Neurosurgery Blog

J Neurosurg 112:681–688, 2010. DOI: 10.3171/2009.4.JNS081377

The object of this study was to determine the efficacy of methylprednisolone in reducing symptomatic vasospasm and poor outcomes after subarachnoid hemorrhage (SAH).

Methods. Ninety-five patients with proven SAH were recruited into a double-blind, placebo-controlled, random- ized trial. Starting within 6 hours after angiographic diagnosis of aneurysm rupture, placebo or methylprednisolone, 16 mg/kg, was administered intravenously every day for 3 days to 46 and 49 patients, respectively. Deterioration, defined as development of a focal sign or decrease of more than 1 point on the Glasgow Coma Scale for more than 6 hours, was investigated by using clinical criteria and transcranial Doppler ultrasonography, cerebral angiography, or CT when appropriate. The end points were incidence of symptomatic vasospasm (delayed ischemic neurological deficits associated with angiographic arterial narrowing or accelerated flow on Doppler ultrasonography, or both) and outcome 1 year after entry into the study according to a simplified Rankin scale (Functional Outcome Scale [FOS]) in living patients and the Glasgow Outcome Scale in all patients included.

Results. All episodes of deterioration and all living patients with a 1-year outcome were assessed by a review committee. In patients treated with methylprednisolone, the incidence of symptomatic vasospasm was 26.5% com- pared with 26.0% in those given placebo. Poor outcomes according to FOS were significantly reduced in the Meth- ylprednisolone Group at 1 year of follow-up; the risk difference was 19.3% (95% CI 0.5–37.9%). The outcome was poor in 15% (6/40) of patients in the Methylprednisolone Group versus 34% (13/38) in the Placebo Group.

Conclusions. A safe and simple treatment with methylprednisolone did not reduce the incidence of symptomatic vasospasm but improved ability and functional outcome at 1 year after SAH.

J Neurosurg 112:648–657, 2010. DOI: 10.3171/2009.7.JNS081677

Intracranial pressure (ICP) monitoring is increasingly used in the treatment of patients with malignant middle cerebral artery (MCA) infarction. However, neurological deterioration may exist independent from intracranial hypertension. This study aimed to present the findings of continuous ICP monitoring in a cohort of patients with malignant MCA infarction and to correlate these findings with clinical and radiological features.

Methods. The authors studied a prospective cohort of 25 patients with malignant MCA infarction consecutively admitted to the neurotrauma intensive care unit of the Vall d’Hebron University Hospital between March 2002 and September 2006. The patients were treated using a combined protocol of initial moderate hypothermia and hemi-craniectomy. The latter was performed when patients showed a midline shift (MLS) ≥ 5 mm or ICP > 20 mm Hg. Six patients had an MLS ≥ 5 mm on the first CT scan and underwent surgery without prior ICP monitoring. This study focuses on the subgroup of 19 patients who underwent intraparenchymatous ICP monitoring before surgery.

Results. Intracranial pressure readings were evaluated and correlated with pupillary abnormalities, MLS, and ischemic tissue volume. In 12 of the 19 patients, ICP values were always ≤ 20 mm Hg, despite a mean (± SD) MLS of 6.7 ± 2 mm and a mean ischemic tissue volume of 241.3 ± 83 cm3. In 2 patients with anisocoria, ICP values were also normal.

Conclusions. In patients with a malignant MCA infarction, pupillary abnormalities and severe brainstem compression may be present despite normal ICP values. Therefore, continuous ICP monitoring cannot substitute for close clinical and radiological follow-up in the management of these patients.

Acta Neurochir (2010) 152:417–42.DOI10.1007/s00701-009-0525-9

Between 15 and 30 % of patients with subarachnoid hemorrhage (SAH) have no bleeding source and usually have a benign clinical course and outcome. The objectives of this study were to classify the pattern of blood distribution on initial computed tomography (CT) and to correlate it with clinical outcome in aneurysmal (ASAH) and SAH of unknown origin (SAHuO).

Methods We reviewed 112 CTs of SAHuO and 104 CTs of ASAH patients. Blood distribution was classified according to a new grading system (type 0–4) and correlated to Hunt and Hess (H&H) grade and modified Rankin scores (MRS) at short- and long-term follow-up.

Results Fifty percent of 112 SAHuO patients were classified as type 0 (no visible blood on CT) or 1 (blood restricted to prepontine cisterns). Most ASAH patients presented with bleeding into the lateral Sylvian fissure (66%; type 3) or with intracerebral hemorrhage (27%; type 4) whereas types 0 and 1 were not observed. SAHuO patients were in better clinical condition on admission than ASAH patients (p<0.0001). H&H grades of SAHuO patients correlated with the amount of subarachnoid blood according to the new classification (p=0.004). Short-term outcome was obtained from 100% and long-term outcome from 95% patients (follow-up 29±31 months). Short- and long-term MRS correlated with blood distribution in SAHuO patients (p=0.012) and was significantly better than in ASAH patients (p<0.0001). No correlation was observed between blood distribution, H&H grade, and short- and long-term outcome in aneurysmal patients.

Conclusions In SAH of unknown origin, a new classification allows to predict outcome based on the extent of blood on CT.

DOI: 10.1227/01.NEU.0000365518.47684.98

OBJECTIVES: Existing studies reporting the risk of surgery for brain arteriovenous malformations (AVMs) are often biased by the exclusion of patients not offered surgery. In this study, we examine the risk of surgery, including cases excluded from surgery because of the high surgical risk.
METHODS: Data were collected on 640 consecutively enrolled AVMs in a database that included all patients not considered for surgery.
RESULTS: Patients with Spetzler-Martin grade 1 to 2 AVMs (n = 296) were treated with a surgical risk of 0.7% (95% confidence interval [CI], 0%-3%); patients with Spetzler-Martin grade 3 to 4 AVMs in noneloquent cortex (n = 65) were treated with a surgical risk of 17% (95% CI, 10%-28%). Patients with Spetzler-Martin grade 3 to 5 AVMs in eloquent cortex (n = 168) were treated with a surgical risk of 21% (95% CI, 15%-28%). However, because 14% of patients in this series with similar AVMs were refused surgery because of perceived surgical risk, these results are not generalizable to the population of patients with similar AVMs.
CONCLUSION: The results of this series suggest that it is reasonable to offer surgery as a preferred treatment option for Spetzler-Martin grade 1 to 2 AVMs. This study also reinforces the predictive value of the Spetzler-Martin grading system, with some caveats.

DOI: 10.1227/01.NEU.0000365364.87303.AC

OBJECTIVE: The objective of this study was to determine cognitive functioning and health related quality of life one year after aneurysmal subarachnoid hemorrhage in preoperative comatose patients.

METHODS: Patients were investigated for one year using a comprehensive neuropsychological test battery and two HRQOL questionnaires.

RESULTS: Thirty-five of 70 patients survived the bleed, and 26 underwent neuropsychological testing. Two distinct patient groups emerged; one (n = 14) with good cognitive function, and the other (n = 12) with poor cognitive and motor function. Patients performing poorly were older (p = 0.04), had fewer years of education, (p = 0.005) larger preoperative ventricular scores, and were more often shunted (p = 0.02). There were also differences between the two groups in the Glasgow Outcome Scale (p = 0.001), modified Rankin Scale (p = 0.001), and employment status. HRQOL was more reduced in patients with poor cognitive function.

CONCLUSION: A high fraction of survivors among preoperative comatose aneurysmal SAH patients (Hunt and Hess grade V patients) recover to a good physical and cognitive function.

Neurosurgery 66:465-474, 2010 DOI: 10.1227/01.NEU.0000365272.77634.6B

OBJECTIVE: To evaluate the reliability of the gravitation-assisted adjustable proGAV shunt system with a prospective multicenter study conducted in 10 German hospitals.

METHODS: Enrollment for this observational study began in April 2005 and concluded in February 2006. The protocol required re-examinations 3 and 6 months postoperatively and fixed the endpoint of follow-up at 12 months after implantation. Patients with different types of adult, juvenile, and pediatric hydrocephalus were included and 165 patients were enrolled; 9 died and 12 had incomplete follow-up.

RESULTS: Of the assessable 144 patients, 130 completed the protocol after 12 months, whereas 14 failed because of the need to explant the device, mainly because of infection. In 12 patients, components of the shunt, not the valve, were revised. In 65 of the 144 patients, there were 102 readjustments of the valve in 67 incidences because of underdrainage and in 35 because of overdrainage. In 1 case, readjustment was not possible. Determination of pressure level with the verification instrument was safe and corresponded to the required x-ray controls after adjustments. No unintended readjustments were noted.

CONCLUSION: The proGAV is a safe and reliable device.

Neurosurgery 66:523-529, 2010 DOI: 10.1227/01.NEU.0000364996.97762.73

During the past decade, numerous reports have supported the contribution  of awake mapping in surgical removal of brain lesions in eloquent areas, with a significant  increase of the extent of resection while minimizing the risk of permanent deficit—and  even improving quality of life.

METHODS: Most of these awake procedures were performed in patients with lesions in  language areas, to avoid postoperative aphasia. Surprisingly, mapping of nonlanguage  functions received less attention, despite the possible consequences of deficits other than  aphasia on daily life. Visuospatial and cognitive deficits are reported after brain surgery,  because of more objective and extensive neuropsychological assessments.

RESULTS AND CONCLUSION: This review provides new insights into the indications of  awake craniotomies for nonlanguage mapping in surgery for lesions in areas not related  to language processing.

Acta Neurochir (2010) 152:393–404. DOI 10.1007/s00701-009-0529-5

Degenerative disc disease is one of the most frequent spinal disorders. The anatomy and the biomechanics of the intervertebral disc are very complex, and the pathomechanics of its degeneration are poorly understood. Despite this complexity and uncertainty, great advances have been made in the field of disc replacement technology, with promising results. Difficulties are continuously being encountered, but careful analysis of the results and intensive research and development will assist in countering these problems. There are approximately 40 clinical reports in the literature describing various aspects of randomised controlled trials involving intervertebral disc arthroplasty. However, the majority of these publications do not provide reliable information, in that they give only interim results and/or the results from just one of the many centres in multicentre studies. Such publications must be interpreted with caution, since they do not always represent the results of the whole study population and may hence be underpowered. We identified six randomised controlled trials that compared the final clinical outcomes of disc arthroplasty and spinal fusion. The present systematic review attempts to give an overview of the current status of disc arthroplasty.

J Neurooncol (2010) 96:385–392. DOI 10.1007/s11060-009-9970-9

Apparent diffusion coefficient (ADC) describes water diffusion within tissues. Previous studies report a negative linear correlation between minimum ADC and tumour cellularity in different types of gliomas, but there are no studies in oligodendroglial tumours. This study evaluated the relationship between ADC and tumour cellularity in oligodendroglial tumours characterized by genotype.

Methods: ADC was assessed in 17 patients with known 1p/19q status: 3 grade II oligodendrogliomas (OII), 9 grade II oligoastrocytomas (OAII), 5 grade III oligoastrocytomas (OAIII). Regions of interest were placed on ADC maps around tumour margins to generate mean tumour ADC, and over minimum and maximum tumour ADC. Histopathology assessment of tumour cellularity determined minimum, maximum and mean cell density in serial stereotactic biopsies.

Results: 1p/19q loss was present in 2/3 OII, 5/9 OAII, 2/5 OAIII. Grade III tumours had higher maximum cell density than grade II tumours (17.2 vs. 10.57%: Mann Whitney U; P = 0.20). Oligoastrocytoma were more likely to have a lower minimum cell density than oligodendrogliomas (Mann Whitney U; P = 0.032). There was no relationship between cell density and genotype. There was no linear correlation between mean ADC and mean cell density (Spearman’s rho; r = 0.486: P = 0.438), minimum ADC and maximum cell density (Spearman’s rho; r = 0.158: P = 0.660), and maximum ADC and minimum cell density (Spearman’s rho; r = 0.039: P = 0.985).

Conclusions: In oligodendroglial tumours there is no relationship between quantitative assessment of cellularity and ADC. This may reflect differences in oligodendroglial tumour biology compared to other gliomas, although the composition of the extracellular matrix may influence ADC more than cellularity.

J Neurosurg Spine 12:144–153, 2010. (DOI: 10.3171/2009.6.SPINE08910)

The goal in this study was to review a series of patients who underwent surgical removal of intramedul- lary high-grade gliomas, focusing on the functional outcome, recurrence rates, and technical problems continually debated in neurosurgical practice.

Methods. Between December 1976 and December 2006, 22 patients underwent removal of intramedullary high- grade gliomas. Lesions were located in the cervical spinal cord in 12 patients, and in the thoracic cord in 10.

Results. Histological examinations showed 10 Grade III astrocytomas and 12 glioblastomas. Only 2 of the 22 high-grade astrocytomas could be completely removed. The clinical postoperative status worsened in 14 patients (63.6%), was unchanged in 7 patients (31.8%), and there was 1 case of intraoperative death (4.5%). None of the 22 patients showed improvement in their neurological status postoperatively. In this series, excluding the 1 intraopera- tive death, all patients died of progression of the malignancy.

Conclusions. Surgical treatment did not ameliorate the postoperative neurological status; instead, in the majority of cases, it prompted a worsening of the deficit. Radiotherapy and chemotherapy have a little influence on the length of survival. In this series, multimodality treatment of intramedullary high-grade astrocytomas has been shown to increase length of survival without improving the neurological status.

Neurosurgery: February 2010 – Volume 66 – Issue 2 – p 368–375. doi: 10.1227/01.NEU.0000363858.17782.82

Microsurgical and endoscopic colloid cyst excision differ with regard to operative time, length of hospital stay, and extent of resection.

METHODS: A retrospective review of a single surgeon’s microsurgical colloid cyst resection in 10 consecutive patients was performed. Cyst size, hydrocephalus, symptoms, operative time, postoperative stay, complications, and objective testing of memory, concentration, calculation, and attention (cognition), along with performance at job, were noted.

RESULTS: All 10 patients had complete excision. Mean cyst size, mean operative time, and median postoperative stay were 1.6 cm, 124 minutes, and 3.5 days respectively. The mean operative time from cyst visualization to complete excision was 18 minutes. Follow-up ranged from 6 to 111 months (mean, 49.5 months). There were no recurrences; symptoms (headache, visual and balance problems) improved significantly in 70%. Postoperative cognitive performance, including memory, was the same in 8 patients (5 of whom had preoperative memory problems) and worse in 2 patients who had no preoperative memory problems. The bone flap was removed in 1 patient for wound dehiscence. Hemiparesis in another patient, seen immediately after surgery, completely resolved before discharge. One patient with loculated ventricles and multiple previous shunt revisions had unresolved hydrocephalus after cyst excision.

CONCLUSION: We report the very short operative times and postoperative stay for microsurgery, which are comparable to some endoscopic series. We also report results of objective tests of cognitive performance. With adoption of a callosal incision of 1 cm or less, meticulous dissection around the fornix, and complete excision, acceptable long-term cognitive function and functional performance were achieved. Our results support the microsurgical approach. A larger sample size can more conclusively establish whether it should be chosen over the endoscopic technique.

Journal of Neurosurgery: Pediatrics. (DOI: 10.3171/2009.9.PEDS09196)

In Uganda, childhood hydrocephalus is common and difficult to treat. In some children, endoscopic third ventriculostomy (ETV) can be successful and avoid dependence on a shunt. This can be especially beneficial in Uganda, because of the high risk of infection and long-term failure associated with shunting. Therefore, the authors developed and validated a model to predict the chances of ETV success, taking into account the unique characteristics of a large sub-Saharan African population.

Methods. All children presenting with hydrocephalus at CURE Children’s Hospital of Uganda (CCHU) between 2001 and 2007 were offered ETV as first-line treatment and were prospectively followed up. A multivariable logistic regression model was built using ETV success at 6 months as the outcome. The model was derived on 70% of the sample (training set) and validated on the remaining 30% (validation set).

Results. Endoscopic third ventriculostomy was attempted in 1406 patients. Of these, 427 were lost to followup prior to 6 months. In the remaining 979 patients, the ETV was aborted in 281 due to poor anatomy/visibility and in 310 the ETV failed during the first 6 months. Therefore, a total of 388 of 979 (39.6% and [55.6% of completed ETVs]) procedures were successful at 6 months. The mean age at ETV was 12.6 months, and 57.8% of cases were postinfectious in origin. The authors’ logistic regression model contained the following significant variables: patient age at ETV, cause of hydrocephalus, and whether choroid plexus cauterization was performed. In the training set (676 patients) and validation set (303 patients), the model was able to accurately predict the probability of successful ETV (Hosmer-Lemeshow p value > 0.60 and C statistic > 0.70). The authors developed the simplified CCHU ETV Success Score that can be used in the field to predict the probability of ETV success.

Conclusions. The authors’ model will allow clinicians to accurately identify children with a good chance of successful outcome with ETV, taking into account the unique characteristics and circumstances of the Ugandan population.

J Neurosurg Spine 12:214–220, 2010 (DOI: 10.3171/2009.9.SPINE08952)

Object. Using a synthetic vertebral model, the authors quantified the comparative fixation strengths and failure mechanisms of 6 cervical disc arthroplasty devices versus 2 conventional methods of cervical arthrodesis, highlighting biomechanical advantages of prosthetic endplate fixation properties.
Methods. Eight cervical implant configurations were evaluated in the current investigation: 1) PCM Low Profile; 2) PCM V-Teeth; 3) PCM Modular Flange; 4) PCM Fixed Flange; 5) Prestige LP; 6) Kineflex/C disc; 7) anterior cervical plate + interbody cage; and 8  ) tricortical iliac crest. All PCM treatments contained a serrated implant surface (0.4 mm). The PCM V-Teeth and Prestige contained 2 additional rows of teeth, which were 1 mm and 2 mm high, respectively. The PCM Modular and Fixed Flanged devices and anterior cervical plate were augmented with 4 vertebral screws. Eight pullout tests were performed for each of the 8 conditions by using a synthetic fixation model consisting of solid rigid polyurethane foam blocks. Biomechanical testing was conducted using an 858 Bionix test system configured with an unconstrained testing platform. Implants were positioned between testing blocks, using a compressive preload of −267 N. Tensile load-to-failure testing was performed at 2.5 mm/second, with quantification of peak load at failure (in Newtons), implant surface area (in square millimeters), and failure mechanisms.
Results. The mean loads at failure for the 8 implants were as follows: 257.4 ± 28.54 for the PCM Low Profile; 308.8 ± 15.31 for PCM V-Teeth; 496.36 ± 40.01 for PCM Modular Flange; 528.03± 127.8 for PCM Fixed Flange; 306.4 ± 31.3 for Prestige LP; 286.9 ± 18.4 for Kineflex/C disc; 635.53 ± 112.62 for anterior cervical plate + interbody cage; and 161.61 ± 16.58 for tricortical iliac crest. The anterior plate exhibited the highest load at failure compared with all other treatments (p < 0.05). The PCM Modular and Fixed Flange PCM constructs in which screw fixation was used exhibited higher pullout loads than all other treatments except the anterior plate (p < 0.05). The PCM VTeeth and Prestige and Kineflex/C implants exhibited higher pullout loads than the PCM Low Profile and tricortical iliac crest (p < 0.05). Tricortical iliac crest exhibited the lowest pullout strength, which was different from all other treatments (p < 0.05). The surface area of endplate contact, measuring 300 mm2 (PCM treatments), 275 mm2 (PrestigeLP), 250 mm2 (Kineflex/C disc), 180 mm2 (plate + cage), and 235 mm2 (tricortical iliac crest), did not correlate with pullout strength (p > 0.05). The PCM, Prestige, and Kineflex constructs, which did not use screw fixation, all failed by direct pullout. Screw fixation devices, including anterior plates, led to test block fracture, and tricortical iliac crest failed by direct pullout.
Conclusions. These results demonstrate a continuum of fixation strength based on prosthetic endplate design.Disc arthroplasty constructs implanted using vertebral body screw fixation exhibited the highest pullout strength. Prosthetic endplates containing toothed ridges (≥ 1 mm) or keels placed second in fixation strength, whereas endplates containing serrated edges exhibited the lowest fixation strength. All treatments exhibited greater fixation strength than conventional tricortical iliac crest. The current study offers insights into the benefits of various prosthetic endplate designs, which may potentially improve acute fixation following cervical disc arthroplasty.

Neurosurg Focus 28 (2):E8, 2010. DOI: 10.3171/2009.12.FOCUS09236

Recent surgical studies have demonstrated that the extent of resection is significantly correlated with median survival in WHO Grade II gliomas. Consequently, thanks to advances in intraoperative functional mapping, the authors questioned whether it is actually necessary to leave a “security” margin around eloquent structures.
Methods. The authors first reviewed the classic literature, especially that based on epilepsy surgery and functional neuroimaging techniques, which led them to propose the rule of a security margin. Second, they detailed new developments in the field of intrasurgical electrical mapping, especially with regard to subcortical stimulation of the projection and long-distance association pathways. On the basis of these advances, the removal of gliomas according to functional boundaries has recently been suggested, with no margin around eloquent structures.
Results. Comparative results showed that the rate of permanent deficit was similar with or without a security margin, that is, < 2%. However, a higher rate of transient neurological worsening in the immediate postsurgical period was associated with the absence of a margin, with recovery following adapted rehabilitation. On the other hand, the extent of resection was in essence improved with no margin.
Conclusions. This no-margin technique, based on the subpial dissection, and the repetition of both cortical and subcortical stimulation to preserve eloquent cortex as well as the white matter tracts (U-fibers, projection pathways, and long-distance connectivity) allow optimization of the extent of resection while preserving the quality of life (despite transitory impairment) thanks to mechanisms of brain plasticity.

The Spine Journal 10 (2010) 159–166

Bupivacaine is a local anesthetic commonly used to relieve or control pain in interventional spine procedures. Bupivacaine has been shown to be toxic to articular cartilage, which has similarities to intervertebral disc (IVD) cartilage, raising concern over a potentially negative effect of bupivacaine on the disc.

PURPOSE: To determine bupivacaine’s effect on cell viability of IVD cells in vitro and to elucidate whether this is through apoptosis or necrosis.

STUDY DESIGN: In vitro controlled study of bupivacaine effect on cell viability in human and rabbit IVD cells.

SUBJECTS: Rabbit annulus fibrosus (AF) tissue, nucleus pulposus (NP) cells, and knee articular chondrocytes were isolated from New Zealand white rabbits. Human AF and NP cells were isolated from stage 3 to 4 degenerative disc surgical specimens.

OUTCOME MEASURES: Cell viability was assessed after exposure to bupivacaine via trypan blue staining or flow cytometry.

METHODS: Annulus fibrosus and NP cells were grown in monolayer and alginate beads, respectively, to simulate their physiologic environment. The cells were then exposed to bupivacaine or saline control at 60 and 120 minutes and examined for cell viability. RESULTS: Rabbit NP cell death demonstrated a time and dose dependence in response to bupivacaine. In addition, cell death was greater than that observed for articular chondrocytes. Rabbit AF tissue also demonstrated increased cell death in response to bupivacaine exposure. Human NP cells demonstrated time-dependent cell death, with greater necrosis than apoptosis. Annulus fibrosus cells grown in monolayers also resulted in similar effects, with greater necrosis rather than apoptosis.

CONCLUSIONS: Despite its pain relieving properties, bupivacaine decreases cell viability in rabbit and human disc cells in a time-dependent manner. In addition, the changes observed are greater than that seen for articular chondrocytes. This increase in cell death appears to be related to an increase in necrosis rather than apoptosis. Whether bupivacaine exerts similar effects in vivo or how this relates to overall clinical outcome remains to be explored.

Acta Neurochir (2010) 152:213–219. DOI 10.1007/s00701-009-0427-x

With the frequent use of magnetic resonance imaging (MRI), patients with subtle and diffuse symptoms due to small syrinx cavities increasingly present to neurosurgical care. In this respect, a dilated central canal, hydromyelia, must be separated from patients with true syringomyelia with an underlying disorder, as they do not share clinical and radiological features. We hypothesize that a differentiation of these two entities with distinct diagnostic tools is possible.

Methods To describe the entity of hydromyelia, we excluded all patients from the syringomyelia database (n=142) with any obvious cause of a syringomyelia, any objective neurological deficits on clinical examination, pathological results on electrophysiological monitoring (SSEP, MEP, silent periods) or a widening of the spinal cord cavity of more than 6 mm on MRI [routine acquisitions with FLAIR, T1/T2-weighted images, Cine and CISS (constructive interference in steady-state) studies]. Life quality was assessed through SF-36 questionnaires and an individualized questionnaire for the clinical history, pain and alternative therapies.

Results Forty patients (15 males/25 females) matched the criteria of a hydromyelia. With a mean age of 36.7 years (range 11–62), they almost all presented with pain (79%) or dysaesthesia of the limbs, with some having been an incidental finding (10%). Over a follow-up time of 36.9 months (range 6–93) there was no neurological or radiological deterioration.

Conclusions Patients with a hydromyelia do not share clinical or radiological characteristics with patients harbouring a true syringomyelia. As hydromyelia does not represent a disease with an underlying pathology, no clinical or radiological progression has been seen. With sophisticated diagnostic tools to rule out any pathology this subset of patients can be identified.

INTRODUCTION:We evaluated the feasibility, usefulness, and limitations of near-infrared indocyanine green (ICG) videoangiography during procedures involving the extracranial vertebral artery (VA).

METHODS: Nine patients (2 women, 7 men; mean age, 55 years) were evaluated at 2 neurosurgical centers. Near-infrared ICG videoangiography was applied during transposition and rerouting of the first segment of VA (V1; n = 6) and during resection of neurinomas near the second (V2; n = 1) and third (V3; n = 2) segments of VA.

RESULTS: Early after ICG injection, V1 fluoresced homogenously. The fluorescence of V2 and V3 varied. Without extrinsic compression, these segments appeared as noncontiguous hot spots because the VA runs freely in a periosteal sheath surrounded by a venous plexus that attenuates the fluorescent light. Hot spots corresponded to areas where the artery neared the surface. With extrinsic compression, VA enhanced homogenously because it was pushed against the periosteal layer. During the late phase, the V1 signal was attenuated, whereas the venous plexus surrounding V2 and V3 enhanced homogeneously, thereby masking the VA itself. Near-infrared ICG videoangiography helped to confirm VA patency during transposition and rerouting but was not helpful during VA exposure because the periosteal sheath must already be exposed to detect the VA or its surrounding plexus. After exposure, videoangiography can help to determine the position of the VA within its periosteal sheath.

CONCLUSION: Videoangiography can be used to provide information about the patency of the VA and its location within the periosteal sheath to prevent injury during resection of tumor adherent to the periosteal sheath.

J Neurosurg 112: 399–409, 2010. (DOI: 10.3171/2009.4.JNS081664)

Object. The test-retest method is commonly used in the management of patients with normal-pressure hydrocephalus (NPH). One of the most widely used techniques in the diagnosis of this condition is evaluation of the
patient’s response to CSF evacuation by lumbar puncture (a so-called tap test or spinal tap). However, interpretation of improved results in subsequent evaluations is controversial because higher scores could reflect a real change in specific abilities or could be simply the result of a learning effect.
Methods. To determine the effect of testing-retesting in patients with NPH, the authors analyzed changes documented on 5 neuropsychological tests (the Toulouse-Pieron, Trail Making Test A, Grooved Pegboard, Word Fluency, and Bingley Memory tests) and several motor ability scales (motor performance test, length of step, and walking speed tests) in a series of 32 patients with NPH who underwent the same battery on 4 consecutive days. The same tests were also applied in 30 healthy volunteers. In both groups, the authors used the generalized least-squares regression method with random effects to test for learning effects. To evaluate possible differences in response depending on the degree of cognitive impairment at baseline, the results were adjusted by using the Mini-Mental State Examination scores of patients and controls when these scores were significant in the model.
Results. In patients with NPH there were no statistically significant differences in any of the neuropsychological
or motor tests performed over the 4 consecutive days, except in the results of the Toulouse-Pieron test, which
were significantly improved on Day 3. In contrast, healthy volunteers had statistically significant improvement in the results of the Toulouse-Pieron test, Trail Making Test A, and Grooved Pegboard test but not in the remaining neuropsychological tests. Patients in the healthy volunteer group also exhibited statistically significant improvement in the motor performance test but not in step length or walking speed.
Conclusions. No learning effect was found in patients with NPH on any of the neuropsychological or motor tests. Clinical improvement after retesting in these patients reflects real changes, and this strategy can therefore be used in both the diagnosis and evaluation of surgical outcomes.

J Neurosurg 112:345–353, 2010.(DOI: 10.3171/2009.6.JNS09223)

Object. An important complication of external CSF drainage is bacterial meningitis or ventriculitis, resulting in increased morbidity, mortality, and health care costs. In 2003, a high rate (37%) of probable drain-related infections was identified at the authors’ hospital. A multidisciplinary working group was installed to reduce this incidence to < 10% within 1.5 years.

Methods. An intervention strategy based on 5 pillars (increased awareness, focused standard operating procedures, a diagnostic and therapeutic algorithm, timely administration of prophylaxis, and improvement of the drainage system) was designed and implemented from 2004 to 2006. During this period all patients with external CSF drainage were prospectively monitored.

Results. Between 2004 and 2006, there were 467 patients in whom 579 drains (external ventricular and exter- nal lumbar) had been placed. The overall incidence of drain-related infections was 16.2% in 2004, 8.9% in 2005, and 11.3% in 2006. For external lumbar drains the number of infections per 100 drain days was 2.4 in 2004, 0.6 in 2005, and 0.8 in 2006. For external ventricular drains these rates were 1.7, 1.0, and 1.2, respectively. Meanwhile, the causative noncutaneous microorganisms, indicative for systemic-contamination during manipulation, decreased. By retrospective analysis, the proportion of patients with a probable drain-related infection decreased from 37% in 2003 to 9% in 2005 and 2006.

Conclusions. The authors’ multidisciplinary approach in which different preventive measures were combined was associated with a significant reduction in the incidence of drain-related secondary meningitis, and thus provides an important improvement of patient safety.

Neurosurgery 66:389-399, 2010. DOI: 10.1227/01.NEU.0000363702.67016.5D

OBJECTIVE: The supracerebellar infratentorial (SCIT) approach can be performed at the midline (median variant), lateral to the midline (paramedian variant), or at the level of the angle formed by the transverse and sigmoid sinuses (extreme lateral variant). We analyzed our experience with SCIT approaches for the surgical treatment of cavernous malformations of the brainstem (CMBs).

METHODS: Demographic, clinical, radiologic, and surgical data from 45 patients (20 males and 25 females; mean age, 36.2 years) with CMBs surgically removed through SCIT approaches were reviewed retrospectively. Anatomic information was explored using cadaver head dissection.

RESULTS: Twenty-three lesions were in the midbrain, 3 were at the midbrain and extended to the thalamus, 9 were at the pontomesencephalic junction, and 10 were in the upper pons. All patients presented with hemorrhage. The median variant was used in 13 patients, the paramedian variant in 9, and the extreme lateral variant in 23. Intraoperatively, all CMBs were associated with a developmental venous anomaly. At last follow-up, 88% of the patients were the same or better. After a mean follow-up of 20 months, their mean Glasgow Outcome Scale score was 4.1.

CONCLUSION: SCIT approaches provide excellent exposure to CMBs located at the posterior incisural space, not only in the midline but also in the posterolateral surface of the upper pons and midbrain. Careful preoperative planning and neuronavigational assistance are needed to determine the best angle of attack and trajectory for SCIT approaches. Refined microsurgical techniques are paramount to achieve safe surgical removal of CMBs with good outcomes.