Cerebrovascular diseases and especially ischemic stroke are a leading cause of death. They occur mostly due to an insufficient oxygen (O2) supply to the central neural tissue as a result of thromboembolic events and/or obstructive vessel disease. The primary damage of the brain tissue cannot be restored. However, adequate therapy could minimize secondary impairment of brain tissue and restore neuronal function in the so-called "penumbra region". Apart from reopening occluded vessels, additional O2 supply is essential for survival of malfunctioning neural tissue. Breathing of 100% O2 under hyperbaric conditions, hyperbaric oxygenation (HBO), is the only method to increase the O2 concentration in tissue with impaired blood supply. Experimental as well as clinical studies have reported a positive effect of HBO therapy. Survival rate has increased under HBO therapy and neurological outcome has improved. The optimal levels of pressure as well as duration and numbers of HBO sessions need to be specified to avoid undesirable effects. Unfortunately, many questions remain unanswered before routinely recommending HBO as additional therapy in clinical practice. In this review we consider the (patho-)physiological background of HBO-therapy, the latest results of experimental and clinical studies and stress the evidence in patients with cerebrovascular disease.

Stroke is a great matter of interest especially in the industrialised countries, because of pronounced morbidity and mortality. Recurrent ischemic brain attacks are usually caused due to embolism by arrhythmic heart diseases or by occlusive disease of carotid artery (CA) due to atherosclerosis, furthering with risk factors such as hypertension, metabolic disorders, smoking, and other life-style factors. In patients with CA occlusion and reduced cerebrovascular reserve capacity (CVR), revealed by different technical modalities of CCT, MRI or PET, the EC-IC bypass can apparently prevent recurrent ischemic attacks. Some studies as well as own experiences with brain revascularisation by means of EC-IC bypass, has documented cessation of symptoms in majority of patients. Brain revascularisation should be taken into account in the proper group of patients with occlusion of CA, if sufficient anticoagulating therapy is not effective. Which of the patients with recurrent ischemic stroke based on occluded CA are proper candidates for the revascularization is not definitive. Further trials especially for redefined subgroups of patients must bring decision in this matter, as recommended by the Carotid Occlusion Surgery Study group. Unfortunately, the data published in 1985 by the EC-IC Bypass Study Group do not considered diverse subgroups of patients and their differed CVR owing to occlusion of internal carotid artery. This issue should be a matter of interest for the future.

Meningiomas of the spinal canal are rare, in contrast to their cranial counterparts. This study reports on the dominant features of spinal meningiomas before and after treatment. We treated 30 patients (23 female) with meningiomas of the spinal canal from 1992 to 2003. The mean age was 68 (range: 43–91). Upon admission, 26 patients presented with a marked neurological deficit (11 paraparesis, 9 motor weakness, 4 myelopathic ataxia, 1 quadriplegia, and 1 cauda equina syndrome). Two patients had sensory deficits, and two had pain only. The distribution of the tumors was as follows: 8 cases were cranio-cervical, 1 case was cervical, 6 cases were at the cervico-thoracic junction, 9 cases were of the thoracic spine, 5 cases were of the thoracolumbar spine, and 1 case was of the lumbar spine. Five cases also had intracranial manifestations. The mean interval between the onset of the first symptoms and treatment was 12 months. All cases were treated via (hemi)-laminectomy for complete removal of the tumor and occasionally via duraplasty. After a mean follow-up of 3 years, symptoms had improved by 3 points (on a 5-point scale) in 3 cases, by 2 points in 7 cases, and by 1 point in 12 cases; 7 cases were unchanged, and 1 case had worsened by 1 point. We observed 3 local recurrences. One case developed manifestations at a different site. Spinal meningiomas are often diagnosed late, after they have already caused major neurological deficits. Nevertheless, owing to their benign character, the outcome is favorable when treated appropriately. The outcome depends above all on the initial neurological status. The worse the deficit is, the less probable it is that the patient will recover neurologically.

BACKGROUND:Amyloid deposits within the brain can be found in a heterogeneous group of diseases. Some of them involve only the central nervous system (AD); others are of systemic origin. Isolated deposits either in the brain, cranial nerves or within the spinal neural structures are extremely rare. So far, we do not know the natural origin, nor the clinical course.METHODS:We reviewed the overall published cases as far as available and added our own case to learn more about the natural history, clinical and imaging characteristics of this rare brain lesion.RESULTS:Together with our own case, 27 patients with cerebral amyloidoma were collected in the literature. The lesion always occurred supratentorially, moreover in another two cases also infratentorially. The initial symptoms as well as the results of different neuroimaging features were not specific. There was no predominance for sex and localization. Diagnosis could only be established by histopathological examination after surgical intervention. No recurrence was seen after radical resection; but there was progression in some cases of tumor biopsy.CONCLUSION:Complete surgical removal of cerebral AL amyloidoma seems to be the only way to prevent progression or recurrence of such a brain lesion.

Surgical intervention for extracranial carotid artery stenosis remains a major potential therapeutic modality for the prevention of stroke. Nevertheless, every kind of surgical technique for carotid entarterectomy (CEA) has its specific complications, compromising the final surgical result. The authors report about a 70-year old man, suffering from recurrent transient ischemic attacks by suspected internal carotid artery (ICA) re-stenosis, 11 and 13 years after CEA with patch angioplasty. In relation to neurological symptomatic and angiographic appearance of ICA re-stenosis an open surgery of the left ICA was preferred. Intraoperatively the old patch material was such vulnerable that it was not possible to maintain the continuity of ECA and ICA or CCA and ICA. Consequently reconstruction and replacement of ICA and ECA with 6 mm Gore-Tex grafts was performed. Follow-up three years after surgery showed no symptoms of insufficient brain metabolism as well as a good flow within the grafts. Patch angioplasty by CEA seems to be favourable to reduce the risk of early ICA re-stenosis but for all that there are other accompanying problems, which can compromise utility of patch technique. For this the authors prefer a patient adapted surgical treatment, based not only on so far not significant data but moreover on personal experience.

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

Editor: We read with interest the article by Beate Neuhauser and colleagues concerning patch angioplasty with two different materials. The authors highlight the superiority of bovine pericardium in comparison with polyester patching with regard to late results of carotid endarterectomy (CEA). Furthermore, they appreciate bovine pericardium because it combines all of the attributes of biologic tissue with the advantages concerning suitability in surgical practice. Nevertheless, one should be aware of a possible risk of prion transmission between different species when using biologic material. In spite of the efforts referring to patch angioplasty, there remains the question of whether such a procedure is necessary in CEA at all. As the authors discussed, above all, with patching there is an obligation for anesthetic attentiveness and intraoperative neuromonitoring, such as Doppler ultrasonography and electroencephalography. The usefulness of somatosensory evoked potentials should also be stressed. From our point of view, the application of neuroprotective measures, such as barbiturates, among others, should also be used to minimize the risk of brain metabolic disturbances. The adoption of microtechniques (operating microscope and microequipment) for precise performance of endarterectomy contributes to a low complication rate, as experienced by our senior authors (S.P., H.W.) in more than three decades of carotid and cerebrovascular surgery. With use of these principles, we rarely use patch angioplasty during CEA because the risk of pseudoaneurysm or other serious complications using patching cannot be entirely neglected. Of our patients with long follow-up after primary closure and microsurgical performance of CEA, in conformity with the findings of other authors, 6.4% developed restenosis, and only 3% underwent reoperation. The incidence of periand post-operative ischemic events was 3.8%. The high rate of restenosis with primary closure (34%) published by AbuRahma and colleagues is not common and may be related to deficiency or difficulty during surgery. In our opinion, the necessity of using any kind of patch in CEA is rare. Usually, the arteriosclerotically affected carotid artery is already dilated and after endarterectomy widened more than the healthy carotid artery, so there is no indication for a patch if suturing is performed carefully. Adoption of microtechnique is decisive for more precise performance of surgery and prevention of recurrent stenosis.

Despite a favourable prognosis, pilocytic astrocytomas may exhibit signs of malignancy on various neuroimaging modalities. This retrospective analysis was conducted to determine whether scintigraphic features of malignancy are also found on single-photon emission tomography (SPET) using L-3-[123I]iodo-α-methyl tyrosine (IMT) as a tracer. Twenty patients with pilocytic astrocytomas were retrospectively selected from a large series of patients referred for the evaluation of primary or recurrent brain tumours. IMT SPET was performed in 16 patients, positron emission tomography (PET) using 2-[18F]fluoro-2-deoxy-D-glucose (FDG) was available in 10 of the patients and SPET using technetium-99m tetrofosmin or thallium-201 had been performed in 11. Image analysis was performed using standard protocols to determine how many patients exceeded the respective thresholds of malignancy. Features of malignancy were found in 7/16 IMT SPET studies, in 7/10 FDG PET studies and in 7/11 of the residual SPET investigations. A significant correlation of tumour size and IMT uptake in primary pilocytic astrocytomas indicated partial volume effects to partly account for the differential uptake behaviour (n=10, r=0.87, P<0.05). Differences in IMT uptake in primaries (1.7±0.6, n=10) and in recurrent tumours (2.3±0.7, n=6) did not attain statistical significance. IMT SPET results indicative of malignancy are regularly found in pilocytic astrocytomas, despite their good prognosis. No uptake may be detected in largely cystic or in small tumours.

Both thallium-201 and iodine-123 α-methyltyrosine (123I-IMT) have been shown to be useful in the diagnostic evaluation of brain tumours. The aim of this study was to investigate the respective contributions of 201Tl and 123I-IMT single-photon emission tomography (SPET) in the non-invasive evaluation of intracerebral tumours. We analysed 65 patients with the following brain tumours: 8 non-neoplastic lesions, 4 meningiomas, 12 low-grade gliomas, 28 high-grade gliomas, 11 metastases and 2 high-grade lymphomas. 201Tl SPET and 123I-IMT SPET were performed [start of 201Tl SPET: 15 min p.i. (early) and 180 min p.i. (delayed); start of 123I-IMT SPET: 15 min p.i.]. The intensity of uptake was quantified as the ratio between tracer accumulation in the tumour and in the contralateral hemisphere. None of the non-neoplastic lesions or low-grade gliomas expressed marked 201Tl uptake. All malignant tumours except one small metastasis and all meningiomas except one small, cystic and degenerated lesion showed significant 201Tl accumulation [Tl(15’)>2.0]; 123I-IMT uptake was either absent or intermediate in non-malignant lesions except in two low-grade gliomas; the highest levels were observed in high-grade gliomas followed by metastases and lymphomas (mean IMT: 2.7 vs 2.1 vs 1.8), with metastases showing a high variability in 123I-IMT uptake (range: 0.8–3.6). Using 201Tl to distinguish non-neoplastic lesions from malignant tumours and meningiomas, 63 of 65 patients were characterised correctly. In the latter group, high-grade gliomas were correctly identified in 27 of 28 cases by their amino acid uptake. It is concluded that the combination of 201Tl and 123I-IMT surpasses the accuracy of each single test in the differentiation of space-occupying lesions of the brain. Based on these preliminary results, a sequential strategy is proposed involving an initial 201Tl SPET study and an additional 123I-IMT SPET study in the event of positive 201Tl uptake.

Single photon emission computed tomography (SPECT) with 201T1 and 123I-α-methyl tyrosine (123I-IMT) are routine methods for the evaluation of brain tumors. 123-I-IMT transport across the blood brain barrier is mediated by an amino acid carrier, 201T1 accumulation is analogous to cerebral potassium uptake.

lodine-123-alpha-methyl tyrosine (IMT) allows the investigation of amino acid transport rate in brain neoplasms. It was the aim of this study to evaluate the potential of IMT-SPECT to diagnose the recurrence of gliomas after primary therapy. Methods: Using a triple-headed SPECT camera, the cerebral uptake of IMT was determined in 27 patients 22 mo, on average, after surgical removal of a primary brain tumor. Eighteen patients had suffered from high-grade gliomas, and nine had suffered from low-grade tumors. Four patients were examined before and after surgical revision of a presumed tumor recurrence. A total of 31 studies were evaluated. The final diagnosis was based on prospective clinicopathological follow-up. Recurrence was diagnosed in 23 cases, with marked clinical deterioration occurring 3.1 mo, on average, after SPECT, and was confirmed by histopathology in 14 instances. Eight cases were free of recurrence, as evidenced by inconspicuous clinical follow-up, ranging from 6 mo to 17 mo after SPECT in seven cases, and by clinical course and histopathology in the remaining subject. Results: Patients with recurrence had significantly higher ratios of IMT uptake in the tumor area to that in a background region than did patients without recurrence (2.27 +/- 0.59 compared to 1.47 +/- 0.29; p < 0.002). The best cutoff level of the IMT uptake ratio in the differentiation between recurrence and benign posttherapeutic lesion was 1.8. Using this study-specific discrimination threshold, the sensitivity and specificity of IMT-SPECT for detecting glioma recurrence were 18 of 23 (78%) and 8 of 8 (100%), respectively. The area under the binormal receiver operating characteristic curve, fitted to the data, was 0.90 +/- 0.06. Conclusion: lodine-123-alpha-methyl tyrosine-SPECT is a promising new tool in the follow-up of patients with gliomas after primary therapy.

Use of iodine-123-α-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.

Using single-photon emission tomography (SPET), the radiopharmaceutical l-3-iodine-123-alpha-methyl tyrosine (IMT) has been applied to the imaging of amino acid transport into brain tumours. It was the aim of this study to investigate whether IMT SPET is capable of differentiating between high-grade gliomas, low-grade gliomas and non-neoplastic brain lesions. To this end, IMT uptake was determined in 53 patients using the triple-headed SPET camera MULTISPECT 3. Twenty-eight of these subjects suffered from high-grade gliomas (WHO grade III or IV), 12 from low-grade gliomas (WHO grade II), and 13 from non-neoplastic brain lesions, including lesions after effective therapy of a glioma (five cases), infarctions (four cases), inflammatory lesions (three cases) and traumatic haematoma (one case). IMT uptake was significantly higher in high-grade gliomas than in low-grade gliomas and non-neoplastic lesions. IMT uptake by low-grade gliomas was not significantly different from that by non-neoplastic lesions. Diagnostic sensitivity and specificity were 71% and 83% for differentiating high-grade from low-grade gliomas, 82% and 100% for distinguishing high-grade gliomas from non-neoplastic lesions, and 50% and 100% for discriminating low-grade gliomas from non-neoplastic lesions. Analogously to positron emission tomography with radioactively labelled amino acids and fluorine-18 deoxyglucose, IMT SPET may aid in differentiating high-grade gliomas from histologically benign brain tumours and non-neoplastic brain lesions; it is of only limited value in differentiating between non-neoplastic lesions and histologically benign brain tumours.

The multiple multilocular intracranial recurrence of a hemangiopericytoma (HPC) over 21 years in our patient, who has been successfully operated upon and irradiated several times, confirms the known tendency of the majority of HPCs to marked biological activity. The aggressive behavior of HPCs shows an unusually broad scale of variations. On the basis of clinical observations of this particular case, the relative or potential malignancy of HPCs is discussed.