Rate of perioperative complications in thermal ablation of bone: an animal trial.

INTRODUCTION: While only few data are available yet for radioablation of bone tissue, the occurrence of bone marrow embolisms during cryoablation has been documented. It was the aim of this study to assess perioperative complication rates of thermoablation in animals using state-of-the-art ablation probes. MATERIALS AND METHODS: Eight adult sheep were placed under general anaesthesia, and using a radioprobe, thermoablation was performed on the medial side of the head of the right tibia. In addition, freezing was performed with miniature cryoprobes on both femurs and the head of the left tibia. Haemodynamic monitoring and determination of blood gases and electrolytes were done intraoperatively. The animals were killed 1 week after surgery, and the ablation sites and lung tissue examined macroscopically and microscopically. RESULTS: None of the animals showed pathological changes in any of these parameters. Blood gases remained unremarkable throughout the operation. All eight animals showed an average drop in haemoglobin of 0.97 g/100 ml. Two animals showed fresh embolisms in the pulmonary vessels. CONCLUSION: Experimental thermoablation of bone tissue in large animals failed to show any significant perioperative complications following surgery. The lung embolisms which did occur were not clinically relevant. The use of mini-cryoprobes or radioprobes as alternative or complementary measures for treating pathologically altered bone tissue seems viable and does not involve any undue risks.

Bilateral cerebellar infarctions caused by a stenosis of a congenitally unpaired posterior inferior cerebellar artery.

Bilateral symmetrical cerebellar infarcts in the territory supplied by the medial posterior inferior cerebellar artery (PICA) branches are extremely rare. In the few cases published, it has not been possible to clearly pinpoint the cause of this infarct pattern. The authors present the case history of a 58-year-old man who had acute headaches accompanied by pronounced rotatory vertigo with nausea and vomiting. The neurological examination revealed bilateral cerebellar signs. Cranial magnetic resonance imaging showed bilateral, nearly symmetrical infarcts in the territory of the medial branches of both PICAs. These bilateral PICA infarctions were caused by a stenosis of an unpaired PICA originating from the left vertebral artery supplying both cerebellar hemispheres.

Continuous administration of contrast medium for transcranial colour-coded sonography.

Since the introduction of contrast media, transcranial colour-coded sonography (TCCS) has become increasingly important for examination of the intracranial vessels. However, the widely practised bolus injection of these agents leads to initial blooming artefacts and thereafter the level of contrast enhancement decreases rapidly, reducing the effective time of enhancement. It was our aim to investigate the effect of continuous administration of contrast medium at a defined infusion rate. We performed 28 TCCS examinations of the intracranial vessels in 26 patients using a 2.25 MHz phased-array transducer during administration of 4 g Levovist (Schering, Berlin, Germany) 300 mg/ml with a constant infusion rate of 60 ml/h into an antecubital vein. The degree of enhancement was graded over time in a subjective analysis by two independent observers. During continuous administration, a constant level of contrast enhancement was reached after 60.1+/-26.2 s and this lasted 663.4+/-55.8 s as assessed by the first observer (66.6+/-26.2 s and 664.3+/-55.9 s according to the second observer). The limits of inter-observer agreement ranged from -10.1% to 9.9%. No major blooming effect was seen in the initial phase of the examination.

Three-dimensional transcranial color-coded sonography for the examination of the arteries of the circle of Willis.

Because examinations of the intracranial vessels using conventional transcranial color-coded sonography (TCCS) lack spatial orientation and reproducibility, development of a three-dimensional (3-D) imaging technique is required. Three patients with middle cerebral artery (MCA) stenosis, three with suspected intracranial aneurysm, two with vascular malformation, and one healthy volunteer were investigated by 3-D TCCS using a magnetic spatial positioning sensor mounted on the transducer for simultaneous recording of the probe coordinates to create a volumetric data set. Three-dimensional transcranial color-coded sonography enabled good visualization of intracranial aneurysms and MCA stenoses. However, it failed to detect morphological details in vascular malformations. In conclusion, 3-D TCCS is a promising technique that opens new perspectives in depicting intracranial vessels and provides volume measurement of intracranial aneurysms.

Carotid artery stenting in patients at surgical high risk: clinical and ultrasound findings.

Angioplasty and stenting (A/S) provide an alternative for patients with simultaneous severe cardiac and cerebrovascular disease, or with medical illnesses which carry a high perioperative risk. We conducted A/S in 20 high-risk patients (15 males, 5 females, mean age = 64.5 years, range = 49-83 years) with symptomatic (n = 16) and asymptomatic (n = 4) high-grade stenosis (>70%, NASCET criterion) of the internal carotid artery. Patients had neurological examinations before, during and after the procedure. Color-coded duplex sonography was performed before and 24 h and every 3 months after the procedure; the 3-month examination also included cerebral angiography. The mean degree of stenosis was reduced from 85.75 +/- 7.47 to 8.0 +/- 22.09% in angiography. In an 18-month follow-up with color-coded duplex sonography the effects of the A/S could be visualized effectively: 2 with local, transient vasospasms, 1 with asymptomatic occlusion, 2 carotid arteries with remaining stenosis of 50% and 2 with minimal hyperplasia within the stent. In conclusion, in patients with a high perioperative risk, A/S is a therapeutic alternative to surgery.

Stone age skull surgery in Mecklenburg-Vorpommern: a systematic study.

OBJECTIVE: Trephination of the cranial vault is the oldest known surgical procedure and has often been reported in the literature. The present study was performed to study the incidence, the techniques used, and possible indications for trephinations in the region of Mecklenburg-Vorpommern, the most northeastern German state. METHODS: One hundred thirteen of a total of 115 Neolithic (c. 2000-3500 BC) skulls and eight smaller skull fragments found in the region of Mecklenburg-Vorpommern were examined. Defects and abrasions were detected in 31 of these skulls and underwent further examination (careful microscopic and/or endoscopic examination, three-dimensional computed tomography, and x-rays). RESULTS: Six skulls showed defects resulting from trephination, mainly located along the midline or in the left parieto-occipital region. There was good osteological evidence that at least five of these operations had been survived. Two different techniques for trephination (circular cuts and scraping) had been used. CONCLUSION: From the present study, we conclude that the incidence of trephination in Neolithic skulls in our region is at least 5% and that these operations had been survived in singular cases. There is increasing evidence that these procedures were intended to be curative.

Limitations of clearance determination using the single sample distribution volume method. An error analysis on the basis of compartment models.

To investigate the error possibly contained in the single sample distribution volume method for the determination of renal clearance, a mathematical model was applied to describe the effect of changes in distribution volume, clearance, intravascular space, intracompartmental exchange and the time point of blood sampling. The method was found to be valid only under well-defined circumstances (Topt = 45 +/- 5 min, Cl = 390 +/- 50 ml/min, Vd = 16.7 +/- 4 l, alpha = 0.05.V1 ml/min, V1/Vd = 0.5 +/- 0.05) as shown in sample calculations. Two-compartment model-based error calculations demonstrate that this technique implies at best an uncertainty of +/- 10% or more. Whilst it can be used preferably in healthy, normal-weight adults, it is not applicable, without error, under all other circumstances.