Non-invasive grading of primary brain tumours: Results of a comparative study between SPET with123I-α-methyl tyrosine and PET with18F-deoxyglucose

Use of iodine-123--methyl tyrosine (¹²³I-IMT) allows investigation of the amino acid transport rate in gliomas. It was the aim of this study to compare the value of measurement of glucose metabolism with that of measurement of¹²³I-IMT uptake for the non-invasive grading of brain tumours. The study population comprised 23 patients with histopathologically proven primary brain tumours; 14 had high-grade gliomas, and nine low-grade brain neoplasms. Glucose metabolism was studied using an ECAT EXACT 47 positron emission tomography (PET) camera and fluorine-18 fluorodeoxyglucose (¹⁸F-FDG);¹²³I-IMT uptake was measured with the triple-headed single-photon emission tomography (SPET) camera, MULTISPECT 3.¹⁸F-FDG and¹²³I-IMT uptake was quantified as ratios between the uptake by the tumour and contralateral regions of reference. Glucose metabolism and amino acid uptake of the brain tumours correlated significantly (r=0.71,P <0.001). Assuming discrimination thresholds between high-grade and low-grade tumours of 0.8 for¹⁸F-FDG uptake and 1.8 for¹²³I-IMT uptake, the accuracy values of¹⁸F-FDG PET and¹²³I-IMT SPET for differentiating between high-grade and low-grade tumours were 21/23 (91%) and 19/23 (83%), respectively. The difference in diagnostic performance was not significant on receiver operating characteristic analysis (P >0.4). It is concluded that there is no major difference between the PET investigation of glucose metabolism and the less expensive SPET measurement of amino acid uptake in terms of their accuracy in evaluating the malignancy grade of primary brain tumours. This encourages the performance of further studies to analyse the potential impact of¹²³I-IMT SPET on the therapeutic management of patients with brain tumours.     

Hyperbaric oxygen in neurosurgery

Background  The therapeutic use of pure oxygen, even under hyperbaric conditions, has been well established for about 50 years, whereas the discovery of oxygen occurred 250 years earlier. Many neurosurgical patients suffer from brain tissue damage, due to reduced blood flow, obstructive vessel disease, or as a result of traumatic brain injury. Methods and results  The application of pure oxygen in these patients is the only method of increasing the O₂ concentration in tissue with impaired blood supply and can minimize secondary impairment of brain tissue. Discussion  In this brief historical overview we focus on the development and evidence of hyperbaric oxygenation in this specific field of insufficient oxygen supply to the central neural tissue. Conclusion  With the use of modern biological methods and new study designs, HBO has a place in evidence-based treatment of patients with neural tissue damage.     

Flat and steep terminal negativity in the DC-potential after deprivation of oxygen and glucose in human neocortical slices

The so-called terminal negativity (TN) of the DC-potential is a characteristic reaction of neuronal tissue to hypoxia or ischemia. In a previous study on human neocortical slices, two types of TN with flat and steep slopes of rise (< or >10 mV/min) were found with hypoxia. The aim of the present study was to further investigate causes underlying the occurrence of flat and steep TN. Experiments were performed on 23 human neocortical slices (500 μm) resected from 13 patients (epilepsy and tumour surgery). DC-potential and evoked potentials (white matter stimulation) were recorded in layer III. The extracellular potassium concentration ([K⁺]_o) was measured by K⁺-sensitive microelectrodes. In an interface type chamber, ischemic episodes were induced by oxygen and glucose deprivation. They were terminated when TN had peaked. Both flat and steep TN also existed with ischemic conditions. There was a linear correlation between the slope of rise of TN and the associated slope of rise in [K⁺]_o, respectively, but none regarding latencies of TN or recovery of evoked potentials. Peak levels in [K⁺]_o were 13.9±0.9 mmol/l. Compared to control, the slope of rise and latency of TN were clearly increased by addition of dimethyl sulfoxide (DMSO, 0.4%) to the bath solution, whereas nimodipine (40 μmol/l) in 0.4% DMSO had neither an effect on slope of rise of TN nor on latency of TN. As a whole, our observations suggest, that the actual metabolic state determines the occurrence of flat or steep TN.     

Neuroprotection by 21-aminosteroids: insights from latencies of anoxic terminal negativity in hippocampus slices of guinea pig.

The protection of neuronal function by 21-aminosteroids against a hypoxic challenge was tested in guinea pig hippocampal slices. 21-aminosteroids, which apart from a protective mechanism against membrane lipid peroxidation, provide direct membrane stabilizing effects, are reported. We tested whether the 21-aminosteroid U-74389G delays the anoxic terminal negativity (ATN) of the DC-potential during hypoxia. Hippocampal slices were placed at the interface of artificial cerebrospinal fluid (aCSF) and gaseous phase (normoxic: 95% O2, 5% CO2; hypoxic: 95% N2, 5% CO2). Population spikes obtained by stimulation of Schaffer-collaterals as well as the DC-Potential were recorded in the CA1 region. The latency of appearance of ATN after oxygen deprivation was determined. In control experiments, the latency of ATN was 12.6 +/- 3.1 min (n = 6, mean +/- SEM). With application of U-74389G, the ATN-latency was 8.8 +/- 3.2 min (n = 6). We conclude that the cerebroprotective effect of the 21-aminosteroid is not mediated via direct membrane stabilization.     

Intramedullary spinal cord metastasis as initial presentation of systemic cancer--report of a rare case

We report the rare case of a 74-year-old man who was admitted to our hospital with rapid progression of tetraparesis, which was most apparent in the lower right limb, sensory disturbances from C3 to S1 on the left side and recent onset of constipation and urinary retention. There was no known history of cancer. As MRI of the neck disclosed a cervical intramedullary mass lesion at C 4/5 level suspicious for a primary glial tumour, the patient underwent surgery. After microsurgical excision the histological analysis of the lesion unexpectedly revealed an intramedullary spinal cord metastasis (ISCM) of a poorly differentiated carcinoma, immunohistochemically consistent with a bronchial carcinoma. As intramedullary spinal cord metastases are generally associated with poor survival, a palliative irradiation of the levels C1-6 was additionally performed. Unfortunately tetraparesis and numbness remained. The very rare occurrence of intramedullary spinal cord metastasis and the absence of pathognomonic symptoms often lead to a delay until an underlying malignancy is discovered. Although rare, intramedullary spinal cord metastasis should be considered as a differential diagnosis of a spinal intramedullary lesion. Surgery and radiation are both options in the controversially discussed treatment of ISCM.     

How many “moles” of glucocorticoids?

The entries for i. v. dexamethasone in the German National Formulary [2] are inconsistent and can lead to differences of about 25% in calculating the dosage on a molar basis. The authors recommend a standardization of declarations of the contents of i. v. glucocorticoids.     

Angiolipoma of the spinal cord. Magnetic resonance imaging and microsurgical management

Radiologic diagnosis of intramedullary lipomas has been unreliable for a long time and many of these tumors have not been recognized. The introduction of computed tomography, and lately of magnetic resonance imaging, has led to great progress in the accurate identification of spinal cord tumors as well as in the recognition of type specificity of these lesions. An evaluation of the diagnostic value of magnetic resonance imaging and microsurgical technique for the optimal therapeutic outcome is discussed.     

12 Years’ Experience with Intraoperative Radiotherapy (IORT) of Malignant Gliomas

Background:  

Even after surgery and radiotherapy, malignant gliomas still have a poor prognosis. The authors report on their experience with IORT in 71 patients.