bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of fenestrated aneurysm clips in microvascular decompression surgery
Authors: Attabib Najmedden , Kaufmann Anthony M. 
Published: January 2008

✓The standard techniques of microvascular decompression (MVD) surgery in which implant materials such as shredded Teflon felt are used may be inadequate in some complex cases. The authors evaluated the use of fenestrated aneurysm clips to maintain transposition of culprit vessels in patients with trigeminal neuralgia (TN) and hemifacial spasm (HFS).
The authors conducted a retrospective review of MVD operations in which the culprit vessel was transposed and then maintained in position with a fenestrated aneurysm clip secured in position by suturing it to the dura mater.
Among a consecutive series of more than 450 MVD surgeries, the fenestrated aneurysm clip sling was used in eight of the last 100 cases: six for HFS and two for TN. The follow-up period ranged from 1 to 13 months, and complete symptom resolution was noted in seven of the eight patients. No patient exhibited evidence of any surgical complications.
This approach can be safely performed in complicated MVD cases such as reoperations and transpositions of long ectatic arteries. To the best of the authors' knowledge this is the first report in which the use of fenestrated aneurysm clips in MVD surgery is described.
Application accuracy in frameless image-guided neurosurgery: a comparison study of three patient-to-image registration methods
Authors: Woerdeman Peter A. , Willems Peter W. A. , Noordmans Herke J. , Tulleken Cornelis A. F. , van der Sprenkel Jan Willem Berkelbach 
Published: January 2008

Object
The aim of this study was to compare three patient-to-image registration methods in frameless stereotaxy in terms of their application accuracy (the accuracy with which the position of a target can be determined intraoperatively). In frameless stereotaxy, imaging information is transposed to the surgical field to show the spatial position of a localizer or surgical instrument. The mathematical relationship between the image volume and the surgical working space is calculated using a rigid body transformation algorithm, based on point-pair matching or surface matching.

Methods
Fifty patients who were scheduled to undergo a frameless image-guided neurosurgical procedure were included in the study. Prior to surgery, the patients underwent either computerized tomography (CT) scanning or magnetic resonance (MR) imaging with widely distributed adhesive fiducial markers on the scalp. An extra fiducial marker was placed on the head as a target, as near as possible to the intracranial lesion. Prior to each surgical procedure, an optical tracking system was used to perform three separate patient-to-image registration procedures, using anatomical landmarks, adhesive markers, or surface matching. Subsequent to each registration, the target registration error (TRE), defined as the Euclidean distance between the image space coordinates and world space coordinates of the target marker, was determined.
Independent of target location or imaging modality, mean application accuracy (± standard deviation) was 2.49 ± 1.07 mm when using adhesive markers. Using the other two registration strategies, mean TREs were significantly larger (surface matching, 5.03 ± 2.30 mm; anatomical landmarks, 4.97 ± 2.29 mm; p < 0.001 for both).

Conclusions
The results of this study show that skin adhesive fiducial marker registration is the most accurate noninvasive registration method. When images from an earlier study are to be used and accuracy may be slightly compromised, anatomical landmarks and surface matching are equally accurate alternatives.
Association between absence of epidermal growth factor receptor immunoreactivity and poor prognosis in patients with atypical meningioma
Authors: Smith Justin S. , Lal Anita , Harmon-Smith Miranda , Bollen Andrew W. , McDermott Michael W. 
Published: January 2008

Object
The clinical behavior of meningiomas is variable. Because multiple growth factor receptors have been identified in these tumors, the authors sought to assess the capacity of the expression patterns of a subset of these receptors to stratify meningioma cases.

Methods
Eighty-four meningiomas were analyzed, including 36 benign, 29 atypical, and 19 malignant lesions. Immunohistochemical staining was performed for epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR)–β, basic fibroblast growth factor receptor (BFGFR), and MIB-1. Survival analyses were performed using follow-up data obtained in patients with newly diagnosed tumors.
Immunoreactivity for EGFR was observed in 47% of benign, 48% of atypical, and 42% of malignant tumors. Staining for BFGFR was identified in 89% of benign, 97% of atypical, and 95% of malignant lesions. Immunostaining for PDGFR-β was evident in all the lesions assessed. Mean MIB-1 indices for benign, atypical, and malignant cases were 3.6 (range 0.5–15.3), 8.2 (range 1.5–23.1) and 18.3 (range 1.0–55.8), respectively. Overall mean follow-up duration was 9.0 years (range 5.1–18.8 years). Lack of EGFR immunoreactivity was identified as a strong predictor of shorter overall survival in patients with atypical meningioma (p = 0.003, log-rank test). This association was not evident in cases of benign or malignant meningiomas.

Conclusions
There is a significant association between EGFR immunoreactivity and prolonged survival in patients with atypical meningioma. Given the variable behavior of atypical meningiomas, EGFR assessment could improve existing strategies for patient stratification and treatment.
Microsurgical anatomy of the superior petrosal venous complex: new classifications and implications for subtemporal transtentorial and retrosigmoid suprameatal approaches
Authors: Tanriover Necmettin , Abe Hiroshi , Rhoton Albert L. , Kawashima Masatou , Sanus Galip Z. , Akar Ziya 
Published: January 2008

Object
The purpose of this study was to define the patterns of drainage of the superior petrosal venous complex (SPVC) along the petrous ridge in relation to the Meckel cave and internal acoustic meatus (IAM) and to delineate its effect on the surgical exposures obtained in subtemporal transtentorial and retrosigmoid suprameatal approaches.

Methods
The patterns of drainage of the SPVC along the petrous ridge were characterized according to their relation to the Meckel cave and the IAM based on an examination of 30 hemispheres. Subtemporal transtentorial and retro-sigmoid suprameatal approaches were performed in three additional cadavers to demonstrate the effect of the drainage pattern on the surgical exposures.

Conclusions
The SPVC emptied into the superior petrosal sinus (SPS) within a distance of 1 cm from the midpoint of the Meckel cave. The patterns of drainage of the SPVC were classified into three groups. Type I emptied into the SPS above and lateral to the boundaries of the IAM. The most common type, Type II, emptied between the lateral limit of the trigeminal nerve at the Meckel cave and the medial limit of the facial nerve at the IAM, within an area of approximately 13 mm. Type III emptied into the SPS above or medial to the Meckel cave. The ideal SPVC for a subtemporal transtentorial approach (with or without anterior extradural petrosectomy) seems to be a Type I. In SPVC Type III and those Type II cases in which the SPVC is located near the Meckel cave, the amount of working space is significantly limited in a subtemporal transtentorial approach. In contrast, the ideal type of SPVC for a retrosigmoid suprameatal approach would be a Type III, and the SPVC must be divided in the majority of Type I and II cases for a satisfactory surgical exposure along the Meckel cave and middle fossa dura. The proposed modified classification system and its effect on the surgical exposure may aid in planning the approach directed along the petrous apex and may reduce the probability of venous complications.
Sensitivity of patient-specific numerical simulation of cerebal aneurysm hemodynamics to inflow boundary conditions
Authors: Venugopal Prem , Valentino Daniel , Schmitt Holger , Villablanca J. Pablo , Viñuela Fernando , Duckwiler Gary 
Published: January 2008

Object
Due to the difficulty of obtaining patient-specific velocity measurements during imaging, many assumptions have to be made while imposing inflow boundary conditions in numerical simulations conducted using patient-specific, imaging-based cerebral aneurysm models. These assumptions can introduce errors, resulting in lack of agreement between the computed flow fields and the true blood flow in the patient. The purpose of this study is to evaluate the effect of the assumptions made while imposing inflow boundary conditions on aneurysmal hemodynamics.

Methods
A patient-based anterior communicating artery aneurysm model was selected for this study. The effects of various inflow parameters on numerical simulations conducted using this model were then investigated by varying these parameters over ranges reported in the literature. Specifically, we investigated the effects of heart and blood flow rates as well as the distribution of flow rates in the A1 segments of the anterior cerebral artery.
The simulations revealed that the shear stress distributions on the aneurysm surface were largely unaffected by changes in heart rate except at locations where the shear stress magnitudes were small. On the other hand, the shear stress distributions were found to be sensitive to the ratio of the flow rates in the feeding arteries as well as to variations in the blood flow rate.

Conclusions
Measurement of the blood flow rate as well as the distribution of the flow rates in the patient's feeding arteries may be needed for numerical simulations to accurately reproduce the intraaneurysmal hemodynamics in a specific aneurysm in the clinical setting.
Neurosurgical experience with malpractice litigation: an analysis of closed claims against neurosurgeons in New York State, 1999 through 2003
Authors: Rovit Richard L. , Simon Arlene Stolper , Drew Josephine , B.B.A.  , Murali Raj , Robb James 
Published: January 2008

Object
Neurosurgeons are a high-risk group for allegations of malpractice. To determine the kinds of cases and the neurosurgical practice patterns associated with the highest proportion of litigation, the authors examined the experience over a 5-year period of a major physician-owned and -administered insurance company dealing with this issue, the Medical Liability Mutual Insurance Company (MLMIC) of New York. With the MLMIC cases as a basis, the authors also analyzed areas of physician vulnerability and determined the steps neurosurgeons can take to reduce potential litigation.

Methods
All cases closed against MLMIC-insured neurosurgeons from January 1, 1999, through December 30, 2003, were reviewed. Variables examined included allegation, anatomical site, and the ultimate resolution of the case. Of the 280 cases against neurosurgeons that were closed during the study period, 156 (56%) involved the spine, 109 (39%) involved the head and/or brain, and 15 (5%) reflected miscellaneous allegations. These proportions are relatively similar to the 1999 procedural statistics for neurosurgical practices. Of the cases examined, 98 were closed with a total loss indemnity of approximately $50 million, and 182 resulted in no indemnity payment.

Conclusions
A neurosurgeon's chances of being sued for malpractice are not necessarily related to the medical complexity of a particular case but rather to the types of cases with which the physician is involved. Elective spinal surgery cases constitute the majority of litigation. Neurosurgeons can take steps to reduce their vulnerability to potential litigation and to increase the odds of a successful defense.
Gamma Knife surgery for Cushing's disease
Authors: Jagannathan Jay , Sheehan Jason P. , Pouratian Nader , Laws Edward R. , Steiner Ladislau , Vance Mary Lee 
Published: January 2008

Object
In this study the authors address the efficacy and safety of Gamma Knife surgery (GKS) in patients with adrenocorticotropic hormone–secreting pituitary adenomas.

Methods
A review of data collected from a prospective GKS database between January 1990 and March 2005 was performed in patients with Cushing's disease. All but one patient underwent resection for a pituitary tumor, without achieving remission. Successful endocrine outcome after GKS was defined as a normal 24-hour urinary free cortisol (UFC) concentration posttreatment after a minimum of 1 year of follow up. Patient records were also evaluated for changes in tumor volume, development of new hormone deficiencies, visual acuity, cranial nerve neuropathies, and radiation-induced imaging changes. Ninety evaluable patients had undergone GKS, with a mean endocrine follow-up duration of 45 months (range 12–132 months). The mean dose to the tumor margin was 23 Gy (median 25 Gy).
Normal 24-hour UFC levels were achieved in 49 patients (54%), with an average time of 13 months after treatment (range 2–67 months). In the 49 patients in whom a tumor was visible on the planning magnetic resonance (MR) image, a decrease in tumor size occurred in 39 (80%), in seven patients there was no change in size, and tumor growth occurred in three patients. Ten patients (20%) experienced a relapse of Cushing's disease after initial remission; the mean time to recurrence was 27 months (range 6–60 months). Seven of these patients underwent repeated GKS, with three patients achieving a second remission. New hormone deficiencies developed in 20 patients (22%), with hypothyroidism being the most common endocrinopathy after GKS. Five patients experienced new visual deficits or third, fourth, or sixth cranial nerve deficits; two of these patients had undergone prior conventional fractionated radiation therapy, and four of them had received previous GKS. Radiation-induced changes were observed on MR images in three patients; one had symptoms attributable to these changes.

Conclusions
Gamma Knife surgery is an effective treatment for persistent Cushing's disease. Adenomas with cavernous sinus invasion that are not amenable to resection are treatable with the Gamma Knife. A second GKS treatment appears to increase the risk of cranial nerve damage. These results demonstrate the value of combining two neurosurgical treatment modalities—microsurgical resection and GKS—in the management of pituitary adenomas.
Gamma Knife surgery for adrenocorticotropic hormone–producing pituitary adenomas after bilateral adrenalectomy
Authors: Mauermann William J. , Sheehan Jason P. , Chernavvsky Daniel R. , Laws Edward R. , Steiner Ladislau , Vance Mary Lee 
Published: January 2008

Object
Patients with adrenocorticotropic hormone (ACTH)–secreting pituitary adenomas may require a bilateral adrenalectomy to treat their Cushing's disease. Approximately one third of these patients, however, will experience progressive enlargement of the residual pituitary adenoma, develop hyperpigmentation, and have an elevated level of serum ACTH. These patients with Nelson's syndrome can be treated with Gamma Knife surgery (GKS).

Methods
The prospectively collected University of Virginia Gamma Knife database of patients with pituitary adenomas was reviewed to identify all individuals with Nelson's syndrome who were treated with GKS. Twenty-three patients with a minimum of 6 months of follow up were identified in the database. These patients were assessed for tumor control (that is, lack of tumor growth over time) with neuroimaging studies (median follow-up duration 22 months) and for biochemical normalization of their ACTH levels (median follow-up duration 50 months). Neuroimaging follow-up studies were available for 22 patients, and endocrine follow up was available for 15 patients in whom elevation of ACTH levels was documented prior to GKS.
In the 22 patients in whom neuroimaging follow-up studies were available, 12 had a decrease in tumor size, eight had no tumor growth, and two had an increase in tumor volume. Ten of 15 patients with elevated ACTH levels prior to GKS showed a decrease in their ACTH levels at last follow up; three of these 10 patients achieved normal ACTH levels (< 50 pg/ml) and the other five patients with initially elevated values had an increase in ACTH levels.
Ten patients were thoroughly evaluated for post-GKS pituitary function; four were found to have new pituitary hormone deficiency and six did not have hypopituitarism after GKS. One patient suffered a permanent third cranial nerve palsy and four patients are now deceased.

Conclusions
Gamma Knife surgery may control the residual pituitary adenoma and decrease ACTH levels in patients with Nelson's syndrome. Delayed hypopituitarism or cranial nerve palsies can occur after GKS. Patients with Nelson's syndrome require continued multidisciplinary follow-up care. Given the difficulties associated with management of Nelson's syndrome, even the modest results of GKS may be helpful for a number of patients.
A prospective randomized controlled trial of anterior compared with posterior stabilization for unilateral facet injuries of the cervical spine
Authors: Kwon Brian K. , Fisher Charles G. , Boyd Michael C. , Cobb John , Jebson Hilary , Noonan Vanessa , Wing Peter , Dvorak Marcel F. 
Published: January 2008

Object
Unilateral facet injuries can be treated with either anterior or posterior fixation techniques with reportedly good outcomes. The two approaches have not been directly compared, however, and consensus is lacking as to which is the optimal method. The primary objective of this study was to determine whether acute postoperative morbidity differed between anteriorly and posteriorly treated patients with unilateral facet injuries.

Methods
Forty-two patients were prospectively randomized to undergo either anterior cervical discectomy and fusion or posterior fixation. The primary outcome measure was the postoperative time required to achieve a predefined set of discharge criteria. Secondary outcome measures included postoperative pain, wound infections, radiographically demonstrated fusion and alignment, and patient-reported outcome measures.

Results
The median time to achieve the discharge criteria was 2.75 and 3.5 days for anterior and posterior groups, respectively, a difference that did not reach statistical significance (p = 0.096). Compared with those treated using posterior fixation, anteriorly treated patients exhibited somewhat less postoperative pain, a lower rate of wound infection, a higher rate of radiographically demonstrated union, and better radiographically proven alignment. Nonetheless, the anterior approach was accompanied by a risk of swallowing difficulty in the early postoperative period. Patient-reported outcome measures did not reveal a difference between anterior and posterior fixation procedures.

Conclusions
This prospective randomized controlled trial provided level 1 evidence that both the anterior and posterior fixation approaches appear to be valid treatment options. Although statistical significance was not reached in the primary outcome measure, some secondary outcome measures favored anterior fixation and others favored posterior treatment for unilateral facet injuries.
Results of surgical treatment for thoracic myelopathy: minimum 2-year follow-up study in 132 patients
Authors: Aizawa Toshimi , Sato Tetsuro , Sasaki Hirotoshi , Matsumoto Fujio , Morozumi Naoki , Kusakabe Takashi , Itoi Eiji , Kokubun Shoichi 
Published: January 2008

Object
Thoracic myelopathy is uncommon compared with cervical myelopathy. In this study, data obtained in patients with thoracic myelopathy caused by degenerative processes of the spine were retrospectively analyzed to clarify the surgical outcomes and to examine the various factors affecting the postoperative improvement.

Methods
Between 1988 and 2002, 132 patients with thoracic myelopathy underwent surgery and a minimum 2-year observation period. Clinical data were collected from medical and operative records, and sagittal alignment of the spine was measured on radiographs. The patients were evaluated pre- and postoperatively using the modified Japanese Orthopaedic Association (JOA) scale (maximum score 11). The relationships among various factors affecting the preoperative severity of myelopathy and postoperative improvement were also examined.

Results
The population consisted of 97 men (mean age at surgery was 58 years) and 35 women (mean age at surgery 62 years). Myelopathy was caused by ossification of the ligamentum flavum (OLF) in 73 patients, ossification of the posterior longitudinal ligament (OPLL) in 21, combined OLF–OPLL in 10, intervertebral disc herniation (IDH) in 15, posterior bone spur in 11, and OLF with IDH or posterior bone spur in one patient each. The surgical outcome was relatively good: a mean preoperative JOA score of 5.3 improved to a mean score of 7.8 at the last follow-up, 50 months on average after surgery. Thoracic myelopathy caused by OPLL, however, was associated with lower postoperative scores and recovery rates. In more than half of the patients the authors documented an increase of kyphosis of less than 2°.

Conclusions
Patients with a shorter preoperative duration of symptoms and milder myelopathy experienced significantly better postoperative neurological conditions, which indicated that those who present earlier with fewer disabilities should be recommended to undergo surgery in time, although the surgical treatment for OPLL still involves many problems.
A biomechanical cadaveric analysis of polymethylmethacrylate-augmented pedicle screw fixation
Authors: Frankel Bruce M. , D'Agostino Sabino , Wang Chiang 
Published: January 2008

Object
Instrumentation of the osteoporotic spine can be fraught with complications such as hardware failure. A cadaver study was performed to determine the biomechanical performance of polymethylmethacrylate (PMMA)–augmented pedicle screws.

Methods
Three osteoporotic human cadaveric specimens with a mean bone mineral density of 0.70 g/cm2 were used to evaluate the performance of a novel fenestrated bone tap in pedicle screw augmentation. On this device, tap threads serve a dual purpose in preventing backflow of cement toward neural elements while allowing for a custom form for subsequent screw placement. The tap was used to inject a mean volume of 3.7 ml PMMA/pedicle (range 2–8.0 ml PMMA/pedicle) followed by pedicle screw placement between L-5 and T-5, alternating between augmented and nonaugmented instrumentation. Axial pullout testing was then performed.

Results
Pedicle screw pullout strength was increased in both primary and salvage procedures by 119% (p = 0.001) and 162% (p = 0.01), respectively, after PMMA augmentation. Additionally, the injected cement volumes were divided into two groups, a low-cement group (≤ 2.8 ml/pedicle) and a high-cement group (≥ 5.5 ml/pedicle). Interestingly, the pullout strength did not significantly change with increased cement usage between the two groups (p > 0.05 for all comparisons).

Conclusions
Polymethylmethacrylate-augmented pedicle screw fixation results in a significant increase in the axial pullout strength of augmented pedicle screws in both primary and revision procedures. This technique may be a valuable adjunct in cases in which bolstering of the screw–bone interface is necessary.