkeser Y, et al. The enlarged translabyrint hine approach for removal of large vestibular schwannomas[J]. J Laryngol Otol, 1994, 108(7): 545-550.
, 百拇医药
[4] Lanman TH, Brackmann DE, Hitselberger WE, et al. Report of 190 co nsecutive cases of large acoustic tumors (vestibular schwannoma) removed via the translabyrinthine approach[J]. J Neurosurg, 1999, 90(4): 617-623.
[5] Wu H, Sterkers JM. Translabyrinthine removal of large acoustic neurom as in young adults[J]. Auris Nasus Larynx， 2000, 27(3): 201-205.
[6] Gormley WB, Sekhar LN, Wright DC, et al. Acoustic neuromas: resul ts of current surgical management [J]. Neurosurgery, 1997, 41(1): 50-60.
, 百拇医药
[7] Sterkers JM, Morrison GA, Sterkers O, et al. Preservation of faci al, cochlear and other nerve functions in acoustic neuroma treatment[J]. Otola ryngol Head Neck Surg, 1994, 110(2): 146-155.
[8] Whittaker CK, Luetje CM. Vestibular schwannomas[J]. J Neurosurg, 19 92, 76(6): 897-900.
[Received] 2000-05-22
[Accepted] 2000-08-10, 百拇医药
单位：第二军医大学长海医院耳鼻咽 喉科，上海 200433
关键词：听神经瘤；扩大迷路进路；微创手术
第二军医大学学报001206 [摘要] 目的：探讨通过扩大的迷路进路 切除巨大听神经瘤的手术方法和手术效果。方法：扩大迷路进路的要 点是，充分暴露乙状窦及其后方硬脑膜、岩上窦、颅中窝硬脑膜，暴露并下压颈静脉球，内 听道周围骨质270°以上切除。肿瘤切除应从前下极处开始，以早期暴露脑干及脑干表面面 神经，随后即可从内侧向外侧解剖面神经。术中均使用面神经监护仪，术后均复查CT和MRI 。结果：18例直径在3 cm以上的听神经瘤(平均直径4.2 cm)，均能 手术全切，脑组织无明显损伤，2例术后一过性脑脊液漏自愈，无颅内感染；面神经解剖及 功能保存14例，其中8例面神经功能1～2级(44%)，6例面神经功能3～4级(33%)，4例面神 经中断者均为术前已有重度面瘫或已中断；16例术后1～3月恢复工作，2例恢复生活自理。[ HT5W〗结论：经扩大迷路进路既能达到全切巨大听神经瘤的目的，同时具有损 伤小、面神经保存率高的优点。
, 百拇医药
[中图分类号] R 739.6105; R 764.93 [文献标识码 ] A
Removal of large acoustic neuromas by enlarged translabyrinthine approach
WU Hao Lü Chun-Lei MA Chao-Wu ZHANG Su-Qin ZHOU Shui-Miao LI Zhao-Ji
(Department of Otolaryngology, Changhai Hospital, Second Military Medical Uni versity, Shanghai 200433, China)
[ABSTRACT] Objective: To investigate the surgical methods and outcomes of the enlarged translabyrinthine approach in the removal of large ac ousti c neuromas. Methods: A large mastoidectomy involved complete exp osure of the sigmoid sinus, the dura behind the sinus for at least 1 cm, the sup erior petrosal sinus and the middle fossa dura. The jugular bulb was exposed and pressed downwards if necessary. The internal auditory meatus was skeletonized a nd uncovered for at least 270°. The debulking of the tumor began inside the ant erior and inferior poles in order to find the brainstem and the facial nerve roo t as early as possible, and then the dissection of the nerve was done medially t o laterally. Intraoperative facial nerve monitoring and postoperative CT and MR I were done in all cases. Results: Total removal was achieved in a ll 18 patients with tumors larger than 3 cm (mean size: 4.2 cm). There were no d eaths or other complications such as intracranial infection and persistent cereb rospinal fluid leakage. There were no obvious cerebral sequelae. The facial nerv e was preserved both anatomically and functionally in 14 cases, with Grade Ⅰ or Ⅱ in 8 cases, Grade Ⅲ or Ⅳ in 6 cases. Nerve interruption occurred in 4 pati ents who all had severe facial palsy or nerve interruption before operation. Six teen patients resumed work within 1-3 months. Conclusion: Total removal of large acoustic neuroma could be acomplished via the translabyrin thine approach, with good preservation of facial nerve function and minimum inci dence of morbidity.
, 百拇医药
[KEY WORDS] acoustic neuroma; operative surgery; translabyrinthine ap proach; facial nerve
[Article Code] 0258-879X(2000)12-1116-04
The aim of large acoustic neuroma surgery is to achieve a total removal of t he tumor with low postoperative morbidity, mainly including minimal cerebral seq uelae and optimal facial nerve function. Although the choice of surgical approac hes remains controversial, the translabyrinthine procedure has been described a s the most viable option for removal of large tumors with some modified techniqu es [1, 2]. The following is our report on enlarged transla byrinthine removal of large acoustic neuromas in 18 cases and the outcomes thus achieved.
, 百拇医药
1 MATERIALS AND METHODS
1.1 Clinical data
This study included 18 patients (8 men and 10 women) surgically treated for larg e acoustic neuromas via the enlarged translabyrinthine approach at our dep artmen t between March 1999 and March 2000, whose age ranged from 20 to 74 years, with a mean of 53.1 years. The tumor related history ranged from 6 months to 20 years . Seventeen patients had sporadic acoustic neuromas, and one had bilateral acous tic neuroma. Two patients who had undergone gamma unit treatment 2 and 4 years b efore presented continuous tumor growth. Three patients had recurrence after sub occipital removal of the tumors. The primary symptoms included progressive heari ng loss in 14 cases, sudden hearing loss in 2 , facial palsy in one and facial a naesthesia in one. The main preoperative symptoms included high intracranial pre ssure in 12 cases, profound hearing loss in 14, severe hearing loss in 4, facial anaesthesia in 14, facial neuralgia in one, facial palsy in 4 (grade 4 in one c ase, grade 5 in 2 and grade 6 in one), and ataxia in 11. Two patients who prese nted chronic suppurative otitis media were operated on via a two stage proce dure. Subtotal temporal bone resection was performed to eradicate all active inf ections. Tumor removal was successfully done after two weeks.
, 百拇医药
Preoperative CT scan and MRI were undertaken in all cases. CT scan of the tempor al bone demonstrated enlargement of the internal auditory meatus in all cases, p neumatic mastoid in 15 cases, sclerotic mastoid in 3 cases, and chronic suppura tive otitis media in 2 cases. Fifteen patients were found to have a normal jugul ar bulb, and 3 a high jugular bulb. The mean size of the tumors was 4.2 cm (rang e from 3.0 to 5.7 cm) on MRI . The brainstem was compressed or displaced wit h various degrees. The fourth ventricle was displaced in 11 cases and disappeare d in 7 cases. While mild hydrocephalus occurred in 5 cases, and severe hydrocep halus developed in 2 cases. Widespread cerebellum scars were found in 3 patients who had previously received suboccipital removal procedures and in one who had received gam ma unit treatment. One patient who was diagnosed as having neurofibromatosis typ e Ⅱ presented bilateral acoustic neuromas, meningiomas of the right parietal l obe and lateral ventricle, and multiple neurofibromas of other regions.
, http://www.100md.com
The facial nerve monitoring (NIM2, XOMED) was used to locate and dissect the fac ial nerve. Facial nerve function of each patient was assessed clinically before surgery and 1-3 months postoperatively using the House-Brackmann facial nerve outcome scale (grade 1 to 6). Postoperative CT scans and MRI were undertaken i n all cases.
1.2 Surgical techniques
The aim of enlarged translabyrinthine approach is to achieve a wide operative fi eld by sufficient temporal bone dissection. Briefly, large mastoidectomy involve s complete exposure of the sigmoid sinus, the dura behind the sinus for 1-2 cm and the middle fossa dura. The mastoid segment of the facial nerve is carefully skel etonized to obtain an anterior limit of the dissection. All the bone is removed from the sinodural angle in order to expose the superior petrosal sinus. After t he labyrinthectomy, the internal auditory meatus (IAM) is skeletonized and uncov ered. It is still necessary to drill the superior and inferior walls of the meat u s. The drilling of the superior walls is carried out between IAM and the superio r petrosal sinus, and that of the inferior wall exposes the jugular bulb. If the jugular bulb is highly placed, it may be necessary to displace it, downwards. Th e dura is incised in U shape based posteriorly. Usually in large tumors, there i s no cerebrospinal fluid (CSF) escape after the dural incision, so a dissector m ust run along the lower pole of tumor to reach the arachnoid of the cisterna mag na which is then breached allowing CSF to flow out. Only at this moment does the approach begin to enlarge and allow to remove even a giant tumor. It is also at this step that the lower cranial nerves and the antero-inferior cerebellar a rtery (AICA) are exposed and dissected from the tumor.
, 百拇医药
Tumor removal begins with separating the facial nerve from the root of the tumor in the IAM. The adhesions and the vestibulofacial anastomoses are cut sharply a fter electrical testing of the facial nerve. The debulking of the tumour begins inside the anterior and inferior poles in order to find the brainstem as early a s possible and separate the facial nerve more easily in the CPA. When the inferi or pole is sufficiently debulked, one can find the facial nerve on the brainstem and then the dissection of the nerve is done medially to laterally. At the site s of strong adhesions, we also use a hydro-dissection technique with a spinal a nesthesia needle to find the plane of dissection. Ringer's solution is infiltrat ed between the nerves and the tumor, so that the arachnoid plane is enlarged and the adhesion is softened, and cutting the adhesions will not tear the nerve fib ers.
, 百拇医药
2 RESULTS
Total removal was achieved in all cases. There was no death during the follow-u p period. Two patients had a postoperative CSF leakage in whom lumbar drainage o r surgical revision was required. There was no postoperative meningitis. The ave rage operative time was 5.5 h with a mean blood loss of 300 ml. The facial n erve was anatomically preserved in 14 cases with a postoperative facial function grade Ⅰ in 5 cases, grade Ⅱ in 3, grade Ⅲ in 2 and grade Ⅳ in 4. The facial nerves were interrupted in two patients in whom facial palsy occurred preoperat ively. They underwent immediate repair by hypoglossal-facial anastomosis. One p atient had preoperative facial nerve interruption due to the previous suboccipit al removal procedure. Except the one with preoperative facial nerve interruptio n, the excellent rate of facial function (grade Ⅰ and Ⅱ) was 44% and the accep tion rate (grade Ⅰ to Ⅳ) was 77%. There was no residual tumor as revealed by f ollow-up imaging studies. The brainstem and the fourth ventricle recovered to i ts normal place with no evident cerebral damage (Fig 1A and B). Sixteen patients were discharged between 10 and 14 days postoperatively and returned to work wit hin 3 months. One patient with bilateral acoustic neuromas were transferred to the neurosurgi cal department for parietal meningioma resection due to persistent high intrac ranial pressure 1 month after operation. Another patient had tracheotomy bec ause of postoperative pneumonia. Severe adhesion between tumor and facial ne rve was found in two patients who underwent previous gamma unit treatment.
, 百拇医药
Fig 1 Pre-and post-operative MRI of
an acoustic neuroma patient
A: The brainstem was compressed and displaced before operation;
B: The tumor was totally removed and the brainstem was recovered.
The facial function was grade 1
3 DISCUSSION
Surgical removal is the viable option for the management of acoustic neuromas in most cases. The priorities in acoustic neuroma surgery are first, preservation of life, second, maintenance of the facial nerve function, and third, preservat ion of socially useful hearing of the tumor ear. Three basic approaches are av ailable in the management of acoustic neuroma, that is, the translabyrinthine ap proach, the suboccipital approach and the middle fossa approach. Each procedure has certain advantages and disadvantages in terms of surgical exposure, the capa bility of preserving cranial nerve function, and postoperative morbidity. The ad vantage of the middle fossa approach is the possibility of hearing reservaton. But manipulation within the cerebellopontine angel (CPA) with this approach is v e ry difficult. It is indicated for those small tumors, particularly intracanalicu lar tumors, with a useful preoperative hearing. The hearing preservation is poss ible postoperatively. The advantage of suboccipital approach is that it provides a relatively panoramic exposure of the posterior fossa from the tentorium to th e jugular foramen. In selected cases, it affords the possibility of hearing pres ervation. The need for cerebellar retraction is a disadvantage of the suboccipit al approach. Location of the facial nerve is relatively difficult. The translaby rinthine approach is the most direct route to the CPA region. When compared with the suboccipital approach, the translabyrinthine approach has markedly lower mo rbidity. The surgeon could identify and manipulate the facial nerve at the later al end of the internal auditory meatus at the earliest possible time. The main d isadvantage of the translabyrinthine approach is the need to sacrifice hearing i n the surgical ear. It is usually suggested that this approach is indicated for those small to medium tumors with no serviceable hearing.
, http://www.100md.com
The enlarged translabyrinthine approach is a modification of the classical trans labyrinthine approach designed to maximize the extent of the exposure of the CPA by resecting the bony structure. It is different from those combined approaches in which it doesn't increase the degree of brain damage. Several famous otoneur osurgical centers have reported their experieces in resecting large acoustic ne uromas via this approach[1,3-5]. Hitselberger[2] reported that he had never found a tumor that was too large to be taken out through this appr oach.
, http://www.100md.com
Some have argued that the translabyrinthine approach should sacrifice residual h earing of the surgical ear. In fact, hearing preservation is closely related to tumor size and preoperative speech discrimination level[6,7]. Useful hea ring can seldom be preserved in cases with acoustic neuromas larger than 3 cm. B es ides, hearing preservation attempts can increase the possibility of residual tum or and facial paralysis. Some authors have suggested that hearing conservation s urgery was only suitable for tumors smaller than 2 cm with a preoperative speech discrimination higher than 70%[8].
, 百拇医药
REFERENCES
[1] Desgeorges M, Sterkers JM. Surgery of large neurinomas of the acoustic nerve performed only by the translabyrinthine approach. Apropos of 50 cases[J]. Neurochirurgie, 1984, 30(6): 355-364.
[2] Hitselberger WE. Neurosurgical techniques in acoustic tumor surgery. In: Brackmann DE, Shelton C, Arriage MA, eds. Otologic surgery[M]. Philadelphi a: Saunders, 1994. 617-618.
[3] Naguib MB, Saleh E, Cokkeser Y, et al. The enlarged translabyrint hine approach for removal of large vestibular schwannomas[J]. J Laryngol Otol, 1994, 108(7): 545-550.
, 百拇医药
[4] Lanman TH, Brackmann DE, Hitselberger WE, et al. Report of 190 co nsecutive cases of large acoustic tumors (vestibular schwannoma) removed via the translabyrinthine approach[J]. J Neurosurg, 1999, 90(4): 617-623.
[5] Wu H, Sterkers JM. Translabyrinthine removal of large acoustic neurom as in young adults[J]. Auris Nasus Larynx， 2000, 27(3): 201-205.
[6] Gormley WB, Sekhar LN, Wright DC, et al. Acoustic neuromas: resul ts of current surgical management [J]. Neurosurgery, 1997, 41(1): 50-60.
, 百拇医药
[7] Sterkers JM, Morrison GA, Sterkers O, et al. Preservation of faci al, cochlear and other nerve functions in acoustic neuroma treatment[J]. Otola ryngol Head Neck Surg, 1994, 110(2): 146-155.
[8] Whittaker CK, Luetje CM. Vestibular schwannomas[J]. J Neurosurg, 19 92, 76(6): 897-900.
[Received] 2000-05-22
[Accepted] 2000-08-10, 百拇医药