Background Vestibular schwannoma, the commonest form of intracranial schwannoma, arises from the Schwann cells investing the vestibular nerve. At present, the surgery for vestibular schwannoma remains one of the most ...Background Vestibular schwannoma, the commonest form of intracranial schwannoma, arises from the Schwann cells investing the vestibular nerve. At present, the surgery for vestibular schwannoma remains one of the most complicated operations demanding for surgical skills in neurosurgery. And the trend of minimal invasion should also be the major influence on the management of patients with vestibular schwannomas. We summarized the microsurgical removal experience in a recent series of vestibular schwannomas and presented the operative technique and cranial nerve preservation in order to improve the rates of total tumor removal and facial nerve preservation. Methods A retrospective analysis was performed in 145 patients over a 7-year period who suffered from vestibular schwannomas that had been microsurgically removed by suboccipital retrosigmoid transmeatus approach with small craniotomy. CT thinner scans revealed the tumor size in the internal auditory meatus and the relationship of the posterior wall of the internal acoustic meatus to the bone labyrinths preoperatively. Brain stem evoked potential was monitored intraoperatively. The posterior wall of the internal acoustic meatus was designedly drilled off. Patient records and operative reports, including data from the^electrophysiological monitoring, follow-up audiometric examinations, and neuroradiological findings were analyzed. Results Total tumor resection was achieved in 140 cases （96.6%） and subtotal resection in 5 cases. The anatomical integrity of the facial nerve was preserved in 91.0% （132/145） of the cases. Intracranial end-to-end anastomosis of the facial nerve was performed in 7 cases. Functional preservation of the facial nerve was achieved in 115 patients （Grade ! and Grade ]I, 79.3%）. No patient died in this series. Preservation of nerves and vessels were as important as tumor removal during the operation. CT thinner scan could show the relationship between the posterior wall of the internal acoustic meatus and bone labyrinths, that is helpful for a safe drilling of the posterior wall of the internal acoustic meatus. Conclusions The goal of every surgery should be the preservation of function of all cranial nerves. Using the retrosigmoid approach with small craniotomy is possible even for large schwannomas. Knowing the microanatomy of the cerebellopontine angle and internal auditory meatus, intraoperating neurophysiological monitoring of the facial nerve function, and the microsurgical techniques of the surgeons are all important factors for improving total tumor removal and preserving facial nerve function.展开更多
Background:When utilizing the retrosigmoid approach(RA),accurately identifying the transverse and sigmoid sinus transition(TSST)is a key procedure for neurosurgeons,especially in developing countries restricted by the...Background:When utilizing the retrosigmoid approach(RA),accurately identifying the transverse and sigmoid sinus transition(TSST)is a key procedure for neurosurgeons,especially in developing countries restricted by the lack of expensive devices,such as the neural navigation system and the three-dimensional volumetric image-rendered system.Before operations,a computed tomography scan is a common and cost-effective method of checking patients who suffer lesions located at the cerebellopontine angle.Therefore,we present a technique using only high-resolution computed tomography to identify the transverse and sigmoid sinus transition.Methods:This retrospective study included 35 patients who underwent retrosigmoid approach operations to resect an acoustic neurinoma with the assistance of our technique.In brief,our technique contains 4 steps:(1)All patients’1-mm,consecutive,high-resolution computed tomographic images that clearly displayed landmarks,such as the inion,lambdoid suture,occipitomastoid suture,and the mastoid emissary foramen,were investigated initially.(2)We selected two particular slices(A and B)among all of these high-resolution computed tomographic images in which scanning planes were parallel with the line drawn from the root of the zygoma to the inion(LZI).Slice A contained both the root of the zygoma and the inion simultaneously,and slice B displayed the mastoid emissary foramen.(3)Four points(α,β,γ,δ)were arranged on slices A and B,and pointαwas located at the inner surface of the skull,which represents the posterior part of the sulci of the sigmoid sinus.Pointβwas located at the outer surface of the skull,and the line connecting them was perpendicular to the bone.Similarly,on slice B,we labeled pointγas the point that represents the posterior part of the sulci of the sigmoid sinus at the inner surface and pointδas the point located at the outer surface of the skull,and the line connecting them was also perpendicular to the bone.The distances between pointβand the lambdoid suture/occipitomastoid suture and between pointδand the mastoid emissary foramen were calculated for slices A and B,respectively.(4)During the operation,a line indicating the LZI was drawn on the bone with ink when the superficial soft tissue was pushed away,and this line would cross the lambdoid suture/occipitomastoid suture.With both the crosspoint and the distance obtained from the high-resolution CT images,we could locate pointβ.We also used the same method to locate pointδafter revealing the mastoid emissary foramen.The line connecting pointβand pointδindicated the posterior border of the sigmoid sinus,and the intersection between the line and LZI indicated the inferior knee of the transverse and sigmoid sinus transition(TSST).Results:All 35 patients underwent the RA craniectomies that were safely assisted by our technique,and neither the sigmoid sinus nor the transverse sinus was lacerated during the operations.Conclusion:Our cost-effective technique is reliable and convenient for identifying the transverse and sigmoid sinus transition(TSST)which could be widely performed to guarantee the safety of RA craniectomy.展开更多
文摘Background Vestibular schwannoma, the commonest form of intracranial schwannoma, arises from the Schwann cells investing the vestibular nerve. At present, the surgery for vestibular schwannoma remains one of the most complicated operations demanding for surgical skills in neurosurgery. And the trend of minimal invasion should also be the major influence on the management of patients with vestibular schwannomas. We summarized the microsurgical removal experience in a recent series of vestibular schwannomas and presented the operative technique and cranial nerve preservation in order to improve the rates of total tumor removal and facial nerve preservation. Methods A retrospective analysis was performed in 145 patients over a 7-year period who suffered from vestibular schwannomas that had been microsurgically removed by suboccipital retrosigmoid transmeatus approach with small craniotomy. CT thinner scans revealed the tumor size in the internal auditory meatus and the relationship of the posterior wall of the internal acoustic meatus to the bone labyrinths preoperatively. Brain stem evoked potential was monitored intraoperatively. The posterior wall of the internal acoustic meatus was designedly drilled off. Patient records and operative reports, including data from the^electrophysiological monitoring, follow-up audiometric examinations, and neuroradiological findings were analyzed. Results Total tumor resection was achieved in 140 cases （96.6%） and subtotal resection in 5 cases. The anatomical integrity of the facial nerve was preserved in 91.0% （132/145） of the cases. Intracranial end-to-end anastomosis of the facial nerve was performed in 7 cases. Functional preservation of the facial nerve was achieved in 115 patients （Grade ! and Grade ]I, 79.3%）. No patient died in this series. Preservation of nerves and vessels were as important as tumor removal during the operation. CT thinner scan could show the relationship between the posterior wall of the internal acoustic meatus and bone labyrinths, that is helpful for a safe drilling of the posterior wall of the internal acoustic meatus. Conclusions The goal of every surgery should be the preservation of function of all cranial nerves. Using the retrosigmoid approach with small craniotomy is possible even for large schwannomas. Knowing the microanatomy of the cerebellopontine angle and internal auditory meatus, intraoperating neurophysiological monitoring of the facial nerve function, and the microsurgical techniques of the surgeons are all important factors for improving total tumor removal and preserving facial nerve function.
文摘Background:When utilizing the retrosigmoid approach(RA),accurately identifying the transverse and sigmoid sinus transition(TSST)is a key procedure for neurosurgeons,especially in developing countries restricted by the lack of expensive devices,such as the neural navigation system and the three-dimensional volumetric image-rendered system.Before operations,a computed tomography scan is a common and cost-effective method of checking patients who suffer lesions located at the cerebellopontine angle.Therefore,we present a technique using only high-resolution computed tomography to identify the transverse and sigmoid sinus transition.Methods:This retrospective study included 35 patients who underwent retrosigmoid approach operations to resect an acoustic neurinoma with the assistance of our technique.In brief,our technique contains 4 steps:(1)All patients’1-mm,consecutive,high-resolution computed tomographic images that clearly displayed landmarks,such as the inion,lambdoid suture,occipitomastoid suture,and the mastoid emissary foramen,were investigated initially.(2)We selected two particular slices(A and B)among all of these high-resolution computed tomographic images in which scanning planes were parallel with the line drawn from the root of the zygoma to the inion(LZI).Slice A contained both the root of the zygoma and the inion simultaneously,and slice B displayed the mastoid emissary foramen.(3)Four points(α,β,γ,δ)were arranged on slices A and B,and pointαwas located at the inner surface of the skull,which represents the posterior part of the sulci of the sigmoid sinus.Pointβwas located at the outer surface of the skull,and the line connecting them was perpendicular to the bone.Similarly,on slice B,we labeled pointγas the point that represents the posterior part of the sulci of the sigmoid sinus at the inner surface and pointδas the point located at the outer surface of the skull,and the line connecting them was also perpendicular to the bone.The distances between pointβand the lambdoid suture/occipitomastoid suture and between pointδand the mastoid emissary foramen were calculated for slices A and B,respectively.(4)During the operation,a line indicating the LZI was drawn on the bone with ink when the superficial soft tissue was pushed away,and this line would cross the lambdoid suture/occipitomastoid suture.With both the crosspoint and the distance obtained from the high-resolution CT images,we could locate pointβ.We also used the same method to locate pointδafter revealing the mastoid emissary foramen.The line connecting pointβand pointδindicated the posterior border of the sigmoid sinus,and the intersection between the line and LZI indicated the inferior knee of the transverse and sigmoid sinus transition(TSST).Results:All 35 patients underwent the RA craniectomies that were safely assisted by our technique,and neither the sigmoid sinus nor the transverse sinus was lacerated during the operations.Conclusion:Our cost-effective technique is reliable and convenient for identifying the transverse and sigmoid sinus transition(TSST)which could be widely performed to guarantee the safety of RA craniectomy.
