Category: Surgical technique

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The Mirroring Technique: A Navigation-Based Method for Reconstructing a Symmetrical Orbit and Cranial Vault

Mirroring technique

Neurosurgery 73[ONS Suppl 1]:ons24–ons29, 2013

The reconstruction of orbital structures and the cranial vault curvature can be challenging after trauma or wide resections for tumors. Sophisticated methods have been developed recently, but these are resource- and time-consuming.

OBJECTIVE: We report the mirroring technique, which is an effective and costless application for navigation-guided reconstruction procedures.

METHODS: At the time of the reconstruction, high-resolution images are reloaded while forcing a left-right axial flip. The pointer subsequently enables a virtual 3- dimensional projection of the position of the contralateral normal anatomy.

RESULTS: This method was applied successfully in 2 cases of en plaque sphenoid wing meningiomas with secondary exophthalmia.

CONCLUSION: The mirroring technique represents an accurate method of outlining the contralateral normal anatomy onto the pathological side based on navigation guidance.

KEY WORDS:

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Minimally invasive transforaminal lumbar interbody fusions and fluoroscopy

Minimally invasive transforaminal lumbar interbody fusions and fluoroscopy

Neurosurg Focus 35 (2):E8, 2013

There is an increasing awareness of radiation exposure to surgeons and the lifelong implications of such exposure. One of the main criticisms of minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) is the amount of ionizing radiation required to perform the procedure. The goal in this study was to develop a protocol that would minimize the fluoroscopy time and radiation exposure needed to perform an MIS TLIF without compromising visualization of the anatomy or efficiency of the procedure.

Methods. A retrospective review of a prospectively collected database was performed to review the development of a low-dose protocol for MIS TLIFs in which a combination of low-dose pulsed fluoroscopy and digital spot images was used. Total fluoroscopy time and radiation dose were reviewed for 50 patients who underwent single-level MIS TLIFs.

Results. Fifty patients underwent single-level MIS TLIFs, resulting in the placement of 200 pedicle screws and 57 interbody spacers. There were 28 women and 22 men with an average age of 58.3 years (range 32–78 years). The mean body mass index was 26.2 kg/m2 (range 17.1–37.6 kg/m2). Indications for surgery included spondylolisthesis (32 patients), degenerative disc disease with radiculopathy (12 patients), and recurrent disc herniation (6 patients). Operative levels included 7 at L3–4, 40 at L4–5, and 3 at L5–S1. The mean operative time was 177 minutes (range 139–241 minutes). The mean fluoroscopic time was 18.72 seconds (range 7–29 seconds). The mean radiation dose was 0.247 mGy*m2 (range 0.06046–0.84054 mGy*m2). No revision surgery was required for any of the patients in this series.

Conclusions. Altering the fluoroscopic technique to low-dose pulse images or digital spot images can dramatically decrease fluoroscopy times and radiation doses in patients undergoing MIS TLIFs, without compromising image quality, accuracy of pedicle screw placement, or efficiency of the procedure.

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Combined extradural subtemporal and anterior transpetrosal approach to tumors located in the interpeduncular fossa and the upper clivus

Approach to interpeduncular fossa and upper clivus

Acta Neurochir (2013) 155:1401–1407

Central skull base lesions in the interpeduncular fossa and the upper clival regions can be challenging to access because of their location anterior to the brainstem. We have modified the anterior transpetrosal approach by combination with the extradural subtemporal route to increase the surgical corridor.

Methods Thirty-seven patients underwent surgical treatment via the anterior transpetrosal approach from 2002 to 2012. The combined surgical approach was primarily applied when the tumors arose from the upper clival portion and extended to the interpeduncular fossa. The combined approach was used in seven of these patients, comprising four patients with petroclival meningiomas, one patient with sphenoclival meningiomas, one patient with trigeminal schwannoma, and one patient with an epidermoid cyst extending from the interpeduncular fossa to the prepontine cistern.

Results The combined approach permitted excellent visualization of the interpeduncular fossa in addition to the upper clivus and the lateral aspect of the brain stem. Mobilization of the temporal lobe by the entire epidural dissection of the lateral wall of the cavernous sinus facilitates access via the subtemporal route. The transient symptom of the temporal lobe in the dominant site may be the only drawback for this combined approach, although it may disappear immediately after the surgery.

Conclusion The present approach combines Dolenc’s approach and Kawase’s approach, providing a wide exposure to lesions of the interpeduncular fossa and the clivus.

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Surgical management and outcomes of petroclival meningiomas: a single-center case series of 259 patients

Petroclival meningioma outcomes

Acta Neurochir (2013) 155:1367–1383

Surgical management of petroclival meningiomas is challenging. Various and inconsistent outcome and prognostic factors of the lesions have been evaluated previously. In the present study, the surgical outcome, philosophy, and experience of petroclival meningiomas are detailed based on a large patient series.

Methods A series of 259 patients with petroclival meningiomas (70 males and 189 females) were surgically treated. Clinical charts and radiographs were reviewed. Follow-up results were evaluated.

Results The preoperative Karnofsky Performance Scale (KPS) score was 74.2±10.5. The mean tumor size was 4.3±1.0 cm. The gross total resection (GTR) rate was 52.5 %. During a mean follow-up period of 55.3 months, recurrence/progression (R/P) occurred in 11 patients. The recent KPS score was 78.4±22.7, it improved in 139 (57.2 %) patients and stabilized in 53 (21.8 %) patients, and 201 (82.7 %) patients lived independently. The risk factors affecting the KPS score included (but were not limited to) age≥60, preoperative KPS≤60, and brainstem edema. The adverse factors contributing to R/P-free survival included (but were not limited to) non-total resection and the absence of the subarachnoid space. The R/P-free survival rate was 94.5 % at 5 years and 91.2 % at 9 years. The overall survival rate was 94.7 % at 5 years and 94.7 % at 9 years.

Conclusions Favorable outcomes from petroclival meningiomas could be achieved by microsurgery. Neurological function and quality of life were prioritized, and GTR was attempted. Risk factors should be considered in surgical schemes, and tumor recurrence should be aggressively monitored and treated.

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Outcomes of MITLIF and open TLIF approaches

Short-term and long-term outcomes of minimally invasive and open transforaminal lumbar interbody fusions- is there a difference?

Neurosurg Focus 35 (2):E6, 2013

Previous studies comparing minimally invasive transforaminal lumbar interbody fusion (MITLIF) with open TLIF have demonstrated that MITLIF reduces blood loss and decreases postoperative pain while preserving fusion rates and reducing complications. In this study, the authors wanted to compare outcomes of MITLIF with those of open TLIF to determine whether MITLIF also improves postoperative functional mobility and decreases the usage of pain medication.

Methods. In total, 75 consecutive patients who underwent either single-level open TLIF or MITLIF at the University of California, San Francisco, between 2006 and 2011 were included, and patients were followed up for an average of 5.05 years. Fifty patients underwent MITLIF and 25 underwent open TLIF. Primary outcomes included administration of morphine-equivalent narcotics and functional status on postoperative Day 1. Secondary outcomes included operative characteristics, complications, long-term fusion rates, and visual analog scale (VAS) scores.

Results. No statistically significant differences in age, sex, body mass index (BMI), level of disease, or surgical indication were detected between the open TLIF and MITLIF groups. Similarly, preoperative medication usage did not significantly differ between these groups. Intraoperatively, compared with TLIF, MITLIF resulted in decreased lengths of operation, lower blood loss, and fewer complications (p < 0.05). Total administration of morphine-equivalent pain medication in the hospital also tended to be lower in the MITLIF than in the TLIF group. Functional assessment by physical therapy on postoperative Day 1 demonstrated higher function in the MITLIF patients for transfer-related tasks, ambulatory ability, and distance walked than in the TLIF patients (p < 0.05). This translated to shorter inpatient hospitalizations (6.05 vs 4.8 days for open TLIF vs MITLIF patients, respectively, p = 0.006) and an average cost reduction of $3885 per MITLIF patient. Long-term fusion rates were 92% in the MITLIF group and 100% in the open TLIF group (p = 0.09). Preoperative VAS pain scores were 7.1 for the MITLIF patients and 7.6 for the TLIF patients (p = 0.26). At the last follow-up, the reported VAS pain score was 2.9 in the MITLIF patients and 3.5 in the open TLIF patients, but this difference was not statistically significant (p = 0.25). There was also no statistically significant difference in the degree change in this score (p = 0.44).

Conclusions. The MITLIF approach achieves improved functional mobility, decreases the usage of postoperative pain medication, and significantly reduces cost compared with open TLIF while preserving long-term fusion rates. To the authors’ knowledge, this is the first study comparing the postoperative usage of pain medication between treatments in the postoperative period before discharge.

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Surgery for low-grade glioma infiltrating the central cerebral region

Surgery for low-grade glioma infiltrating the central cerebral region

J Neurosurg 119:318–323, 2013

A main concern with regard to surgery for low-grade glioma (LGG, WHO Grade II) is maintenance of the patient’s functional integrity. This concern is particularly relevant for gliomas in the central region, where damage can have grave repercussions. The authors evaluated postsurgical outcomes with regard to neurological deficits, seizures, and quality of life.

Methods. Outcomes were compared for 33 patients with central LGG (central cohort) and a control cohort of 31 patients with frontal LGG (frontal cohort), all of whom had had medically intractable seizures before undergoing surgery with mapping while awake. All surgeries were performed in the period from February 2007 through April 2010 at the same institution.

Results. For the central cohort, the median extent of resection was 92% (range 80%–97%), and for the frontal cohort, the median extent of resection was 93% (range 83%–98%; p = 1.0). Although the rate of mild neurological deficits was similar for both groups, seizure freedom (Engel Class I) was achieved for only 4 (12.1%) of 33 patients in the central cohort compared with 26 (83.9%) of 31 patients in the frontal cohort (p < 0.0001). The rate of return to work was lower for patients in the central cohort (4 [12.1%] of 33) than for the patients in the frontal cohort (28 [90.3%] of 31; p < 0.0001).

Conclusions. Resection of central LGG is feasible and safe when appropriate intraoperative mapping is used. However, seizure control for these patients remains poor, a finding that contrasts markedly with seizure control for patients in the frontal cohort and with that reported in the literature. For patients with central LGG, poor seizure control ultimately determines quality of life because most will not be able to return to work.

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Surgical techniques for the dissection of encased perforators in giant clinoidal meningiomas

Encased perforators in giant clinoidal meningiomas

Acta Neurochir (2013) 155:1409–1412

Surgical treatment of giant clinoidal meningiomas remains a challenging task for neurosurgeons. Here, we present details of the surgical techniques for the dissection of encased perforators.

Methods The dissection of encased perforators is summarized as follows: (1) split the tumor above the encased arteries and perforators; (2) find the entrance and exit points of the perforators, and estimate the running course of the perforators within the tumor; (3) dissect and expose the perforators along the estimated line.

Conclusions The surgical techniques described in this article will aid in achieving maximum tumor resection while preserving encased perforators.

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Venous preservation–guided resection: a changing paradigm in parasagittal meningioma surgery

Venous preservation–guided resection- a changing paradigm in parasagittal meningioma surgery-1

J Neurosurg 119:74–81, 2013

Surgical treatment of parasagittal meningiomas is challenging. Preserving the venous outflow is the key point, but this may preclude radical resection. Different surgical strategies have been proposed. To contribute to the debate on the optimal strategy for treating these tumors, a single-institutional, single-surgeon series of patients with parasagittal meningiomas was analyzed and the available literature reviewed.

Methods. Clinical charts of patients with parasagittal meningioma, managed at the University of Messina between 1988 and 2008, were retrospectively reviewed. A microsurgical resection, the goal of which was to preserve the venous outflow, was performed. Only if the superior sagittal sinus (SSS) was angiographically occluded, but if alternative venous outflow was clearly recognized, was the tumor resected, together with the sinus without further flow restoration. A MEDLINE review of the literature published between 1955 and 2011 was performed.

Results. Long-term follow-up (mean 80 months) data obtained in 67 patients with meningiomas involving the SSS were analyzed. The recurrence rate was 10.4%; the morbidity and mortality rates were 10.4% and 4.5%, respectively. The authors identified in the literature 19 relevant studies on this issue, and based on their review of the literature, there is no evidence that aggressive management offers an advantage in terms of recurrence rate.

Conclusions. Analysis of the data obtained in the 67 patients confirmed good outcome and long-term tumor control following a surgical strategy aimed to preserve venous outflow. These findings and the results of the authors’ analysis of the literature emphasize that the goal of radical tumor resection should be balanced by an awareness of the increased surgical risk attendant on aggressive management of the SSS and bridging veins.

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Intraoperative Seizures During Awake Craniotomy: Incidence and Consequences: Analysis of 477 Patients

Awake cranio

Neurosurgery 73:135–140, 2013

Awake craniotomy (AC) for removal of intra-axial brain tumors is a well-established procedure. However, the occurrence and consequences of intraoperative seizures during AC have not been well characterized.

OBJECTIVE: To analyze the incidence, risk factors, and consequences of seizures during AC.

METHODS: The database of AC at Tel Aviv Medical Center between 2003 to 2011 was reviewed. Occurrences of intraoperative seizures were analyzed with respect to medical history, medications, tumor characteristics, and postoperative outcome.

RESULTS: Of the 549 ACs performed during the index period, 477 with complete records were identified. Sixty patients (12.6%) experienced intraoperative seizures. The AC procedure failed in 11 patients (2.3%) due to seizures. Patients with intraoperative seizures were significantly younger than nonseizing patients (45 6 14 years vs 52 6 16 years, P = .003), had a higher incidence of frontal lobe involvement (86% vs % 57%, P , .0001), and had higher prevalence of a history of seizures (P = .008). Short-term motor deterioration developed postoperatively in a higher percentage of patients with intraoperative seizures (20% vs 10.1%, P = .02) with a longer hospitalization period (4.0 6 3.0 days vs 3.0 6 3.0 days, P = .045).

CONCLUSION: Although in most cases intraoperative seizures will not result in AC failure, the surgical team should be prepared to treat them promptly to avoid intractable seizures. Intraoperative seizures are more common in younger patients with a tumor in the frontal lobe and those with a history of seizures. Moreover, they are associated with a higher incidence of transient postoperative motor deterioration and protracted length of hospital stay.

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Surgical treatment of thoracic disc disease via minimally invasive lateral transthoracic trans/retropleural approach

Surgical treatment of thoracic disc disease via minimally

Neurosurg Rev (2013) 36:455–465

Thoracic disc herniations are associated with serious neurological consequences if not treated appropriately. Although a number of techniques have been described, there is no consensus about the best surgical approach. In this study, the authors report their experience in the operative management of patients with thoracic disc herniations using minimally invasive lateral transthoracic trans/retropleural approach.

A series of 33 consecutive patients with thoracic disc herniations who underwent anterior spinal cord decompression followed by instrumented fusion through lateral approach is being reported. Demographic and radiographic data, perioperative complications, and clinical outcomes were reviewed.

Forty disc levels in 33 patients (18F/15M; mean age, 52.9) were treated. Twenty-three patients presented with myelopathy (69 %), 31 had radiculopathy (94 %), and 31 had axial pain (94 %). Among patients with myelopathy, 14 (42.4 %) had bladder and/or bowel dysfunction. In the last eight cases (24 %), the approach was retropleural instead of transpleural. Patients were followed up for 18.2 months on average. The mean length of hospital stay was 5 days. None of the patients developed neurological deterioration postoperatively. Among 23 patients who had myelopathy signs, 21 (91 %) had improved postoperatively. The mean preoperative visual analog scale pain score, Oswestry Disability Index score, SF-36 PCS, and mental component summary scores were 7.5, 42.4, 29.6, and 37.5 which improved to 3.5, 33.2, 35.5, and 52.6, respectively. Perioperative complications occurred in six patients (18.1 %), all of which resolved uneventfully.

Minimally invasive lateral transthoracic trans/retropleural approach is a safe and efficacious technique for achieving adequate decompression in thoracic disc herniations in a less invasive manner than conventional approaches.

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Surgical treatment of tentorial dural arteriovenous fistulae located around the tentorial incisura

Surgical treatment of tentorial dural arteriovenous fistulae

Neurosurg Rev (2013) 36:429–435

Tentorial dural arteriovenous fistulae (DAVF) are relatively uncommon and are the most dangerous type of DAVF. Because of a high incidence of hemorrhage and subsequent neurological deficits, treatment is mandatory.

A consecutive series of nine surgically treated patients with symptomatic tentorial DAVF were analyzed in this study. All lesions were located around the tentorial incisura and were treated microsurgically using a subtemporal approach in eight cases and a supracerebellar approach in one case. The dural bases of the lesions were located adjacent to the tentorial edge in six patients and the tentorial apex in three patients.

Complete obliteration was achieved in all treated tentorial DAVF. In one patient, the torcular fistula remained untreated without cortical venous reflux. Postoperative asymptomatic temporal lobe hemorrhage was diagnosed in one patient with a tentorial apex DAVF; however, no new neurological symptoms were present after surgical treatment.

The subtemporal approach for unilateral tentorial DAVF is a favorable and direct approach for the highly skilled surgeon. Perimesencephalic venous dilatation or varix is an important finding onMRI to help localize tentorial DAVF in the tentorial edge or apex.

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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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Transcerebellomedullary fissure approach to lesions of the fourth ventricle: less is more?

TCMF

Acta Neurochir (2013) 155:1011–1016

The transcerebellomedullary fissure (trans-CMF) approach is safe and effective. Nevertheless, previous research documented a few differences in the use of this approach with regard to the opening portion of the fissure and roof of the ventricle. Here, we present a series of patients with fourth ventricular lesions and our experience using the trans-CMF approach.

Methods Fifty patients who underwent the trans-CMF approach were analyzed. The tela choroidea was simply incised in 32 patients: 27 unilaterally and 5 bilaterally. Both the tela and inferior medullary velum were cut in 18 patients: 16 unilaterally and 2 bilaterally. Unless the tumor extended below the C1 level, C1 was preserved intact. Brainstem mapping (BSM) and corticobulbar tract (CBT) motor-evoked potential (MEP) monitoring were used.

Results Gross total removal was achieved in 41 (82 %) cases, and sub-total removal was achieved in 9 (18 %) cases. Two deaths occurred 1–2 months postoperatively because of pulmonary complications. Four patients developed temporary mutism, all of whom underwent the bilateral trans-CMF approach (this rate is significantly higher than that of the unilateral approach, P<0.05). No permanent neurological deficit occurred.

Conclusion The trans-CMF approach provides excellent access to fourth ventricular lesions without splitting the vermis. The opening portion of the fissure and roof of the ventricle should be determined by the location, extension and size of the lesion. In most cases, the unilateral trans- CMF approach with only a tela choroidea incision is adequate; this procedure is mini-invasive and possibly prevents postoperative mutism.

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Degree of kyphosis correction and neurological outcome

Cervical lordosis

J Neurosurg Spine 18:537–544, 2013

Reversal of the normal cervical spine curvature, as seen in cervical kyphosis, can lead to mechanical pain, neurological dysfunction, and functional disabilities. Surgical intervention is warranted in patients with sufficiently symptomatic deformities in an attempt to correct the deformed cervical spine. In theory, improved outcomes should accompany a greater degree of correction toward lordosis, although there are few data available to test this relationship. The purpose of this study is to determine if the degree of deformity correction correlates with improvement in neurological symptoms following surgery for cervical kyphotic deformity.

Methods. A retrospective review of 36 patients with myelopathic symptoms who underwent cervical deformity correction surgery between 2001 and 2009 was performed. Preoperative and postoperative radiographic findings related to the degree of kyphosis were collected and compared with functional outcome measures. The minimum follow-up time was 2 years.

Results. A significant relationship was observed between a greater degree of focal kyphosis correction and improved neurological outcomes according to the modified Japanese Orthopaedic Association (mJOA) score (r = -0.46, p = 0.032). For patients with severe neurological symptoms (mJOA score < 12) a trend toward improved outcomes with greater global kyphosis correction was observed (r = -0.56, p = 0.057). Patients with an mJOA score less than 16 who attained lordosis postoperatively had a significantly greater improvement in total mJOA score than patients who maintained a kyphotic position (achieved lordosis: 2.7 ± 2.0 vs maintained kyphosis: 1.1 ± 2.1, p = 0.044).

Conclusions. The authors’ results suggest that the degree of correction of focal kyphosis deformity correlates with improved neurological outcomes. The authors also saw a positive relationship between attainment of global lordosis and improved mJOA scores. With consideration for the risks involved in correction surgery, this information can be used to help guide surgical strategy decision making.

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5-aminolevulinic acid (5-ALA) fluorescence guided surgery of high-grade gliomas in eloquent areas assisted by functional mapping

5ALA and functional mapping

Acta Neurochir (2013) 155:965–972

Only few data are available on the specific topic of 5-aminolevulinic acid (5-ALA) guided surgery of high-grade gliomas (HGG) located in eloquent areas. Studies focusing specifically on the post-operative clinical outcome of such patients are yet not available, and it has not been so far explored whether such approach could be more suitable for some particular subgroups of patients.

Methods Patients affected by HGG in eloquent areas who underwent surgery assisted by 5-ALA fluorescence and intra-operative monitoring were prospectively recruited in our Department between June 2011 and August 2012. Resection rate was reported as complete resection of enhancing tumor (CRET), gross total resection (GTR) >98 % and GTR>90 %. Clinical outcome was evaluated at 7, 30, and 90 days after surgery.

Results Thirty-one patients were enrolled. Resection was complete (CRET) in 74 % of patients. Tumor removal was stopped to avoid neurological impairment in 26 % of cases. GTR>98 % and GTR>90 % was achieved in 93 % and 100 % of cases, respectively. First surgery and awake surgery had a CRET rate of 80 % and 83 %, respectively. Even though at the first-week assessment 64 % of patients presented neurological impairment, there was a 3 % rate of severe morbidity at the 90th day assessment. Newly diagnosed patients had a significantly lower morbidity (0 %) and post-operative higher median KPS. Both pre-operative neurological condition and improvement after corticosteroids resulted significantly predictive of post-operative functional outcome.

Conclusions 5-ALA surgery assisted by functional mapping makes high HGG resection in eloquent areas feasible , through a reasonable rate of late morbidity. This emerges even more remarkably for selected patients.

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Microneurosurgical Management Of Ophthalmic Segment Aneurysms

Ophthalmic segment aneurysms

Acta Neurochir (2013) 155:1025–1029

Power drilling commonly used for anterior clinoidectomy and optic canal unroofing can result in thermal injury to the optic nerve.

Methods The authors describe an intradural “limited drill” technique of anterior clinoidectomy and optic canal unroofing for microneurosurgical management of ophthalmic segment aneurysms, where optic canal unroofing is done with 1 mm Kerrison punch and the use of the power drill is restricted to anterior clinoidectomy to avoid thermal injury to the optic nerve. The optic nerve, internal carotid artery (ICA), and aneurysm are covered with wet gelfoam pieces to prevent any inadvertent contact with the drill.

Conclusion “Limited drill technique” is a safe and effective technique of anterior clinoidectomy and optic canal unroofing. Key points • Anterior clinoidectomy and optic canal unroofing is an important skull base technique required for safe clipping of the majority of ophthalmic segment aneurysms • Power drilling commonly used for optic canal unroofing can cause thermal injury to optic nerve • More than 2 mm free space is available around the optic nerve in the optic canal • Foot plate of 1 mm Kerrison punch can be safely introduced within a normal optic canal without causing mechanical injury to the optic nerve • Reflection of posteriorly based dural flap acts as a dural barrier, preventing direct contact of drill bit to optic nerve, internal carotid artery and aneurysm during drilling • Entanglement of cottonoids to rotating drill bit is a major problem in intradural anterior clinoidectomy • Wet gelfoam pieces do not get entangled to the rotating drill bit • Structures surrounding the area of drilling can be covered with wet gel foam pieces to prevent direct contact of the drill to neurovascular structures • Opened cisterns can be covered with wet gelfoam pieces during drilling to prevent deposition of bone dust in the subarachnoid space • “Limited drill technique” of anterior clinoidectomy and optic canal unroofing is a safe and effective technique for the exposure of ophthalmic segment aneurysms.

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Dura Splitting Decompression for Chiari I Malformation in Pediatric Patients

Dura_Splitting_Decompression_for_Chiari_I

Neurosurgery 72:922–929, 2013

Dural splitting decompression may be an effective and safe treatment for Chiari I malformation.

OBJECTIVE: To compare clinical outcomes, complications, and resource utilization for patients undergoing Chiari I decompression with or without duraplasty.

METHODS: Between 2000 and 2009, the senior author performed 113 Chiari I decompression operations with dural splitting or duraplasty in children less than 18 years of age; 110 were included in a retrospective cohort analysis of safety, efficacy, and treatment cost. Patients without significant syringomyelia underwent dural splitting decompression, and patients with syringomyelia underwent duraplasty.

RESULTS: Sixty-three patients without significant syringomyelia (57%) underwent dural splitting decompression. They were significantly younger than patients undergoing duraplasty (8.3 ± 4.9 years vs 10.4 ± 4.4 years; P < .05). Headaches improved or resolved in most patients in both groups (90.5% vs 93.6%; P = .59). Dysphagia, long tract signs, cranial nerve, and bulbar symptoms also improved similarly in both groups. Three duraplasty patients were treated medically for aseptic meningitis; one underwent reoperation for a symptomatic pseudomeningocele. No patient undergoing dural splitting decompression experienced a cerebrospinal fluid-related complication. Extradural decompression required less operative time than duraplasty (105.5 vs 168.9 minutes, P < .001), a shorter length of stay (2.4 vs 2.8 days, P = .011), and lower total cost for the primary hospitalization ($26 837 vs $29 862, P = .015).

CONCLUSION: In this retrospective cohort study, dural splitting decompression was equally effective, safer, and lower cost for treatment of Chiari I malformation without syringomyelia. A multicenter trial with groups balanced for the presence of syringomyelia is necessary to determine whether these results are generalizable.

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Foramen magnum meningiomas: To drill or not to drill the occipital condyle?

FMM

Surg Neurol Int 2013;4:73

Despite the development of microsurgery and cranial base techniques, the surgical management of Foramen Magnum Meningiomas (FMM) continues to be a technical challenge to neurosurgeons. Controversy concerning the utility of systematic condyle drilling for approaching FMM has been raised. Our aim was to describe the surgical technique, analyze its safety, and the postoperative outcome in 12 consecutive FMM patients.

Methods: From 1986 to 2011,12 patients with FMM underwent operations in the Department of Neurosurgery at Servidores do Estado Hospital and in a private clinic. All patients were operated using a standard suboccipital craniectomy, preserving the occipital condyle, opening of the Foramen Magnum, and ipsilateral removal of the posterior arch of C1.

Results: There was no operative mortality, nine patients achieved Glasgow Outcome Scale 4 or 5. Condylar resection was not deemed necessary in any case. Gross total resection was achieved in nine patients. After surgery, four patients developed lower cranial nerve weakness. There was no significant postoperative complication in the remaining patients. The average follow-up is 8.2 years.

Conclusion: The vast majority of FMM can be safely removed with a retrocondylar lateral suboccipital approach without condylar resection, using meticulous microsurgical techniques.

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Endoscopic transnasal odontoidectomy to treat basilar invagination with congenital osseous malformations

Basilar invagination

Eur Spine J (2013) 22:1127–1136

Transoral resection of the odontoid has been accepted as a standard procedure to decompress the cervicomedullary junction during the past several decades. The endoscopic transnasal odontoidectomy is emerging as a feasible surgical alternative to conventional microscopic transoral approach. In this article, we describe several operative nuances and pearls from our experience about this approach, which provided successful decompression.

Methods From September 2009 to April 2010, three consecutive patients with basilar invagination, of which the etiology was congenital osseous malformations, underwent endoscopic transnasal odontoidectomy. All patients presented with myelopathy. The last two cases also received occipitocervical fixation and bone fusion during the same surgical episode to ensure stability.

Results All the patients were extubated after recovery from anesthesia and allowed oral food intake the next day. Cerebrospinal fluid rhinorrhea was found in the second case and cured by continuous lumber drainage of cerebrospinal fluid. No infection was noted. The average follow- up time was more than 24 months. Remarkable neurological recovery was observed postoperative in all patients.

Conclusion The endoscopic transnasal odontoidectomy is a feasible approach for anterior decompression of pathology at the cervicomedullary junction. The advantages over the standard transoral odontoidectomy include elimination of risk of tongue swelling and teeth damaging, improvement of visualization, alleviation of prolonged intubation, reduction of need for enteral tube feeding and less risk of affecting phonation. The minimally invasive access and faster recovery associated with this technique make it a valid alternative for decompression of the ventral side of the cervicomedullary junction

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Use of microscope-integrated near-infrared indocyanine green videoangiography in the surgical treatment of intramedullary cavernous malformations

ICG video intram. cavernomas

J Neurosurg Spine 18:443–449, 2013

The characteristics and efficacy of indocyanine green (ICG) videoangiography in cavernous malformation (CM) have not been fully elucidated. The purpose of this paper is to examine the potential utility of ICG videoangiography in the surgical treatment of intramedullary CMs.

METHODS
The authors conducted a retrospective review of 8 cases involving 5 men and 3 women who had undergone surgery for intramedullary CM between January 2008 and July 2011. All patients were evaluated by means of MRI. The MRI findings and clinical history in all cases suggested intramedullary CM as a preoperative diagnosis. In 2 of 8 cases, dilated venous structures associated with CMs were demonstrated. In one of these cases, there were coexisting extramedullary CMs. Intraoperatively, ICG fluorescence was observed for 5 minutes using microscope-integrated videoangiography.

RESULTS
In all 8 cases, intra- and extramedullary CMs were seen as avascular areas on ICG videoangiography. Indocyanine green videoangiography helped surgeons to localize and predict margins of the lesions before performing myelotomy. Importantly, in the cases with associated venous anomalies, ICG videoangiography was useful in delineating and preserving the venous structures. In extramedullary CMs located dorsal to the spinal cord, gradual ICG infiltration was seen, starting at 110 seconds and maximal at 210 seconds after injection. Postoperative MRI confirmed total removal of the lesions in all cases, and subsequent recovery of all patients was uneventful.

CONCLUSIONS
Indocyanine green videoangiography provided useful information with regard to the detection of lesion margins by demonstrating intramedullary CMs as avascular areas. In cases associated with venous anomalies, ICG contributed to safe and complete removal of the CMs by visualizing the venous structure. In extramedullary CMs, ICG videoangiography demonstrated the characteristic of slow blood flow within CMs.

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