Category: skull base surgery

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Solitary clival plasmocytomas

Solitary clival plasmocytomas

Acta Neurochir (2013) 155:1849–1856

Tumours of the clivus are exceptionally rare, representing a diagnostic and a therapeutic challenge. Clival solitary plasmocytomas have been described only as single case reports or included in small clinical series with other intracranial location.

Methods Authors report clinical, radiological, and survival data of four patients, who underwent surgery for clival plasmocytomas between 1989 and 2012 in a single centre. Current knowledge about solitary plasmocytomas of the clivus are reviewed.

Results Follow-up time was 54 months (range: 9–165). Mean age of patient was 57 years, no gender predilection was observed. Main symptoms were headache (75 %) and double vision (75 %), due to third or sixth cranial nerve palsy. Mean time to diagnosis was 8.2 months. All patients underwent surgery as primary treatment, through either a transsphenoidal (75 %) or a transmaxillary approach (25 %). In all cases adjuvant conventional radiotherapy was performed with a median delivered dose of 45 Gy. Only one case of progression into multiple myeloma was observed 13 months after surgery, and the patient died 9 months later. No other recurrences or progression were observed. Mean overall survival and progression free survival time were, respectively, 54 and 51.7 months.

Conclusions Although extremely rare, clival plasmocytomas have to be considered in the differential diagnosis of a solitary clival lesion. Biological and clinical features of these tumours strongly differ from those of similar lesions in other part of the body. Early diagnosis, extensive tumour removal, opportune indication of adjuvant treatment with radiotherapy and chemotherapy are the keys to manage these cases.

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Sphenoid sinus anatomy and suprasellar extension of pituitary tumors

Sphenoid sinus anatomy

J Neurosurg 119:669–674, 2013

As tumors enlarge, they generally grow along paths of least resistance. For pituitary macroadenomas, extrasellar extension into the suprasellar region, cavernous sinus, or sphenoid sinus may occur. The sphenoid sinus is known to have a variable anatomical configuration, and the authors hypothesize that certain anatomical factors may resist tumor expansion into the sphenoid sinus, thereby directing tumor growth into the suprasellar space. In this paper the authors’ goal was to determine if sphenoid anatomy influences pituitary tumor growth.

Methods. The authors conducted a retrospective analysis of 106 consecutive surgical cases of pituitary macroadenoma. Patient demographics, suprasellar extension, sellar width, and features of the sphenoid intersinus septum were recorded on radiographic review. The chi-square test, t-test, logistic regression, and classification and regression tree analysis were used for statistical analysis.

Results. Of the 106 patients included in the study, 71 (67%) demonstrated suprasellar extension of their tumor. Patients with suprasellar tumor extension had significantly greater intersinus septum width (width > 1.27 mm: OR = 14.32; p = 0.0012) and were significantly older (age > 54 yrs: OR = 3.33; p = 0.0176). They also tended to be male and to have two or more sphenoid partitions (OR = 6.58; p = 0.0306). While patients with suprasellar extension tended to be more likely to have a midline partition and a larger sellar width than their counterparts, these differences did not reach statistical significance.

Conclusions. Certain aspects of the sphenoid sinus anatomy may function to resist pituitary tumor growth into the sphenoid sinus. Progressive enlargement of pituitary macroadenomas may extend in a suprasellar direction, in part, as a consequence of the sphenoid sinus anatomy.

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Transmastoid Retrosigmoid Approach to the Cerebellopontine Angle

Transmastoid Retrosigmoid Approach

Neurosurgery 73[ONS Suppl 1]:ons16–ons23, 2013

The traditional suboccipital craniotomy in the retrosigmoid approach gives limited exposure to the cerebellopontine angle (CPA) structures and necessitates cerebellar retraction, whereas the addition of drilling of the mastoid process with reflection of venous sinuses offers wider exposure of the CPA and avoids cerebellar retraction. We describe the details of the surgical technique and provide radiological measurements substantiating the advantages of this approach.

OBJECTIVE: To validate the usefulness of partial mastoidectomy in the retrosigmoid approach and to evaluate the complications of this maneuver.

METHODS: Radiological CPA measurements on computed tomography bone window films were made on the last consecutive 20 patients who underwent CPA surgery via the transmastoid retrosigmoid approach. We measured the distance and angle of work by this approach and compared the measurements with those using the traditional retrosigmoid approach if that would have been used in each case. We also reviewed 432 patients from the records of the senior author to evaluate possible complications of this approach. RESULTS: The mean working distance for the transmastoid approach was 23.06 mm, whereas the working distance in the traditional approach was 46.44 mm. The mean increase in the angle of work after drilling of the mastoid was 25.39 degrees, and the simple average of increased distance in lateral exposure was 26.66 mm.

CONCLUSION: The transmastoid retrosigmoid approach increases the exposure and gives better access to the CPA targets. This approach alleviates cerebellar retraction, facilitates surgery in the supine position, promotes the use of the endoscope, and is associated with negligible complications.

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Endoscopic surgery for tuberculum sellae meningiomas: a systematic review and meta-analysis

TSM. EEA?

Neurosurg Rev (2013) 36:349–359

Recent reports of surgical resection of tuberculum sellae meningiomas through an endoscopic endonasal approach (EEA) have provided an alternative to transcranial approaches in selected cases. However, these published reports have been limited by small sample size from single institutions.We performed a systematic review and metaanalysis to gain insight into potential limitations and benefits of EEA for tuberculum sellae meningiomas.

We performed a systematic review of the literature and analyzed pooled data for descriptive statistics on short-term morbidity and outcomes. We compared EEA to transcranial approaches reported during the same time-frame. Six studies (49 patients) met inclusion criteria for EEA. A pooled analysis of transcranial results reported during a similar time period yielded 11 studies (412 patients).

There were no differences in rate of gross total resection or peri-operative complications between the two groups. Although the EEA group was associated with higher rates of CSF leak (p<0.05; OR 3.9; 95 % CI 1.15, 15.75), EEA were also associated with significantly higher rates of post-operative visual improvement compared to transcranial approaches (p<0.05; OR 1.5; 95 % CI 1.18, 1.82). A systematic review of the small series of EEA for tuberculum sellae meningiomas published to date revealed similar extent of resection and morbidity, but increased post-operative visual improvement compared to transcranial approaches during a similar time period.

Long-term follow-up will be needed to define recurrence rates of EEA as compared to transcranial approaches. Cautious use of EEA for the removal of smaller tuberculum sellae meningiomas after formal endoscopic training may be warranted.

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Modern surgical outcomes following surgery for sphenoid wing meningiomas

Sphenoid wing meningioma

J Neurosurg 119:86–93, 2013

Cushing and Eisenhardt were the first to describe sphenoid wing meningiomas in detail, categorizing globoid tumors into 3 groups: 1) medial; 2) middle; and 3) lateral. The authors review their experience with resection of sphenoid wing meningiomas at a single center, to examine whether this classification predicts clinical presentation and postsurgical outcome.

Methods. All patients undergoing resection of sphenoid wing meningioma at the authors’ institution over a 9-year period were identified. Clinical data were compared from patients with tumors arising at different points along the sphenoid wing to determine if these tumors behaved differently in terms of symptoms, radiographic characteristics, and postsurgical outcome.

Results. A total of 56 patients underwent microsurgical resection for sphenoid wing meningioma during this period. The rates of optic canal invasion (medial 50% vs middle 5% vs lateral 0%; p < 0.0001, chi-square test), supraclinoid internal carotid artery encasement (medial 32% vs middle 5% vs lateral 0%; p < 0.01, chi-square test), and middle cerebral artery encasement (medial 45% vs middle 24% vs lateral 0%; p < 0.01, chi-square test) were all highest with medial-third tumors. New or worsened neurological deficits occurred in 10 (19%) of 56 patients. Of all the imaging characteristics studied, only location of the tumor along the medial third of the sphenoid wing significantly predicted an increased rate of new or worsened neurological deficit (OR 2.7, p < 0.05).

Conclusions. The authors report outcomes in a large series of sphenoid wing meningiomas that were treated using modern surgical techniques.

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Impact of anterior clinoidectomy on visual function after resection of meningiomas in and around the optic canal

Clinoidectomy

Acta Neurochir (2013) 155:1293–1299

Meningiomas of the anterior and middle skull base frequently involve the optic nerve and cause progressive visual impairment. Surgical decompression of the optic nerve is the only option to preserve visual function. Depending on the invaded structures, optic nerve decompression can be part of a complete tumor removal or the main surgical intention in terms of local debulking. However, bony decompression of the optic canal including anterior clinoidectomy for optic nerve decompression is still a surgical maneuver under discussion.

Methods From 2006 to 2011, 46 consecutive patients with skull base meningiomas in and around the optic canal were operated. The pterional approachwas tailored for each patient. Resection included bony decompression of the optic canal with or without anterior clinoidectomy. Visual acuity and fields were evaluated pre- and postoperatively.

Results Fifty-three percent of patients underwent anterior clinoidectomy, 23 % optic canal unroofing, and 24 % any bony decompression. In 21 patients (46 %), gross total resection (GTR, Simpson grade I or II) was achieved, while 25 patients (54 %) received subtotal resection (STR, Simpson grade III or IV). Sixty-three percent of patients presented with preoperative visual impairment. Postoperative visual changes were significantly related to preoperative visual function. While all patients with normal preoperative vision remained unchanged, in patients with impaired vision, surgery caused improvement in 70%and deterioration in 10 % of patients (p<0.0001). In patients with anterior clinoidectomy, vision improved more frequently than without anterior clinoidectomy (p<0.05).

Conclusions Anterior clinoidectomy is safe and may improve visual outcome in meningiomas in and around the optic canal.

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Safety of drilling for clinoidectomy and optic canal unroofing in anterior skull base surgery

Clinoidectomy and optic canal unroofing

Acta Neurochir (2013) 155:1017–1024

Skull base drilling is a necessary and important element of skull base surgery; however, drilling around vulnerable neurovascular structures has certain risks. We aimed to assess the frequency of complications related to drilling the anterior skull base in the area of the optic nerve (ON) and internal carotid artery (ICA), in a large series of patients.

Methods We included anterior skull base surgeries performed from 2000 to 2012 that demanded unroofing of the optic canal, with extra- or intradural clinoidectomy and/or drilling of the clinoidal process and lateral aspect of the tuberculum sella. Data was retrieved from a prospective database and supplementary retrospective file review. Our IRB waived the requirement for informed consent. The nature and location of pathology, clinical presentation, surgical techniques, surgical morbidity and mortality, pre- and postoperative vision, and neurological outcomes were reviewed.

Results There were 205 surgeries, including 22 procedures with bilateral optic canal unroofing (227 optic canals unroofed). There was no mortality, drilling-related vascular damage, or brain trauma. Complications possibly related to drilling included CSF leak (6 patients, 2.9 %), new ipsilateral blindness (3 patients, 1.5 %), visual deterioration (3 patients, 1.5 %), and transient oculomotor palsy (5 patients, 2.4 %). In all patients with new neuropathies, the optic and oculomotor nerves were manipulated during tumor removal; thus, new deficits could have resulted from drilling, or tumor dissection, or both.

Conclusion Drilling of the clinoid process and tuberculum sella, and optic canal unroofing are important surgical techniques, which may be performed relatively safely by a skilled neurosurgeon.

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Dorsal location of the cochlear nerve on vestibular schwannoma: preoperative evaluation, frequency, and functional outcome

Dorsal location of the cochlear nerve on vestibular schwannoma

Neurosurg Rev (2013) 36:39–44

The cochlear nerve is most commonly located on the caudoventral portion of the capsule of vestibular schwannomas and rarely on the dorsal portion. In such a condition, total removal of the tumor without cochlear nerve dysfunction is extremely difficult.

The purpose of our study was to identify the frequency of this anatomical condition and the status of postoperative cochlear nerve function; we also discuss the preoperative radiological findings.

The study involved 114 patients with unilateral vestibular schwannomas operated on via a retrosigmoid (lateral suboccipital) approach. Locations of the cochlear nerve on the tumor capsule were ventral, dorsal, caudal, and rostral. Ventral and dorsal locations were further subdivided into rostral, middle, and caudal third of the tumor capsule. The postoperative cochlear nerve function and preoperative magnetic resonance (MR) findings were reviewed retrospectively.

In 56 patients that had useful preoperative hearing, useful hearing was retained in 50.0 % (28 of 56) of patients after surgery. The cochlear nerve was located on the dorsal portion of the tumor capsule in four patients (3.5 %), and useful hearing was preserved in only one of these patients (25 %) in whom the tumor had been partially resected.

This tumor-nerve anatomical relationship was identified in all tumors of <2 cm at preoperative MR cisternography. MR cisternography has the potential to identify the tumor–nerve anatomical relationship, especially in small-sized tumors that usually require therapeutic intervention that ensures hearing preservation. Hence, careful evaluation of the preoperative MR cisternography is important in deciding the therapeutic indications.

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Microsurgical Management of Jugular Foramen Schwannomas

Primary Jugular Foramen Meningioma- Imaging Appearance and Differentiating Features1

Neurosurgery 72:42–46, 2013

Jugular foramen schwannomas are uncommon and surgically challenging lesions.

OBJECTIVE: To determine the importance of surgical technique on morbidity and recurrence of jugular foramen schwannomas.

METHODS: A retrospective review and case-control analysis of a single-senior-surgeon series of 81 patients with surgically treated jugular foramen schwannomas was performed, focusing on operative technique. Patients undergoing an aggressive, total tumor resection (series 1) were compared with those undergoing more conservative resection focusing on preserving the pars nervosa (series 2).

RESULTS: There was a statistically significant (P = .04) decrease in permanent deficits of the cranial nerve 9/10 complex with a conservative technique. Recurrence was seen in 3 patients (5.7%) in series 1 and in 3 patients (10.7%) in series 2 (P = .36). Recurrence was treated with reoperation in 1 patient, radiation in 1 patient, and observation in the others.

CONCLUSION: Although radical gross total resection is desirable, it is not optimal for cranial nerve preservation in patients with jugular foramen schwannomas. A more conservative approach resulted in a statistically significant decrease in lower cranial nerve deficits. There was a nonstatistically significant trend toward increasing recurrence, which may be treated with multiple modality therapy in the modern era.

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The Naso-Axial Line: A New Method of Accurately Predicting the Inferior Limit of the Endoscopic Endonasal Approach to the Craniovertebral Junction

The Naso-Axial Line- A New Method of Accurately Predicting the Inferior Limit of the Endoscopic Endonasal Approach to the Craniovertebral Junction

Neurosurgery 71[ONS Suppl 2]:ons308–ons314, 2012

The endoscopic endonasal approach (EEA) has developed as an emerging surgical corridor to the craniovertebral junction (CVJ). In addition to understanding its indications and surgical anatomy, the ability to predict its inferior limit is vital for optimal surgical planning.

OBJECTIVE: To develop a method that accurately predicts the inferior limit of the EEA on the CVJ radiologically and to compare this with other currently used methods.

METHODS: Predissection computerized tomographic scans of 9 cadaver heads were used to delineate a novel line, the naso-axial line (NAxL), to predict the inferior EEA limit on the upper cervical spine. A previously described method with the use of the nasopalatine line (NPL or Kassam line) was also used. On computerized tomographic scans obtained following dissection of the EEA, the predicted inferior limits were compared with the actual extent of dissection.

RESULTS: The postdissection inferior EEA limit ranged from the dens tip to the upper half of the C2 body, which matched the limit predicted by NAxL, with no statistically significant difference between them. In contrast to the NAxL, the NPL predicted a significantly lower EEA limit (P , .001), ranging from the lower half of the C2 body to the superior end plate of C3.

CONCLUSION: The novel NAxL more accurately predicts the inferior limit of the EEA than the NPL. This method, which can be easily used on preoperative sagittal scans, accounts for variations in patients’ anatomy and can aid surgeons in the assessment of the EEA to address caudal CVJ pathology.

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Transcranial superior orbitotomy for the treatment of intraorbital intraconal tumors

Neurosurg Rev (2012) 35:573–582

In this article, the authors are presenting their experience and the results with the surgical treatment of intraorbital intraconal tumors based on a review of 33 constitutive cases. Our data were evaluated in comparison to other major series, and possible factors that might influence surgical outcome and survival are discussed. Thirty-three patients diagnosed with intraorbital intraconal tumors between 1998 and 2009 were treated by transcranial approach. Of these patients, there were 14 males (42.4 %) and 19 females (57.8 %). The age ranged between 2 and 70 years (mean036±16.6 years). The follow-up period ranged between 2 and 13 years (mean07.3±3.2 years). The most common presenting symptoms were exophthalmus and decreased visual acuity, which was seen in 21 (63.6 %) and 19 patients (57.6 %), respectively. Total resection was achieved in 23 patients (69.7 %) while subtotal resection was done in ten patients (30.3 %). Cavernoma and optic nerve sheath meningioma were the most common histologic variants, which were found in 11 (33.3 %) and 10 (30.3 %) patients, respectively. In the long-term follow-up, 54.5 % of the patients showed total ophthalmologic improvement, 9.1 % showed partial improvement, 21.2 % demonstrated unchanged ophthalmologic status, and 15.2 % showed worse ophthalmologic outcome.

Transcranial approach for the treatment of intraorbital intraconal tumors is an effective approach for the management of these pathologies. The effectiveness is clearly demonstrated by the clinical results and outcomes of these patients’ groups.

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Localization of transverse-sigmoid sinus junction using preoperative 3D computed tomography: application in retrosigmoid craniotomy

Neurosurg Rev (2012) 35:593–599

In retrosigmoid craniotomy, neurosurgeons usually depend on surface landmarks and their experience to evaluate the position of transverse-sigmoid sinus junction (TSSJ) and place an appropriate initial burr-hole, which is not accurate each time because of variability in different craniums. The authors introduce a simple procedure based on 3D computed tomography (CT) to localize the TSSJ in retrosigmoid craniotomy.

Eighteen patients who underwent retrosigmoid craniotomy were analyzed. On the internal view of skull in 3D CT image, a simulative burr-hole was placed on the margin of transverse-sigmoid sinus groove junction. Then, on the external view of skull in 3D CT image, the center of the simulative burr-hole was marked and a coordinate system was established based on a line connected the digastric point and the asterion. Then the coordinate of the burr-hole’s center was measured in this coordinate system.

In operation, the burr-hole was placed according to the coordinate measured previously and craniotomy was performed. The margin of TSSJ was exposed in each case. No damage of venous sinus was encountered. Post-operative skull base CT demonstrated a good match between the actual and predicted burr-hole and bone defects only existed along the cut line.

This simple method could help in localizing the TSSJ and avoiding the risk of sinus injury and reducing the bone defect. It is sufficiently precise for practical application at surgical planning.

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Giant anterior clinoidal meningiomas: surgical technique and outcomes

J Neurosurg 117:654–665, 2012

Surgery for giant anterior clinoidal meningiomas that invade vital neurovascular structures surrounding the anterior clinoid process is challenging. The authors present their skull base technique for the treatment of giant anterior clinoidal meningiomas, defined here as globular tumors with a maximum diameter of 5 cm or larger, centered around the anterior clinoid process, which is usually hyperostotic.

Methods. Between 2000 and 2010, the authors performed 23 surgeries in 22 patients with giant anterior clinoidal meningiomas. They used a skull base approach with extradural unroofing of the optic canal, extradural clinoidectomy (Dolenc technique), transdural debulking of the tumor, early optic nerve decompression, and early identification and control of key neurovascular structures.

Results. The mean age at surgery was 53.8 years. The mean tumor diameter was 59.2 mm (range 50–85 mm) with cavernous sinus involvement in 59.1% (13 of 22 patients). The tumor involved the prechiasmatic segment of the optic nerve in all patients, invaded the optic canal in 77.3% (17 of 22 patients), and caused visual impairment in 86.4% (19 of 22 patients). Total resection (Simpson Grade I or II) was achieved in 30.4% of surgeries (7 of 23); subtotal and partial resections were each achieved in 34.8% of surgeries (8 of 23). The main factor precluding total removal was cavernous sinus involvement. There were no deaths. The mean Glasgow Outcome Scale score was 4.8 (median 5) at a mean of 56 months of follow-up. Vision improved in 66.7% (12 of 18 patients) with consecutive neuroophthalmological examinations, was stable in 22.2% (4 of 18), and deteriorated in 11.1% (2 of 18). New deficits in cranial nerve III or IV remained after 8.7% of surgeries (2 of 23).

Conclusions. This modified surgical protocol has provided both a good extent of resection and a good neurological and visual outcome in patients with giant anterior clinoidal meningiomas.

 

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Endoscopic Endonasal Transclival Approach to the Jugular Tubercle

Neurosurgery 71[ONS Suppl 1]:ons146–ons159, 2012

The jugular tubercle is a rounded bony prominence that arises from the inferolateral margin of the clivus. In a previous publication, we described the surgical anatomy of the expanded endonasal approach to the jugular tubercle.

OBJECTIVE: To illustrate the translation of laboratory work to the operating room describing the anatomic and technical nuances of the endonasal approach to the jugular tubercle.

METHODS: We review the relevant surgical anatomy needed to perform an endonasal approach to the jugular tubercle, and we select 4 different lesions to illustrate the application of our laboratory findings.

RESULTS: In the first case, exposure and partial drilling of the jugular tubercle was critical to gain an adequate corridor to the meningioma, particularly to its inferolateral margin. This allowed for early devascularization, safe extracapsular dissection, and preservation of surrounding neurovascular structures. In addition, the jugular tubercle was hyperostotic and its resection, along with generous dural removal, provided a grade I Simpson tumor resection. In the second (chondrosarcoma) and third (chordoma) cases, the jugular tubercle was infiltrated by tumor, and consequently its complete resection was essential to achieve total tumor removal. In the last case, an unusual adrenocorticotropic hormone-secreting adenoma recurrence at the jugular tubercle region, the technical modification of the transclival approach presented here was successfully applied to achieve complete resection and Cushing disease remission.

CONCLUSION: The transjugular tubercle variant of the expanded endonasal transclival approach allows for direct access to ventrolateral lesions in the inferior clival/petroclival region with no cerebral or cerebellar retraction, or cranial nerve manipulation during the approach.

 

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Surgery for vestibular schwannomas: a systematic review of complications by approach

Neurosurg Focus 33 (3):E14, 2012

Various studies report outcomes of vestibular schwannoma (VS) surgery, but few studies have compared outcomes across the various approaches. The authors conducted a systematic review of the available data on VS surgery, comparing the different approaches and their associated complications.

Methods. MEDLINE searches were conducted to collect studies that reported information on patients undergoing VS surgery. The authors set inclusion criteria for such studies, including the availability of follow-up data for at least 3 months, inclusion of preoperative and postoperative audiometric data, intraoperative monitoring, and reporting of results using established and standardized metrics. Data were collected on hearing loss, facial nerve dysfunction, persistent postoperative headache, CSF leak, operative mortality, residual tumor, tumor recurrence, cranial nerve (CN) dysfunction involving nerves other than CN VII or VIII, and other neurological complications. The authors reviewed data from 35 studies pertaining to 5064 patients who had undergone VS surgery.

Results. The analyses for hearing loss and facial nerve dysfunction were stratified into the following tumor categories: intracanalicular (IC), size (extrameatal diameter) < 1.5 cm, size 1.5–3.0 cm, and size > 3.0 cm. The middle cranial fossa approach was found to be superior to the retrosigmoid approach for hearing preservation in patients with tumors < 1.5 cm (hearing loss in 43.6% vs 64.3%, p < 0.001). All other size categories showed no significant difference between middle cranial fossa and retrosigmoid approaches with respect to hearing loss. The retrosigmoid approach was associated with significantly less facial nerve dysfunction in patients with IC tumors than the middle cranial fossa method was; however, neither differed significantly from the translabyrinthine corridor (4%, 16.7%, 0%, respectively, p < 0.001). The middle cranial fossa approach differed significantly from the translabyrinthine approach for patients with tumors < 1.5 cm, whereas neither differed from the retrosigmoid approach (3.3%, 11.5%, and 7.2%, respectively, p = 0.001). The retrosigmoid approach involved less facial nerve dysfunction than the middle cranial fossa or translabyrinthine approaches for tumors 1.5–3.0 cm (6.1%, 17.3%, and 15.8%, respectively; p < 0.001). The retrosigmoid approach was also superior to the translabyrinthine approach for tumors > 3.0 cm (30.2% vs 42.5%, respectively, p < 0.001). Postoperative headache was significantly more likely after the retrosigmoid approach than after the translabyrinthine approach, but neither differed significantly from the middle cranial fossa approach (17.3%, 0%, and 8%, respectively; p < 0.001). The incidence of CSF leak was significantly greater after the retrosigmoid approach than after either the middle cranial fossa or translabyrinthine approaches (10.3%, 5.3%, 7.1%; p = 0.001). The incidences of residual tumor, mortality, major non-CN complications, residual tumor, tumor recurrence, and dysfunction of other cranial nerves were not significantly different across the approaches.

Conclusions. The middle cranial fossa approach seems safest for hearing preservation in patients with smaller tumors. Based on the data, the retrosigmoid approach seems to be the most versatile corridor for facial nerve preservation for most tumor sizes, but it is associated with a higher risk of postoperative pain and CSF fistula. The translabyrinthine approach is associated with complete hearing loss but may be useful for patients with large tumors and poor preoperative hearing.

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Technical nuances of resection of giant (> 5 cm) vestibular schwannomas: pearls for success

Neurosurg Focus 33 (3):E15, 2012

Removal of vestibular schwannomas (VSs, or acoustic neuromas) remains one of the most challenging operations in neurosurgery. Giant or huge tumors (> 5 cm) heighten these challenges, and technical nuances play a special role in maximizing tumor resection while minimizing complications.

In this article, the senior author describes his technical experience with microsurgical excision of giant VSs. The accompanying video further illustrates these details.

 

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Surgery for vestibular schwannomas: a systematic review of complications by approach

Neurosurg Focus 33 (3):E14, 2012

Various studies report outcomes of vestibular schwannoma (VS) surgery, but few studies have compared outcomes across the various approaches. The authors conducted a systematic review of the available data on VS surgery, comparing the different approaches and their associated complications.

Methods. MEDLINE searches were conducted to collect studies that reported information on patients undergoing VS surgery. The authors set inclusion criteria for such studies, including the availability of follow-up data for at least 3 months, inclusion of preoperative and postoperative audiometric data, intraoperative monitoring, and reporting of results using established and standardized metrics. Data were collected on hearing loss, facial nerve dysfunction, persistent postoperative headache, CSF leak, operative mortality, residual tumor, tumor recurrence, cranial nerve (CN) dysfunction involving nerves other than CN VII or VIII, and other neurological complications. The authors reviewed data from 35 studies pertaining to 5064 patients who had undergone VS surgery.

Results. The analyses for hearing loss and facial nerve dysfunction were stratified into the following tumor categories: intracanalicular (IC), size (extrameatal diameter) < 1.5 cm, size 1.5–3.0 cm, and size > 3.0 cm. The middle cranial fossa approach was found to be superior to the retrosigmoid approach for hearing preservation in patients with tumors < 1.5 cm (hearing loss in 43.6% vs 64.3%, p < 0.001). All other size categories showed no significant difference between middle cranial fossa and retrosigmoid approaches with respect to hearing loss. The retrosigmoid approach was associated with significantly less facial nerve dysfunction in patients with IC tumors than the middle cranial fossa method was; however, neither differed significantly from the translabyrinthine corridor (4%, 16.7%, 0%, respectively, p < 0.001). The middle cranial fossa approach differed significantly from the translabyrinthine approach for patients with tumors < 1.5 cm, whereas neither differed from the retrosigmoid approach (3.3%, 11.5%, and 7.2%, respectively, p = 0.001). The retrosigmoid approach involved less facial nerve dysfunction than the middle cranial fossa or translabyrinthine approaches for tumors 1.5–3.0 cm (6.1%, 17.3%, and 15.8%, respectively; p < 0.001). The retrosigmoid approach was also superior to the translabyrinthine approach for tumors > 3.0 cm (30.2% vs 42.5%, respectively, p < 0.001). Postoperative headache was significantly more likely after the retrosigmoid approach than after the translabyrinthine approach, but neither differed significantly from the middle cranial fossa approach (17.3%, 0%, and 8%, respectively; p < 0.001). The incidence of CSF leak was significantly greater after the retrosigmoid approach than after either the middle cranial fossa or translabyrinthine approaches (10.3%, 5.3%, 7.1%; p = 0.001). The incidences of residual tumor, mortality, major non-CN complications, residual tumor, tumor recurrence, and dysfunction of other cranial nerves were not significantly different across the approaches.

Conclusions. The middle cranial fossa approach seems safest for hearing preservation in patients with smaller tumors. Based on the data, the retrosigmoid approach seems to be the most versatile corridor for facial nerve preservation for most tumor sizes, but it is associated with a higher risk of postoperative pain and CSF fistula. The translabyrinthine approach is associated with complete hearing loss but may be useful for patients with large tumors and poor preoperative hearing.

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Surgical nuances for nasoseptal flap reconstruction of cranial base defects with high-flow cerebrospinal fluid leaks after endoscopic skull base surgery

Neurosurg Focus 32 (6):E7, 2012. DOI: 10.3171/2012.5.FOCUS1255

Extended endoscopic endonasal approaches have allowed for a minimally invasive solution for removal of a variety of ventral skull base lesions, including intradural tumors. Depending on the location of the pathological entity, various types of surgical corridors are used, such as transcribriform, transplanum transtuberculum, transsellar, transclival, and transodontoid approaches. Often, a large skull base dural defect with a high-flow CSF leak is created after endoscopic skull base surgery. Successful reconstruction of the cranial base defect is paramount to separate the intracranial contents from the paranasal sinus contents and to prevent postoperative CSF leakage. The vascularized pedicled nasoseptal flap (PNSF) has become the workhorse for cranial base reconstruction after endoscopic skull base surgery, dramatically reducing the rate of postoperative CSF leakage since its implementation.

In this report, the authors review the surgical technique and describe the operative nuances and lessons learned for successful multilayered PNSF reconstruction of cranial base defects with high-flow CSF leaks created after endoscopic skull base surgery. The authors specifically highlight important surgical pearls that are critical for successful PNSF reconstruction, including target-specific flap design and harvesting, pedicle preservation, preparation of bony defect and graft site to optimize flap adherence, multilayered closure technique, maximization of the reach of the flap, final flap positioning, and proper bolstering and buttressing of the PNSF to prevent flap dehiscence. Using this technique in 93 patients, the authors’ overall postoperative CSF leak rate was 3.2%.

An illustrative intraoperative video demonstrating the reconstruction technique is also presented.

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Repair of middle fossa cerebrospinal fluid leaks using a novel combination of materials

Neurosurg Focus 32 (6):E8, 2012. (http://thejns.org/doi/abs/10.3171/2012.4.FOCUS1258)

Methods for repairing middle fossa CSF (MFCSF) leaks have varied and yielded mixed results. The objective of this study was to evaluate the safety and durability of the authors’ repair technique using a novel combination of 3 synthetic materials.

Methods. The authors performed a retrospective case review of patients treated for CSF leaks between January 2009 and September 2011. Eight patients were found to have undergone middle fossa craniotomies for CSF leaks. Inclusion criteria for the study included age greater than 18 years, neuroimaging-documented temporal bone defect, and symptoms consistent with CSF leaks or gross CSF otorrhea. Seven patients, 3 men and 4 women, met the inclusion criteria, and their charts were reviewed. Hydroxyapatite cement, collagen-based dural substitute matrix, and polyethylene glycol hydrogel sealant were used in all patients for the repair.

Results. In all patients the MFCSF leaks were successfully repaired. Initial presenting symptoms included CSF otorrhea in 4 patients (57.1%), hearing loss in 3 (42.9%), and CSF rhinorrhea in 1 (14.3%). The mean follow-up duration was 12 months (range 5–33 months). In 1 patient an epidural hematoma developed at the operative site on postoperative Day 2, and in another patient a superficial wound dehiscence occurred on postoperative Day 48. During the follow-up period, the authors found no evidence of wound infections, neurovascular damage, or CSF leakage requiring reoperation.

Conclusions. The middle fossa approach involving a combination of hydroxyapatite cement, collagen-based dural substitute matrix, and polyethylene glycol hydrogel sealant is a safe, effective method for repairing MFCSF leaks. The combination of synthetic materials provides an alternative to existing materials for skull base surgeons.

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The Middle Fossa Approach and Extended Middle Fossa Approach: Technique and Operative Nuances

Neurosurgery 70[ONS Suppl 2]:ons192–ons201, 2012 DOI: 10.1227/NEU.0b013e31823583a1

The middle fossa approach and extended middle fossa approach, also known as the anterior transpetrosal approach, are cranial base techniques for addressing small vestibular schwannomas, medial temporal bone lesions, midbasilar trunk aneurysms, and selected petroclival lesions.

OBJECTIVE: To provide an outline of a number of technical nuances that are important to correct application of these approaches, maximizing exposure, and limiting potential morbidity.

METHODS: Via a temporal craniotomy, the petrous apex is removed in variable degrees, depending on the exposure requirements of the lesion. The technique is described in detail with appropriate nuances of the technique provided.

RESULTS: The described nuances of technique in the performance of the approaches have resulted in successful application of these techniques in a significant number of cases.

CONCLUSION: Significant familiarity and practice with these surgical approach techniques are critical to applying them safely to clinical problems. A number of technical details can assist the surgeon in achieving optimal exposure and limited morbidity.

 

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