EAN consensus statement for management of patients with neurological diseases during the COVID-19 pandemic.

BACKGROUND AND PURPOSE: The recent SARS-CoV-2 pandemic has posed multiple challenges to the practice of clinical neurology including recognition of emerging neurological complications and management of coexistent neurological diseases. In a fast-evolving pandemic, evidence-based studies are lacking in many areas. This paper presents European Academy of Neurology (EAN) expert consensus statements to guide neurologists caring for patients with COVID-19. METHODS: A refined Delphi methodology was applied. In round 1, statements were provided by EAN scientific panels (SPs). In round 2, these statements were circulated to SP members not involved in writing them, asking for agreement/disagreement. Items with agreement >70% were retained for round 3, in which SP co-chairs rated importance on a five-point Likert scale. Results were graded by importance and reported as consensus statements. RESULTS: In round one, 70 statements were provided by 23 SPs. In round two, 259/1061 SP member responses were received. Fifty-nine statements obtained >70% agreement and were retained. In round three, responses were received from 55 co-chairs of 29 SPs. Whilst general recommendations related to prevention of COVID-19 transmission had high levels of agreement and importance, opinion was more varied concerning statements related to therapy. CONCLUSION: This is the first structured consensus statement on good clinical practice in patients with neurological disease during the COVID-19 pandemic that provides immediate guidance for neurologists. In this fast-evolving pandemic, a rapid response using refined Delphi methodology is possible, but guidance may be subject to change as further evidence emerges.

The international European Academy of Neurology survey on neurological symptoms in patients with COVID-19 infection.

BACKGROUND AND PURPOSE: Although the main clinical features of COVID-19 infection are pulmonary, several associated neurological signs, symptoms and diseases are emerging. The incidence and characteristics of neurological complications are unclear. For this reason, the European Academy of Neurology (EAN) core COVID-19 Task Force initiated a survey on neurological symptoms observed in patients with COVID-19 infection. METHODS: A 17-question online survey was made available on the EAN website and distributed to EAN members and other worldwide physicians starting on 9 April 2020. RESULTS: By 27 April 2020, proper data were collected from 2343 responders (out of 4199), of whom 82.0% were neurologists, mostly from Europe. Most responders (74.7%) consulted patients with COVID-19 mainly in emergency rooms and in COVID-19 units. The majority (67.0%) had evaluated fewer than 10 patients with neurological manifestations of COVID-19 (neuro COVID-19). The most frequently reported neurological findings were headache (61.9%), myalgia (50.4%), anosmia (49.2%), ageusia (39.8%), impaired consciousness (29.3%) and psychomotor agitation (26.7%). Encephalopathy and acute cerebrovascular disorders were reported at 21.0%. Neurological manifestations were generally interpreted as being possibly related to COVID-19; they were most commonly recognized in patients with multiple general symptoms and occurred at any time during infection. CONCLUSION: Neurologists are currently and actively involved in the management of neurological issues related to the COVID-19 pandemic. This survey justifies setting up a prospective registry to better capture the prevalence of patients with neuro COVID-19, neurological disease characteristics and the contribution of neurological manifestations to outcome.

Demand for neurological services in Central Eastern Europe: a 10-year national survey in Hungary.

BACKGROUND AND PURPOSE: In order to plan neurological capacities at a national level for the next decade, the current use of neurological services should be evaluated. We analyzed the utilization of neurological services in Hungary, a country with a single-payer health insurance system covering the whole population. METHODS: We created a database from medical reports submitted to the National Health Insurance Fund from all hospitals and outpatient services between 2004 and 2013. The number of subjects presenting to the neurological healthcare system and their major diagnoses by 10th International Classification of Diseases categories were analyzed. The overall healthcare service utilization of these patients was also estimated. RESULTS: Of the 10 million inhabitants, 2.9 million people used an inpatient or outpatient neurological service at least once over the 10-year period. Annually, 1% of the population was admitted to neurological inpatient wards and 6% of the population used some neurological outpatient service. Major reasons for using neurological services were: cerebrovascular diseases (I60-I69; 1.2 million patients), episodic and paroxysmal disorders (G40-G47; 1.3 million patients) and general symptoms and signs (R50-R56; 1.3 million patients). The 2.9 million people had 12.7 million hospital admissions to any ward and 365.7 million outpatient visits to any specialist during the 10 years. CONCLUSIONS: The demand for neurological services is high in Hungary; close to 30% of the population used an inpatient or outpatient neurological service at least once during this 10-year period. Results from this project provide data for international comparisons and help to ensure better informed and more focused resource allocation.

Comparing ischaemic stroke in six European countries. The EuroHOPE register study.

BACKGROUND AND PURPOSE: The incidence of hospitalizations, treatment and case fatality of ischaemic stroke were assessed utilizing a comprehensive multinational database to attempt to compare the healthcare systems in six European countries, aiming also to identify the limitations and make suggestions for future improvements in the between-country comparisons. METHODS: National registers of hospital discharges for ischaemic stroke identified by International Classification of Diseases codes 433-434 (ICD-9) and code I63 (ICD-10), medication purchases and mortality were linked at the patient level in each of the participating countries and regions: Finland, Hungary, Italy, the Netherlands, Scotland and Sweden. Patients with an index admission in 2007 were followed for 1 year. RESULTS: In all, 64,170 patients with a disease code for ischaemic stroke were identified. The number of patients registered per 100,000 European standard population ranged from 77 in Scotland to 407 in Hungary. Large differences were observed in medication use. The age- and sex-adjusted all-cause case fatality amongst hospitalized patients at 1 year from stroke was highest in Hungary at 31.0% (95% confidence interval 30.5-31.5). Regional differences in age- and sex-adjusted 1-year case fatality within countries were largest in Hungary (range 23.6%-37.6%) and smallest in the Netherlands (20.5%-27.3%). CONCLUSIONS: It is feasible to link population-wide register data amongst European countries to describe incidence of hospitalizations, treatment patterns and case fatality of ischaemic stroke on a national level. However, the coverage and validity of administrative register data for ischaemic stroke should be developed further, and population-based and clinical stroke registers should be created to allow better control of case mix.

High-resolution ultrasonography of peripheral nerves: measurements on 14 nerve segments in 56 healthy subjects and reliability assessments.

PURPOSE: The aim of this study was to assess different aspects of reliability in high-resolution ultrasonography (HRUS) of the peripheral nerves and to establish reference values for the most frequently examined nerve segments. MATERIALS AND METHODS: A nerve size parameter, the cross-sectional area (CSA) of the C5, C6 and C7 cervical roots, the median, ulnar, radial, superficial radial, peroneal, tibial, and the sural nerves was measured using HRUS at a total of 14 predefined anatomical sites in two different cohorts of healthy subjects (n = 56), and the inter-rater, intra-rater and inter-equipment reliability of measurements was assessed. RESULTS: The mean CSA of the 14 nerve segments ranged from 2 to 10 mm(2). The intra-rater, inter-rater and inter-equipment reliability was high with intraclass correlation coefficients of 0.93, 0.98, and 0.86, respectively. The CSA values showed no consistent correlation with age, height, and body weight, but males had significantly larger values than females for nerve segments on the arm after correcting for age, weight and height in multivariate analysis. CSA values did not differ when two independent cohorts were compared. CONCLUSION: Peripheral nerve ultrasonography is a reliable and reproducible diagnostic method in the hands of experienced examiners. Normal values for several upper and lower extremity nerves are provided by our study.

Etiology of first-ever ischaemic stroke in European young adults: the 15 cities young stroke study.

BACKGROUND AND PURPOSE: Risk factors for IS in young adults differ between genders and evolve with age, but data on the age- and gender-specific differences by stroke etiology are scare. These features were compared based on individual patient data from 15 European stroke centers. METHODS: Stroke etiology was reported in detail for 3331 patients aged 15-49 years with first-ever IS according to Trial of Org in Acute Stroke Treatment (TOAST) criteria: large-artery atherosclerosis (LAA), cardioembolism (CE), small-vessel occlusion (SVO), other determined etiology, or undetermined etiology. CE was categorized into low- and high-risk sources. Other determined group was divided into dissection and other non-dissection causes. Comparisons were done using logistic regression, adjusting for age, gender, and center heterogeneity. RESULTS: Etiology remained undetermined in 39.6%. Other determined etiology was found in 21.6%, CE in 17.3%, SVO in 12.2%, and LAA in 9.3%. Other determined etiology was more common in females and younger patients, with cervical artery dissection being the single most common etiology (12.8%). CE was more common in younger patients. Within CE, the most frequent high-risk sources were atrial fibrillation/flutter (15.1%) and cardiomyopathy (11.5%). LAA, high-risk sources of CE, and SVO were more common in males. LAA and SVO showed an increasing frequency with age. No significant etiologic distribution differences were found amongst southern, central, or northern Europe. CONCLUSIONS: The etiology of IS in young adults has clear gender-specific patterns that change with age. A notable portion of these patients remains without an evident stroke mechanism according to TOAST criteria.

Miller Fisher syndrome: brief overview and update with a focus on electrophysiological findings.

Miller Fisher syndrome (MFS), a variant of the Guillain-Barré syndrome (GBS), is characterized by ophthalmoplegia, ataxia, and areflexia. The annual incidence is around one patient per one million population. The antiganglioside anti-GQ1b IgG antibody has a role in the pathogenesis of the syndrome, especially of ophthalmoplegia. The presence of this antibody in the serum can be identified in over 80% of the patients, peaking in the first week, whereas albuminocytological dissociation in the cerebrospinal fluid (CSF) appears later. The most consistent electrophysiological findings in MFS are reduced sensory nerve action potentials and absent H reflexes. More variability is seen with F waves and various investigations involving cranial structures. Although there are usually no abnormalities in MFS by routine neuroimaging, in a few cases, contrast enhancement of nerve roots and signs of central nervous system involvement were described supporting the hypothesis of an anti-GQ1b-syndrome, a continuum involving GBS, MFS, and Bickerstaff's brainstem encephalitis. Owing to the lack of randomized trials, treatments used for GBS (intravenous immunoglobulin and plasmapheresis) are usually applied, although from retrospective analyses, the outcome was similar between treated and untreated subjects. The outcome of MFS is usually good with case fatality of < 5%. In the few autopsy cases, macroscopic abnormalities were generally not seen in the nervous system. Microscopic examination of the peripheral nervous system (including cranial nerves) showed segmental demyelination with minimal perivascular infiltration with normal spinal cord and brain stem.

Vinpocetine for acute ischaemic stroke.

BACKGROUND: Vasoactive and neuroprotective drugs such as vinpocetine are used to treat stroke in some countries. OBJECTIVES: To assess the effect of vinpocetine in acute ischaemic stroke. SEARCH STRATEGY: We searched the Cochrane Stroke Group Trials Register (last searched February 2007), MEDLINE (1966 to February 2007) and Scopus (1960 to February 2007). We also searched the Internet Stroke Center Stroke Trials Registry, Google Scholar, the science-specific search engine Scirus and Wanfang Data, the leading information provider in China. We contacted researchers in the field and four pharmaceutical companies that manufacture vinpocetine. Searches were complete to February 2007. SELECTION CRITERIA: Unconfounded randomised trials of vinpocetine compared with placebo, or any other reference treatment, in people with acute ischaemic stroke. We included trials if treatment started no later than 14 days after stroke onset. DATA COLLECTION AND ANALYSIS: Two review authors independently applied the inclusion criteria. One review author extracted the data, which was then checked by the second review author. We assessed trial quality. The primary outcome measure was death or dependency. MAIN RESULTS: We included two trials, involving a total of 70 participants. Data for 63 participants were reported in the two trials combined. The rate of death or dependency did not differ between the treatment and placebo groups at one and three months. The 95% confidence intervals for the outcome measures were wide and included the possibility of both significant benefit and significant harm. No adverse effects were reported. AUTHORS' CONCLUSIONS: There is not enough evidence to evaluate the effect of vinpocetine on survival or dependency in patients with acute ischaemic stroke.

Mannitol for acute stroke.

BACKGROUND: Mannitol is an osmotic agent and a free radical scavenger which might decrease oedema and tissue damage in stroke. OBJECTIVES: To test whether treatment with mannitol reduces short and long-term case fatality and dependency after acute ischaemic stroke or intracerebral haemorrhage (ICH). SEARCH STRATEGY: We searched the Cochrane Stroke Group Trials Register (searched December 2006), MEDLINE (1966 to January 2007), the Chinese Stroke Trials Register (searched November 2006), the China Biological Medicine Database (searched December 2006) and the Latin-American database LILACS (1982 to December 2006). We also searched the database of Masters and PhD degree theses at Sao Paulo University (searched January 2007), and neurology and neurosurgery conference proceedings in Brazil from 1965 to 2006. In an effort to identify further published, ongoing and unpublished studies we searched reference lists and contacted authors of published trials. SELECTION CRITERIA: We included randomised controlled trials comparing mannitol with placebo or open control in patients with acute ischaemic stroke or non-traumatic intracerebral haemorrhage. DATA COLLECTION AND ANALYSIS: Two review authors independently selected trials, assessed quality, extracted data, and performed the data analysis. MAIN RESULTS: Three small trials, involving 226 participants, were included. One trial included patients with presumed ischaemic stroke without computerised tomography (CT) verification, and the other two trials included patients with CT-verified ICH. Data on the primary outcome measure (death and dependency) were not available in any of the trials. Death and disability could be calculated in the larger ICH trial without differences between the mannitol and control groups. Case fatality was not reported in the trial of ischaemic stroke. Case fatality did not differ between the mannitol and control groups in the ICH trials. Adverse events were either not found or not reported. The change in clinical condition was reported in two trials, and the proportion of those with worsening or not improving condition did not differ significantly between mannitol-treated patients and controls. Based on these three trials neither beneficial nor harmful effects of mannitol could be proved. Although no statistically significant differences were found between the mannitol-treated and control groups, the confidence intervals for the treatment effect estimates were wide and included both clinically significant benefits and clinically significant harms as possibilities. AUTHORS' CONCLUSIONS: There is currently not enough evidence to support the routine use of mannitol in acute stroke patients. Further trials are needed to confirm or refute whether mannitol is beneficial in acute stroke.

Factors influencing hemorrhagic transformation in ischemic stroke: a clinicopathological comparison.

As hemorrhagic transformation (HTr) is a frequent complication and can worsen the outcome of acute ischemic stroke, our aim was to assess the risk factors of HTr. Using the database of our neuropathological laboratory, 245 consecutive acute ischemic stroke patients were analyzed. An exploratory logistic regression procedure was carried out to find the best multiple model identifying the factors associated with HTr. The autopsy revealed ischemic infarct in 175 (71%) and ischemic infarct with HTr in 70 (29%) patients. Mean age was 71.5 +/- 11.4 years (mean +/- SD) and 74.8 +/- 10.2 years (mean +/- SD), respectively. The multiple model confirmed age in case of embolic stroke, and diabetes mellitus and infarct size as independent risk factors of HTr. It seems that not serum glucose level but diabetes mellitus in the case history is an independent predictor of HTr.

Impairment of cerebrovascular reactivity in long-term type 1 diabetes.

The early preclinical detection of cerebrovascular complications in individuals with diabetes is one of the goals of care described in the St. Vincent Declaration. In accordance with this goal, the aim of the present work was to investigate whether altered cerebral microvascular function in patients suffering from type 1 diabetes can be detected with a transcranial Doppler probe after the administration of acetazolamide. A total of 72 type 1 diabetic patients and 40 healthy control subjects entered the study. Patients were divided into two groups: those with long-term diabetes (disease duration of >10 years, n = 37) and those with short-term diabetes (disease duration of < or =10 years, n = 35). Mean blood-flow velocity in the middle cerebral artery (MCAV) was measured at rest and at 5, 10, 15, and 20 min after intravenous administration of 1 g acetazolamide with a transcranial Doppler probe and expressed as the percentage change from the pretest measurement. The percentage increase in MCAV (cerebrovascular reactivity) was calculated at each time point and compared between the groups. Cerebrovascular reserve capacity (CRC), expressed as the maximal percentage increase of the MCAV, was compared between the groups. Additionally, a reproducibility study of CRC was performed in 10 patients, using intraclass correlations. Cerebrovascular reactivity in the long-term diabetes group was lower (means +/- SD: 5 min, 23.4 +/- 15.4%; 10 min, 28.8 +/- 17.0%; 15 min, 30.0 +/- 15.6%; 20 min, 24.2 +/- 17.8%) than that of the control subjects (5 min, 43.5 +/- 23.9%; 10 min, 55.3 +/- 24.0%; 15 min, 56.7 +/- 23.8%; 20 min, 54.8 +/- 25.9%) and the short-term diabetic patients (5 min, 43.6 +/- 25.9%; 10 min, 52.2 +/- 27.7%; 15 min, 55.3 +/- 32.2%; 20 min, 45.8 +/- 35.8%). CRC was lower in the long-term diabetes group than in the control group or the short-term diabetes group. Impairment of cerebrovascular reactivity was associated with retino- and nephropathy and increased levels of fibrinogen. In contrast, CRC was independent from actual glucose, insulin, glycosylated hemoglobin, von Willebrand factor antigen, and alpha-2 macroglobulin levels. Transcranial Doppler measurements of the changes in MCAV after stimulation with acetazolamide can detect altered cerebral microvascular function in patients with diabetes. Cerebrovascular reactivity and reserve capacity are reduced in patients with long-term diabetes. Further prospective studies should delineate the clinical significance of our results.

Cochrane report: A systematic review of mannitol therapy for acute ischemic stroke and cerebral parenchymal hemorrhage.

BACKGROUND: Mannitol was reported to decrease cerebral edema associated with tissue damage and is used to treat acute stroke in many countries. SUMMARY OF REVIEW: We tested whether there is any evidence from unconfounded randomized clinical trials that treatment with mannitol reduces short- and long-term case fatality and dependency if administered after ischemic stroke or cerebral parenchymal hemorrhage. Trials were identified by the standard search strategy of the Cochrane Collaboration Stroke Review Group. A supplementary MEDLINE search was performed, and the Chinese Stroke Trials Register and the Latin-American databank LILACS were checked. A search was performed of master's and PhD degree theses in the databank of Sao Paulo University and in abstracts of medical congresses on neurology and neurosurgery during 1965-1997 in Brazil. Investigators were contacted for unpublished information. Only truly randomized unconfounded clinical trials were eligible for inclusion. Two of the reviewers independently extracted data from the trials. Data synthesis and analysis was performed with the use of the Cochrane Review Manager software (RevMan version 4.0.4). CONCLUSIONS: Only 1 trial fulfilled the inclusion criteria. The number of included patients was small, and the follow-up was short. Case fatality, the proportion of dependent patients, and side effects were not reported and were not available from the investigators. As a result of lack of appropriate randomized trials, currently no conclusion can be drawn on the effects of mannitol in acute stroke. The routine use of mannitol in all patients with acute stroke is not supported by evidence from randomized controlled clinical trials.

A population study of stroke in West Ukraine: incidence, stroke services, and 30-day case fatality.

BACKGROUND AND PURPOSE: According to World Health Organization statistics, Ukraine has extremely high stroke mortality. No population-based prospective studies of stroke incidence have been performed yet in this European country with approximately 50 million inhabitants. High reported rates of stroke mortality in official statistics conflict with some locally published incidence data in Ukraine. To obtain accurate data, we evaluated stroke incidence and 30-day case fatality in a prospective population study in the West Ukrainian city of Uzhgorod with a population of 126 000 inhabitants. METHODS: Case certification by neurologists and follow-up at 30 days after stroke for all patients identified by any level of the health service system were performed for a 12-month period. RESULTS: We identified 352 stroke cases. The age-standardized incidence was 341 and 238 of 100 000 and mortality was 83 and 69 of 100 000 with the use of the European or world standard population for standardization. Mean age of stroke patients was 63.4+/-12.5 years. Rate of hospitalization was 66%. Hospitalized patients were >10 years younger than those treated in their homes. The 30-day case fatality rates were 15.4% among hospitalized patients and 36.8% among those treated at home. Overall 30-day case fatality was 23.3%. CONCLUSIONS: Stroke incidence and 30-day case fatality in this West Ukrainian city were similar to those of some West European countries and were much lower than what could be expected from World Health Organization statistics. The relatively low incidence rate seems accurate; because of the organization of local stroke services, it is not probable that a considerable proportion of patients with acute stroke could bypass all levels of the acute care health system. Local health statistics reported a much lower number of stroke cases and stroke deaths than found in our survey; thus, further study is needed to clarify the reason for the discrepancy between local data and the high reported stroke mortality in Ukraine.

Hypoxia increases velocity of blood flow through parenchymal microvascular systems in rat brain.

The postulation that hypoxia increases local cerebral blood flow (lCBF) mainly by perfusing more capillaries (the capillary recruitment hypothesis) was tested in awake adult male Sprague-Dawley rats exposed to 10% O2 and control rats. The [14C]iodoantipyrine technique was used to measure lCBF. Local cerebral blood volume was determined by measuring plasma and red cell distribution spaces within the brain parenchyma with 125I-labeled serum albumin (RISA) and 55Fe-labeled red cells (RBC), respectively. Tissue radioactivity in 44 brain areas was estimated by quantitative autoradiography. Hypoxia raised lCBF by 25-90% in all brain areas. In about one-quarter of the brain areas, the rise in blood flow was associated with a small increase in microvascular plasma and blood volumes. This change in blood volume, which could be the result of perfusing more parenchymal microvessels and/or increasing parenchymal microvessel diameter, is not sufficient to account for the observed rise in lCBF. In the remaining areas the RISA, RBC, and blood spaces were either unchanged or only marginally increased by hypoxia. For this hypoxic perturbation, the major mechanism of raising blood flow appears to be increased velocity of microvessel perfusion and not perfusion of more capillaries. These findings provide only limited support for the capillary recruitment hypothesis.

The velocities of red cell and plasma flows through parenchymal microvessels of rat brain are decreased by pentobarbital.

Local cerebral blood flow is lowered in many brain areas of the rat by high-dose pentobarbital (50 mg/kg). In the present study, the mechanism of this flow change was examined by measuring the distribution of radiolabeled red blood cells (RBCs) and albumin (RISA) in small parenchymal microvessels and calculating the microvascular distribution spaces and mean transit times of RBCs, RISA, and blood. In most brain areas, pentobarbital slightly decreased the RISA space, modestly increased the RBC space, and did not alter the blood space. The mean transit times of RBCs, RISA, and blood through the perfused microvessels were considerably greater in treated rats than in controls. These findings indicate that the mechanism by which high-dose pentobarbital diminishes local cerebral blood flow in rat brain is, in the main, a lowered linear velocity of plasma and RBC flow through small parenchymal microvessels and not decreased percentage of perfused capillaries (capillary retirement). This response is probably driven mainly by lowered local metabolism and may well entail a slight increase in the number of small microvessels that are perfused by RBCs.

Nicotine raises the influx of permeable solutes across the rat blood-brain barrier with little or no capillary recruitment.

Nicotine (1.75 mg/kg s.c.) was administered to rats to raise local CBF (lCBF) in various parts of the brain, test the capillary recruitment hypothesis, and determine the effects of this increase in lCBF on local solute uptake by brain. lCBF as well as the local influx rate constants (K1) and permeability-surface area (PS) products of [14C]antipyrine and [14C]-3-O-methyl-D-glucose (3OMG) were estimated by quantitative autoradiography in 44 brain areas. For this testing, the finding of significantly increased PS products supports the capillary recruitment hypothesis. In 17 of 44 areas, nicotine treatment increased lCBF by 30-150%, K1 of antipyrine by 7-40%, K1 of 3OMG by 5-27%, PS product of antipyrine by 0.20% (mean 7%), and PS product of 3OMG by 0-23% (mean 8%). Nicotine had no effect on blood flow or influx in the remaining 27 areas. The increases in lCBF and K1 of antipyrine were significant, whereas those in K1 of 3OMG and in PS for both antipyrine and 3OMG were not statistically significant. The lack of significant changes in PS products implies that in brain areas where nicotine increased blood flow: (a) essentially no additional capillaries were recruited and (b) blood flow within brain capillary beds rises by elevating linear velocity. The K1 results indicate that the flow increase generated by nicotine will greatly raise the influx and washout rates of highly permeable materials, modestly elevate those of moderately permeable substances, and negligibly change those of solutes with extraction fractions of < 0.2, thereby preserving the barrier function of the blood-brain barrier.

Technique-dependent variations in cerebral microvessel blood volumes and hematocrits in the rat.

To quantitate small parenchymal microvessel blood volumes in the brain, the distribution spaces of radiolabeled red blood cells (RBC) and serum albumin (RISA) were assessed in rats by different methods of tissue sampling and radioassay. Three minutes after intravenous administration of 55Fe-RBCs and/or 125I-RISA, the rats were decapitated. The brain was either immediately frozen within the skull and later removed (head-frozen group) or rapidly removed from the skull and then frozen (brain-frozen group). Radioactivity was measured either by liquid scintillation counting of tissue pieces, which contained pial plus large and small parenchymal microvessels, or by quantitative autoradiography (QAR) of tissue sections, which indicated small parenchymal microvessel blood only. In 12 of 15 areas, the RISA, RBC, and blood volumes determined by liquid scintillation counting of head-frozen tissue pieces were equal to or greater than those of brain-frozen tissue; this indicated less than or equal to 25% greater blood retention in pial and parenchymal microvessels with head freezing. At the parenchymal microvessel level (QAR assay), the distribution volumes of RBCs, RISA, and blood were similar with the two freezing techniques; hence with QAR either freezing procedure can be used to assess small parenchymal microvessel blood volumes.

A simple technique for the estimation of regional blood content in brain.

A simple and inexpensive technique is described for the assessment of regional cerebral blood volume (CBV) using a color reaction based on the pseudoperoxidase activity of hemoglobin. Cryostat sections are placed on a commercially available reagent strip originally designed for quantitative estimation of blood content in urine. After melting of the brain section, a blue color reaction appears which is darker in areas with higher hemoglobin content. The image is analyzed by a computerized image-processing system and evaluated by standards prepared from brain homogenate with different hemoglobin content. From the optical density data, regional CBV is calculated with correction for the difference between microvascular and large vessel hematocrit. The method was validated by a radiolabel procedure. Values of regional CBV are reported in gray matter areas of control rabbits and in brains embolized by autologous clot. This simple inexpensive technique is a useful supplementary tool in multiparametric metabolic studies.

Polyamine metabolism in transient focal ischemia of rat brain.

Polyamine metabolism was studied in rat brains subjected to 30 min transient cerebral ischemia by measuring the activity of the key enzyme ornithine decarboxylase (ODC) and levels of the polyamines putrescine, spermidine and spermine. A transient increase in ODC activity was apparent after 4 h of recirculation in the ipsilateral cortex and striatum (P less than 0.05). Putrescine levels were significantly increased in the ipsilateral striatum after 4 h of recirculation, and after 24 h of recirculation in both the ipsilateral cortex and striatum. During ischemia spermidine levels were significantly reduced in the ipsilateral hemisphere and spermine levels in the ipsilateral cortex. It is suggested that during ischemia polyamines are released from neurons into the extracellular compartment and cleared into the blood.