Metabolic changes in patients with aneurysmal subarachnoid hemorrhage apart from perfusion deficits: neuronal mitochondrial injury?

BACKGROUND AND PURPOSE: Neuronal damage in aSAH apart from perfusion deficits has been widely discussed. We aimed to test if cerebral injury occurs in aSAH independently from visible perfusion deficit by measuring cerebral metabolites in patients with aSAH without infarction or impaired perfusion. MATERIALS AND METHODS: We performed 3T MR imaging including (1)H-MR spectroscopy, DWI, and MR perfusion in 58 patients with aSAH and 11 age-matched and sex-matched control patients with incidental aneurysm. We compared changes of NAA, Cho, Glx, Lac, and Cr between all patients with aSAH and controls, between patients with and without visible perfusion deficit or infarction and controls, and between patients with and without visible perfusion deficit or infarction by using the Wilcoxon signed-rank test. RESULTS: We found that NAA significantly (P < .005) decreased in all patients with aSAH. Cho was significantly increased in all patients compared with controls (P < .05). In patients without impaired perfusion or infarction, Glx was significantly decreased compared with both controls (P = .005) and patients with impaired perfusion or infarction (P = .006). CONCLUSIONS: The significant decrease of NAA and Glx in patients with aSAH but without impaired perfusion or infarction strongly suggests global metabolic changes independent from visible perfusion deficits that might reflect neuronal mitochondrial injury. Further, impaired perfusion in aSAH seems to induce additional metabolic changes from increasing neuronal stress that might, to some extent, mask the global metabolic changes.

Age-related changes of cerebral autoregulation: new insights with quantitative T2'-mapping and pulsed arterial spin-labeling MR imaging.

BACKGROUND AND PURPOSE: Cerebral perfusion and O(2) metabolism are affected by physiologic age-related changes. High-resolution motion-corrected quantitative T2'-imaging and PASL were used to evaluate differences in deoxygenated hemoglobin and CBF of the gray matter between young and elderly healthy subjects. Further combined T2'-imaging and PASL were investigated breathing room air and 100% O(2) to evaluate age-related changes in cerebral autoregulation. MATERIALS AND METHODS: Twenty-two healthy volunteers 60-88 years of age were studied. Two scans of high-resolution motion-corrected T2'-imaging and PASL-MR imaging were obtained while subjects were either breathing room air or breathing 100% O(2). Manual and automated regions of interest were placed in the cerebral GM to extract values from the corresponding maps. Results were compared with those of a group of young healthy subjects previously scanned with the identical protocol as that used in the present study. RESULTS: There was a significant decrease of cortical CBF (P < .001) and cortical T2' values (P < .001) between young and elderly healthy subjects. In both groups, T2' remained unchanged under hyperoxia compared with normoxia. Only in the younger but not in the elderly group could a significant (P = .02) hyperoxic-induced decrease of the CBF be shown. CONCLUSIONS: T2'-mapping and PASL in the cerebral cortex of healthy subjects revealed a significant decrease of deoxygenated hemoglobin and of CBF with age. The constant deoxyHb level breathing 100% O(2) compared with normoxia in young and elderly GM suggests an age-appropriate cerebral autoregulation. At the younger age, hyperoxic-induced CBF decrease may protect the brain from hyperoxemia.

Neuroradiological viewpoint on the diagnostics of space-occupying brain lesions.

Conventional magnetic resonance (MR) imaging of space-occupying lesions may answer most of the questions concerning the diagnosis and subsequent treatment strategies if patient age, clinical and paraclinical findings are considered as well. However, crucial and relevant differential diagnoses require additional MR methods, such as diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI) and magnetic resonance spectroscopy (MRS). In necrotic ring-enhancing lesions DWI may detect inflammatory processes, whereas characteristics of the peritumoral area may help to distinguish between metastases and glioblastomas. In solid tumors DWI, PWI and MRS may also aid the differentiation between low-grade gliomas and malignant tumors, such as gliomas WHO (World Health Organization) grade III and IV and lymphomas. This review briefly explains special MR methods with respect to brain tumors and illustrates the diagnostic pathways necessary for supplying a reliable diagnosis as well as optimal pre-operative imaging of space-occupying brain lesions.

Morphometry of the pituitary gland and hypothalamus in long-term survivors of childhood trauma.

PURPOSE: Chronic pituitary dysfunction is increasingly recognized as a sequela of traumatic brain injury (TBI). Our aim was to rule out any late morphometric changes of the pituitary gland and hypothalamus in survivors of TBI during childhood requiring intensive care. METHODS: We assessed morphometric abnormalities of the sella region and hypothalamus in patients who sustained TBI during childhood. The patients showed no clinical hormonal dysfunction at the acute phase and pituitary hormone levels at the time of our study were within normal limits. From the 18 enrolled patients in the magnetic resonance study, five were removed due to morphological changes or anatomical variations. We studied the MRI of 13 male survivors (mean age 27 years, mean time after trauma 20 years) and compared them to 13 male control subjects who were matched in terms of age (mean age, 26 years), education and ethnicity. Analyses of the pituitary gland and sella on a midsagittal T2- and T1-weighted image were performed. We used voxel-based morphometry (VBM), an unbiased MRI morphometric method to investigate hypothalamic region in this group of patients. RESULTS: There was only a trend towards a reduced pituitary gland width in the patient group compared to controls. However, no significant morphological and morphometric abnormality was seen and VBM showed no hypothalamic grey matter loss. CONCLUSION: In the absence of hormonal dysfunction, no persisting morphometric changes of the pituitary gland and hypothalamus were seen in survivors of childhood TBI requiring intensive care.

MR imaging of midbrain pathologies.

The spectrum of pathologic processes affecting the midbrain features some differences to other brain areas. The midbrain is exposed to traumatic alterations due to its position between the tentorial edges, and some neurodegenerative and metabolic-toxic diseases may typically involve the midbrain. Isolated midbrain ischemia is rare, whereas the midbrain is typically part of the "top of the basilar" syndrome. Primary midbrain tumors are also infrequent and often show a benign clinical course. Apart from multiple sclerosis other inflammatory autoimmune processes and some infectious agents predominantly affect the brainstem including the midbrain. This review discusses the different pathologic processes of the midbrain, i.e., infarction, hemorrhage and trauma, inflammation, toxic and metabolic diseases, neurodegeneration, neoplastic diseases, as well as pathologies typically involving the perimesencephalic cisterns.

[Corpus callosum. Landmark of the origin of cerebral diseases]. / Corpus callosum. Landmarke für die Genese zerebraler Erkrankungen.

Diseases of the corpus callosum include developmental disorders, immunomodulated CNS diseases, vascular malformations, disturbances of metabolism including the electrolyte homeostasis, secondary degenerations and mechanical injuries. This report provides information on the differential diagnosis of reversible and irreversible pathological changes of the corpus callosum with special focus on the localization, which often allows conclusions on the pathogenesis to be drawn.

[Postictal MR-changes. A rare and important differential diagnosis]. / Postiktale MR-Veränderungen. Eine seltene und wichtige Differenzialdiagnose.

BACKGROUND: Postictal MR findings are analyzed in the context of MR morphological differential diagnoses. PATIENTS AND METHODS: Postictal MRI was performed in 11 patients. The patterns of MR changes and their differential diagnoses were analyzed. RESULTS: Focal accentuation of signal increase in the cortex was found on T2-weighted images in 90% of these cases, pial enhancement in 70% and signal changes of the pulvinar/thalamus in 40%. The most common differential diagnoses were encephalitis, and in tumor patients carcinomatous involvement of the meninges. CONCLUSION: Postictal MR changes vary widely and are difficult to differentiate from illnesses such as encephalitis and carcinomatosis involving the meninges. Nevertheless, knowledge of the typical pattern of postictal MR findings and the clinical course may help to avoid mistaken diagnoses.

Proton magnetic resonance spectroscopy in childhood brainstem lesions.

BACKGROUND: Diagnosis of brainstem lesions in children based on magnetic resonance imaging alone is a challenging problem. Magnetic resonance spectroscopy (MRS) is a noninvasive technique for spatial characterization of biochemical markers in tissues and gives information regarding cell membrane proliferation, neuronal damage, and energy metabolism. METHODS: We measured the concentrations of biochemical markers in five children with brainstem lesions and evaluated their potential diagnostic significance. Images and spectra were acquired on a 1.5-T imager. The concentrations of N-acetylaspartate, tetramethylamines (e.g., choline), creatine, phosphocreatine, lactate, and lipids were measured within lesions located at the brainstem using Point-resolved spectroscopy sequences. RESULTS: Diagnosis based on localized proton spectroscopy included brainstem glioma, brainstem encephalitis, demyelination, dysmyelination secondary to neurofibromatosis type 1 (NF 1), and possible infection or radiation necrosis. In all but one patient, diagnosis was confirmed by biopsy or by clinical follow-up. CONCLUSIONS: This small sample of patients suggests that MRS is important in the differential diagnosis between proliferative and nonproliferative lesions in patients without neurofibromatosis. Unfortunately, in cases of NF 1, MRS can have a rather misdiagnosis role.

[Endovascular treatment for intracranial stenoses. A common statement by neurologists and neuroradiologists]. / Endovaskuläre Behandlung intrakranieller Stenosen. Eine gemeinsame Stellungnahme von Neurologen und Neuroradiologen.

Intracranial stenoses cause 5-10% of all strokes and are increasingly detected by means of modern imaging methods. The stroke danger of high-grade symptomatic stenoses is relatively high, with an annual risk of approximately 10% under medical treatment. Coumadin increases the risk of hemorrhage, and after risk/benefit considerations, antiplatelets should be preferred for antithrombotic therapy. Despite optimized medical treatment, a small group of patients with recurrent symptoms or symptomatic stenoses without adequate collateral supply probably carry higher spontaneous stroke risk and may be considered for intracranial stenting, which itself is associated with procedural risks of up to 10%. Currently published case series show relatively high complication rates as a major drawback of endovascular treatment, mainly strokes after occlusion of perforating branches extending from the stenotic vessel segment or hemorrhagic complications. According to data from smaller feasibility studies, stroke rates in follow-up after successful stenting seem to be low. The average rate of high-grade restenosis with possible indication for reintervention is 10%. Improvements in endovascular treatment aim at reducing vessel wall trauma during balloon angioplasty by underdilatation or the use of self-expanding stents. Until complication rates are dependably reduced to values of 5-6%, indication for endovascular treatment should be restricted to patients without therapeutic alternatives. According to limited data with large variation between different studies, a prospective multicentric registry is proposed for systematic evaluation and further development of the method.

Conformability of balloon-expandable stents to the carotid siphon: an in vitro study.

BACKGROUND AND PURPOSE: Endovascular placement of coronary balloon-expandable stents in patients with recurrent cerebral ischemia has emerged as a treatment option for intracranial arterial occlusive disease. We have developed an in vitro model matching the tortuous curve of the carotid siphon that allows the assessment of apposition of stents to a curved vessel wall. METHODS: Six types of balloon-expandable coronary stents were implanted in a silicone model of the carotid siphon. Digital radiographs and 3D rotational angiograms were obtained. Stent morphology was evaluated and the degree of apposition between stent and wall of the model was measured on a digital workstation. RESULTS: All 6 stents showed lack of apposition between stent and the wall at the convexity of the anterior segment of the carotid siphon and the wall at the concavity at both extremities of the stent. In and around the curve, the modules of the stents did not expand completely to their nominal diameter and were distorted to an oval shape. CONCLUSION: The tested coronary balloon-expandable stents did not completely conform to the vessel wall of the model of the carotid siphon and further development is needed to approach the goal of an "ideal intracranial stent."

Accelerated myelination associated with venous congestion.

Magnetic resonance imaging is currently the gold standard in the assessment of brain myelination. The normal pattern of brain myelination conforms to a fixed chronological sequence. Focal accelerated myelination is a usual pathological state and previously has only been associated with Sturge-Weber syndrome. The purpose of our study is to describe alternate causes for accelerated myelination. We retrospectively reviewed serial MR scans, MR angiography, conventional angiography and the clinical progress of three children with accelerated myelination. Two patients with accelerated myelination had an underlying cerebral sinovenous thrombosis. The third patient had Sturge-Weber syndrome. Our study strongly suggests that cerebral venous thrombosis with the consequent restriction of venous outflow could be a key factor in the induction of accelerated myelination. We recommend that in patients with accelerated myelination, the search for an underlying etiology should include careful evaluation of the intracranial vascular pathology, especially cerebral venous thrombosis.

Importance of diffusion-weighted imaging in the diagnosis of cystic brain tumors and intracerebral abscesses.

OBJECTIVE: It is often difficult to decide whether a cystic brain lesion is a tumor or an abscess by means of conventional MRI techniques. The immediate diagnosis of a brain abscess is important for the patient's outcome. Our goal was to study the ability of diffusion-weighted imaging and calculation of the apparent diffusion coefficient (ADC) to differentiate between these two pathologies. PATIENTS AND METHODS: Ten patients (five men, five women) with cystic brain lesions were examined with MRI. The ADC maps were calculated for each subject and the ADC value of each lesion was measured. Histology revealed glioblastoma multiforme in six patients and abscess in four patients. RESULTS: All brain abscesses showed markedly hyperintense signal changes on diffusion-weighted imaging, whereas the appearance of glioblastoma varied from slightly hyperintense to hypointense signal conversion. The mean ADC value calculated in the six patients with cystic brain tumor was: 2.05 x 10 (-3) mm(2)/s (1.38-2.88 x 10 (-3) mm(2)/s). The mean ADC value of the four patients with brain abscess was: 0.57 x 10 (-3) mm(2)/s (0.38-0.77 x 10 (-3) mm(2)/s). CONCLUSION: Diffusion-weighted imaging and calculation of ADC maps constitute a helpful tool to differentiate between cystic brain tumors and brain abscesses.

[Local chemotherapy for squamous cell cancer of the oral cavity and oropharynx]. / Lokale Chemotherapie oraler und oropharyngealer Plattenepithelkarzinome.

BACKGROUND: Modern treatment concepts for patients suffering from oral and oropharyngeal cancer include more and more adjuvant therapeutic options. Local chemotherapy offers the possibility to apply an extremely high drug concentration at the tumor site while minimizing possible side effects by systemic neutralization at the same time. PATIENTS AND METHODS: A total of 289 patients with histologically proven carcinoma of the oral cavity and the oropharynx underwent neoadjuvant intra-arterial chemotherapy with high-dosage cisplatin within a multimodal therapeutic setting. Concerning the TNM classification, more than 70% of the patients were classified as stages III and IV. The mean age at the time of intervention was 60 years, and 71% of the patients were male. RESULTS: After the first cycle 19.3% of the patients presented with complete remission (grade I); 35.4% and 41.5% showed partial remissions (grade II) or stable disease (grade III), respectively. The mean observation time after treatment was 28 months (median: 24.2 months). Of the 137 patients who completed the full multimodal therapeutic scheme, 11% developed local recurrence, and 12.4% developed lymph node or distant metastasis. At the time of evaluation, 72.5% of these patients were still alive. CONCLUSION: Intra-arterial chemotherapy is a safe and highly effective procedure that should be considered as an important option in multimodal therapeutic concepts for oral and oropharyngeal cancer.

Central nervous system lymphoma in children.

This paper describes the rare MR and CT features of central nervous system (CNS) lymphoma in immunocompetent children and in survivors of childhood acute lymphoblastic leukemia (ALL) and discusses the causative role of cranial irradiation and/or leukoencephalopathy preceding central nervous system (CNS) lymphoma in survivors of childhood leukemia. The authors reviewed MR and CT scans of 3 children with biopsy-proved CNS lymphoma. One child had tumor infiltration within the optic nerve sheaths and optic chiasm by previously known non-Hodgkin lymphoma. In 2 patients, CNS lymphoma developed 8 and 10 years after initial ALL treatment. In both cases CNS lymphoma was preceded by cranial irradiation and leukoencephalopathy. A single lesion was present in 3 out of 4 patients. All lesions were isointense or hypointense on the T1-weighted images relative to gray matter and showed homogeneous enhancement. One lesion was centered in the central gray matter, one lesion was centered within a cerebral hemisphere, one lesion was in optic nerve, and there were 2 parasellar lesions. CNS lymphoma has a variable appearance in children. Knowledge of risk factors in children may help in the early recognition of disease, allowing for timely intervention. This may prompt early biopsy or a conservative management in the appropriate clinical setting.

[Stenting in acute stroke]. / Stenting beim akuten Schlaganfall.

Hemodynamic impairment caused by pseudo-occlusion or occlusion of the internal carotid artery (ICA) is a rare etiology of stroke. Acute revascularization of the vessel can restore the flow to the brain. This retrospective study shows that ICA stenting with proximal and distal protection devices in patients with acute stroke and pseudo-occlusion or occlusion of the ICA is technically feasible and can prevent further hemodynamic strokes. In contrast, selected patients have a high risk of reperfusion syndrome with intracranial hemorrhage and peri-interventional monitoring of blood pressure in an ICU is recommended.

[Mechanical recanalization in acute stroke treatment]. / Mechanische Rekanalisation beim akuten Schlaganfall.

The development of endovascular techniques for the treatment of acute stroke began with the introduction of local intra-arterial fibrinolysis. In parallel to designing new systemic therapy approaches, catheter systems for loosening, disintegrating, or removing cerebral thrombi have undergone assessment in recent years to serve as alternatives or supplements to fibrinolytic treatment. Mechanical alteration of intracranial thrombi with balloon catheters, manipulations with the guide wire, or ultrasound waves transmitted into the vascular system as well as techniques for thrombus aspiration, snare extraction, or more complex hydrodynamic or laser-guided thrombectomy systems have been tested in feasibility studies, which evidenced basic functionality and relative safety. Broad clinical applications outside of the clinical trial setting cannot yet be recommended since the new catheter systems are still in early phase clinical testing.

Isolated CNS relapse in neuroblastoma.

We report three patients with primary extracerebral neuroblastoma and central nervous system (CNS) relapse. As the survival of children with metastatic neuroblastoma improves with recent advances in treatment, CNS involvement becomes more frequently detected. MR imaging of the brain and spine are strongly indicated in the follow-up of patients with increased risk of developing CNS disease.

Assessment of changes in cerebral circulation time due to vasospasm in a specific arterial territory: effect of angioplasty.

This study demonstrates that in experienced hands, intracranial angioplasty is a feasible and safe option in a selected group of patients with severe (>50% stenosis) symptomatic vasospasm following subarachnoid hemorrhage. Cerebral circulation time is a surrogate parameter closely linked to cerebral perfusion. The study presented shows that not only stenosis but also changes in circulation time are obtained by angioplasty. Twenty angioplasties of one or two vessel segments were performed over 2 years in 18 consecutive patients with posthemorrhagic vasospasm fulfilling criteria for invasive treatment. In all patients, degree of stenosis and circulation time could be reduced by angioplasty. Clinical results were ranked according to Glasgow Outcome Scale. Imaging after 15/20 angioplasties showed no additional infarction. In 4/20 cases, CT showed demarcation of infarction after angioplasty. In 1/20 cases of posterior circulation angioplasty, CT is not sensitive enough to exclude smaller infarctions. Imaging and clinical outcome reveal a definite benefit.