Cranioplasty after decompressive craniectomy: the effect of timing on postoperative complications

Decompressive craniectomy (DC) due to intractably elevated intracranial pressure mandates later cranioplasty (CP). However, the optimal timing of CP remains controversial. We therefore analyzed our prospectively conducted database concerning the timing of CP and associated post-operative complications. From October 1999 to August 2011, 280 cranioplasty procedures were performed at the authors' institution. Patients were stratified into two groups according to the time from DC to cranioplasty (early, ≤2 months, and late, >2 months). Patient characteristics, timing of CP, and CP-related complications were analyzed. Overall CP was performed early in 19% and late in 81%. The overall complication rate was 16.4%. Complications after CP included epidural or subdural hematoma (6%), wound healing disturbance (5.7%), abscess (1.4%), hygroma (1.1%), cerebrospinal fluid fistula (1.1%), and other (1.1%). Patients who underwent early CP suffered significantly more often from complications compared to patients who underwent late CP (25.9% versus 14.2%; p=0.04). Patients with ventriculoperitoneal (VP) shunt had a significantly higher rate of complications after CP compared to patients without VP shunt (p=0.007). On multivariate analysis, early CP, the presence of a VP shunt, and intracerebral hemorrhage as underlying pathology for DC, were significant predictors of post-operative complications after CP. We provide detailed data on surgical timing and complications for cranioplasty after DC. The present data suggest that patients who undergo late CP might benefit from a lower complication rate. This might influence future surgical decision making regarding optimal timing of cranioplasty.

Microsurgical management of large intra-and extracranial calvarial meningiomas

Objective: Based on the largest series reported of giant intra- and extracranial calvarial meningiomas (GIECM) the purpose of the present study was to characterize the treatment and outcome data associated with patients operated on GIECM and to describe our experience in the management of this rare and therapeutically demanding tumour entity. Methods: The data of 12 patients (7/12 males, 5/12 females) with surgically treated GIECM at the University Hospitals Aachen and Bern between 1994 and 2011 were retrospectively analyzed. The mean patient age was 58 years (range, 22 to 78 years). Symptom distribution included extracranial swelling (12/12), seizures (5/12), headache (4/12), gait disturbance (3/12), dizziness (2/12), and impaired vision (1/12). GIECM were located frontal (6/12), temporal (3/12), parietal, fronto-parietal, and parieto-occipital (1/12 each). Microsurgical resection with acrylic-augmented cranioplasty was performed in all patients and 11/12 patients received dural repair with synthetic (7/11) or autologous (4/11) patch grafts. Surgical excision in two stages with primary removal of the extracranial meningioma component was undertaken in 2/12 patients, whereas preoperative embolization and postoperative radiotherapy were applied in 1/12 patient each. Results: In contrast to intradural meningiomas GIECM mainly affect male patients at a comparatively younger age. GIECM could be completely (9/12) or subtotally (3/12) resected. Surgical-associated complications included minor CSF leak (6/12), wound healing disturbance (3/12), venous engorgement, and haemorrhage (2/12 each), requiring reoperation in 3/12 cases. Histopathological examination revealed meningothelial (6/12), atypical (4/12), and transitional (1/12) GIECM. 10/12 patients exhibited excellent postoperative clinical outcome, 1/12 patient each deteriorated or died of pulmonary embolism. Conclusions: The operative management of GIECM is challenging, carries a substantial risk, and demands special strategies because of the large tumour size, anatomical involvement of scalp, calvaria, meninges, brain or vascular structures, and more frequent atypical histology. Although microsurgical resection with cranioplasty and mostly dural grafting usually results in a good clinical outcome, the potential complication rate is markedly higher when compared to smaller meningiomas without extracranial component. Preoperative embolization and staging of surgical resection are possible additional therapeutic options.

Experience with a gravitational valve in the management of symptomatic overdrainage in children with shunts

Symptomatic overdrainage in children with shunt-treated hydrocephalus represents one of the more difficult shunt-related diseases and may require repeated surgery. Gravity-assisted valve design has become a standard device to avoid overdrainage in many European pediatric hydrocephalus centers. However, the use of a gravitational valve for relieving symptoms associated with overdrainage has not yet been addressed. The goal of this study was to evaluate the effectiveness of a gravitational valve in the treatment of symptomatic overdrainage in children with shunts.

Second valve implantation for the treatment of a malpositioned transcatheter aortic valve

Unfavorable immediate or delayed results after transcatheter aortic valve implantation (TAVI) may be a consequence of bioprosthesis malfunctioning, malpositioning, embolization, or degeneration. Deployment of a second valve within the first one implanted (TAVI-in-TAV) may be a potentially helpful therapeutic strategy.

Connective tissue growth factor level is increased in patients with liver cirrhosis but is not associated with complications or extent of liver injury

Connective tissue growth factor (CTGF) is a profibrotic protein whose systemic levels are increased in liver cirrhosis. Here, association of CTGF with stages of liver injury and complications of cirrhotic liver disease has been analyzed in patients with different aetiologies of hepatic injury. CTGF is significantly increased in portal venous serum (PVS), hepatic venous serum (HVS) and systemic venous serum (SVS) of 46 patients with liver cirrhosis compared to eight liver-healthy controls. In patients´ blood samples CTGF in HVS is about 6% higher than PVS levels indicating that CTGF produced in the liver is released to the circulation. CTGF is not associated with stages of liver cirrhosis defined by CHILD-PUGH or MELD score nor with secondary complications of portal hypertension (varices, ascites, spontaneous bacterial peritonitis). Transforming growth factor β (TGFβ) induces CTGF synthesis in hepatocytes and a positive association of systemic TGFβ1 and SVS and HVS CTGF is found. Three months after placing transjugular intrahepatic portosystemic shunt (TIPS) hepatic venous pressure gradient is reduced whereas CHILD-PUGH score, TGFβ1 and CTGF are not altered in serum of 15 patients. Current data show that the cirrhotic liver releases little CTGF but SVS, HVS and PVS CTGF levels are not associated with residual liver function and complications of cirrhosis.

Long-term patency of complex bilobular, bisaccular, and broad-neck aneurysms in the rabbit microsurgical venous pouch bifurcation model

In experimental aneurysm models, long-term patency without spontaneous thrombosis is the most important precondition for analyses of embolization devices. We recently reported the feasibility of creating complex venous pouch bifurcation aneurysms in the rabbit with low morbidity, low mortality, and high short-term aneurysm patency. In order to further evaluate our model, we examined the long-term patency rate.

Respiratory function during anesthesia: effects on gas exchange

Anaesthesia causes a respiratory impairment, whether the patient is breathing spontaneously or is ventilated mechanically. This impairment impedes the matching of alveolar ventilation and perfusion and thus the oxygenation of arterial blood. A triggering factor is loss of muscle tone that causes a fall in the resting lung volume, functional residual capacity. This fall promotes airway closure and gas adsorption, leading eventually to alveolar collapse, that is, atelectasis. The higher the oxygen concentration, the faster will the gas be adsorbed and the aleveoli collapse. Preoxygenation is a major cause of atelectasis and continuing use of high oxygen concentration maintains or increases the lung collapse, that typically is 10% or more of the lung tissue. It can exceed 25% to 40%. Perfusion of the atelectasis causes shunt and cyclic airway closure causes regions with low ventilation/perfusion ratios, that add to impaired oxygenation. Ventilation with positive end-expiratory pressure reduces the atelectasis but oxygenation need not improve, because of shift of blood flow down the lung to any remaining atelectatic tissue. Inflation of the lung to an airway pressure of 40 cmH2O recruits almost all collapsed lung and the lung remains open if ventilation is with moderate oxygen concentration (< 40%) but recollapses within a few minutes if ventilation is with 100% oxygen. Severe obesity increases the lung collapse and obstructive lung disease and one-lung anesthesia increase the mismatch of ventilation and perfusion. CO2 pneumoperitoneum increases atelectasis formation but not shunt, likely explained by enhanced hypoxic pulmonary vasoconstriction by CO2. Atelectasis may persist in the postoperative period and contribute to pneumonia.

[Oesophageal and fundic variceal bleeding]

Oesophageal and fundic varices belong to the most frequent complications of cirrhosis and portal hypertension. Due to their significant morbidity and mortality, bleedings from oesophageal or fundic varices represent a challenge for the emergency medical team as well as for the gastroenterologist. The patient with a variceal bleeding should be accurately monitored and his/her hemodynamic parameters should be maintained stable with the administration of plasma expanders and blood units when indicated. An antibiotic prophylaxis in this setting--norfloxacin or ceftriaxon--has been demonstrated to significantly reduce morbidity and mortality. Additionally, the early administration of vasoactive compounds, such as terlipressin, somatostatin or octreotide, is associated with beneficial effects in reducing the bleeding. An upper gastrointestinal endoscopy should be generally performed within the first twelve hours from the beginning of the bleeding in order to obtain an accurate diagnosis and to provide an adequate treatment. Endoscopic procedures to control the bleeding include the rubber band ligation, the treatment of the varix with a sclerosing agent or the injection of tissue glue into the varix. In case of recurrent bleeding, beyond the above methods, different techniques, such as the transjugular porto-caval shunt, surgical shunt procedures, as well as embolisation of splanchnic blood vessels, represent additional therapeutic options. However, they are associated with very high mortality rates and their indication has to be discussed case by case by an interdisciplinary team of experts. Future therapies include the optimisation and the improvement of the current medical and endoscopic armamentarium, as well as the application of treatments to novel targets, such as the coagulation cascade.

The hepato-pulmonary syndrome--where do we stand in the year 2006?

The hepato-pulmonary syndrome (HPS) is characterized by a combination of liver disease and pulmonary gas exchange abnormalities with arterial hypoxemia, intrapulmonary vasodilatation and arteriovenous shunting in the absence of intrinsic cardiopulmonary disease. The course of the disease is typically progressive. The mortality rate correlates with the pulmonary shunt volume and the degree of hypoxemia at room air. While the patho-physiology of HPS is still not fully understood, a multifactorial etiology is favored. Apart from functional intrapulmonary arteriovenous shunts which appear to represent a major factor in the development of HPS, both ventilation-perfusion mismatch and limited oxygen diffusion contribute to the HPS. Regarding its clinical appearance, pulmonary and hepatic symptoms have to be distinguished. Contrast echocardiography is the primary diagnostic tool. Symptomatically, hypoxemia can be treated with oxygen. So far, the only successful treatment approach which has been tested in larger patient groups, is liver transplantation. Given this background, the aim of this review is to critically discuss current concepts of this serious complication of liver diseases.

Biofilm-related infections of cerebrospinal fluid shunts

Cerebrospinal fluid (CSF) shunts carry a high risk of complications. Infections represent a major cause of shunt failure. Diagnosis and therapy of such infections are complicated by the formation of bacterial biofilms attached to shunt surfaces. This study correlated the pathophysiology and clinical course of biofilm infections with microscopical findings on the respective shunts. Surface irregularities, an important risk-factor for shunt colonisation with bacteria, were found to increase over time because of silicone degradation. Scanning electron-microscopy (SEM) documented residual biological material (dead biofilm), which can further promote extant bacterial adhesion, on newly manufactured shunts. Clinical course and SEM both documented bacterial dissemination against CSF flow and the monodirectional valve. In all cases, biofilms grew on both the inner and outer surfaces of the shunts. Microscopy and conventional culture detected all bacterial shunt infections. Analyses of 16S rDNA sequences using conserved primers identified bacteria in only one of three cases, probably because of previous formalin fixation of the samples.

A dedicated animal model for mechanical thrombectomy in acute stroke

BACKGROUND: Recent studies have focused on mechanical thrombectomy as a means to reduce the time required for revascularization and increase the revascularization rate in acute stroke. To date no systematic evaluation has been made of the different mechanical devices in this novel and fast-developing field of endovascular interventions. To facilitate such evaluations, we developed a specific in vivo model for mechanical thrombectomy that allows visualization of dislocation or fragmentation of the thrombus during angiographic manipulation. METHODS: Angiography and embolization with a preformed thrombus was performed in 8 swine. The thrombus was generated by mixing 25 IU bovine thrombin and 10 mL autologous blood. For visualization during angiography, 1 g barium sulfate was added. RESULTS: The preformed thrombus exhibited mechanical stability, reproducibility, and high radiographic absorption, providing excellent visibility during angiography. The setting allowed selective embolization of targeted vessels without thrombus fragmentation. Despite the application of barium sulfate no local or systemic reaction occurred. Histologic evaluation revealed no intimal damage caused by the thrombus or contrast agent washout. CONCLUSION: The model presented here allows selective and reliable thromboembolization of vessels that reproduce the anatomic and hemodynamic situation in acute cerebrovascular stroke. It permits visualization of the thrombus during angiography and intervention, providing unique insight into the behavior of both thrombus and device, which is potentially useful in the development and evaluation of mechanical clot retrieval in acute cerebrovascular stroke.

Mechanical thrombectomy for acute ischemic stroke: thrombus-device interaction, efficiency, and complications in vivo

BACKGROUND AND PURPOSE: Mechanical thrombectomy is a promising new modality of interventional stroke treatment. The various devices differ with regard to where they apply force on the thrombus, taking a proximal approach such as aspiration devices or a distal approach such as basket-like devices. The study compares the in vivo effectiveness and thrombus-device interaction of these 2 approaches. METHODS: Angiography and embolization with a radioopaque whole blood thrombus was performed in 10 swine. Mechanical thrombectomy was performed in 20 cranial vessels using a proximal aspiration device (Vasco35) and a distal basket-like device (Catch) with and without proximal balloon occlusion. Fifty-six retrieval attempts were made. RESULTS: The proximal device allowed fast repeated application with a low risk of thromboembolic events (3%) and vasospasm, but it had a significantly lower success rate (39.4%) in retrieving thrombotic material than the distal device (DD) (82.6%; odds ratio, 7.3; 95% CI, 2.0 to 26.4). The compaction of the thrombus during retrieval with DD increased the risk of vessel wall irritation significantly (P<0.01) and complicated retrieval into the guiding catheter. The number of embolic events was significantly higher with DD (26%; odds ratio, 11.3; 95% CI, 1.35 to 101.6) unless proximal balloon occlusion was used. CONCLUSIONS: The proximal and the distal approaches to mechanical thrombectomy proved to be effective at achieving recanalization of cranial vessels. The proximal device is faster in application and allowed repeated attempts with a low complication rate. The DD is more successful at removing thrombotic material, but its method of application and attendant thrombus compaction increase the risk of thromboembolic events and vasospasms.

[Acute "difficult" gastrointestinal bleeding]

Gastrointestinal bleeding with its point of origin outside the reach of conventional gastro- and colonoscopy represents an extraordinary diagnostic and therapeutic challenge. Bleeding may originate from the small bowel distal to the duodenojejunal junction (middle gastrointestinal bleeding) or from the biliary tree (haemobilia) or from the pancreatic ductal system (haemosuccus pancreaticus). This particular type of gastrointestinal bleeding is often intermittend and caused by a variety of different pathologies. Angiography is the diagnostic method of choice for further investigation. It allows precise localization of the bleeding site and simultaneous interventional therapy (embolization/coiling). The importance of further diagnostic modalities such as scintigraphy, capsule endoscopy, push-enteroscopy and double-balloon-enteroscopy is discussed.

Contrast-enhanced transcranial Doppler ultrasound for diagnosis of patent foramen ovale

The suspected cause of clinical manifestations of patent foramen ovale (PFO) is a transient or a permanent right-to-left shunt (RLS). Contrast-enhanced transcranial Doppler ultrasound (c-TCD) is a reliable alternative to transesophageal echocardiography (TEE) for diagnosis of PFO, and enables also the detection of extracardiac RLS. The air-containing echo contrast agents are injected intravenously and do not pass the pulmonary circulation. In the presence of RLS, the contrast agents bypass the pulmonary circulation and cause microembolic signals (MES) in the basal cerebral arteries, which are detected by TCD. The two main echo contrast agents in use are agitated saline and D-galactose microparticle solutions. At least one middle cerebral artery (MCA) is insonated, and the ultrasound probe is fixed with a headframe. The monitored Doppler spectra are stored for offline analysis (e.g., videotape) of the time of occurrence and number of MES, which are used to assess the size and functional relevance of the RLS. The examination is more sensitive, if both MCAs are investigated. In the case of negative testing, the examination is repeated using the Valsalva maneuver. Compared to TEE, c-TCD is more comfortable for the patient, enables an easier assessment of the size and functional relevance of the RLS, and allows also the detection of extracardiac RLS. However, c-TCD cannot localize the site of the RLS. Therefore, TEE and TCD are complementary methods and should be applied jointly in order to increase the diagnostic accuracy for detecting PFO and other types of RLS.

Membrane microdialysis: Evaluation of a new method to assess splanchnic tissue metabolism

OBJECTIVE: Measuring peritoneal lactate concentrations could be useful for detecting splanchnic hypoperfusion. The aims of this study were to evaluate the properties of a new membrane-based microdialyzer in vitro and to assess the ability of the dialyzer to detect a clinically relevant decrease in splanchnic blood flow in vivo. DESIGN: A membrane-based microdialyzer was first validated in vitro. The same device was tested afterward in a randomized, controlled animal experiment. SETTING: University experimental research laboratory. SUBJECTS: Twenty-four Landrace pigs of both genders. INTERVENTIONS: In vitro: Membrane microdialyzers were kept in warmed sodium lactate baths with lactate concentrations between 2 and 8 mmol/L for 10-120 mins, and microdialysis lactate concentrations were measured repeatedly (210 measurements). In vivo: An extracorporeal shunt with blood reservoir and roller pump was inserted between the proximal and distal abdominal aorta, and a microdialyzer was inserted intraperitoneally. In 12 animals, total splanchnic blood flow (measured by transit time ultrasound) was reduced by a median 43% (range, 13% to 72%) by activating the shunt; 12 animals served as controls. MEASUREMENTS AND MAIN RESULTS: In vitro: The fractional lactate recovery was 0.59 (0.32-0.83) after 60 mins and 0.82 (0.71-0.87) after 90 mins, with no further increase thereafter. At 60 and 90 mins, the fractional recovery was independent of the lactate concentration. In vivo: Abdominal blood flow reduction resulted in an increase in peritoneal microdialysis lactate concentration from 1.7 (0.3-3.8) mmol/L to 2.8 (1.3-6.2) mmol/L (p = .006). At the same time, mesenteric venous-arterial lactate gradient increased from 0.1 (-0.2-0.8) mmol/L to 0.3 (-0.3 -1.8) mmol/L (p = .032), and mesenteric venous-arterial Pco2 gradients increased from 12 (8-19) torr to 21 (11-54) torr (p = .005). CONCLUSIONS: Peritoneal membrane microdialysis provides a method for the assessment of splanchnic ischemia, with potential for clinical application.