Alexander Hartmann

Crossed cerebello-cerebral diaschisis in a patient with cerebellar infarction

After supratentorial infarction crossed cerebellar diaschisis has been described. This report concerns the rare phenomenon of crossed cerebral diaschisis in cerebellar infarction. Relative distribution of cerebral and cerebellar blood flow was measured using three-dimensional, qualitative single-photon-emission-computed-tomography (SPECT) with a rotating gamma camera and 123I-IMP. Regional cerebral blood flow was calculated with the two-dimensional, quantitative 133Xe-inhalation-technique. Reduced uptake was observed in the left cerebral hemisphere (-13.9%) contralateral to the cerebellar infarction with the most marked reduction in the left premotor region (-21%). This might be explained by the functional depression of cerebello-ponto-thalamo-cerebral pathways.

Detectability and detection rate of acute cerebral hemisphere infarcts on CT and diffusion-weighted MRI.

Abstract Our purpose was to compare the detectability and detection rate of acute ischaemic cerebral hemisphere infarcts on CT and diffusion-weighted MRI (DWI). We investigated 32 consecutive patients with acute hemisphere stroke with unenhanced CT and DWI within 6 h of stroke onset. The interval between CT and DWI ranged from 15 to 180 min (mean 60 min). Infarct detectability on CT and DWI was determined by comparing the initial CT, DWI and later reference images in a consensus reading of five independent examiners. The “true” detection rate was assessed by analysing all single readings. Two patients had intracerebral haematomas on DWI and CT and were excluded. There were 27 patients with ischaemic infarcts; all were visible on DWI and proven by follow-up. DWI was negative in three patients without a final diagnosis of infarct (100 % sensitivity, 100 % specificity, χ2 = 30, P < 0.0001). Ischaemic infarcts were visible on 15 and not seen on 12 CT studies (55 % sensitivity, 100 %specificity, χ2 = 1.48, P = 0.224). With regard to the single readings (30 examinations × 5 examiners = 150 readings), 63 CT readings were true positive and 72 false negative (sensitivity 47 %, specificity 86 %, χ2 = 2.88, P = 0.089). Of the DWI readings 128 were true positive and 7 false negative (sensitivity 95 %, specificity 87 %, χ2 = 70.67, P < 0.0001). Interobserver agreement was substantial for CT (ϰ = 0.72, 95 % confidence interval, 0.6–0.84) and DWI (ϰ = 0.82, 95 % confidence interval, 0.46–1). Taken together, detectability and detection rate of acute (< 6 h) hemisphere infarcts are significantly higher with DWI than with CT.

Regional cerebral blood flow single-photon emission tomography with 99mTc-HMPAO and the acetazolamide test in the evaluation of vascular and Alzheimer's dementia

Abstract. The diagnostic potential of technetium-99m hexamethylpropylene amine oxime (HMPAO) following systemic administration of the cerebral vasodilator acetazolamide (acetazolamide test) was evaluated by regional cerebral blood flow (rCBF) single-photon emission tomography (SPET) in patients with Alzheimer’s disease (AD) or vascular dementia (VD). An initial, high-resolution SPET study was performed with 99mTc-HMPAO, and after 2 days the patients were re-evaluated with 99mTc-HMPAO following systemic administration of acetazolamide. Reconstructed SPET slices were evaluated visually and semiquantitatively by a semi-automatic rCBF map method. When 99mTc-HMPAO alone was used, bilateral hypoperfusion was found in the temporal and/or parietal regions in 33% (6/18) of the VD patients and in 70% (23/33) of the AD patients. The corresponding data obtained by quantitative evaluation were 41% (7/17) and 71% (15/21), respectively. The vascular reserve capacity, as determined with the acetazolamide test, was preserved visually in 22% (4/18) and quantitatively in 29% (5/17) of the VD patients, but in 73% (24/33) and 76% (16/21) of the AD patients. The differences in the perfusion patterns between the VD and AD patients were statistically significant (P<0.01, Fischer’s exact test). Of the VD patients with hypoperfusion (bilateral temporal and/or parietal), 4/6 (67%, visual evaluation) and 4/7 (57%, quantitative evaluation) had a decreased vascular reserve capacity as determined with the acetazolamide test. In the AD group of patients the corresponding results were 3/23 (13%) and 4/15 (27%). It is concluded that the acetazolamide test is promising in rCBF SPET to differentiate VD from AD.

Immersion and perfusion staining with 2,3,5-triphenyltetrazolium chloride (TTC) compared to mitochondrial enzymes 6 hours after MCA-occlusion in primates.

2,3,5-triphenyltetrazolium chloride (TTC) is commonly applied in rodents and cats as a marker of infarcted tissue as early as 20 min after the onset of focal ischaemia. At this stage it is suggested that it reflects hypoperfusion rather than failure of respiratory chain. Immersion of brain slices in TTC solution is preferable in comparison to perfusion with TTC in order to ensure, that enough TTC enters the post-occlusion tissue. We compared immersion technique versus perfusion technique 6 h after permanent occlusion of the left middle cerebral artery in 18 baboons. In addition, we assessed the function of the respiratory chain enzymes of stained and unstained tissue in three baboons. The immersion technique revealed an absence of TTC staining limited to subcortical structures in two animals. In seven experiments TTC indicated involvement of almost the entire MCA territory. The extent of the ischaemic lesion indicated by the perfusion technique was very similar. Tissue samples from the presumed infarcted areas revealed normal mitochondrial function. We conclude that perfusion and immersion technique do not cause significant different ischaemic delineation 6 h after middle cerebral artery occlusion. TTC staining appears to be a reliable method of evaluating volume of infarction in primates. Furthermore, absence of TTC staining 6 h after stroke onset is caused by energy or oxygen depletion rather than by mitochondrial injury.

18F-fluorodeoxyglucose-PET and99mTc-bicisate-SPECT in Creutzfeldt-Jakob disease

In a patient with the occipitoparietal form of Creutzfeldt-Jakob disease (CJD) (Heidenhain type) positron emission tomography (PET) demonstrated decreased glucose utilization in the occipital lobes and adjacent cortical regions. Single photon emission computed tomography (SPECT) with99mTc-bicisate showed a “coupled” decrease in blood flow in identical cortical areas in this patient. In contrast, magnetic resonance imaging (MRI) was normal. In the early stage of CJD, when still no major morphological abnormalities can be observed, functional imaging is useful for differential diagnosis, particularly to exclude other causes of dementia or pathological EEG patterns.

Abnormalities of interictal cerebral perfusion in classic but not common migraine.

Regional cerebral blood flow (rCBF) was measured as gray matter blood flow using the 133Xe inhalation technique in 50 pain-free headache patients: Eight patients having classic migraine with normal computed tomograms were matched to patients having common migraine and to normal controls. Interictal rCBF was determined at least 6 days after the last migraine attack and more than 24 hours before the next one. There were no between-group differences for age, PCO2, mean hemispheric blood flow, interindividual and intraindividual variabilities, hyperfrontality, or rCBF symmetry. However, when subjects were classified as to overall abnormal perfusion, a significant number (n = 4, p less than 0.04) of patients with classic migraine had rCBF abnormalities, whereas only one such patient was seen in the group with common migraine. Patients with classic migraine had abnormal mean hemispheric blood flows or disturbed intrahemispheric rCBF patterns. Oligemic and hyperemic regions topographically corresponded to the clinical symptoms in one patient. We conclude that during migraine attacks and interictally there is an instability of rCBF control in patients with classic but not common migraine.

Multifocal myelitis in Behçet’s disease

A diagnosis of Behcet disease was made in a 26-year-old human leukocyte antigen-B51–positive Turkish man presenting with recurrent oral aphthosis, spastic paraparesis, and a sensory level at D10. CSF contained 168/μL …

A Controlled Study on the Effect of Pentoxifylline and an Ergot Alkaloid Derivative on Regional Cerebral Blood Flow in Patients with Chronic Cerebrovascular Disease

Regional cerebral blood flow (rCBF) in 90 patients with CBF decreased due to vascular diseases was studied by using the xenon 133 inhalation technique and a 32-detector setup. Whereas 30 patients received their standard basic ther apy only and were regarded as controls, 30 others received 3 x 2 mg/day of an ergot alkaloid (co-dergocrine mesylate), and 30 others received 3 x 400 mg pen toxifylline (slow-release formulation)/day orally. Therapy was performed for eight weeks and CBF measured before start of treatment, after a four-week treatment period, and at the end of the study. CBF did not change significantly in the control group; both the pentoxifylline and the ergot alkaloid group pre sented with a significant increase in the CBF. This positive effect was signifi cantly more pronounced in the pentoxifylline group and affected more ischemic than other brain tissues. In addition, symptoms like sleep disturbances, vertigo, and tinnitus improved significantly during the pentoxifylline observation peri od.

Myocardial and cerebral hemodynamics during tachyarrhythmia-induced hypotension in the rat.

The different vulnerabilities of heart and brain to hypotension and hypoxia have been discussed. Hemorrhagic or cardiogenic hypotension appears to cause greater cerebral lesions than drug-induced hypotension. The present model was established to evaluate myocardial blood flow (MBF) and function of the heart and cerebral blood flow (CBF) during tachyarrhythmias and to characterize the capacity of blood flow regulation in the heart and brain during tachycardia-induced borderline hypotension. Methods and ResultsMBF and CBF were determined with radiolabeled microspheres. Coronary and central venous oxygen tensions were measured to estimate myocardial and cerebral oxygen consumption (M&OV0622;o2 and C&OV0622;o2. Measurements were performed in 62 Sprague-Dawley rats during sinus rhythm and high-rate left ventricular pacing and after hemorrhage. In control rats, MBF and CBF were 5.08±1.07 and 1.09±0.29 mL · g−1 · min−1 · MBF increased (7.21±1.98 mL · g−1 · min−1, P < .05), whereas CBF decreased (0.99±0.29 mL · g−1 · min−1, P=NS) during normotensive high-rate pacing. MBF and CBF dropped to 4.27±2.24 mL · g−1 · min−1 (P < =NS) and 0.68±0.29 mL · g−1 · min−1 (P < .05) during pacing-induced borderline hypotension and decreased further during severe hypotension (1.77±0.81 mL · g−1 · min−1, P < .01; 0.45±0.18 mL · g−1 · min−1, P < .01). During borderline hypotension due to hemorrhage, MBF and CBF were 4.05±0.95 mL · g−1 · min−1 (P=NS) and 0.71±0.23 mL · g−1 · min−1 (P < .05). MVo2 and CVo2 were 72.7±15.4 and 12.7plusmn;3.3 mL · 100 g−1 · min−1 in control rats. MVo2 increased during normotensive pacing (100.3plusmn;27.4 mL · 100 g−1 · min−1, P=NS). Mean M&OV0622;o2 was reduced during pacing-induced borderline hypotension (64.1±35.6 mL · 100 g−1 · min−1, P=NS) and severe hypotension (29.8±15.4 mL · 100 g−1 · min−1, P < .05). CVo2 decreased in correlation to CBF. Coronary and cerebrovascular resistance and autoregulation indexes indicated a maintenance of MBF regulation and a failure of CBF regulation during borderline hypotensive tachycardias. These results show a dissociation of MBF and CBF after onset of hypotensive tachycardias. Thus, brain tissue appears to be jeopardized at an earlier stage than myocardial muscle during tachyarrhythmias. ConclusionsThe proposed hypotension model is suitable to analyze tachyarrhythmia-induced hemodynamic changes and end-organ perfusion in the presence of myocardial dysfunction. It has the potential to test therapeutic strategies in the treatment of tachycardias.

Changes of Cerebral Blood Flow Following Dexamethasone Treatment in Brain Tumour Patients. A Xe/CT Study

Summary Background. It is not exactly known how dexamethasone improves the function of brain that is affected by tumour. Whether and in what sense dexamethasone influences cerebral blood flow has rarely been addressed and previous investigations have yielded inconsistent results. Method. Stable xenon-enhanced computed tomography (Xe/CT) was used to assess the regional cerebral blood flow (rCBF) in 67 patients with supratentorial primary and secondary brain tumours. rCBF studies were done at least once prior to resection or stereotactic biopsy of the tumours. In nine patients repeated studies before surgery and in 15 patients additional studies after resective surgery were obtained. Dexamethasone was administered according to the clinical needs before surgery and systematically after surgery. Of the preoperative studies 30 were obtained before and 47 during dexamethasone treatment. The rCBF data were analysed upon correlations with daily dose, cumulative dose, and duration of dexamethasone treatment. Moreover, individual courses before and after surgery were examined. Findings. Mainly inverse correlations were found between the treatment parameters, particularly the daily dose of dexamethasone, and rCBF. Only in the subgroup of glioblastoma patients, a positive correlation was found of both duration and cumulative dose of dexamethasone with rCBF in oedema. Serial observations of individual patients confirmed the above findings, yet with possible exceptions. After tumour resection a clear improvement of rCBF was regularly observed. Interpretation. The beneficial effect of dexamethasone is not attributed to an increase of cerebral blood flow, because rather decreases of rCBF are mostly observed.