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Minimally Invasive Lumbar Interbody Fusion in Patients Older Than 70 Years of Age: Analysis of Peri- and Postoperative Complications

Neurosurgery 68:897–902, 2011 DOI: 10.1227/NEU.0b013e3182098bfa

The number of spine operations performed in the elderly population is rising.

OBJECTIVE: To identify and describe perioperative and postoperative complications in patients 70 years and older who have undergone minimally invasive lumbar interbody spine fusion.

METHODS: A retrospective analysis was performed on 66 consecutive patients aged 70 years or older who underwent a minimally invasive interbody lumbar fusion. Electronic medical records were analyzed for patient demographics, procedures, and perioperative and postoperative complications.

RESULTS: Between 2000 and 2009, 66 patients with an average age of 74.9 years (range, 70-86 years) underwent 68 lumbar interbody fusions procedures. The mean follow-up was 14.7 months (range, 1.5-50 months). The minimally invasive approaches included 41 cases of extreme lateral interbody fusion and 27 minimally invasive transforaminal lumbar interbody fusions. We observed 5 major (7.4%) and 17 minor (25%) complications. The 5 major complications consisted of 4 cases of interbody graft subsidence and 1 adjacent level disease. There were no intraoperative medical complications. There were no myocardial infarctions, pulmonary embolisms, hardware complications requiring removal, wound infections, major visceral, vascular, neural injuries, or death in the study period.

CONCLUSION: Minimally invasive interbody fusions can be performed in the elderly (ages 70 years and older) with an overall low rate of major complications. Graft subsidence in this population when not supplemented with posterior instrumentation is a concern. Age should not be a deterrent to performing complex minimally invasive interbody fusions in the elderly.

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Evans’ Index Revisited: The Need for an Alternative in Normal Pressure Hydrocephalus

Neurosurgery 68:939–944, 2011 DOI: 10.1227/NEU.0b013e318208f5e0

The international guidelines for the diagnosis of normal pressure hydrocephalus (NPH) define ventricular enlargement as Evans’ index greater than 0.3.

OBJECTIVE: To establish whether there is a correlation between Evans’ index and ventricular volume (VV) in NPH and whether choosing different planes for the measurements could produce significantly different results.

METHODS: Pre–shunt insertion, thin-section CT scans of the brains of 10 patients with shunt-responsive NPH were reviewed retrospectively, measuring Evans’ index, frontal horn index, VV, and total intracranial volume (ICV). The ventricular/intracranial volume index (VV/ICV) was calculated. Correlation between each of the linear indices and VV and VV/ICV was done.

RESULTS: Significant differences were found in the index values calculated at different planes. The frontal horn index at a plane 16 mm parallel to the anterior commissure– posterior commissure (AC-PC) plane showed best correlation with VV and VV/ICV (r: 0.658 and 0.587, respectively). Evans’ index, also obtained at a plane 16 mm parallel to the AC-PC plane, showed best correlation with VV and VV/ICV (r: 0.619 and 0.498, respectively).

CONCLUSION: Evans’ index value can vary significantly in a patient with NPH, depending on the level of the brain CT scan image at which the frontal horns and maximal inner skull diameters are measured. Evans’ index is not an ideal method for estimating the VV in NPH patients. Volumetric measurements represent the logical accurate estimate of true ventricular size as well as the size of the other intracranial compartments.

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The transorbital keyhole approach: early and long-term outcome analysis of approach-related morbidity and cosmetic results

J Neurosurg 114:852–856, 2011. DOI: 10.3171/2010.9.JNS1095

In 2003 the authors introduced a minimally invasive transorbital keyhole approach. Because this approach requires removal of the orbital rim and orbital roof, there have been concerns regarding perioperative morbidity, long-term morbidity, and cosmetic results. The authors evaluated approach-related morbidity and cosmetic results in their patients to determine the rate of complications and compared this to published reports of similar approaches.

Material. Seventy-one patients (41 female, 30 male) underwent operations using this approach between 2004 and 2008. Immediate approach-related morbidity was recorded after the operation. Late morbidity was determined after 7 months by an independent examiner while cosmetic results were self-rated by the patient using a questionnaire.

Results. Fifty-one (72%) of 71 patients had no postoperative complications and 12 (16.9%) had minor complications, the most common of which was subgaleal CSF collection (7.0%). Other minor complications included facial nerve palsy (2.8%), hyposphagma (2.8%), periorbital swelling due to periorbital hematoma (2.8%), and subdural hematoma (1.4%). Major complications requiring surgical revision occurred in 4 patients (5.6%); these were CSF fistulas in 2 patients, pneumocephalus in 1 patient, and a hematoma in 1 patient. Forty-nine (90.7%) of all 54 examined patients rated the cosmetic results as very good or good. Major long-term morbidity was hyposmia or anosmia (14 patients) followed by hypoesthesia around the scar (9 patients).

Conclusions. The transorbital keyhole approach is a feasible approach with a low-risk profile for postoperative or long-term morbidity and excellent cosmetic outcome.

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Reduction in external ventricular drain infection rate. Impact of a minimal handling protocol and antibiotic-impregnated catheters

Acta Neurochir (2011) 153:647–651. DOI 10.1007/s00701-010-0905-1

Many strategies have been developed with the aim of reducing external ventricular drain-related infections. Antibiotic-impregnated catheters are one of them.

Material and methods We report 648 cases of external ventricular drain from a total of 534 patients treated at the Virgen del Rocío Hospital between 1995 and 2006. Three subgroups were considered: group 1 included patients treated between 1995 and 2000, as well as a total of 190 external ventricular drains and 59 cases of infection (31.05%); group 2, with patients treated between 2000 and 2004 and managed with a minimal handling protocol, included 210 external ventricular drains and nine cases of infection (4.29%); and group 3, treated between 2004 and 2006, with 248 external ventricular drains and six cases of infection (2.41%). This latter subgroup included patients managed with a minimal handling protocol and antibiotic-impregnated catheters.

Results Infection rate was 17% when non-antibioticimpregnated catheters were employed and 2.41% when antibiotic-impregnated catheters were inserted (p<0.001). This difference was statistically significant before and after the introduction of a minimal handling protocol, with percentages of 5.31% and 3.27%, respectively (p<0.001; odds ratio 0.08; absolute risk reduction 27.26%). However, no statistically significant difference was observed in infection rate when the impact of a minimal handling protocol was considered: 4.29% when only the protocol was introduced and 2.41% when both the protocol and antibiotic-impregnated catheters were used (p>0.05).

Conclusion Minimal handling protocols constitute an essential strategy in the reduction of external ventricular drain-related infections. Besides that, the use of antibiotic-impregnated catheters may reduce infection-related hospital costs.

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Intracranial Cysts Containing Cerebrospinal Fluid- Like Fluid: Results of Endoscopic Neurosurgery in a Series of 64 Consecutive Cases

Neurosurgery 68:788–803, 2011 DOI: 10.1227/NEU.0b013e318207ac91

Intracranial cysts containing cerebrospinal fluid (CSF) may be developmental or acquired.

OBJECTIVE: To analyze the results of endoscopic neurosurgery in the management of intracranial CSF cysts.

METHODS: In a 7-year period, 64 consecutive patients underwent endoscopic neurosurgery for CSF cysts. Group 1 consisted of 13 patients with acquired cysts; group 2 included 51 patients with developmental cysts. In all cases, the cyst walls were fenestrated through small burr holes with frameless guided operative endoscopes. Follow-up ranged from 1 to 6 years (mean, 3.4 years).

RESULTS: There were no mortality and no permanent morbidity, apart from a patient (1.6%) who remained neurologically intact but required ventriculoperitoneal shunting because of intraoperative hemorrhage. The planned fenestrations could be performed in all patients except 2, owing to thick, opaque cyst walls. In group 1, 6 patients fully recovered and remained intact throughout the follow-up, whereas 7 improved but had various degrees of neurological disabilities that were related to their initial diseases. Radiological results were excellent in all cases. In group 2, there were 7 asymptomatic patients who remained unchanged and 44 ‘‘symptomatic’’ patients: 40 (91%) clinically improved, 4 (9%) remained unchanged, and none worsened. Cyst size decreased in 37 patients (74%) and remained unchanged in 13 (26%).

CONCLUSION: In this series, patients of different ages, harboring cysts of various sizes and locations, could be satisfactorily treated with endoscopic neurosurgery.

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Functional mapping–guided resection of low-grade gliomas in eloquent areas of the brain: improvement of long-term survival

J Neurosurg 114:566–573, 2011. DOI: 10.3171/2010.6.JNS091246

Low-grade gliomas (LGGs) frequently infiltrate highly functional or “eloquent” brain areas. Given the lack of long-term survival data, the prognostic significance of eloquent brain tumor location and the role of functional mapping during resective surgery in presumed eloquent brain regions are unknown.

Methods. We performed a retrospective analysis of 281 cases involving adults who underwent resection of a supratentorial LGG at a brain tumor referral center. Preoperative MR images were evaluated blindly for involvement of eloquent brain areas, including the sensorimotor and language cortices, and specific subcortical structures. For high-risk tumors located in presumed eloquent brain areas, long-term survival estimates were evaluated for patients who underwent intraoperative functional mapping with electrocortical stimulation and for those who did not.

Results. One hundred and seventy-four patients (62%) had high-risk LGGs that were located in presumed eloquent areas. Adjusting for other known prognostic factors, patients with tumors in areas presumed to be eloquent had worse overall and progression-free survival (OS, hazard ratio [HR] 6.1, 95% CI 2.6–14.1; PFS, HR 1.9, 95% CI 1.2–2.9; Cox proportional hazards). Confirmation of tumor overlapping functional areas during intraoperative mapping was strongly associated with shorter survival (OS, HR 9.6, 95% CI 3.6–25.9). In contrast, when mapping revealed that tumor spared true eloquent areas, patients had significantly longer survival, nearly comparable to patients with tumors that clearly involved only noneloquent areas, as demonstrated by preoperative imaging (OS, HR 2.9, 95% CI 1.0–8.5).

Conclusions. Presumed eloquent location of LGGs is an important but modifiable risk factor predicting disease progression and death. Delineation of true functional and nonfunctional areas by intraoperative mapping in high-risk patients to maximize tumor resection can dramatically improve long-term survival.

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Minimally invasive percutaneous transpedicular screw fixation: increased accuracy and reduced radiation exposure by means of a novel electromagnetic navigation system

Acta Neurochir (2011) 153:589–596. DOI 10.1007/s00701-010-0882-4

Minimally invasive percutaneous pedicle screw instrumentation methods may increase the need for intraoperative fluoroscopy, resulting in excessive radiation exposure for the patient, surgeon, and support staff. Electromagnetic field (EMF)-based navigation may aid more accurate placement of percutaneous pedicle screws while reducing fluoroscopic exposure. We compared the accuracy, time of insertion, and radiation exposure of EMF with traditional fluoroscopic percutaneous pedicle screw placement.

Methods Minimally invasive pedicle screw placement in T8 to S1 pedicles of eight fresh-frozen human cadaveric torsos was guided with EMF or standard fluoroscopy. Setup, insertion, and fluoroscopic times and radiation exposure and accuracy (measured with post-procedural computed tomography) were analyzed in each group.

Results Sixty-two pedicle screws were placed under fluoroscopic guidance and 60 under EMF guidance. Ideal trajectories were achieved more frequently with EMF over all segments (62.7% vs. 40%; p=0.01). Greatest EMF accuracy was achieved in the lumbar spine, with significant improvements in both ideal trajectory and reduction of pedicle breaches over fluoroscopically guided placement (64.9% vs. 40%, p=0.03, and 16.2% vs. 42.5%, p=0.01, respectively). Fluoroscopy time was reduced 77% with the use of EMF (22 s vs. 5 s per level; p<0.0001) over all spinal segments. Radiation exposure at the hand and body was reduced 60% (p=0.058) and 32% (p=0.073), respectively. Time for insertion did not vary between the two techniques.

Conclusions Minimally invasive pedicle screw placement with the aid of EMF image guidance reduces fluoroscopy time and increases placement accuracy when compared with traditional fluoroscopic guidance while adding no additional time to the procedure.

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Diffusion tensor imaging in the cervical spinal cord

Eur Spine J (2011) 20:422–428. DOI 10.1007/s00586-010-1587-3

There are discrepancy between MR findings and clinical presentations. The compressed cervical cord in patients of the spondylotic myelopathy may be normal on conventional MRI when it is at the earlier stage or even if patients had severe symptoms. Therefore, it is necessary to take a developed MR technique—diffusion tensor imaging (DTI)—to detect the intramedullary lesions.

Prospective MR and DTI were performed in 53 patients with cervical compressive myelopathy and twenty healthy volunteers. DTI was performed along six non-collinear directions with single-shot spin echo echo-planar imaging (EPI) sequence. Intramedullary apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured in four segments (C2/3, C3/4, C4/5, C5/6) for volunteers, in lesions (or the compressed cord) and normal cord for patients. DTI original images were processed to produce color DTI maps.

In the volunteers’ group, cervical cord exhibited blue on the color DTI map. FA values between four segments had a significant difference (P<0.01), with the highest FA value (0.85 ±  0.03) at C2/3 level. However, ADC value between them had no significant difference (P> 0.05). For patients, only 24 cases showed hyperintense on T2-weighted image, while 39 cases shown patchy green signal on color DTI maps. ADC and FA values between lesions or the compressed cord and normal spinal cord of patients had a significant difference (both P< 0.01). FA value at C2/3 cord is the highest of other segments and it gradually decreases towards the caudal direction. Using single-shot spin echo EPI sequence and six non-collinear diffusion directions with b  value of 400 s mm-2 ,

DTI can clearly show the intramedullary microstructure and more lesions than conventional MRI.

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Coregistered fluorescence-enhanced tumor resection of malignant glioma: relationships between δ-aminolevulinic acid–induced protoporphyrin IX fluorescence, magnetic resonance imaging enhancement, and neuropathological parameters

J Neurosurg 114:595–603,2011.DOI: 10.3171/2010.2.JNS091322.

The aim of this study was to investigate the relationships between intraoperative fluorescence, features on MR imaging, and neuropathological parameters in 11 cases of newly diagnosed glioblastoma multiforme (GBM) treated using protoporphyrin IX (PpIX) fluorescence-guided resection.

Methods. In 11 patients with a newly diagnosed GBM, δ-aminolevulinic acid (ALA) was administered to enhance endogenous synthesis of the fluorophore PpIX. The patients then underwent fluorescence-guided resection, coregistered with conventional neuronavigational image guidance. Biopsy specimens were collected at different times during surgery and assigned a fluorescence level of 0–3 (0, no fluorescence; 1, low fluorescence; 2, moderate fluorescence; or 3, high fluorescence). Contrast enhancement on MR imaging was quantified using two image metrics: 1) Gd-enhanced signal intensity (GdE) on T1-weighted subtraction MR image volumes, and 2) normalized contrast ratios (nCRs) in T1-weighted, postGd-injection MR image volumes for each biopsy specimen, using the biopsy-specific image-space coordinate transformation provided by the navigation system. Subsequently, each GdE and nCR value was grouped into one of two fluorescence categories, defined by its corresponding biopsy specimen fluorescence assessment as negative fluorescence (fluorescence level 0) or positive fluorescence (fluorescence level 1, 2, or 3). A single neuropathologist analyzed the H & E–stained tissue slides of each biopsy specimen and measured three neuropathological parameters: 1) histopathological score (0–IV); 2) tumor burden score (0–III); and 3) necrotic burden score (0–III).

Results. Mixed-model analyses with random effects for individuals show a highly statistically significant difference between fluorescing and nonfluorescing tissue in GdE (mean difference 8.33, p = 0.018) and nCRs (mean difference 5.15, p < 0.001). An analysis of association demonstrated a significant relationship between the levels of intraoperative fluorescence and histopathological score (χ2 = 58.8, p < 0.001), between fluorescence levels and tumor burden (χ2 = 42.7, p < 0.001), and between fluorescence levels and necrotic burden (χ2 = 30.9, p < 0.001). The corresponding Spearman rank correlation coefficients were 0.51 (p < 0.001) for fluorescence and histopathological score, and 0.49 (p < 0.001) for fluorescence and tumor burden, suggesting a strongly positive relationship for each of these variables.

Conclusions. These results demonstrate a significant relationship between contrast enhancement on preoperative MR imaging and observable intraoperative PpIX fluorescence. The finding that preoperative MR image signatures are predictive of intraoperative PpIX fluorescence is of practical importance for identifying candidates for the procedure. Furthermore, this study provides evidence that a strong relationship exists between tumor aggressiveness and the degree of tissue fluorescence that is observable intraoperatively, and that observable fluorescence has an excellent positive predictive value but a low negative predictive value.

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Gamma Knife radiosurgery for larger-volume vestibular schwannomas

J Neurosurg 114:801–807, 2011.DOI: 10.3171/2010.8.JNS10674

Stereotactic radiosurgery (SRS) is an important management option for patients with small- and medium- sized vestibular schwannomas. To assess the potential role of SRS in larger tumors, the authors reviewed their recent experience.

Methods. Between 1994 and 2008, 65 patients with vestibular schwannomas between 3 and 4 cm in one extracanalicular maximum diameter (median tumor volume 9 ml) underwent Gamma Knife surgery. Seventeen patients (26%) had previously undergone resection.

Results. The median follow-up duration was 36 months (range 1–146 months). At the first planned imaging follow-up at 6 months, 5 tumors (8%) were slightly expanded, 53 (82%) were stable in size, and 7 (11%) were smaller. Two patients (3%) underwent resection within 6 months due to progressive symptoms. Two years later, with 63 tumors overall after the 2 post-SRS resections, 16 tumors (25%) had a volume reduction of more than 50%, 22 (35%) tumors had a volume reduction of 10–50%, 18 (29%) were stable in volume (volume change < 10%), and 7 (11%) had larger volumes (5 of the 7 patients underwent resection and 1 of the 7 underwent repeat SRS). Eighteen (82%) of 22 patients with serviceable hearing before SRS still had serviceable hearing after SRS more than 2 years later. Three patients (5%) developed symptomatic hydrocephalus and underwent placement of a ventriculoperitoneal shunt. In 4 patients (6%) trigeminal sensory dysfunction developed, and in 1 patient (2%) mild facial weakness (House-Brackmann Grade II) developed after SRS. In univariate analysis, patients who had a previous resection (p = 0.010), those with a tumor volume exceeding 10 ml (p = 0.05), and those with Koos Grade 4 tumors (p = 0.02) had less likelihood of tumor control after SRS.

Conclusions. Although microsurgical resection remains the primary management choice in patients with low comorbidities, most vestibular schwannomas with a maximum diameter less than 4 cm and without significant mass effect can be managed satisfactorily with Gamma Knife radiosurgery.

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Counterbalancing risks and gains from extended resections in malignant glioma surgery: a supplemental analysis from the randomized 5-aminolevulinic acid glioma resection study

J Neurosurg 114:613–623, 2011. DOI: 10.3171/2010.3.JNS097

Accumulating data suggest more aggressive surgery in patients with malignant glioma to improve outcome. However, extended surgery may increase morbidity. The randomized Phase III 5-aminolevulinic acid (ALA) study investigated 5-ALA–induced fluorescence as a tool for improving resections. An interim analysis demonstrated more frequent complete resections with longer progression-free survival (PFS). However, marginal differences were found regarding neurological deterioration and the frequency of additional therapies. Presently, the authors focus on the latter aspects in the final study population, and attempt to determine how safety might be affected by cytoreductive surgery.

Methods. Patients with malignant gliomas were randomized for fluorescence-guided (ALA group) or conventional white light (WL) (WL group) microsurgery. The final intent-to-treat population consisted of 176 patients in the ALA and 173 in the WL group. Primary efficacy variables were contrast-enhancing tumor on early MR imaging and 6-month PFS. Among secondary outcome measures, the National Institutes of Health Stroke Scale (NIH-SS) score and the Karnofsky Performance Scale (KPS) score were used for assessing neurological function.

Results. More frequent complete resections and improved PFS were confirmed, with higher median residual tumor volumes in the WL group (0.5 vs 0 cm3, p = 0.001). Patients in the ALA group had more frequent deterioration on the NIH-SS at 48 hours. Patients at risk were those with deficits unresponsive to steroids. No differences were found in the KPS score. Regarding outcome, a combined end point of risks and neurological deficits was attempted, which demonstrated results in patients in the ALA group to be superior to those in participants in the WL group. Interestingly, the cumulative incidence of repeat surgery was significantly reduced in ALA patients. When stratified by completeness of resection, patients with incomplete resections were quicker to deteriorate neurologically (p = 0.0036).

Conclusions. Extended resections performed using a tool such as 5-ALA–derived tumor fluorescence, carries the risk of temporary impairment of neurological function. However, risks are higher in patients with deficits unresponsive to steroids.

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Surgery guided by 5-aminolevulinic fluorescence in glioblastoma: volumetric analysis of extent of resection in single-center experience

J Neurooncol (2011) 102:105–113.DOI 10.1007/s11060-010-0296-4

We analyzed the efficacy and applicability of surgery guided by 5-aminolevulinic acid (ALA) fluorescence in consecutive patients with glioblastoma multiforme (GBM).

Thirty-six patients with GBM were operated on using ALA fluorescence. Resections were performed using the fluorescent light to assess the right plane of dissection. In each case, biopsies with different fluorescent quality were taken from the tumor center, from the edges, and from the surrounding tissue. These samples were analyzed separately with hematoxylin–eosin examination and immunostaining against Ki67. Tumor volume was quantified with pre- and postoperative volumetric magnetic resonance imaging.

Strong fluorescence identified solid tumor with 100% positive predictive value. Invaded tissue beyond the solid tumor mass was identified by vague fluorescence with 97% positive predictive value and 66% negative predictive value, measured against hematoxylin–eosin examination. All the contrast-enhancing volume was resected in 83.3% of the patients, all patients had resection over 98% of the volume and mean volume resected was 99.8%. One month after surgery there was no mortality, and new or increased neurological morbidity was 8.2%.

The fluorescence induced by 5-aminolevulinic can help to achieve near total resection of enhancing tumor volume in most surgical cases of GBM. It is possible during surgery to obtain separate samples of the infiltrating cells from the tumor border.

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A 3-tier classification of cerebral arteriovenous malformations

J Neurosurg 114:842–849, 2011.DOI: 10.3171/2010.8.JNS10663

The authors propose a 3-tier classification for cerebral arteriovenous malformations (AVMs). The classification is based on the original 5-tier Spetzler-Martin grading system, and reflects the treatment paradigm for these lesions. The implications of this modification in the literature are explored.

Methods. Class A combines Grades I and II AVMs, Class B are Grade III AVMs, and Class C combines Grades IV and V AVMs. Recommended management is surgery for Class A AVMs, multimodality treatment for Class B, and observation for Class C, with exceptions to the latter including recurrent hemorrhages and progressive neurological deficits. To evaluate whether combining grades is warranted from the perspective of surgical outcomes, the 3-tier system was applied to 1476 patients from 7 surgical series in which results were stratified according to Spetzler- Martin grades.

Results. Pairwise comparisons of individual Spetzler-Martin grades in the series analyzed showed the fewest significant differences (p < 0.05) in outcomes between Grades I and II AVMs and between Grades IV and V AVMs. In the pooled data analysis, significant differences in outcomes were found between all grades except IV and V (p = 0.38), and the lowest relative risks were found between Grades I and II (1.066) and between Grades IV and V (1.095). Using the pooled data, the predictive accuracies for surgical outcomes of the 5-tier and 3-tier systems were equivalent (receiver operating characteristic curve area 0.711 and 0.713, respectively).

Conclusions. Combining Grades I and II AVMs and combining Grades IV and V AVMs is justified in part because the differences in surgical results between these respective pairs are small. The proposed 3-tier classification of AVMs offers simplification of the Spetzler-Martin system, provides a guide to treatment, and is predictive of outcome. The revised classification not only simplifies treatment recommendations; by placing patients into 3 as opposed to 5 groups, statistical power is markedly increased for series comparisons.

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Surgical treatment of trigonocephaly: technique and long-term results in 48 cases

J Neurosurg Pediatrics 7:000–000, 2011.DOI: 10.3171/2010.12.PEDS10359

The authors present their experience in the surgical treatment of metopic synostosis by orbital bandeau remodeling and frontal bone rotation. The pitfalls and advantages of the surgical technique are discussed, along with the long-term clinical results in 48 consecutive cases.

Methods. Forty-eight consecutive patients in whom trigonocephaly was diagnosed between 1990 and 2009 were treated with frontal bone rotation and frontoorbital bandeau remodeling. Of these patients, 38 (79%) were boys and 10 (21%) were girls. The age at the time of surgical treatment ranged between 4 and 42 months (mean ± SD 11.4 ± 8.7 months). The average follow-up period was 5.5 ± 4.2 years (range 5 months–19 years). The preoperative and latest postoperative photographs of the patients were evaluated for the following features: 1) shape of the forehead; 2) hypotelorism; and 3) temporal depression. Scores of 0, 1, or 2 were assigned for each item: 0 was normal, 1 meant moderate deformity, and 2 denoted severe deformity.

Results. In the early postoperative period, no complications were documented. The average hospitalization period was 4 days. Follow-up radiographs or 3D CT scans were obtained at regular intervals. The mean preoperative scores for the evaluated items were 1.38 ± 0.49 for the shape of the forehead, 1.33 ± 0.48 for hypotelorism, and 1.7 ± 0.46 for the temporal depression. The mean postoperative scores were 0.06 ± 0.24 for the shape of the forehead, 0.21 ± 0.4 for hypotelorism, and 0.67 ± 0.48 for the temporal depression. Overall, the total preoperative score dropped from 4.4 to 0.93 postoperatively (p < 0.05). All the patients were contented with the cosmetic results.

Conclusions. Early detection and treatment of metopic suture synostosis has a significant, favorable influence on the outcomes. Good understanding of the structural abnormality and the pathophysiological mechanisms of the possible complications is very important for performing proper surgical reconstruction.

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Identification of diagnostic serum protein profiles of glioblastoma patients

J Neurooncol (2011) 102:71–80.DOI 10.1007/s11060-010-0284-8

Diagnosis of a glioblastoma (GBM) is triggered by the onset of symptoms and is based on cerebral imaging and histological examination. Serum-based biomarkers may support detection of GBM. Here, we explored serum protein concentrations of GBM patients and used data mining to explore profiles of biomarkers and determine whether these are associated with the clinical status of the patients.

Gene and protein expression data for astrocytoma and GBM were used to identify secreted proteins differently expressed in tumors and in normal brain tissues. Tumor expression and serum concentrations of 14 candidate proteins were analyzed for 23 GBM patients and nine healthy subjects. Datamining methods involving all 14 proteins were used as an initial evaluation step to find clinically informative profiles.

Data mining identified a serum protein profile formed by BMP2, HSP70, and CXCL10 that enabled correct assignment to the GBM group with specificity and sensitivity of 89 and 96%, respectively (p< 0.0001, Fischer’s exact test). Survival for more than 15 months after tumor resection was associated with a profile formed by TSP1, HSP70, and IGFBP3, enabling correct assignment in all cases (p< 0.0001, Fischer’s exact test). No correlation was found with tumor size or age of the patient.

This study shows that robust serum profiles for GBM may be identified by data mining on the basis of a relatively small study cohort. Profiles of more than one biomarker enable more specific assignment to the GBM and survival group than those based on single proteins, confirming earlier attempts to correlate  single markers with cancer. These conceptual findings will be a basis for validation in a larger sample size.

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Video-Assisted Thoracoscopic Surgery Combined With a Tubular Retractor System for Minimally Invasive Thoracic Discectomy

Neurosurgery 68[ONS Suppl 1]:ons138–ons143, 2011 DOI: 10.1227/NEU.0b013e318209348c

Several approaches have been proposed for the treatment of thoracic disc herniations. Posterior approaches include transpedicular, costotransversectomy, and lateral extracavitary; anterior approaches include retropleural and transpleural thoracotomy and thoracoscopy.

OBJECTIVE: We present a novel minimally invasive approach to thoracic discectomies, combining thoracoscopy and a tubular retractor system. We discuss the utility and safety of this technique.

METHODS: The patient is placed in a lateral decubitus position, with a double-lumen endotracheal tube for single-lung ventilation. With use of thoracoscopic techniques, the disc space is identified; approximately 2 cm of the head and neck of the rib is removed to expose the pedicle of the lower vertebral body. The tubular retractor is deployed with continuous thoracoscopic visualization and a trough is created anterior to the canal by drilling the adjacent vertebral bodies straddling the disc space. The operative microscope is utilized to dissect the disc, pulling it anteriorly into the trough.

RESULTS: There were 5 patients in the past 9 months who were candidates for anterior thoracic discectomy. Disc herniations from T3-4 to T10-11 were treated without any significant complications. Patients were followed up clinically and radiographically.

CONCLUSION: Combining thoracoscopy with the tubular retractors allows continuous monitoring of the lung, aorta, and vena cava during the placement of the retractors. Additionally, use of the tubular retractors, as opposed to a complete thoracoscopic discectomy reduces the working distance and allows the use of the microscope with 3- dimensional visualization, thus enhancing the safety of this approach.

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Typical 3-D localization of tumor remnants of WHO grade II hemispheric gliomas—lessons learned from the use of intraoperative high-field MRI control

Acta Neurochir (2011) 153:479–487. DOI 10.1007/s00701-010-0911-3

Complete resection of grade II gliomas might prolong survival but is not always possible. The goal of the study was to evaluate the location of unexpected grade II gliomas remnants after assumed complete removal with intraoperative (iop) MRI and to assess the reason for their non-detection.

Methods Intraoperative MR images of 35 patients with hemispheric grade II gliomas, acquired after assumed complete removal of preoperatively segmented tumor/ tumor part, were studied for existence of unexpected tumor remnants. Remnants location was classified in relation to tumor cavity in axial and vertical planes. The relation of remnants to retractor position and to surgeons’ visual axis, and the role of neuronavigational accuracy and brain shift, was assessed.

Results Unexpected remnants were found in 16 patients (46%). In 29.2%, the reason was loss of neuronavigational accuracy. In 21%, remnants were in that part of the resection cavity, where the retractor had been placed initially. In 17%, they were deeply located and hidden by the retractor. In 13%, remnants were hidden by the overlapping brain; and in 21%, the reason was not obvious. In 75% of all temporomesial tumors, remnants were posterolateral to the resection cavity. Remnants detection with iopMRI and update of neuronavigational data allowed further removal in 14 of 16 cases. In two cases, remnant location precluded their removal.

Conclusions Distribution of tumor remnants of grade II gliomas tends to follow some patterns. Targeted attention to the areas of possible remnants could increase the radicality of surgery, even if intraoperative imaging is not performed.

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Stereotactic Brain Biopsy With a Low-Field Intraoperative Magnetic Resonance Imager

Neurosurgery 68[ONS Suppl 1]:ons217–ons224, 2011 DOI: 10.1227/NEU.0b013e31820826c2

Techniques for stereotactic brain biopsy have evolved in parallel with the imaging modalities used to visualize the brain.

OBJECTIVE: To describe our technique for performing stereotactic brain biopsy using a compact, low-field, intraoperative magnetic resonance imager (iMRI).

METHODS: Thirty-three patients underwent stereotactic brain biopsies with the PoleStar N-20 iMRI system (Medtronic Navigation, Louisville, Colorado). Preoperative iMRI scans were obtained for biopsy target identification and trajectory planning. A skull-mounted device (Navigus, Medtronic Navigation) was used to guide an MRI-compatible cannula to the target. An intraoperative image was acquired to confirm accurate cannula placement within the lesion. Serial images were obtained to track cannula movement and to rule out hemorrhage. Frozen sections were obtained in all but 1 patient with a brain abscess.

RESULTS: Diagnostic tissue was obtained in 32 of 33 patients. In all cases, imaging demonstrated cannula placement within the lesion. Histological diagnoses included 22 primary brain tumors and 10 nonneoplastic lesions. In 61% of the cases, initial trajectory was corrected on the basis of the intraoperative scans. In 1 patient, biopsy was nondiagnostic despite accurate cannula placement. No patient suffered a clinically or radiographically significant hemorrhage during or after surgery. There were no intraoperative complications.

CONCLUSION: Stereotactic biopsy with a low-field iMRI is an accurate way to obtain specimens with a high diagnostic yield. This accuracy, combined with the acceptable additional procedural time, may obviate the need for frozen section. The ability to correct biopsy cannula placement during surgery eliminates the chance of misdiagnosis because of faulty targeting, as well as the risks associated with inconclusive frozen sections and ‘‘blind’’ replacement of the cannula.

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A Moveable 3-Tesla Intraoperative Magnetic Resonance Imaging System

Neurosurgery 68[ONS Suppl 1]:ons168–ons179, 2011 DOI: 10.1227/NEU.0b013e3182045803

Based on success with a prototype 1.5T intraoperative magnetic resonance imaging (iMRI) system and the desire for increased signal-to-noise ratio, along with its relationship to image quality and advanced applications, a 3.0T system that uses the same novel moveable magnet configuration was developed.

OBJECTIVE: To assess clinical applicability by prospectively applying the higher-field system to a neurosurgical cohort.

METHODS: Upgrading to 3.0T required substantial modification of an existing iMRIequipped operating room. The 1.5T magnet was replaced with a ceiling-mounted, moveable 3.0T magnet with a 70-cm working aperture. Local radiofrequency shielding was replaced with whole-room shielding. A new hydraulic operating table, highperformance gradients, and advanced image processing software were also installed. The new system was used as an adjunct to standard neurosurgical practice.

RESULTS: The iMRI system upgrade required 6 months. Since completion, the 3.0T iMRI system has successfully guided neurosurgery in 120 patients without system failure in a patient-focused environment. Intraoperative image quality was superior to that obtained at 1.5T and enabled intraoperative acquisition of advanced imaging sequences, including tractography. Intraoperative imaging was found to modify surgery in a substantial number of patients.

CONCLUSION: Implementation of an iMRI system based on a moveable 3.0T magnet is feasible. From clinical experience with 120 patients, iMRI at 3.0T is safe, reliable, and capable of directing image-guided surgery with exceptional image quality.

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Lumbar spinal stenosis in elderly patients: is a unilateral microsurgical approach sufficient for decompression?

J Neurosurg Spine 14:305–312, 2011. DOI: 10.3171/2010.10.SPINE09708

For the treatment of lumbar spinal stenosis, less invasive procedures, which preserve maximal bony and ligamentous structures, have been recommended to reduce associated morbidity. The authors examined the outcome after decompression of spinal stenosis in the elderly by comparing 3 different surgical approaches. Their focus was whether a unilateral microsurgical decompression provided sufficient outcomes in the elderly population.

Methods. The authors investigated 108 elderly patients (age ≥ 60 years) with lumbar spinal stenosis (mean age 71 years [range 60–93 years]) who underwent surgery between 2004 and June 2006 at the authors’ institution. Three different modes of decompression were analyzed in this study: a unilateral partial hemilaminectomy, a hemilaminectomy, and a laminectomy. The outcome was assessed 12 months postoperatively using the Quebec Back Pain Disability Scale and the Hannover Functional Back Pain Questionnaire.

Results. The authors performed a unilateral partial hemilaminectomy in 53 patients (49%). Patients who underwent unilateral partial hemilaminectomies achieved favorable results of at least 80% as assessed using the Quebec Back Pain Disability Scale and Hannover Functional Back Pain Questionnaire. Hemilaminectomies were performed in 45 patients (41.7%), and laminectomies were performed in 10 patients (9.3%). However, there was no statistically significant difference between the various techniques regarding the postoperative results (p < 0.05).

Conclusions. Laminectomies did not show any advantage when compared with unilateral transmedian approaches. A unilateral partial hemilaminectomy combined with a transmedian decompression sufficiently treated the stenosis. This method seemed advantageous in minimizing the procedure and associated morbidity in this elderly population. Further investigations with long-term results (> 5 years) are still necessary.

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