Impact of a new metal artefact reduction algorithm in the noninvasive follow-up of intracranial clips, coils, and stents with flat-panel angiographic CTA: initial results.

INTRODUCTION: Flat-panel angiographic CT after intravenous contrast agent application (ivACT) is increasingly used as a follow-up examination after coiling, clipping, or stenting. The purpose of this study was to evaluate the feasibility of a new metal artefact reduction algorithm (MARA) in patients treated for intracranial aneurysms and stenosis. METHODS: IvACT was performed on a flat-panel detector angiography system after intravenous application of 80 ml contrast media. The uncorrected raw images were transferred to a prototype reconstruction workstation where the MARA was applied. Two experienced neuroradiologists examined the corrected and uncorrected images on a commercially available workstation. RESULTS: Artefacts around the implants were detected in all 16 uncorrected cases, while eight cases showed remaining artefacts after correction with the MARA. In the cases without correction, there were 11 cases with "extensive" artefacts and five cases with "many" artefacts. After correction, seven cases showed "few" and only one case "many" artefacts (Wilcoxon test, P < 0.001). Parent vessels were characterized as "not identifiable" in 62% of uncorrected images, while the delineation of parent vessels were classified as "excellent" in 50% of the cases after correction (Wilcoxon test, P = 0.001). CONCLUSIONS: Use of the MARA in our study significantly reduced artefacts around metallic implants on ivACT images and allowed for the delineation of surrounding structures.

Cranioplasty after decompressive hemicraniectomy: underestimated surgery-associated complications?

OBJECTIVE: Decompressive hemicraniectomy (DC) and duroplasty after malignant brain infarction or traumatic brain injury is a common surgical procedure. Usually, preserved bone flaps are being reimplanted after resolution of brain swelling. Alloplast cranioplasties are seldom directly implanted due to the risk of wound healing disorders. While numerous studies deal with DC, little is known about the encountered problems of bone flap reimplantation. Thus, aim of the study was to identify surgery-associated complications after bone flap reimplantation. METHODS: We performed a retrospective chart analysis of patients that underwent DC and subsequent bone flap reimplantation between 2001 and 2011 at our institution. We registered demographic data, initial clinical diagnosis and surgery-associated complications. RESULTS: We identified 136 patients that underwent DC and subsequent reimplantation. Forty-one patients (30.1%) had early or late surgery-associated complications after bone flap reimplantation. Most often, bone flap resorption and postoperative wound infections were the underlying causes (73%, n=30/41). Multivariate analysis identified age (p=0.045; OR=16.30), GOS prior to cranioplasty (p=0.03; OR=2.38) and nicotine abuse as a prognostic factor for surgery-associated complications (p=0.043; OR=4.02). Furthermore, patients with early cranioplasty had a better functional outcome than patients with late cranioplasty (p<0.05). CONCLUSIONS: Almost one-third of the patients that are operated on for bone flap reimplantation after DC suffer from surgery-associated complications. Most often, wound healing disorders as well as bone flap resorption lead to a second or even third operation with the need for artificial bone implantation. These results might raise the question, if subsequent operations can be avoided, if an artificial bone is initially chosen for cranioplasty.

Indocyanine green angiography in endoscopic third ventriculostomy.

BACKGROUND: Endoscopic third ventriculostomy (ETV) has become a well-established method for the treatment of noncommunicating hydrocephalus with a high success rate and a relatively low morbidity rate. However, vessel injury has been repeatedly reported, often with a fatal outcome. Vessel injury is considered to be the most threatening complication. The use of indocyanine green (ICG) angiography has become an established tool in vascular microneurosurgery. OBJECTIVE: We report our initial experience with endoscopic ICG angiography in ETV for intraoperative visualization of the basilar artery and its perforators to reduce the risk of vascular injury. METHODS: Eleven patients with noncommunicating hydrocephalus underwent ETV. Before opening of the third ventricular floor, ICG angiography was performed using a prototype neuroendoscope for intraoperative visualization of ICG fluorescence. RESULTS: In 10 patients, ETV and ICG angiography were successfully performed. In 1 case, ICG angiography failed. Even in the presence of an opaque floor of the third ventricle (n = 5), ICG angiography clearly demonstrated the course of the basilar artery and its major branches and was considered useful. CONCLUSION: ICG angiography has the potential to become a useful adjunct in ETV for better visualization of vessel structures, especially in the presence of aberrant vasculature, a nontranslucent floor of the third ventricle, or in case of reoperations.

Fluorescence-guided operation in recurrent glioblastoma multiforme treated with bevacizumab-fluorescence of the noncontrast enhancing tumor tissue?

The oral application of 5-aminolevulinic acid (ALA) leads to an accumulation of fluorescent porphyrins in malignant glioma tissue, which simplifies complete tumor resection. If pretreated with bevacizumab, a vascular endothelial growth factor (VEGF) antibody, these patients might not show a contrast enhancement on magnetic resonance imaging (MRI) despite tumor progression. As VEGF antibodies induce a normalization of the tumor vasculature, it is not known whether fluorescence-guided surgery is of any value in patients pretreated with this antibody. One might speculate that missing contrast enhancement on MRI could result in minor or missing fluorescence after the application of ALA. Attempting to give some answers, we report the case of a patient who underwent fluorescence-guided reoperation of recurrent glioblastoma multiforme pretreated with bevacizumab.

Spinal cord cavernoma--operative strategy and results in 30 patients.

BACKGROUND: Many case reports and small series addressing the surgical management of spinal cord cavernoma have been published. However, only few larger series that would allow identifying operative strategies exist. After having treated 30 patients, we feel encouraged to report our experiences. METHODS: A total of 30 patients (13 men and 17 women) were mainly admitted to our institution because of sensory deficits (83.3%), paresis (33.3%), and bladder dysfunction (26.6%). Magnetic resonance imaging revealed a spinal cavernoma mostly in the thoracic region (63.3%). All patients underwent surgery. The relation between pial surface and cavernoma guided the choice of approach and the myelotomy site. RESULTS: After laminectomy/laminoplasty, median myelotomy was done in 16.7% to reach a medially located cavernoma. In 60.0%, myelotomy was located at the dorsal root entry zone, for which a (partial) hemilaminectomy was sufficient. The laterality of the location guided the bony approach in the remaining 23.3% with exophytic cavernoma. Immediately after surgery, neurological worsening was seen in 56.7%, an improvement in 10.0% and an unchanged neurological status in 33.3%. During the follow-up, the rate of neurological worsening dropped to 10.0%, the improvement rate increased to 50.0%. In 40.0% of the patients, the symptoms remained unchanged or returned to preoperative status. CONCLUSION: The exact localization in relation to the pial surface guides the approach and area of myelotomy. In the majority of patients limited approaches are sufficient for successful cavernoma removal. In our series anterior approaches had not been necessary.

The role of neuronavigation in intracranial endoscopic procedures.

In occlusive hydrocephalus, cysts and some ventricular tumours, neuroendoscopy has replaced shunt operations and microsurgery. There is an ongoing discussion if neuronavigation should routinely accompany neuroendoscopy or if its use should be limited to selected cases. In this prospective clinical series, the role of neuronavigation during intracranial endoscopic procedures was investigated. In 126 consecutive endoscopic procedures (endoscopic third ventriculostomy, ETV, n = 65; tumour biopsy/resection, n = 36; non-tumourous cyst fenestration, n = 23; abscess aspiration and hematoma removal, n = 1 each), performed in 121 patients, neuronavigation was made available. After operation and videotape review, the surgeon had to categorize the role of neuronavigation: not beneficial; beneficial, but not essential; essential. Overall, neuronavigation was of value in more than 50% of the operations, but its value depended on the type of the procedure. Neuronavigation was beneficial, but not essential in 16 ETVs (24.6%), 19 tumour biopsies/resections (52.7%) and 14 cyst fenestrations (60.9%). Neuronavigation was essential in 1 ETV (2%), 11 tumour biopsies/resections (30.6%) and 8 cyst fenestrations (34.8%). Neuronavigation was not needed/not used in 48 ETVs (73.9%), 6 endoscopic tumour operations (16.7%) and 1 cyst fenestration (4.3%). For ETV, neuronavigation mostly is not required. In the majority of the remaining endoscopic procedures, however, neuronavigation is at least beneficial. This finding suggests integrating neuronavigation into the operative routine in endoscopic tumour operations and cyst fenestrations.

Pituitary insufficiency after operation of supratentorial intra- and extraaxial tumors outside of the sellar-parasellar region?

Recent studies investigating pituitary function after non-sellar brain tumor surgery showed that up to 38.2% of patients have pituitary insufficiency (PI). It has been assumed that the operation causes the PI, but preoperative hormone testing, which would have been necessary to prove this assumption, was not performed. The objective of this study is to answer the question if indeed microsurgery is the culprit of PI in patients with operatively treated non-sellar brain tumors. In this prospective trial, 54 patients with supratentorial non-sellar tumors were included. The basal levels of cortisol, prolactin, testosterone, estrogen, IGF-1, fT3, fT4, STH, TSH, ACTH, FSH, and LH were recorded preoperatively on days 1 and 7 after surgery. If basal hormone screening revealed an abnormality, a releasing hormone assay was performed. Before surgery, 24 of the 54 patients (44.4%) already had PI. Additional 25 patients showed either hypocortisolism or hypothyreoidism. As those patients had been pre-treated with dexamethasone and L-thyroxine, these findings were considered not to represent PI but drug effects. Hormone testing on days 1 and 7 after surgery revealed no changes. With 44.4% PI is a frequent finding in brain tumor patients already before surgery. The factors causing preoperative PI remain yet to be identified. The endocrine results after surgery are unchanged which rules out that surgery is the cause of PI.

Microsurgery can cure most intracranial dural arteriovenous fistulae of the sinus and non-sinus type.

There is consensus that intracranial dural arteriovenous fistulae (dAVF) with direct (non-sinus-type) or indirect (sinus-type) retrograde filling of a leptomeningeal vein should be treated due to the high risk of neurological deficits and hemorrhage. No consensus exists on treatment modality (surgery and/or embolization) and, if surgery is performed, on the best surgical strategy. This series aims to evaluate the role of surgery in the management of aggressive dAVFs. Forty-two patients underwent surgery. Opening and packing the sinus with thrombogenic material was performed in 9 of the 12 sinus-type dAVFs. In two sinus-type fistulae of the cavernous sinus and 1 of the torcular, microsurgery was used as prerequisite for subsequent embolization by providing access to the sinus. In the 30 non-sinus-type dAVFs, surgery consisted of interruption of the draining vein at the intradural entry point. In 41 patients undergoing 43 operations, elimination of the dAVF was achieved (97.6%). In one case, a minimal venous drainage persisted after surgery. The transient surgical morbidity was 11.9% (n=5) and the permanent surgical morbidity 7.1% (n=3). Our surgical strategy was to focus on the arterialized leptomeningeal vein in the non-sinus-type and on the arterialized sinus segment in the sinus-type dAVFs allowing us to obliterate all but one dAVF with a low morbidity rate. We therefore propose that microsurgery should be considered early in the treatment of both types of aggressive dAVFs. In selected cases of cavernous sinus dAVFs, the role of microsurgery is reduced to that of an adjunct to endovascular therapy.

Lower incidence of transcranial Doppler and symptomatic vasospasm after aneurysmal subarachnoid hemorrhage and aneurysm clipping in the elderly patient?

BACKGROUND: Vasospasm is the major cause of morbidity and mortality after aneurysmal subarachnoid hemorrhage. It is well known that the vasoreactivity decreases with advancing age, but it is not well investigated in a large patient cohort whether, as a consequence, the incidence of vasospasm is lower in elderly patients. OBJECTIVE: To investigate whether transcranial Doppler vasospasm, delayed ischemic neurological deficits, and vasospasm-associated ischemic lesions are less frequent in older patients. METHODS: Seven hundred fifty-eight patients who suffered from subarachnoid hemorrhage were included in this study. Clinical presentation, Hunt and Hess score, Fisher grade, incidence of vasospasm, neurological deficits and ischemic lesions on radiographic imaging, transcranial Doppler blood flow velocities, medical complications, and outcome were registered. RESULTS: Four hundred seventy-eight patients < 60 years of age and 280 patients ≥ 60 years of age were identified; 55.2% of the younger and 25.7% of the older age group developed post-hemorrhagic vasospasm (P < .001). Older patients developed less vasospasm (P = .00), fewer neurological deficits (P < .001), and fewer ischemic lesions on computed tomography imaging (P = .06). On the other hand, older patients had significantly worse outcomes than younger patients (P = .01) and more frequently died of medical complications (P = .01). CONCLUSION: Vasospasm, delayed ischemic neurological deficits, and vasospasm-associated ischemic lesions are more likely to occur in patients < 60 years of age than in older patients. The lower incidence of vasospasm and vasospasm-related ischemia in the elderly patient does not translate into better outcome because of the higher rate of fatal medical complications in patients ≥ 60 years of age.

Transcranial direct current stimulation induces polarity-specific changes of cortical blood perfusion in the rat.

OBJECTIVE: Transcranial direct current stimulation (tDCS) induces changes in cortical excitability and improves hand-motor function in chronic stroke. These effects depend on polarity, duration of stimulation and current intensity applied. Towards evaluating the therapeutic potential of tDCS in acute stroke, we investigated tDCS-effects on cerebral blood flow (CBF) in a tDCS rat model adapted for this purpose. METHODS: In a randomised crossover design eight Sprague-Dawley rats received three single cathodal and anodal tDCS for 15 min every other day. At each polarity, current intensities of 25, 50 and 100 µA were applied. CBF was measured prior and after tDCS for at least 30 min with laser Doppler flowmetry (LDF). RESULTS: At higher intensities (50 and 100 µA) anodal tDCS increased CBF up to 30 min. At 100 µA CBF was increased by about 25%, at 50 µA by about 18%. In contrast, cathodal tDCS led to a decrease of CBF, likewise depending on the current intensity applied. At 100 µA the effects were about 25% of baseline levels and persisted for at least 30 min. At 25 and 50 µA, baseline-levels were mostly re-established within 30 min. CONCLUSIONS: tDCS modulates CBF in a polarity specific way, the extent of modulation depending on the stimulation parameters applied. Because of its polarity-specificity, we assume that CBF-alterations are causally related to tDCS-induced alterations in cortical excitability via neuro-vascular coupling. tDCS may constitute a therapeutic option in acute stroke patients or in patients at risk for vasospasm-induced ischemia after subarachnoid hemorrhage.

Early surgery of multiple versus single aneurysms after subarachnoid hemorrhage: an increased risk for cerebral vasospasm?

OBJECT: As many as 33% of patients suffering from subarachnoid hemorrhage (SAH) present with multiple intracranial aneurysms (MIAs). It is believed that aneurysm surgery has the potential to increase the risk of cerebral vasospasm due to surgical manipulations of the parent vessels and brain tissue. Consequently, 1-stage surgery of MIAs, which usually takes longer and requires more manipulation, could even further increase the risk of vasospasm. The aim of this study is to define the correlation between vasospasm and the operative treatment of single intracranial aneurysms versus MIAs in a 1-stage operation. METHODS: The authors analyzed a database including 1016 patients with SAH, identified retrospectively between 1989 and 1996 and prospectively collected between 1997 and 2004. Exclusion criteria were endovascular treatment, surgery after SAH Day 3, and, in patients with MIAs, undergoing more than 1 operation. Cerebral vasospasm was diagnosed by transcranial Doppler (TCD) ultrasonography and was defined as a maximum mean blood flow velocity > 120 cm/second. The diagnosis of symptomatic vasospasm was made if a new neurological deficit occurred that could not be explained by concomitant complications. RESULTS: A total of 643 patients who experienced 810 aneurysms were included. Four hundred twenty-four patients were female (65.9%) and 219 were male (34.1%) with an average age of 53.1 years. One hundred twenty-one patients (18.8%) were diagnosed with MIAs. Maximum mean flow velocities measured by TCD were 131 cm/second in patients with MIAs and 129.5 cm/second in patients with single intracranial aneurysms. The incidence of TCD vasospasm (p = 0.561) as well as of symptomatic vasospasm (p = 0.241) was not significantly different in the 2 groups. CONCLUSIONS: Clipping of more than 1 aneurysm in a 1-stage operation within 72 hours after SAH can be performed without increasing the risk of cerebral (TCD) vasospasm and symptomatic vasospasm.

2-Octyl-cyanoacrylate for wound closure in cervical and lumbar spinal surgery.

It is claimed that wound closure with 2-octyl-cyanoacrylate has the advantages that band-aids are not needed in the postoperative period, that the wound can get in contact with water and that removal of stitches is not required. This would substantially enhance patient comfort, especially in times of reduced in-hospital stays. Postoperative wound infection is a well-known complication in spinal surgery. The reported infection rates range between 0% and 12.7%. The question arises if the advantages of wound closure with 2-octyl-cyanoacrylate in spinal surgery are not surpassed by an increase in infection rate. This study has been conducted to identify the infection rate of spinal surgery if wound closure was done with 2-octyl-cyanoacrylate. A total of 235 patients with one- or two-level surgery at the cervical or lumbar spine were included in this prospective study. Their pre- and postoperative course was evaluated. Analysis included age, sex, body mass index, duration and level of operation, blood examinations, 6-week follow-up and analysis of preoperative risk factors. The data were compared to infection rates of similar surgeries found in a literature research and to a historical group of 503 patients who underwent wound closure with standard skin sutures after spine surgery. With the use of 2-octyl-cyanoacrylate, only one patient suffered from postoperative wound infection which accounts for a total infection rate of 0.43%. In the literature addressing infection rate after spine surgery, an average rate of 3.2% is reported. Infection rate was 2.2% in the historical control group. No risk factor could be identified which limited the usage of 2-octyl-cyanoacrylate. 2-Octyl-cyanoacrylate provides sufficient wound closure in spinal surgery and is associated with a low risk of postoperative wound infection.

Pituitary insufficiency after traumatic brain injury.

After traumatic brain injury (TBI), patients present with psychological disorders that may be explained by post-traumatic pituitary insufficiency (PI). The goal of this study was to determine the relationship between hypopituitarism, neuropsychological changes and findings on CT scans after TBI. Hospital charts of 55 TBI patients were screened for age, Glasgow Coma Scale (GSC) score, hypoxia or hypotension. The first two CT scans were analyzed for hemorrhagic lesions. Basal levels of the following hormones were recorded: cortisol, prolactin, estradiol, testosterone, insulin-like growth factor 1 and free thyroxine. Hormonal stimulation tests were performed either if the basal hormone screening revealed an abnormality or if the patient answered "yes" to at least one question in the non-evaluated neuropsychological questionnaire. Overall, 14 out of 55 patients (25.4%) presented with PI; one of them with two hormonal deficits. Growth hormone deficit, hypothyroidism and hypocortisolism were found in one, one and two patients, respectively. Neuropsychological complaints were present in 67% of the patients and were associated with intracerebral hemorrhagic lesions and not PI. Neuropsychological complaints after TBI are more frequent than PI. Brain tissue damage is most important than PI in the development of psychological changes after TBI.

Arteriovenous differences of oxygen and transcranial Doppler sonography in the management of aneurysmatic subarachnoid hemorrhage.

After subarachnoid hemorrhage (SAH) the detection of hemodynamically significant vasospasm is frequently difficult, especially in comatose patients. Most clinicians use transcranial Doppler sonography (TCD) to detect increasing mean blood flow velocities in the basal arteries as markers of cerebral vasospasm, without accounting for the effects of sedation and variations in blood pressure or pCO(2). This study was conducted to test the hypothesis that the arteriovenous difference of oxygen (avDO(2); in terms of % volume) could also be useful for the evaluation of vasospasm. A total of 22 SAH patients (M : F = 1 : 1.75, age 58+/-10 years, median Hunt and Hess grade 4) were prospectively enrolled. All patients were sedated with continuous doses of midazolam/fentanyl and/or propofol. TCD studies and avDO(2) measurements were conducted at the same time or in close succession. The blood flow velocity of the middle cerebral artery was recorded. A cranial CT scan was conducted if the avDO(2) increased by at least 0.8%. Overall, 82 measurements were recorded in 22 patients between days 1 and 13 after SAH. TCD mean flow velocities increased as expected. In contrast, avDO(2) decreased until post-hemorrhage day 4 before it increased again. Overall, after SAH, avDO(2) was significantly lower than in normal individuals. Cerebral infarction occurred primarily in patients with a maximal change of avDO(2) of more than 1%. TCD velocities alone are poor indicators of the severity of vasospasm. In contrast, daily avDO(2) seems to be a more robust parameter. However, collection of additional metabolic information is warranted.

Cerebral energy failure after subarachnoid hemorrhage: the role of relative hyperglycolysis.

After subarachnoid hemorrhage (SAH) cerebral metabolism is significantly impaired. Hyperglycolysis describes the reduction of oxidative metabolism followed by a relative increase of anaerobic glycolysis to maintain energy supply. This phenomenon is known in head injury but has not as yet been shown after SAH. This study was conducted to test the hypothesis that hyperglycolysis is present in SAH patients and is associated with vasospasm. A total of 105 measurements were conducted on 21 SAH patients (age 49+/-15 years, median World Federation of Neurosurgical Societies Grade 4) over the first 5 days following admission. Arteriovenous differences were calculated for oxygen (avDO2) and glucose (avDGlc). Relative hyperglycolysis was defined as metabolic ratio (MR=avDO2[mmol/L]/avDGlc[mmol/L])<3.44. Jugular-venous saturation for oxygen (SjvO2), mean arterial blood pressure (MAP), intracranial pressure (ICP), cerebral perfusion pressure (CPP) were monitored. Relative hyperglycolyis was recorded in 34% of studies after SAH. In hyperglycolytic studies both jugular-venous lactate and SjvO2 were significantly elevated (jugular-venous lactate 14.9+/-9.9 vs. 11.8+/-5.5 mg/dL, p=0.04; SjvO2: 70.0+/-18% vs. 81.7+/-9%, p=0.002). Relative hyperglycolysis is associated with outcome after SAH. In patients who died after SAH almost 50% of studies showed hyperglycolysis, whereas patients who survived without neurological deficit had no hyperglycolytic events. Relative hyperglycolysis is a common event after SAH. It may be associated with relative hyperemia but most importantly with outcome.