Trigeminal neurinomas extending into multiple fossae: surgical methods and review of the literature.

OBJECT: Since 1974, 27 patients with trigeminal neurinomas (TNs) have been treated at Keio University Hospital and ancillary institutes. In the present study the clinical features and developmental patterns of these 27 cases are analyzed, and the clinical features of 402 cases reported in the literature are reviewed. Based on the analysis of the developmental patterns of the TNs, the surgical strategy for a one-stage removal of TNs involving multiple fossae is described. METHODS: Trigeminal neurinomas are classified into six types according to tumor location. Types M, P, and E are tumors involving a single compartment, that is, the middle fossa, posterior fossa, or extracranial space, respectively. Types MP (middle and posterior fossae), ME (middle fossa and extracranial space), or MPE (middle and posterior fossae and extracranial space) are tumors involving multiple compartments. Advances in neuroimaging technologies, such as magnetic resonance imaging, have revealed a high incidence of TNs extending into multiple fossae, namely 36.2% in cases reported since 1983 and 59% in the authors' series. All but one of the most recent 19 patients in this series underwent skull base surgery, whereas the remaining nine patients were surgically treated via the conventional subdural approach. The rate of total tumor removal and the clinical outcome were significantly better in those patients treated by skull base surgery than those treated by conventional surgery. CONCLUSIONS: The TNs extending into multiple fossae can be totally removed using the following single-stage surgical techniques: Type MP by the anterior transpetrosal approach; Type ME by the zygomatic or orbitozygomatic infratemporal approach; and Type MPE by the zygomatic transpetrosal approach. In 12 of 13 cases involving multiple fossae in this series, total tumor removal was achieved using single-stage skull base surgery.     

Intracranial chondrosarcoma--case report.

The authors report the case of a 54-year-old male who was found to have a large intracranial chondrosarcoma at the site from which chondromas had been partially removed twice, 6 and 10 years previously. On the third admission, the second through tenth and the twelfth cranial nerves on the right side were involved. Computed tomographic scans showed a large mass in the right middle and posterior fossae and the right ethmoid sinus. Angiography demonstrated an extradural mass in the right middle fossa. The tumor in the middle and posterior fossae was subtotally removed, and second, third, and eighth cranial nerve function improved postoperatively. Histological examination of tumor specimens showed active proliferation of poorly differentiated cartilagenous cells, suggestive of sarcomatous transformation of the pre-existing chondroma. It is emphasized that chondromas should be removed as completely as possible and that patients must be followed carefully after surgery.     

显微手术治疗三叉神经鞘瘤

目的 总结各种类型三叉神经鞘瘤手术入路的优缺点。方法 回顾分析１９８０年４月￣１９９７年６月手术治疗的３４例三叉神经鞘瘤的临床效果。结果 肿瘤完全位于中颅窝的３例,均采用颞下入路切除,肿瘤位于后颅窝的１３例,１０例经枕下入路,２例采用颞下经小脑幕入路,１例经乙状窦前入路切除。另１８例哑铃型肿瘤中１４例采用颞下经小脑幕入路,４例采用经颞下－乙状窦前入路切除。结论 颞下入路适用中颅窝型肿瘤切除,枕下入     

Size of posterior fossa in Chiari type 1 malformation in adults

Summary The clinical and neuroradiological findings in five patients with Chiari Type 1 malformation presenting symptoms in adult life are presented. New posterior fossa ratio methods have been applied to this material. The posterior cranial fossae are demonstrated to be small, and the most significant deviation from normal gave the ratio h/Tw: posterior fossa height in proportion to Twining's line. The implications of these findings are discussed in relation to the static and dynamic factors that are operating in the development of neurological symptoms in Chiari type 1 malformation. A final discussion is given comparing the Chiari type 1 malformation to meningo-myelocele. The findings using posterior fossa ratio methods may strengthen the indications for suboccipital craniectomy in these patients.     

Trigeminal schwannomas: removal of dumbbell-shaped tumors through the expanded Meckel cave and outcomes of cranial nerve function

OBJECT: As in patients with vestibular schwannomas, advances in surgical procedures have markedly improved outcomes in patients with trigeminal schwannomas. In this article the authors address the function of cranial nerves in a series of patients with trigeminal schwannomas that were treated with gross-total surgical removal. The authors emphasize a technique they use to remove a dumbbell-shaped tumor through the expanded Meckel cave, and discuss the advantage of the extradural zygomatic middle fossa approach for total removal of tumor and preservation or improvement of cranial nerve function. METHODS: Within an 11-year period (1989-2000), 25 patients (14 female and 11 male patients with a mean age of 44.4 years) with benign trigeminal schwannomas were surgically treated by the senior author (O.A.) with the aim of total removal of the tumor. Three patients had undergone previous surgery elsewhere. Trigeminal nerve dysfunction was present in all but two patients. Abducent nerve paresis was present in 40%. The approach in each patient was selected according to the location and size of the lesion. Nineteen tumors were dumbbell shaped and extended into both middle and posterior fossae. All 25 tumors involved the cavernous sinus. The zygomatic middle fossa approach was particularly useful and was used in 14 patients. The mean follow-up period was 33.12 months. In patients who had not undergone previous surgery, the preoperative trigeminal sensory deficit improved in 44%, facial pain decreased in 73%, and trigeminal motor deficit improved in 80%. Among patients with preoperative abducent nerve paresis, recovery was attained in 63%. Three patients (12%) experienced a persistent new or worse cranial nerve function postoperatively. Fifth nerve sensory deficit persisted in one of these patients, sensory and motor dysfunction in another, and motor trigeminal weakness in the third patient. In all patients a good surgical outcome was achieved. One patient died 2 years after treatment from an unrelated cause. In three patients the tumors recurred after an average of 22.3 months. CONCLUSIONS: Preservation or improvement of cranial nerve function can be achieved through total removal of a trigeminal schwannoma, and skull base approaches are better suited to achieving this goal. The zygomatic middle fossa approach is particularly helpful and safe. It allows extradural tumor removal from the cavernous sinus, the infratemporal fossa, and the posterior fossa through the expanded Meckel cave.     

Transtentorial epidermoid cysts

Summary Epidermoid cysts may occur simultaneously above and below the tentorium. Eleven patients with involvement of both infra- and supra-tentorial cisterns are presented. In two cases the epidermoid, located mainly in the cerebello-pontine angle, spread into the middle cranial fossa; in three the epidermoid extended from the parasellar cisterns to the posterior cranial fossa; in six patients the epidermoid, enlarging the tentorial notch, occupied extensively both cranial fossae.The surgical approach was influenced both by the experience of the surgeon and by the main extension of the epidermoid. Total removal was feasible in two patients only but only one of the eleven patients had a recurrence of the epidermoid. The long term results appear to be unrelated to the size of the epidermoid and to the choice of approach.     

En bloc resection of the temporal bone by the lateral approach in carcinoma of the middle ear associated with skull base infiltration with reference to the resection of the petrous apex

En bloc resection of the temporal bone was performed by the lateral approach on two patients with carcinoma of the middle ear, which was associated with destruction in the temporal bone and tumor infiltration of the cranial base. In one of the patients, the petrous apex was resected along with the temporal bone.En bloc resection on the temporal bone with the petrous apex is believed to be difficult because the internal carotid artery (ICA), cavernous sinus, and the brainstem are adjacent to each other in the petrous apex. However, the intra- and extracranial surgical procedures by this approach allow resection of the temporal bone ranging from the anterior part including the petrous apex to the posterior part including the mastoid process, the dura of the middle and posterior cranial fossae, and the sigmoid sinus, without exposure of the tumor. Special attention should be paid to the procedural points of surgery, such as, exposure of the petrous ICA, bleeding from the petrous sinus, and dural suturing in the vicinity of the apex. With regard to surgical indication, it is important to determine whether tumor infiltration is confined to the temporal bone and the dura of the middle and posterior fossa. If tumor infiltration into the petrous ICA, the dominant side of sigmoid sinus and/or the inferior cranial nerve is observed, then indication for surgery should be determined in a more critical manner.     

股骨髁间窝的应用解剖及其临床研究

目的 探讨如何完善髌韧带中1／3重建前叉韧带术式，防止重建韧带撞 现象的发生。方法 测量42例和73例正常干、湿性股骨髁间窝标本的横径、纵径及其相关值；通过对湿性膝关节标本股骨髁间窝与前交叉韧带和重建韧带解剖关系的观测，确定膝关节伸展时髁间窝与韧带发生撞击的部位，在髌韧带中1／3重建前叉韧带的模拟和临床手术中， 切除股骨髁间窝前外侧壁及顶部部分骨质，加宽加深髁间窝，保持重建韧带与其有5mm间距。结果 临床应用19例中随访1年以上者11例，无1例出现重建韧带撞击现象，膝关节稳定性恢复良好。结论 股骨髁间窝扩大成形能有效地防止髁间窝对髌韧带的撞击，保证其顺利地替代前叉韧带的功能。     

Quantification of the Advantages of the Extended Frontal Approach to Skull Base

This anatomic study evaluated the extent that a fronto-orbital osteotomy (FOO) added to a bilateral frontal craniotomy widened the exposure to the midline compartment of the anterior, middle, and posterior cranial fossae. The goal was to determine if osteotomy would significantly increase angles for two targets: the foramen magnum (FM) and anterior clinoid process (ACP). Stepwise dissections were performed on five cadaveric heads. A bilateral frontal craniotomy was made, followed by FOO. After the ethmoids were removed, the planum sphenoidale was drilled to enter the sphenoid sinus. Further drilling exposed the anterior clivus, which was drilled down to FM. Excellent exposure of the basilar artery, vertebral artery, and brain stem was achieved. With and without FOO, angles of exposure were measured for two targets: the ACP and FM. The angle of exposure after FOO increased markedly with an average gain of 76% for the ACP and of 80% for FM. Compared with a conventional bifrontal craniotomy, the addition of FOO increased the surgical exposure and minimized frontal lobe retraction for accessing lesions of the anterior, middle, and posterior cranial fossae.     

En Bloc Resection of the Temporal Bone by the Lateral Approach in Carcinoma of the Middle Ear Associated with Skull Base Infiltration with Reference to the Resection of the Petrous Apex

En bloc resection of the temporal bone was performed by the lateral approach on two patients with carcinoma of the middle ear, which was associated with destruction in the temporal bone and tumor infiltration of the cranial base. In one of the patients, the petrous apex was resected along with the temporal bone.

En bloc resection on the temporal bone with the petrous apex is believed to be difficult because the internal carotid artery (ICA), cavernous sinus, and the brainstem are adjacent to each other in the petrous apex. However, the intra- and extracranial surgical procedures by this approach allow resection of the temporal bone ranging from the anterior part including the petrous apex to the posterior part including the mastoid process, the dura of the middle and posterior cranial fossae, and the sigmoid sinus, without exposure of the tumor. Special attention should be paid to the procedural points of surgery, such as, exposure of the petrous ICA, bleeding from the petrous sinus, and dural suturing in the vicinity of the apex. With regard to surgical indication, it is important to determine whether tumor infiltration is confined to the temporal bone and the dura of the middle and posterior fossa. If tumor infiltration into the petrous ICA, the dominant side of sigmoid sinus and/or the inferior cranial nerve is observed, then indication for surgery should be determined in a more critical manner.

     

Unusual tumors of the posterior fossa skull base.

Five unusual cases of posterior skull base tumors were treated through different skull base approaches. Two or more staged operations were required to achieve total or near-total excision and decompression of two extensive tumors. Total excision of an extensive en plaque meningioma of the foramen magnum that encircled the brain stem and cervical spinal cord could not be achieved through the extreme lateral and suboccipital craniectomy approach. However, the vital structures were decompressed and the patient's postoperative morbidity was acceptable. An extended middle fossa approach was required to excise a hemangiopericytoma of the middle and posterior fossae in a 12-year-old. Extension of the tumor into the posterior fossa precluded a retromastoid approach because the mass draped the lower cranial nerves posteriorly. Two men had undifferentiated adenocarcinomas involving the jugular foramen and middle to posterior fossa, respectively. The origin of one was renal in a 37-year-old man. A 63-year-old man survived 1.5 years after a good decompression of his extensive tumor and irradiation. The histological diagnosis of paraganglioma of the occipital bone was a surprise in a 25-year-old man with pure bony involvement. These cases indicate that the appropriate selection of skull base approaches and their combination can provide the needed access to achieve adequate excision or decompression of masses located in challenging anatomical regions of the skull base. Furthermore, good surgical excision improves palliation in radioresistant metastatic tumors of the skull base.     

Lateral Orbital Rim Osteotomy in the Treatment of Certain Skull Base Lesions

Quantitative data from a recent human cadaveric study suggested that removal of the lateral orbital rim alone may be sufficient to reach many targets for which the orbitozygomatic craniotomy has been used. Consequently, a lateral orbital rim osteotomy was substituted for an orbitozygomatic craniotomy in seven patients with a variety of pathologies located in the anterior, middle, and interpeduncular fossae. In each case, lateral orbitotomy provided a satisfactory surgical corridor for diagnosis and treatment. Compared with the orbitozygomatic craniotomy, the lateral orbital rim osteotomy offers several advantages: technical simplicity, shorter operating time, and a low risk of postoperative malocclusion. If, however, prolonged access to a wide expanse of the anterior portion of the middle fossa and inferotemporal area is needed, an orbitozygomatic approach is a better choice.     

Multiple perineal abscesses and sinus tracts as a complication of vaginal mesh

Understanding the occurrence and management of mesh kit complications has become increasingly important. A 54-year-old woman presented to our tertiary care center with complaints of constant perineal pain, and copious, foul-smelling vaginal discharge after anterior and posterior placement of a synthetic mesh and mid-urethral sling 3 months earlier. She was found to have two vaginocutaneous sinus tracts (to the left ischiorectal fossa and to the left labia majora), as well as bilateral abscess cavities within the ischiorectal fossae. The posterior mesh was completely excised, the tracts were opened, and the wound was packed and allowed to heal by secondary intention.     

A cranio-orbital-zygomatic approach to dumbbell-shaped trigeminal neurinomas using the petrous window.

We applied a cranio-orbital-zygomatic approach that extends the temporal craniotomy more posteriorly and minimizes the frontal orbitotomy of an ordinary orbitozygomatic approach in order to provide wide access to the already eroded petrous apices along the long axis of trigeminal neurinomas. We treated seven dumbbell-shaped trigeminal neurinomas between 1991 and 1998 (mean follow-up, 38 months; range, 9 to 109 months). The configuration of the tumor mass was assessed on magnetic resonance imaging by measuring its long diameter in the middle and posterior fossae and the width of petrous erosion. Tumors were then classified into five types based on their distribution over the petrous ridge. Total removal was achieved in six patients, who showed no evidence of tumor recurrence during the follow-up period. The only major complication was one case of anesthesia dolorosa. The one patient with a subtotal removal developed a recurrence 12 months after surgery, in the posterior fossa. The cranioorbital-zygomatic approach could be an effective method for removing dumbbell-shaped trigeminal neurinomas, particularly in cases of wide petrous erosion from the tumor. If, however, the tumor has a larger posterior fossa component, this approach may not provide adequate exposure to achieve a total resection.     

Anterior tentorium-based epidermoid tumours: results of radical surgical treatment in 96 cases

A retrospective analysis of 96 surgically treated tentorium and anterior tentorial hiatus-based epidermoid tumours from 1997 - 2004 is presented. The most prominent symptoms were headache (53.1%) and ataxia (44.8%). The average tumour size was 4.4 cm. Surgical approaches included posterior cranial fossa route (85 cases), basal subtemporal middle fossa route (9 cases) and combined posterior fossa and subtemporal routes in two cases. Total tumour resection was performed in 46 patients. Eight and four patients developed transient and sustained postoperative neurological deficits respectively. There was mortality in two patients. There was non-symptomatic recurrence of the tumour in two cases. Ninety-four patients are leading active functional lives. Radical and safe resection of anterior tentorium-based epidermoid tumours is associated with symptomatic relief and lasting cure. Extensive drilling of the petrous bone can be avoided. Gentle dissection of the tumour and capsule from the critical neurovascular structures can limit post-operative morbidity.     

Surgical treatment of trigeminal schwannomas

Schwannomas that arise from the trigeminal nerve are rare, but this nerve is the second most frequent intracranial site of schwannoma occurrence next to the vestibular nerve. The advent of microsurgical techniques and skull-base approaches has greatly enhanced the surgical management of these tumors, and outcomes have improved markedly. This report documents 18 cases of histologically verified schwannomas that arose from the trigeminal nerve and were treated surgically in our clinic between January 1992 and July 2005. The patients were ten women and eight men of age 39.7 years (range, 22–62 years). The tumor was located in the middle fossa (type A) in five cases, in the middle and posterior fossae (type C) in nine cases, in the posterior fossa (type B) in two cases, and in the branches of the trigeminal nerve (type D) in two cases. Total excision was achieved in 17 cases, and there was no mortality in the series. Our results indicate that trigeminal schwannomas, regardless of type, can be removed via skull-base approaches. We present an algorithm for surgical management of trigeminal schwannomas based on our experience and information from the literature.     

Giant dumbbell-shaped middle cranial fossa trigeminal schwannoma with extension to the infratemporal and posterior fossae

Summary We present a 38-year-old female with a giant dumbbell-shaped trigeminal neurinoma originating primarily in the middle cranial fossa, extending to the infratemporal and posterior fossae through the foramen ovale and Meckel’s cave, respectively. Because of the large tumour extension into the Infratemporal Fossa, a combined skull base approach (zygomatic infratemporal – transmandibular) was utilised for tumour removal, with a subsequent excellent outcome. An extensive literature review since 1935, revealed 580 cases of surgically treated trigeminal neurinomas. Among these, only three were located in three distinct compartments, making this the rarest developmental pattern for trigeminal neurinomas.     

Trans-zygomatic middle cranial fossa approach to access lesions around the cavernous sinus and anterior parahippocampus: a minimally invasive skull base approach

Purpose  Exposure of the cavernous sinus or anterior parahippocampus often involves a wide exposure of the temporal lobe and mobilization of the temporalis muscle associated with temporal lobe retraction. The authors present a cadaveric study to illustrate the feasibility, advantages and landmarks necessary to perform a trans-zygomatic middle fossa approach to lesions around the cavernous sinus and anterior parahippocampus. Methods  The authors performed bilateral trans-zygomatic middle fossae exposures to reach the cavernous sinus and parahippocampus in five cadavers (10 sides). We assessed the morbidity associated with this procedure and compared the indications, advantages, and disadvantages of this method versus more extensive skull base approaches. A vertical linear incision along the middle portion of the zygomatic arch was extended one finger breadth inferior to the inferior edge of the zygomatic arch. Careful dissection inferior to the arch allowed preservation of facial nerve branches. A zygomatic osteotomy was followed via a linear incision through the temporalis muscle and exposure of the middle cranial fossa floor. Results  A craniotomy along the inferolateral temporal bone and middle fossa floor allowed extradural dissection along the middle fossa floor and exposure of the cavernous sinus including all three divisions of the trigeminal nerve. Intradural inspection demonstrated adequate exposure of the parahippocampus. Exposure of the latter required minimal or no retraction of the temporal lobe. Conclusions  The trans-zygomatic middle fossa approach is a simplified skull base exposure using a linear incision, which may avoid the invasivity of more extensive skull base approaches while providing an adequate corridor for resection of cavernous sinus and parahippocampus lesions. The advantages of this approach include its efficiency, ease, minimalism, preservation of the temporalis muscle, and minimal retraction of the temporal lobe.     

Surgical removal of giant acoustic neurinomas involving the skull base. Report of two cases

Neurinomas arising from the peripheral branch of the acoustic nerve distal to the internal auditory canal in the temporal bone are rare. Two advanced skull-base neurinomas are described which were situated mainly in the temporal petrous bone, and extended to the parapharyngeal space anteriorly, to the lateral cervical portion inferiorly, into the sphenoidal sinus medially, and into the middle and posterior cranial fossae compressing the brain stem. Both patients had been deaf for several years without other neurological deficits. The operative findings revealed that the fifth, seventh, and caudal cranial nerves were intact; therefore, it was suspected that these neurinomas originated primarily within the cochlea or the vestibule in the temporal bone. The tumors were completely removed via an extradural approach, with good results. Since the surgical treatment of such advanced skull-base neurinomas is difficult, the operative infratemporal fossa approach is described in detail.     

Cranial-base surgery: a reconstructive algorithm.

Skull-base surgery is associated with a high risk of cerebrospinal fluid (CSF) leak, infection, and functional and aesthetic deformity. Appropriate reconstruction of cranial-base defects following surgery helps to prevent these complications. Between March 1998 and May 2000, 28 patients (age: 1-68 years) underwent reconstruction of the anterior and middle cranial fossae. The indications for surgery were tumours, trauma involving the anterior cranial fossa, midline dermoid cysts with intracranial extension, late post-traumatic CSF leak, craniofacial deformity and recurrent frontal mucocoele. We used local anteriorly based pericranial flaps (23 flaps, alone or in combination with other flaps), bipedicled galeal flaps (seven patients) and free flaps (nine patients; radial forearm fascial/fasciocutaneous flaps, rectus abdominis muscle flap and latissimus dorsi muscle flap). Follow-up has been 4-24 months. We had no deaths, no flap failure and no incidence of infection. Complications included two CSF leaks, three intracranial haematomas and one pulsatile enophthalmos. All patients had a very good aesthetic result. We present an algorithm for skull-base reconstruction and comment on the design and vascularity of the bipedicled galeal flap. The monitoring of intracranial flaps and the difficulties of perioperative management of free flaps in neurosurgical patients are also discussed.