Neurosurgery Blog

Neurosurgery 67:633-639, 2010 DOI: 10.1227/01.NEU.0000377861.14650.98

Trigeminal neuralgia (TN) is the most common facial pain syndrome, with an incidence of approximately 27 per 100 000 patient-years.

OBJECTIVE: To prospectively compare facial pain outcomes for patients having either a posterior fossa exploration (PFE) or stereotactic radiosurgery (SRS) as their first surgery for idiopathic TN.

METHODS: Prospective cohort study of 140 patients with idiopathic TN who had either PFE (n = 91) or SRS (n = 49) from June 2001 until September 2007. The groups were similar with regard to sex, pain location, and pain duration. Patients who had SRS were older (67.1 vs 58.2 years; P < .001). The median follow-up after surgery was 38 months.

RESULTS: Patients who had PFE more commonly were pain free off medications (84% at 1 year, 77% at 4 years) compared with the SRS patients (66% at 1 year, 56% at 4 years; hazard ratio = 2.5; 95% confidence interval, 1.4-4.6; P = .003). Additional surgery for persistent or recurrent face pain was performed in 14 patients after PFE (15%) compared with 17 patients after SRS (35%; P = .009). Nonbothersome facial numbness occurred more frequently in the SRS group (33% vs 18%; P = .04). No difference was noted in other complications between patients who had PFE (12%) (dysesthetic facial pain, n = 3; cerebrospinal fluid leakage, n = 3; hearing loss, n = 2; wound infection, n = 1; pneumonia, n = 1; deep vein thrombosis, n = 1) and patients who had SRS (8%) (dysesthetic facial pain, n = 4; P = .47).

CONCLUSION: PFE is more effective than SRS as a primary surgical option for patients with idiopathic TN

J Neurosurg 113:581–584, 2010. DOI: 10.3171/2009.10.JNS09930

Traumatic brain injury (TBI) is a major cause of serious morbidity and mortality. The incidence is 100–500/100,000 inhabitants/year. Chronic pituitary dysfunction is increasingly recognized after TBI. To define the incidence of endocrine dysfunction and risk factors, the authors describe a prospectively assessed group of patients in whom they documented hormonal functions, early diagnosis, and treatment of neuroendocrine dysfunction after TBI.

Methods. Patients aged 18–65 years were prospectively observed from the time of injury to 1 year postinjury; the Glasgow Coma Scale score ranged from 3 to 14. Patients underwent evaluation of hormonal function at the time of injury and at 3, 6, and 12 months postinjury. Magnetic resonance imaging was also conducted at 1 year postinjury.

Results. During the study period, 89 patients were observed. The mean age of the patients was 36 years, there were 23 women, and the median Glasgow Coma Scale score was 7. Nineteen patients (21%) had primary hormonal dysfunction. Major deficits included growth hormone dysfunction, hypogonadism, and diabetes insipidus. Patients in whom the deficiency was major had a worse Glasgow Outcome Scale score, and MR imaging demonstrated empty sella syndrome more often than in patients without a deficit.

Conclusions. To the authors’ knowledge, this is the third largest study of its kind worldwide. The incidence of chronic hypopituitarism after TBI was higher than the authors expected. After TBI, patients are usually observed on the neurological and rehabilitative wards, and endocrine dysfunction can be overlooked. This dysfunction can be life threatening and other clinical symptoms can worsen the neurological deficit, extend the duration of physiotherapy, and lead to mental illness. The authors recommend routine pituitary hormone testing after moderate or severe TBI within 6 months and 1 year of injury.

Neurosurgery 67:743-748, 2010 DOI: 10.1227/01.NEU.0000374770.09140.FB

We retrospectively evaluated whether antiplatelet preparation lowered the thromboembolic complication rate during the perioperative period.

METHODS:We reviewed 328 elective coil embolization procedures in which only microcatheters were used for coiling. No antiplatelet medication was prescribed before the procedure in 95 cases (29%, group 1), whereas antiplatelet therapy was used in 233 cases (71%, group 2; 61 [18.6%] with a single agent [aspirin or clopidogrel] and 172 [52.4%] with both agents). Antiplatelet agents were not given after coiling unless atherosclerosis, severe coil protrusion, or a thromboembolic complication occurred during the procedure. A thromboembolic complication was defined as a procedural thromboembolic event or transient ischemic attack or stroke occurring within 2 days of embolization.

RESULTS: Thromboembolic complications occurred in 11 cases (3.4%): 6 (6.3%) in group 1 and 5 (2.1%) in group 2 (P = .085). In 195 cases (59.5%) treated by the single microcatheter technique, the risk of thromboembolic complications was low and not affected by antiplatelet preparation (1.8% [no preparation] vs 2.2% [preparation]; P = 1.000). However, in 133 cases (40.5%) treated by the multiple microcatheter technique, antiplatelet preparation significantly reduced the thromboembolic complication risk by 85.2% (12.8% [no preparation] vs 2.1% [preparation]; odds ratio, 0.148; 95% confidence interval, 0.027-0.798; P = .023). The aneurysms treated by the multiple microcatheter technique had more complex configurations for coiling (P < .001). The risk of hemorrhage was not increased by antiplatelet preparation (P = .171).

CONCLUSION: Antiplatelet preparation lowered the periprocedural thromboembolic complication rate in unruptured aneurysms treated by the multiple microcatheter technique and did not increase the risk of hemorrhage. Therefore, antiplatelet preparation can help to reduce complications in patients in whom technical difficulties are expected without the risk of hemorrhage.

Eur Spine J. DOI 10.1007/s00586-010-1482-y

The concept of minimally invasive lumbar disc surgery comprises reduced muscle injury. The aim of this study was to evaluate creatine phosphokinase (CPK) in serum and the cross-sectional area (CSA) of the multifidus muscle on magnetic resonance imaging as indicators of muscle injury.

We present the results of a double-blind randomized trial on patients with lumbar disc herniation, in which tubular discectomy and conventional microdiscectomy were compared. In 216 patients, CPK was measured before surgery and at day 1 after surgery. In 140 patients, the CSA of the multifidus muscle was measured at the affected disc level before surgery and at 1 year after surgery. The ratios (i.e. post surgery/pre surgery) of CPK and CSA were used as outcome measures. The multifidus atrophy was classified into three grades ranging from 0 (normal) to 3 (severe atrophy), and the difference between post and pre surgery was used as an outcome. Patients’ low-back pain scores on the visual analogue scale (VAS) were documented before surgery and at various moments during follow-up.

Tubular discectomy compared with conventional microdiscectomy resulted in a nonsignificant difference in CPK ratio, although the CSA ratio was significantly lower in tubular discectomy. At 1 year, there was no difference in atrophy grade between both groups nor in the percentage of patients showing an increased atrophy grade (14% tubular vs. 18% conventional). The postoperative low-back pain scores on the VAS improved in both groups, although the 1-year between-group mean difference of improvement was 3.5 mm (95% CI; 1.4–5.7 mm) in favour of conventional microdiscectomy.

In conclusion, tubular discectomy compared with conventional microdiscectomy did not result in reduced muscle injury. Postoperative evaluation of CPK and the multifidus muscle showed similar results in both groups, although patients who underwent tubular discectomy reported more lowback pain during the first year after surgery.

Stroke. 2010;41:1969-1977.DOI: 10.1161/STROKEAHA.110.585059

The natural history and optimal management of incidentally found small unruptured aneurysms 5 mm in size remain unclear. A prospective study was conducted to determine the optimal management for incidentally found small unruptured aneurysms.

Methods—From September 2000 to January, 2004, 540 aneurysms (446 patients) were registered. Four hundred forty-eight unruptured aneurysms 5 mm in size (374 patients) have been followed up for a mean of 41.0 months (1306.5 person-years) to date. We calculated the average annual rupture rate of small unruptured aneurysms and also investigated risk factors that contribute to rupture and enlargement of these aneurysms.

Results—The average annual risks of rupture associated with small unruptured aneurysms were 0.54% overall, 0.34% for single aneurysms, and 0.95% for multiple aneurysms. Patient 50 years of age (P=0.046; hazard ratio, 5.23; 95% CI, 1.03 to 26.52), aneurysm diameter of 4.0 mm (P=0.023; hazard ratio, 5.86; 95% CI, 1.27 to 26.95), hypertension (P=0.023; hazard ratio, 7.93; 95% CI, 1.33 to 47.42), and aneurysm multiplicity (P=0.0048; hazard ratio, 4.87; 95% CI, 1.62 to 14.65) were found to be significant predictive factors for rupture of small aneurysms.

Conclusions—The annual rupture rate associated with small unruptured aneurysms is quite low. Careful attention should be paid to the treatment indications for single-type unruptured aneurysms 5 mm. If the patient is 50 years of age, has hypertension, and multiple aneurysms with diameters of 4 mm, treatment should be considered to prevent future aneurysmal rupture.

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.

J Neurosurg Pediatrics 6:000–000, 2010. DOI: 10.3171/2010.5.PEDS09457

Significant variation exists in the surgical and medical management of CSF shunt infection. The objectives of this study were to determine CSF shunt reinfection rates following initial CSF shunt infection in a large patient cohort and to determine management, patient, hospital, and surgeon factors associated with CSF shunt reinfection.

Methods. This retrospective cohort study included children who were in the Pediatric Health Information System (PHIS) database, who ranged in age from 0 to 18 years, and who underwent uncomplicated initial CSF shunt placement in addition to treatment for initial CSF shunt infection between January 1, 2001, and December 31, 2008. The outcome was CSF shunt reinfection within 6 months. The main predictor variable of interest was surgical approach to treatment of first infection, which was determined for 483 patients. Covariates included patient, hospital, surgeon, and other management factors.

Results. The PHIS database includes 675 children with initial CSF shunt infection. Surgical approach to treatment of the initial CSF shunt infection was determined for 483 children (71.6%). The surgical approach was primarily shunt removal/new shunt placement (in 286 children [59.2%]), but a substantial number underwent externalization (59 children [12.2%]), of whom a subset went on to have the externalized shunt removed and a new shunt placed (17 children [3.5% overall]). Other approaches included nonsurgical management (64 children [13.3%]) and complete shunt removal without shunt replacement (74 children [15.3%]). The 6-month reinfection rate was 14.8% (100 of 675 patients). The median time from infection to reinfection was 21 days (interquartile range [IQR] 5–58 days). Children with reinfection had less time between shunt placement and initial infection (median 50 vs 79 days, p = 0.06). No differences between those with and without reinfection were seen in patient factors (patient age at either shunt placement or initial infection, sex, race/ethnicity, payer, indication for shunt, number of comorbidities, distal shunt location, and number of shunt revisions at first infection); hospital volume; surgeon volume; or other management factors (for example, duration of intravenous antibiotic use). Nonsurgical management was associated with reinfection, and complete shunt removal was negatively associated with reinfection. However, reinfection rates did not differ between the 2 most common surgical approaches: shunt removal/new shunt placement (44 [15.4%] of 286; 95% CI 11.4%–20.1%) and externalization (total 12 [20.3%] of 59; 95% CI 11.0%–32.8%). Externalization followed by shunt removal/new shunt placement (5 [29.4%] of 17; 95% CI 10.3%–56.0%) and nonsurgical management (15 [23.4%] of 64; 95% CI 13.8%–35.7%) had higher, but nonstatistically significant, reinfection rates. The length of stay was shorter for nonsurgical management.

Conclusions. Surgical approach to treatment of initial CSF shunt infection was not associated with reinfection in this large cohort of patients.

Stroke. 2010;41:2108-2129. DOI: 10.1161/STR.0b013e3181ec611b

Purpose—The aim of this guideline is to present current and comprehensive recommendations for the diagnosis and treatment of acute spontaneous intracerebral hemorrhage.

Methods—A formal literature search of MEDLINE was performed. Data were synthesized with the use of evidence tables. Writing committee members met by teleconference to discuss data-derived recommendations. The American Heart Association Stroke Council’s Levels of Evidence grading algorithm was used to grade each recommendation. Prerelease review of the draft guideline was performed by 6 expert peer reviewers and by the members of the Stroke Council Scientific Statements Oversight Committee and Stroke Council Leadership Committee. It is intended that this guideline be fully updated in 3 years’ time.

Results—Evidence-based guidelines are presented for the care of patients presenting with intracerebral hemorrhage. The focus was subdivided into diagnosis, hemostasis, blood pressure management, inpatient and nursing management, preventing medical comorbidities, surgical treatment, outcome prediction, rehabilitation, prevention of recurrence, and future considerations.

Conclusions—Intracerebral hemorrhage is a serious medical condition for which outcome can be impacted by early, aggressive care. The guidelines offer a framework for goal-directed treatment of the patient with intracerebral hemorrhage.

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.

J Neurosurg Spine 13:371–380, 2010. DOI: 10.3171/2010.3.SPINE09399

The aim of this retrospective study was to evaluate the predictive value of diffusion tensor (DT) imaging with respect to resectability of intramedullary spinal cord tumors and to determine the concordance of this method with intraoperative surgical findings.

Methods. Diffusion tensor imaging was performed in 14 patients with intramedullary lesions of the spinal cord at different levels using a 3-T magnet. Routine MR imaging scans were also obtained, including unenhanced and enhanced T1-weighted images and T2-weighted images. Patients were classified according to the fiber course with respect to the lesion and their lesions were rated as resectable or nonresectable. These results were compared with the surgical findings (existence vs absence of cleavage plane). The interrater reliability was calculated using the κ coefficient of Cohen.

Results. Of the 14 patients (7 male, 7 female; mean age 49.2 ± 15.5 years), 13 had tumors (8 ependymomas, 2 lymphomas, and 3 astrocytoma). One lesion was proven to be a multiple sclerosis plaque during further diagnostic workup. The lesions could be classified into 3 types according to the fiber course. In Type 1 (5 cases) fibers did not pass through the solid lesion. In Type 2 (3 cases) some fibers crossed the lesion, but most of the lesion volume did not contain fibers. In Type 3 (6 cases) the fibers were completely encased by tumor. Based on these results, 6 tumors were considered resectable, 7 were not. During surgery, 7 tumors showed a good cleavage plane, 6 did not. The interrater reliability (Cohen κ) was calculated as 0.83 (p < 0.003), which is considered to represent substantial agreement. The mean duration of follow-up was 12.0 ± 2.9. The median McCormick grade at the end of follow-up was II.

Conclusions. These preliminary data suggest that DT imaging in patients with spinal cord tumors is capable of predicting the resectability of the lesion. A further prospective study is needed to confirm these results and any effect on patient outcome.

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.

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.

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.

J Neurosurg Spine 13:403–406, 2010.DOI: 10.3171/2010.3.SPINE09657

Pedicle screws placed in the thoracic, lumbar, and sacral spine occasionally come in contact with the aorta, vena cava, or iliac vessels. When such screws are seen on postoperative imaging in an asymptomatic patient, the surgeon must decide whether it is riskier to revise the screw or to observe it. The authors hypothesized that the incidence of screw placement causing perioperative vessel injury is low and, further, that screws placed in contact with major vessels do not always result in vessel injury.

Methods. A retrospective review of the operative records of 182 consecutive patients undergoing thoracic, lumbar, and lumbosacral pedicle screw fusion was performed to determine the frequency of intraoperative vessel injury. Postoperative imaging for 107 patients was available to determine the incidence of screws in contact with major vessels. Charts were examined to determine if any adverse sequelae had resulted from malpositioned screws. Patient outcomes were documented.

Results. There were no intraoperative vessel injuries or deaths in 182 consecutive operations. One hundred seven patients with available postoperative films had 680 pedicle screws placed between T-3 and the sacrum during 115 operations. No patient had arterial screw penetration or deformation on postoperative imaging. Thirty-three of the 680 inserted screws were in contact with a major vessel on routine postoperative imaging. The contacted vessels included the aorta (4 cases), the iliac artery (7 cases), and the iliac veins (22 cases). Patients were followed up until death or November 2009, for a mean follow-up of 44 months (median 44 months, range 5–109 months). None of the patients with vessel contact was noted to suffer symptoms or sequelae as a result of vessel contact. Radiographic follow-up as long as 50 months after surgery revealed no detectable vessel abnormality at the contacted site.

Conclusions. Placing pedicle screws in contact with major vessels is a known risk of spinal surgery. The risk of repositioning a screw in contact with a major vessel but causing no symptoms must be weighed against the relative risk of leaving it in place.

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.

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.

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.

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.

Neurosurgery 67:611-616, 2010 DOI: 10.1227/01.NEU.0000378026.23116.E6

Cavernous hemangioma in the cavernous sinus (CS) is a rare vascular tumor. Direct microsurgical approach usually results in massive hemorrhage. Radiosurgery has emerged as a treatment alternative to microsurgery.

OBJECTIVE: To further investigate the role of Gamma Knife surgery (GKS) in treating CS hemangiomas.

METHODS: This was a retrospective analysis of 7 patients with CS hemangiomas treated by GKS between 1993 and 2008. Data from 84 CS meningiomas treated during the same period were also analyzed for comparison. The patients underwent follow-up magnetic resonance imaging at 6-month intervals. Data on clinical and imaging changes after radiosurgery were analyzed.

RESULTS: Six months after GKS, magnetic resonance imaging revealed an average of 72% tumor volume reduction (range, 56%-83%). After 1 year, tumor volume decreased 80% (range, 69%-90%) compared with the pre-GKS volume. Three patients had > 5 years of follow- up, which showed the tumor volume further decreased by 90% of the original size. The average tumor volume reduction was 82%. In contrast, tumor volume reduction of the 84 cavernous sinus meningiomas after GKS was only 29% (P < .001 by Mann-Whitney U test). Before treatment, 6 patients had various degrees of ophthalmoplegia. After GKS, 5 improved markedly within 6 months. Two patients who suffered from poor vision improved after radiosurgery.

CONCLUSION: GKS is an effective and safe treatment modality for CS hemangiomas with long-term treatment effect. Considering the high risks involved in microsurgery, GKS may serve as the primary treatment choice for CS hemangiomas.

Neurosurgery 67:844-854, 2010 DOI: 10.1227/01.NEU.0000374684.10920.A2

Multidetector computerized tomography angiography (MDCTA) is now a widely accepted technique for the management of intracranial aneurysms.

OBJECTIVE: To evaluate its accuracy for the postoperative assessment of clipped intracranial aneurysms.

METHODS:We analyzed a consecutive series of 31 patients that underwent direct surgical clipping procedures of 38 aneurysms. A 64 slice MDCT scanner (Aquilion 64, Toshiba) was used and results were compared with digital subtraction angiographies (DSA). Two independent neuroradiologists analyzed the following data: examination quality, artifacts, aneurysm remnant, and patency of collateral branches. Interobserver agreement, sensitivity, and specificity were calculated.

RESULTS: Seventy-nine percent of the aneurysms were located in the anterior circulation. Significant artifacts were found with multiple and cobalt-alloy clips. According to DSA, remnants >2 mm were found in 21% of the cases, and 2 patients had one collateral branch occluded. Sensitivity and specificity of 64-MDCTA for the detection of aneurysm remnants were 50% and 100%, respectively. Sensitivity and specificity of 64-MDCTA for the detection of a significant remnant (>2 mm) and the detection of the occlusion of a collateral branch were, respectively, 67% and 100% and 50% and 100%. No relationship was found with the location, type, shape, size, or number of clips, but missed remnants tended to be larger with cobalt-alloy clips.

CONCLUSIONS: 64-MDCTA is a valuable technique to assess the presence of a significant postoperative remnant in single titanium clip application cases and might be useful for longterm follow-up. DSA remains the most accurate postoperative radiological examination.