Category: Surgical technique

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The endoscopic, endonasal, transmaxillary transpterygoid approach to the pterygopalatine fossa, infratemporal fossa, petrous apex, and the Meckel cave

J Neurosurg 113:967–974, 2010. DOI: 10.3171/2009.10.JNS09157

In this paper the authors’ goal was to present their clinical experience with lesions of the pterygopalatine fossa, infratemporal fossa, lateral sphenoid sinus, cavernous sinus, petrous apex, and Meckel cave using simple and extended endoscopic transpterygoid approaches to the lateral skull base.

Methods. Simple and expanded endoscopic transpterygoid approaches were performed in a series of 13 patients with varying pathology that included lateral sphenoid sinus encephaloceles, benign and malignant sinonasal tumors, and lesions of neural origin.

Results. A gross-total resection was achieved in 5 of 9 patients, while a subtotal resection for tissue diagnosis and cytoreduction prior to further adjuvant treatment was performed in the remaining patients. Sphenoid sinus encephaloceles were successfully repaired via a transpterygoid approach in all 4 patients. The skull base defect was reconstructed using a multilayered closure. One patient developed a postoperative CSF leak, which was successfully treated conservatively. The mean follow-up time was 16 months. Five patients complained of recurrent sinusitis. One patient experienced xerophthalmia and palate numbness. Three patients had died by the time of this report. Two patients died of unrelated causes. The third patient died of progression of an aggressive pterygopalatine osteosarcoma despite undergoing cytoreductive surgery and adjuvant chemotherapy.

Conclusions. An endoscopic transpterygoid approach is a minimally invasive endoscopic approach for lesions located or extending to the pterygopalatine fossa, infratemporal fossa, petrous apex, Meckel cave, and other regions of the paramedian skull base.

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Trigeminal schwannomas: experience with 57 cases and a review of the literature

Neurosurg Rev. DOI 10.1007/s10143-010-0289-y

Trigeminal schwannoma is a mostly benign tumor that can be cured by complete resection. Over the last few decades, several pioneers have developed surgical approaches enabling the total removal of such tumors.

We analyzed 57 patients who underwent radical surgery, including 45 patients who underwent skull base surgery as their initial treatment, for removal of trigeminal schwannomas. Here, we report the surgical management of these cases. Since 1990, all such patients have been treated using three main types of middle fossa skull base approaches, which minimize the exposure of the brain: the anterior transpetrosal approach, subtemporal interdural approach (Dolenc), or a combination of these approaches.

Before 1990, total tumor removal was achieved in only three of eight patients (38%). After 1990, the tumors were totally removed in 43 patients (90%) and were nearly completely removed in an additional three patients (6%). Among the patients who underwent skull base surgery as their initial treatment, a complete resection was achieved in 93% (42/45 patients) of the cases. However, total surgical removal after surgery and Gamma knife surgery was very difficult because of dense adhesions to the brain stem and cranial nerves. No surgery-related mortalities occurred in this series, and the individual KPS scores were more than 90% among the patients who underwent skull base surgery. No recurrences requiring additional surgery have occurred after an average follow-up period of 4.9 years.

Most of the trigeminal schwannomas could be removed totally and safely during a single operation after the introduction of skull base surgery. Therefore, radiosurgery should not be applied as the treatment of first choice for younger patients. A correct anatomical knowledge is critical for minimizing brain exposure and avoiding surgical complications.

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Surgical Treatment of Giant Intracranial Arteriovenous Malformations

Neurosurgery 67:1359–1370, 2010 DOI: 10.1227/NEU.0b013e3181eda216

The treatment of giant arteriovenous malformations (AVMs) remains a challenge in the neurosurgical field. Microsurgery is one of the most effective ways for eliminating giant cerebral AVMs.

OBJECTIVE: To review surgical outcomes in treating the disease, and form conclusions regarding the indications for and outcomes of surgical treatment in giant intracranial AVMs.

METHODS: We studied 40 consecutive cases of giant AVMs treated in Beijing Tiantan Hospital between 2000 and 2008. The radiologic and clinical features were analyzed. The Spetzler-Martin grading system was used to classify the patients. All patients were surgically treated, and the final outcomes of the patients were gathered for analysis.

RESULTS: The major presenting symptoms were seizures, headaches, hemorrhage, and neurological deficits. The mean AVM diameter was 6.3 cm. According to the Spetzler- Martin grading system, 5 patients had grade III lesions, 21 had grade IV lesions, and 14 had grade V lesions. Out of the total 40 patients, 31 (77.5%) demonstrated excellent or good outcome. Complications included hemiparalysis, aphasia, hemianopia, cranial nerve dysfunction, and seizures. After follow-up, 27 of 30 (90%) surviving patients presented normal function or minimal symptoms.

CONCLUSION: Presurgical evaluation of every candidate and treatment choice is the determining factor in therapy for giant AVMs. For giant cerebral AVMs located superficially or not involving critical components, a good outcome can be expected through surgical resection. The obliteration and recurrence rates were satisfying, and the complication rate was acceptable.

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Surgical treatment of cervical kyphosis

Eur Spine J. DOI 10.1007/s00586-010-1602-8

Cervical kyphosis is an uncommon but potentially debilitating and challenging condition.

We reviewed the etiology, presentation, clinical and radiological evaluation, and treatment of cervical kyphosis. Based on the current controversy as to the ideal mode of surgical management, we paid particular attention to the available surgical strategies.

There are three approaches for cervical kyphosis: the anterior, posterior or combined procedures. The principal indication for the posterior strategy is a flexible kyphosis or kyphosis caused by ankylosing spondylitis.

The main point of debate is between the choice of the anterior or the combined strategy. The two strategies were compared with regard to clinical outcome, correction of deformity, rate of fusion, complications, revision surgery, and mortality. The combined strategy appears to result in a greater degree of correction than the anterior-alone strategy, and it is more likely to improve the cervical alignment to achieve a lordosis. However, the procedure carries a higher rate of postoperative neurological deterioration, complications, revision surgery, and mortality. Although the anterior alone strategy achieves a smaller reduction of cervical kyphosis, it has a lower rate of postoperative neurological deterioration, complications, revision surgery, and mortality.

We recommend that the surgical treatment of cervical kyphosis should be planned on an individual basis.

A multicenter, prospective, randomized controlled study would be necessary to determine the ideal mode of treatment for complex cervical kyphosis.

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Intraoperative 5-aminolevulinic-acid-induced fluorescence in meningiomas

Acta Neurochir (2010) 152:1711–1719. DOI 10.1007/s00701-010-0708-4

5-aminolevulinic acid (5-ALA) has gained importance as an intraoperative photodynamic diagnostic agent for the extirpation of malignant gliomas. The application of this technique for resection of meningiomas has barely been explored. The aim of this study was to evaluate the utility of 5-ALA-induced fluorescence as a visual tool in meningioma resection and its correlation with histological findings.

Methods A total of 33 consecutive patients undergoing resection of intracranial meningiomas from December 2007 to August 2009 were included in this study. After confirmation of normal liver function, 5-ALA was administered orally (20 mg/kg) within 3–5 h prior to skin incision. All cases were operated on using standard microsurgical and neuronavigation-guided techniques. Intraoperative 440 nm fluorescence was applied periodically during and at the end of resection in order to detect tumor-infiltrated sites. The fluorescence of the tumor was evaluated intraoperatively by the surgeon and confirmed by subsequent video analysis.

Results A total of 32 (97%) patients presented with benign meningiomas (WHO I–II). In 1 (3%) patient, histological anaplastic signs (WHO III) could be demonstrated. 5-ALAinduced fluorescence of the tumor was confirmed in a total of 31 (94%) patients. The fluorescence did not correlate with the histological findings (n=30 WHO I–II, n=1 WHO grade III) or with preoperative brain edema and administration of steroids. A total resection could be postoperatively demonstrated in 25 (76%) patients. No adverse effects attributable to 5-ALA occurred.

Conclusions 5-ALA-induced fluorescence is a useful and promising intraoperative tool for the visualization of meningioma tissue. The novel findings demonstrated in this study in terms of high fluorescence and poor correlation with histological findings highlight the usefulness of this technique as a routine visual tool to achieve optimal resection of meningiomas.

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Postauricular, transpetrous, presigmoid approach for extensive skull base tumors in the petroclival region: the successes and the travails

Acta Neurochir (2010) 152:1633–1645.DOI 10.1007/s00701-010-0701-y

Postauricular, transpetrous, presigmoid approach combines a supra/infratentorial exposure with partial petrosectomy to access third to the twelfth cranial nerves and extraaxial lesions situated anterolateral to brainstem. It provides a shorter working distance to large petrosal, petroclival, cerebellopontine, and cerebellomedullary cisternal lesions and their extensions to the subtemporal–infratemporal areas. This study reviews the surgical technique, corridors of extension, and complications encountered utilizing this approach for excising extensive lesions in these locations.

Methods The lesions (n=14) included petroclival meningiomas [(n=5), including three recurrent lesions], dumbbell lower cranial nerve schwannomas (n=2), giant acoustic schwannomas (n=2), recurrent giant trigeminal nerve schwannoma (n=1), glomus jugulare (n=3), and recurrent petrous aneurysmal bone cyst (n=1). The approach was combined with a retrosigmoid suboccipital craniectomy (n=3), with an infratemporal approach (n=2), and with an extreme lateral transcondylar approach and a translabyrinthine approach in one patient each, respectively. External auditory canal was not ligated in nine patients, superior petrosal sinus and tentorial division was performed in all patients, and sigmoid sinus–internal jugular vein was excised in three patients (with a glomus jugulare (n=1) and petroclival meningioma (n=2), respectively). Repair was performed with fat–fascia, pedicled pericranium, and temporalis muscle. Lumbar drain was placed for three to five postoperative days.

Results Total excision was performed in nine patients. Small tumor remnants were left attached to the brainstem (n=3, petroclival meningioma), carotid canal and cavernous sinus (n=1, glomus jugulare), and sigmoid sinus–jugular bulb (n=1, recurrent trigeminal schwannoma). A two-staged procedure was performed in three patients. Two patients with recurrent giant petroclival meningiomas died: one with lower cranial nerve paresis due to aspiration pneumonitis and the other with cerebrospinal fluid otorrhoea and secondary meningitis.

Conclusions The approach facilitates direct tumor decompression and its retraction away from the brainstem without initially encountering the intracisternal cranial nerves and neuraxis. It provides multiple corridors for excising extensive posterior fossa tumors. Preoperative assessment of sigmoid sinus dominance, jugular bulb height, labyrinth, vein of Labbe, and space available through Trautman’s triangle considerably helps in complication avoidance.

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The presigmoid approach to anterolateral pontine cavernomas

J Neurosurg 113:701–708, 2010. DOI: 10.3171/2010.1.JNS08413

Anterolateral cavernomas of the pons have been surgically removed via a variety of approaches, commonly retrosigmoid or transventricular. The goal in this study was to evaluate the presigmoid approach as an alternative.

Methods. Clinical data were reviewed in 9 patients presenting with anterolateral pontine cavernomas between 1999 and 2007.

Results. All patients were treated via a presigmoid approach, which provided a nearly perpendicular trajectory to the anterolateral pons. The brainstem was entered through a “safe zone” between the trigeminal nerve and the facial/ vestibulocochlear nerve complex. Complete resection was achieved in all cases. No patient experienced recurrent events during follow-up (1–24 months). The patients’ modified Rankin Scale score improved within 1 year of surgery (1.7 ± 0.4) compared with baseline (2.6 ± 0.2; p < 0.05). Only one patient experienced a new deficit (decreased hearing), which was corrected with a hearing aid.

Conclusions. The presigmoid approach is recommended for the resection of anterolateral pontine cavernomas. With this approach, the need for cerebellar retraction is nearly eliminated. The lateral “presigmoid” entry point creates a trajectory that allows complete resection of even deep lesions at this level, or anterior to the internal acoustic meatus.

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Outcomes after a purely endoscopic transsphenoidal resection of growth hormone

Neurosurg Focus 29 (4):E5, 2010. DOI: 10.3171/2010.7.FOCUS10153

Using strict biochemical remission criteria, the authors assessed surgical outcomes after endoscopic transsphenoidal resection of growth hormone (GH)–secreting pituitary adenomas and identified preoperative factors that significantly influence the rate of remission.

Methods. A retrospective review of a prospectively maintained database was performed. The authors reviewed cases in which an endoscopic resection of GH-secreting pituitary adenomas was performed. The cohort consisted of 26 patients who had been followed for 3–60 months (mean 24.5 months). The thresholds of an age-appropriate, normalized insulin-like growth factor–I concentration, a nadir GH level after oral glucose load of less than 1.0 μg/l, and a random GH value of less than 2.5 μg/l were required to establish biochemical cure postoperatively.

Results. Overall, in 57.7% of patients undergoing a purely endoscopic transsphenoidal pituitary adenectomy for acromegaly, an endocrinological cure was achieved. The mean clinical follow-up duration was 24.5 months. In patients with microadenomas (4 cases) the cure rate was 75%, whereas in patients harboring macroadenomas (22 cases) the cure rate was 54.5%. Cavernous sinus invasion (Knosp Grades 3 and 4) was associated with a significantly lower remission rate (p = 0.0068). Hardy Grade 3 and 4 tumors were also less likely to achieve biochemical cure (p = 0.013). The overall complication rate was 11.5% including 2 incidents of transient diabetes insipidus and 1 postoperative CSF leak, which were treated nonoperatively.

Conclusions. A purely endoscopic transsphenoidal approach to GH-secreting pituitary adenomas leads to similar outcome for noninvasive macroadenomas compared with traditional microsurgical techniques. Furthermore, this approach may often provide maximal visualization of the tumor, the pituitary gland, and the surrounding neurovascular structures.

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Minimally invasive or open transforaminal lumbar interbody fusion as revision surgery for patients previously treated by open discectomy and decompression of the lumbar spine

Eur Spine J. DOI 10.1007/s00586-010-1578-4

Minimally invasive lumbar fusion techniques have been developed in recent 20 years. The goals of these procedures are to reduce approach-related soft tissue injury, postoperative pain, and disability while allowing the surgery to be conducted in an effective manner. There have been no prospective clinical reports published on the comparison of minimally invasive transforaminal lumbar interbody fusion as revision surgery for patients previously treated by open discectomy and decompression or a traditional open approach.

A prospective clinical study was performed by evaluating the clinical and radiographic results of minimally invasive transforaminal lumbar interbody fusion as an alternative new technique in the revision surgery for patients previously treated by open procedure. 52 patients (28 M, 24 F) with an average age of 55.7 (31–76) were prospectively evaluated. All patients who had previous discectomy (n = 13), hemilaminectomy (n = 16), laminectomy (n = 12) and facetectomy (n = 11) underwent monosegmental and bisegmental minimally invasive transforaminal lumbar interbody fusion (MiTLIF) (n = 25) or open transforaminal lumbar interbody fusion (OTLIF) (n = 27) by two experienced surgeons at one hospital, from March 2006 to October 2008 (minimum 12-month follow-up). The following data were compared between the two groups: the clinical and radiographic results, operative time, blood loss, X-ray exposure time, postoperative back pain, and complications. Clinical outcome was assessed using the visual analogue scale and the Oswestry disability index (ODI). The operative time and clinical and radiographic results were basically identical in both groups.

Comparing with the OTLIF group, the MiTLIF group had significantly less blood loss and less postoperative back pain at the second day postoperatively. The radiation time was significantly longer in the MiTLIF group. Complications included three cases of small dural tear in the MiTLIF group. There were five cases of dural tear and two cases of superficial wound infection in the OTLIF group. One case of nonunion was observed from each group.

Minimally invasive TLIF is a safe and effective procedure for treatment of selected revision patients previously treated by open surgery with some potential advantages. However, this technique needs longer X-ray exposure time.

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Perioperative and Long-term Outcomes From the Management of Parasagittal Meningiomas Invading the Superior Sagittal Sinus

Neurosurgery 67:885–893, 2010 DOI: 10.1227/NEU.0b013e3181ef2a18

Parasagittal meningiomas invading the superior sagittal sinus (SSS) pose formidable obstacles to surgical management. Invasion is often considered a contraindication to surgery because of associated morbidity, such as cerebral venous thrombosis.

OBJECTIVE: We report our most recent experience with the resection of parasagittal meningiomas invading the SSS.

METHODS: Between 1992 and 2004, 110 patients with parasagittal meningiomas underwent surgery at the Johns Hopkins Medical Institutions. Clinical charts, radiological studies, pathological features, and operative notes were retrospectively analyzed; only those patients with minimum 24 months follow-up (n = 61) were further studied.

RESULTS: Tumor distribution by location along the SSS was: 21% anterior, 62% middle, and 17% posterior. All patients were managed with initial surgical resection with radiosurgery for residual/recurrent disease if indicated (19.6%). Pathological examination revealed 80% grade I meningiomas, 13% grade II meningiomas, and 7% grade III meningiomas. Simpson grade I/II resection was achieved in 81% of patients. Major complications included venous thrombosis/infarction (7%), intraoperative air embolism (1.5%), and death (1.5%); long-term outcomes assessed included recurrence (11%) and improvement in Karnofsky Performance Score (85%).

CONCLUSION: On the basis of our study, the incidence of postoperative venous sinus thrombosis is 7% in the setting of a recurrence rate of 11% with a mean follow-up of 41 months. In comparison with the published literature, the data corroborate the rationale for our treatment paradigm; lesions invading the sinus can initially be resected to the greatest extent possible without excessive manipulation of vascular structures, whereas residual/recurrent disease can be observed and managed with radiosurgery.

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Factors That Influence Outcome of Percutaneous Balloon Compression in the Treatment of Trigeminal Neuralgia

Neurosurgery 0:1–10, 2010 DOI: 10.1227/NEU.0b013e3181eb5230

Percutaneous balloon compression is an effective, low-cost, simple therapeutic modality with the special advantage of being the only percutaneous technique that can be simply performed with the patient under general anesthesia for the treatment of trigeminal neuralgia.

OBJECTIVE: To identify surgical and individual parameters that could influence outcome in patients with trigeminal neuralgia treated with percutaneous balloon compression.

METHODS: Within a 5-year period, 66 consecutive percutaneous balloon compressions were performed in 47 patients. The medical and surgical records of all patients were retrospectively reviewed and analyzed for a possible correlation between the following parameters and outcome: balloon shape, balloon volume, compression time, age, sex, type of pain, duration of disease, previous procedures, and trigeminal division affected. Univariate and multivariate analyses were used to test for statistical significance.

RESULTS: The initial success rate was 85%, and 36% of the responders are still pain free with a mean follow-up of approximately 20 months, whereas in 33 patients, trigeminal pain recurred after a mean of approximately 17 months. Of the investigated parameters, significant correlations were obtained between balloon shape and all aspects of outcome, previous operations and complication rate, pain type and complication rate, and compression time and postoperative numbness.

CONCLUSION: The balloon shape is a parameter with a very strong impact on outcome, and balloon volume should be adjusted to this parameter. Persistent elliptical balloon shapes should raise consideration of aborting the procedure. There were no differences in outcomes between 60 seconds and longer compression times. The number of previous operations did not correlate with pain relief, but seemed to increase the risk of complications. Patients with multiple sclerosis seemed to obtain similar benefit from the procedure as do patients with classic trigeminal neuralgia.

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Endovascular Treatment of Side Wall Aneurysms Using a Liquid Embolic Agent: A US Single-Center Prospective Trial

Neurosurgery 67:855-860, 2010 DOI: 10.1227/01.NEU.0000374772.22745.C3

Onyx HD-500 is a liquid embolic agent consisting of ethylene vinyl alcohol copolymer dissolved in dimethylsulfoxide and mixed with tantalum. This viscous embolic agent was designed to treat intracranial side wall aneurysms, but there have been no prospective published series from the United States. From this early experience, we developed several protocol revisions, technical details, and clinical pearls that have not been published for liquid embolic embolization of aneurysms.

CLINICAL PRESENTATION:We present our single-center prospective series of patients treated with Onyx HD-500 from a multicenter, randomized, controlled trial. Thirteen patients received Onyx HD-500, and their ages ranged from 43 to 81 years. Twelve patients had aneurysms on the internal carotid artery, and 1 patient had an aneurysm the vertebral artery. Every patient had an immediate postangiographic result with 90% or more occlusion by an independent core laboratory assessment. In 1 patient, the Onyx HD-500 injection was aborted, and the aneurysm was embolized with coils. Eleven of 13 patients (85%) underwent 6-month follow-up angiography that demonstrated persistent durable occlusion with no recanalization. There was 1 complication (8%) and no deaths.

CONCLUSION: This is the only prospective series of intracranial aneurysms treated with Onyx HD-500 in the United States. This is also the first publication that describes detailed procedure techniques, recommended protocol revisions, lessons learned from early complications, clinical pearls, and advantages and disadvantages of liquid embolic embolization of aneurysms.

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A Comparative Analysis of the Results of Vertebroplasty and Kyphoplasty in Osteoporotic Vertebral Compression Fractures

Neurosurgery 67[ONS Suppl 1]:ons171-ons188, 2010 DOI: 10.1227/01.NEU.0000380936.00143.11

The most common complication of osteoporosis is vertebral fractures, which occur more frequently than all other fractures (hip, wrist, and ankle).

OBJECTIVE: To prospectively analyze vertebroplasty compared with kyphoplasty for the treatment of osteoporotic vertebral compression fractures using improvement in pain, functional capacity, and quality of life as outcome measures.

METHODS: The study population included 28 patients in the vertebroplasty group and 24 patients in the kyphoplasty group. The mean follow-up period was 42.2 weeks and 42.3 weeks in the vertebroplasty and kyphoplasty groups, respectively. Outcomes were measured pre- and postoperatively using the visual analogue scale, the Oswestry Disability Index, the EuroQol-5D questionnaire, and the Short-Form 36 Health Survey.

RESULTS: In the vertebroplasty group, visual analogue scale scores improved from a mean of 8.0 cm to 5.5 cm at last follow-up (P = .001). Preoperatively, the Oswestry Disability Index was 57.6, which improved to 38.4 (P = .006). The EuroQol-5D score preoperatively was 0.157 and improved to 0.504 (P = .001). The Short-Form 36 Health Survey showed greatest improvement in the areas of physical health, role physical, body pain, and vitality. In the kyphoplasty group, visual analogue scale scores improved from a mean of 7.5 cm preoperatively to 2.5 cm postoperatively (P = .000001). The mean Oswestry Disability Index preoperatively was 50.7 and improved to 28.8 (P = .002). The EuroQol-5D score improved from a mean of 0.234 preoperatively to 0.749 (P = .00004). The Short-Form 36 Health Survey showed greatest improvement in the areas of physical health, physical functioning, role physical, body pain, and social functioning.

CONCLUSION: Both vertebroplasty and kyphoplasty are effective at improving pain, functional disability, and quality of life; however, kyphoplasty provides better results, which are maintained over long-term follow-up.

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Surgical approaches to brainstem cavernous malformations

Neurosurg Focus 29 (3):E8, 2010. DOI: 10.3171/2010.6.FOCUS10128

Brainstem cavernous malformations (CMs) are low-flow vascular lesions in eloquent locations. Their presentation is often marked with symptomatic hemorrhages that appear to occur more frequently than hemorrhage from supratentorial cavernomas.

Brainstem CMs can be removed using 1 of the 5 standard skull-base approaches: retrosigmoid, suboccipital (with or without telovelar approach), supracerebellar infratentorial, orbitozygomatic, and far lateral.

Patients being referred to a tertiary institution often have lesions that are aggressive with respect to bleeding rates. Nonetheless, the indications for surgery, in the authors’ opinion, are the same for all lesions: those that are symptomatic, those that cause mass effect, or those that abut a pial surface. Patients often have relapsing and remitting courses of symptoms, with each hemorrhage causing a progressive and stepwise decline.

Many patients experience new postoperative deficits, most of which are transient and resolve fully. Despite the risks associated with operating in this highly eloquent tissue, most patients have had favorable outcomes in the authors’ experience. Surgical treatment of brainstem CMs protects patients from the potentially devastating effects of rehemorrhage, and the authors believe that the benefits of intervention outweigh the risks in patients with the appropriate indications.

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Colloid Cysts of the Third Ventricle: Endoscopic Versus Microsurgical Removal

Neurosurg Q 2010;20:142–145

Study Design: A comparative randomized prospective clinical study.

Background and Purpose: The endoscopic approach to colloid cysts of the third ventricle is receiving increasing interest. However, its effectiveness is a matter of discussion. The aim of the study was to present a direct and long-term outcome after endoscopy of a colloid cyst versus microsurgery.

Materials and Methods: Ten patients with colloid cysts were prospectively analyzed. Group A consisted of 5 patients treated endoscopically, whereas 5 patients treated using a transcorticaltransventricular approach comprised group B. Clinically, symptoms of raised intracranial pressure were predominant. All patients had hydrocephalus. Tumor diameter ranged from 10 to 27 mm. The mean follow-up period was 22 months.

Results: The mean surgery time was 122 minutes in group A and 201 minutes in group B. Hospital stay was 1.5 days in the intensive care unit and 2.5 days in the ward in group A as compared with 3.5 days in the intensive care unit and 7 days in the ward in group B.

Postoperative complications in group A were in the form of 1 transient hemiparesis and 1 transient short-term memory loss. Two patients in group B suffered transient short-term memory loss postoperatively and 1 patient suffered from transient hemiparesis. Clinically, the preoperative symptoms resolved in all the patients. One patient who underwent microsurgery required a ventriculoperitoneal shunt postoperatively. All patients who underwent endoscopy remained shunt independent.

Conclusions: The endoscopic approach to colloid cysts of the third ventricle is safe, effective, and carries a low complication rate. Endoscopy may be recommended as a treatment option.

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Utility and the Limit of Motor Evoked Potential Monitoring for Preventing Complications in Surgery for Cerebral Arteriovenous Malformation

Neurosurgery 67[ONS Suppl 1]:ons222-ons228, 2010 DOI: 10.1227/01.NEU.0000374696.84827.22

OBJECTIVE: To evaluate the usefulness of motor evoked potential (MEP) monitoring andmapping in arteriovenous malformation surgery.

METHODS: Intraoperative MEP monitoring was performed in 21 patients whose AVMs were located near the motor area or fed by arteries related to the corticospinal tract to detect blood flow insufficiency and/or direct injury to the corticospinal tract and/or to map the motor area.

RESULTS: In 4 of 16 patients monitored for blood flow insufficiency, the MEP changed intraoperatively. In 2 patients, the changes were attributable to temporary occlusion of the feeding artery (anterior choroidal or lenticulostriate artery): 1 patient had a venous infarction around the internal capsule caused by thrombosis of the draining vein and the other bled intraoperatively from the nidus. In 17 patients, the MEP was monitored to rule out direct injury. In 1 patient, the MEP changed on coagulation of fragile vessels around the nidus in the precentral gyrus; it recovered after coagulation was discontinued. In 1 of 5 patients with MEP changes, the MEP did not recover; permanent hemiparesis developed in this patient because of venous infarction. In 1 of 11 patients subjected to MEP mapping of the motor area, we found translocation to the postcentral sulcus.

CONCLUSION: In arteriovenous malformation surgery, MEP monitoring facilitates the detection of blood flow insufficiency and/or direct injury of the corticospinal tract and mapping of the motor area. It contributes to reducing the incidence of postoperative motor paresis.

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Choosing the best operation for chronic subdural hematoma: a decision analysis

J Neurosurg 113:615–621, 2010.DOI: 10.3171/2009.9.JNS08825

Chronic subdural hematoma (CSDH), a condition much more common in the elderly, presents an increasing challenge as the population ages. Treatment strategies for CSDH include bur-hole craniostomy (BHC), twist-drill craniostomy (TDC), and craniotomy. Decision analysis was used to organize existing data and develop recommendations for effective treatment.

Methods. A Medline search was used to identify articles about treatment of CSDH. Direct assessment by health care professionals of the relative health impact of common complications and recurrences was used to generate utility values for treatment outcomes. Monte Carlo simulation and sensitivity analyses allowed comparisons across treatment strategies. A second simulation examined whether intraoperative irrigation or postoperative drainage affect the outcomes following BHC.

Results. On a scale from 0 to 1, the utility of BHC was found to be 0.9608, compared with 0.9202 for TDC (p = 0.001) and 0.9169 for craniotomy (p = 0.006). Sensitivity analysis confirmed the robustness of these values. Craniotomy yielded fewer recurrences, but more frequent and more serious complications than did BHC. There were no significant differences for BHC with or without irrigation or postoperative drainage.

Conclusions. Bur-hole craniostomy is the most efficient choice for surgical drainage of uncomplicated CSDH. Bur-hole craniostomy balances a low recurrence rate with a low incidence of highly morbid complications. Decision analysis provides statistical and empirical guidance in the absence of well-controlled large trials and despite a confusing range of previously reported morbidity and recurrence.

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Direct visualization of deep brain stimulation targets in Parkinson disease with the use of 7-tesla magnetic resonance imaging

J Neurosurg 113:639–647, 2010.DOI: 10.3171/2010.3.JNS091385

A challenge associated with deep brain stimulation (DBS) in treating advanced Parkinson disease (PD) is the direct visualization of brain nuclei, which often involves indirect approximations of stereotactic targets. In the present study, the authors compared T2*-weighted images obtained using 7-T MR imaging with those obtained using 1.5- and 3-T MR imaging to ascertain whether 7-T imaging enables better visualization of targets for DBS in PD.

Methods. The authors compared 1.5-, 3-, and 7-T MR images obtained in 11 healthy volunteers and 1 patient with PD.

Results. With 7-T imaging, distinct images of the brain were obtained, including the subthalamic nucleus (STN) and internal globus pallidus (GPi). Compared with the 1.5- and 3-T MR images of the STN and GPi, the 7-T MR images showed marked improvements in spatial resolution, tissue contrast, and signal-to-noise ratio.

Conclusions. Data in this study reveal the superiority of 7-T MR imaging for visualizing structures targeted for DBS in the management of PD. This finding suggests that by enabling the direct visualization of neural structures of interest, 7-T MR imaging could be a valuable aid in neurosurgical procedures.

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Comparison of percutaneous balloon compression and glycerol rhizotomy for the treatment of trigeminal neuralgia

J Neurosurg 113:486–492, 2010.DOI: 10.3171/2010.1.JNS091106

The aim of this study was to compare percutaneous balloon compression (PBC) and percutaneous retrogasserian glycerol rhizotomy (PRGR) in terms of effectiveness, complications, and technical aspects.

Methods. Sixty-six consecutive PBC procedures were performed in 45 patients between January 2004 and December 2008, and 120 PRGR attempts were performed in 101 patients between January 2006 and December 2008. The PRGR procedures were not completed due to technical reasons in 19 cases. Five patients in the Balloon Compression Group and 9 patients in the Glycerol Group were lost to follow-up and were excluded from the study. The medical records and the intraoperative fluoroscopic images from the remaining cases were retrospectively examined, and the follow-up was completed with telephone contact, when necessary. The 2 groups were compared in terms of initial effect, duration of effect, and rates of complications as well as severity and type of complications.

Results. The rates for immediate pain relief were 87% for patients treated with glycerol injection and 85% for patients treated with balloon compression. The Kaplan-Meier plots for the 2 treatment modalities were similar. The 50% recurrence time was 21 months for the balloon procedure and 16 months for the glycerol procedure. When the groups were broken down by the “previous operations” criterion, the 50% recurrence time was 24 months for the Glycerol First Procedure Group, 6 months for the Balloon First Procedure Group, 8 months for the Glycerol Previous Procedures Group, and 21 months for the Balloon Previous Procedures Group. The rates of complications (excluding numbness) were 11% for PRGR and 23% for PBC, and this difference was statistically significant (chi-square test, p = 0.04).

Conclusions. Both PRGR and PBC are effective techniques for the treatment of trigeminal neuralgia, with PRGR presenting some advantages in terms of milder and fewer complications and allowing lighter anesthesia without compromise of analgesia. For these reasons the authors consider PRGR as the first option for the treatment of trigeminal neuralgia in patients who are not suitable candidates or are not willing to undergo microvascular decompression, while PBC is reserved for patients in whom the effect of PRGR has proven to be short or difficult to repeat due to cisternal fibrosis.

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Near-infrared indocyanine green videoangiography versus microvascular Doppler sonography in aneurysm surgery

Acta Neurochir (2010) 152:1519–1525.DOI 10.1007/s00701-010-0723-5

The quality of surgical treatment of intracranial aneurysms is determined by complete aneurysm occlusion and restoration of flow in the parent, branching and perforating vessels. In postoperative digital subtraction angiography (DSA), unexpected aneurysm residuals and vessel occlusions are frequently detected. Here, the value of two nearly noninvasive and cost-effective techniques for intraoperative flow evaluation (near-infrared indocyanine green video angiography (ICG-VA) and microvascular Doppler sonography (mDs)) is investigated in a prospective study.

Patients and methods Over a period of 10months, the authors surgically clipped 50 aneurysms under intraoperative pre- and post-clipping evaluation of flow in the parent, branching and perforating vessels and the aneurysm sack by the two techniques. Intraoperative applicability of each technique was compared to each other and to postoperative digital subtraction angiography as standard evaluation technique.

Results Forty-five aneurysms were totally occluded without vessel compromise (90%). Intraoperatively, ICG-VA was considered useful in 43 cases (86%) and mDs in 44 cases (88%), respectively. Both techniques could compensate each other’s weak points to a certain degree; but two branch occlusions (4%) and three neck remnants (6%) were revealed by postoperative DSA.

Conclusion Both techniques have specific drawbacks that could be compensated by each other, to a certain extent. Intraoperatively, ICG-VA and mDs should not be considered competitive, but complementary. This study implicates that the combination of both applications on a routine basis assures the quality of aneurysm surgery by nearly noninvasive and cost-effective techniques. However, DSA remains the gold standard for evaluation of aneurysm occlusion.

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