Axonal excitability and motor propagation velocity of peripheral nerves in patients with acute vascular lesions of the brain

From measurements of maximum and minimum motor nerve propagation velocity and neuronal excitability we conclude that there is a functional loss of motor units and distal nerve "dying back" in persons affected with unilateral acute cerebral vascular lesions. The study also suggests that transynaptic degeneration affects the lower motor neurone function on both sides.     

The relationship between orthostatic dysregulation and the orthostatic test in dizzy patients

The orthostatic test was administered to 134 dizzy patients (37 males and 97 females) who were identified as having orthostatic dysregulation from December 1990 through November 1994. The mean age of the male and female patients was 42.5 and 44.6 years, respectively, and the peak age decade was the 50s. Among the questionnaire items for orthostatic dysregulation, orthostatic dizziness was the most frequent major symptom and occurred in 116 of the patients (86.6%). Fatigue was the most frequent minor symptom and was found in 97 (72.4%). The incidence of positive orthostatic test results in the patients with orthostatic dysregulation (50.7%) was significantly higher (P < 0.01) than that in the control subjects (27.8%). There was also a significant difference (P < 0.01 or P < 0.05) between systolic pressure decrease during the orthostatic test procedure in the patients with orthostatic dysregulation and that in the control subjects. These results suggest that autonomic imbalance as reflected by the orthostatic dysregulation questionnaire and orthostatic test results is closely related to the occurrence of dizziness or vertigo.     

The decoding of emotional concepts in patients with focal cerebral lesions

The effects of focal brain lesions on the decoding of emotional concepts in facial expressions were investigated. Facial emotions are hierarchically organized patterns comprising (1) structural surface features, (2) discrete (primary) emotional categories and (3) secondary dimensions, such as valence and arousal. Categorical decoding was measured using (1) selection of category labels and selection of the named emotion category; (2) matching one facial expression with two choice expressions. Dimensional decoding was assessed by matching one face with two different expressions with regard to valence or arousal. 70 patients with well documented cerebral lesions and 15 matched hospital controls participated in the study. 27 had left brain damage (LBD; 10 frontal, 10 temporal, 7 parietal); 37 had right brain damage (RBD; 15 frontal, 11 temporal, 11 parietal). Six additional patients had lesions involving both frontal lobes. Right temporal and parietal lesioned patients were markedly impaired in the decoding of primary emotions. The same patients also showed a reduced arousal decoding. In contrast to several patients with frontal and left hemisphere lesions, emotional conceptualization and face discrimination was not independent in these groups. No group differences were observed in valence decoding. However, right frontal lesions appeared to interfere with the discrimination of negative valence. Moreover, a distraction by structural features was noted in RBD when facial identities were varied across stimulus and response pictures in matching tasks with differing conceptual load. Our results suggest that focal brain lesions differentially affect the comprehension of emotional meaning in faces depending on the level of conceptual load and interference of structural surface features.     

The relationship between brain atrophy and asymptomatic cerebral lesions]

Serratia marcescens has emerged in the last few years as an important nosocomial pathogen. Many methods for typing this organism have been described. In this study the random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) was shown to be a convenient typing method for S. marcescens. Different combinations of primers previously used for typing other gram-negative bacilli were assessed. The combination of primer HLWL-74 and 1254 gave distinguishable patterns for different serotypes and proved to be the most satisfactory. By applying this combination to 175 isolates of S. marcescens, which could be classified into 38 groups on the basis of serotyping and phage typing, 73 different RAPD patterns with good reproducibility were obtained. This is, to our knowledge, the first application of the method to a large collection of S. marcescens representing a wide range of serotypes.     

Fibrinolytic activity of the human brain after contusive injuries

Histochemical and biochemical evaluation of cerebral tissue fibrinolysis following cranioencephalic trauma was studied in 20 cases seen at necropsy, with varying periods of survival after injury. Fibrinolysis was mainly located at the vasal intima and was very intense in areas rich in vascularised connective tissue, such as the dura mater. Its activity diminished soon after injury to reach minimum values during the first day. Thereafter it remained at very low levels in sites with gross lesions, whereas it returned to nearly normal values elsewhere on the 2nd or 3rd day. Attention is drawn to the territorial character of this pattern. Extension of these results to the fields of diagnosis and treatment, however, is considered premature.     

Hypocapnia and cerebral hypoperfusion in orthostatic intolerance

BACKGROUND AND PURPOSE: Orthostatic and other stresses trigger tachycardia associated with symptoms of tremulousness, shortness of breath, dizziness, blurred vision, and, often, syncope. It has been suggested that paradoxical cerebral vasoconstriction during head-up tilt might be present in patients with orthostatic intolerance. We chose to study middle cerebral artery (MCA) blood flow velocity (BFV) and cerebral vasoregulation during tilt in patients with orthostatic intolerance (OI). METHODS: Beat-to-beat BFV from the MCA, heart rate, CO2, blood pressure (BP), and respiration were measured in 30 patients with OI (25 women and 5 men; age range, 21 to 44 years; mean age, 31.3+/-1.2 years) and 17 control subjects (13 women and 4 men; age range, 20 to 41 years; mean age, 30+/-1.6 years); ages were not statistically different. These indices were monitored during supine rest and head-up tilt (HUT). We compared spontaneous breathing and hyperventilation and evaluated the effect of CO2 rebreathing in these 2 positions. RESULTS: The OI group had higher supine heart rates (P<0.001) and cardiac outputs (P<0.01) than the control group. In response to HUT, OI patients underwent a greater heart rate increment (P<0.001) and greater reductions in pulse pressure (P<0.01) and CO2 (P<0.001), but total systemic resistance failed to show an increment. Among the cerebrovascular indices, all BFVs (systolic, diastolic, and mean) decreased significantly more, and cerebrovascular resistance (CVR) was increased in OI patients (P<0.01) compared with control subjects. In both groups, hyperventilation induced mild tachycardia (P<0.001), a significant reduction of BFV, and a significant increase of CVR associated with a fall in CO2. Hyperventilation during HUT reproduced hypocapnia, BFV reduction, and tachycardia and worsened symptoms of OI; these symptoms and indices were improved within 2 minutes of CO2 rebreathing. The relationships between CO2 and BFV and heart rate were well described by linear regressions, and the slope was not different between control subjects and patients with OI. CONCLUSIONS: Cerebral vasoconstriction occurs in OI during orthostasis, which is primarily due to hyperventilation, causing significant hypocapnia. Hypocapnia and symptoms of orthostatic hypertension are reversible by CO2 rebreathing.     

Factor-defined abilities in patients with unilateral brain lesions.

Administered a battery of 4 tests adapted from the structure of intellect model of differential abilities to 72 adults with right and left cerebral lesions and normals. Findings show that both brain-damaged groups exhibited slower response times than normals and that there was a relation between locus of the lesion and performance. However, results do not sufficiently demonstrate the advantage of factor-defined ability tests over tests of global intelligence and question the validity of these factor-defined tests in that they do not distinguish behaviors that are factorially distinct in normal populations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Imitative response tendencies in patients with frontal brain lesions.

It is widely accepted that patients with frontal lesions have problems inhibiting automatic response tendencies. Whereas inhibition deficits of overlearned responses have been extensively investigated using interference tasks like the Stroop task (J. R. Stroop, 1935), it is controversial whether patients with frontal brain lesions also have problems inhibiting imitative responses. Using an interference paradigm, the present study investigated imitative response tendencies in patients with frontal lesions. In addition, it tested whether patients deficient in the inhibition of imitative responses correspondingly have problems inhibiting overlearned responses. It was found that the group with frontal lesions displayed significantly stronger imitative response tendencies than the group with nonfrontal lesions. Furthermore, it was shown that the inhibition of imitative responses is functionally unrelated to Stroop interference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

MRI assessment of cerebral blood volume in patients with brain infarcts

MRI perfusion studies have focussed mainly on acute ischaemia and characterisation in ischaemia. Our purpose was to analyse regional brain haemodynamic information in acute, subacute, and chronic ischaemia. We performed 16 examinations of 11 patients on a 1.5 T MR images. Conventional and dynamic contrast-enhanced imaging were employed in all examinations. For the dynamic susceptibility sequences, a bolus (0.2 mmol/kg) of gadopentetate dimeglumine was injected. Reconstructed regional relative cerebral blood volume (rCBV) maps, bolus maps, and conventional images were analysed by consensus reading. In all examinations decreases in rCBV were observed in the lesions. The distribution of regional rCBV in lesions was heterogeneous. The rCBV of the periphery of the lesions was higher than that at their center. There was a correlation between the time since onset and abnormalities on the rCBV map and T2-weighted images (T2WI). In the early stage of acute stroke, the abnormalities tended to be larger on the rCBV than on T2WI. Many patterns of bolus passage were observed in ischaemic regions. rCBV maps provide additional haemodynamic information in patients with brain infarcts.     

Ideation in patients with unilateral or bilateral midline brain lesions.

Hypothesized that persons with left vs. right unilateral brain lesions differ in complicated ideational processes in 50 Ss with well localized lesions. On a multiple-discriminant analysis, 7 selected Rorschach variables differentiated the left, right, and midline-bilateral groups at the .0001 level. Interpretation of Discriminant I, ideation, yields a modus operandi of left-hemisphere Ss which is limited and constricted; of right-hemisphere Ss which is expansive and uncritically innovative. Discriminant II, uniqueness of pathology, indicates that left and right groups differ significantly and are significantly divergent, with the midline group undistinguished on this dimension. (18 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A study of cerebral perfusion using single photon emission computed tomography in neonates with brain lesions

In this study we used a single photon emission computed tomography technique (SPECT) with radiolabelled 99mTcHMPAO to assess cerebral perfusion in newborn infants with documented cerebral lesions and to determine to what extent brain SPECT might be useful in the neonatal period. A total of 15 newborn infants with the following cerebral pathologies were enrolled: severe parietal bilateral periventricular leucomalacia (PVL, n = 6); moderate parietal bilateral PVL (n = 2); intraventricular haemorrhage grade II with unilateral parietal parenchymal extension (IHV + PE, n = 3); cerebral infarction (CI, n = 2) in the zone of middle cerebral artery; and post-haemorrhagic hydrocephalus (n = 2). Follow-up was available in all infants. Alterations in cerebral perfusion were seen in only 12 of 15 infants and at the location of severe PVL, PE and CI. We have noted that the regions of diminished perfusion extended beyond the apparent extent of cerebral pathology delineated by ultrasound or magnetic resonance imaging. Markedly diminished perfusion was seen in 1 infant with hydrocephalus, which recovered following placement of ventriculo-peritoneal shunt. Regarding outcome, SPECT data failed to provide additional information than that of neuroradiological investigations. We conclude that the use of SPECT, under these conditions, to assess alteration of cerebral perfusion in the neonatal period will not provide any additional information than that of neuroradiological investigations.     

The effect of an infusion of low molecular weight dextran on peripheral resistance in patients with arteriosclerosis

Low molecular weight dextran is frequently given to improve the flow of blood to the periphery, but its mode of action is uncertain. We measured the effect of an infusion of 500 ml of Dextran 40 on the peripheral resistance in 12 patients undergoing reconstructive surgery for atherosclerotic occlusion of the superficial femoral artery. After the infusion, values of packed cell volume and blood viscosity indicated haemodilution. There was a consistent increase in mean flow and a fall in peripheral resistance. There was no correlation between change in viscosity and change in peripheral resistance, but there was a good correlation between the percentage change in resistance and the initial resistance. This suggests that the increase in flow of blood was due to reflex vasodilatation rather than to any reduction in viscosity.     

Effects of cisatracurium on cerebral and cardiovascular hemodynamics in patients with severe brain injury

BACKGROUND: For neuroanesthesia and neurocritical care the use of drugs that do not increase or preferentially decrease intracranial pressure (ICP) or change cerebral perfusion pressure (CPP) and cerebral blood flow (CBF) are preferred. The current study investigates the effects of a single rapid bolus dose of cisatracurium on cerebral blood flow velocity, ICP, CPP, mean arterial pressure (MAP) and heart rate (HR) in 24 mechanically ventilated patients with intracranial hypertension after severe brain trauma (Glasgow coma scale <6) under continuous sedation with sufentanil and midazolam. METHODS: Patients were randomly assigned to receive either 2xED95 (n=12) or 4xED95 (n=12) of cisatracurium as a rapid i.v. bolus injection. Before and after bolus administration mean cerebral blood flow velocity (BFV, cm/s) was measured in the middle cerebral artery using a 2-MHz transcranial Doppler sonography system, ICP (mm Hg) was measured using an extradural probe, and MAP (mm Hg) and HR (b/min) were measured during a study period of 20 min. Cerebral perfusion pressure (CPP=MAP-ICP) was also calculated. RESULTS: Our data show that a single bolus dose of up to 4xED95 cisatracurium caused no significant (P<0.05) changes in BFV, ICP, CPP, MAP and HR. Possible histamine-related events were not observed during the study. CONCLUSIONS: The results from this study suggest that cisatracurium is a safe neuromuscular blocking agent for use in adult severe brain-injured patients with increased ICP under mild hyperventilation and continuous sedation.     

Effects of sufentanil on cerebral hemodynamics and intracranial pressure in patients with brain injury

BACKGROUND: The current study investigates the effects of sufentanil on cerebral blood flow velocity and intracranial pressure (ICP) in 30 patients with intracranial hypertension after severe brain trauma (Glasgow coma scale < 6). METHODS: Mechanical ventilation (FIO2 0.25-0.4) was adjusted to maintain arterial carbon dioxide tensions of 28-30 mmHg. Continuous infusion of midazolam (200 micrograms/kg/h intravenous) and fentanyl (2 micrograms/kg/h intravenous) was used for sedation. Mean arterial blood pressure (MAP, mmHg) was adjusted using norepinephrine infusion (1-5 micrograms/min). Mean blood flow velocity (Vmean, cm/s) was measured in the middle cerebral artery using a 2-MHz transcranial Doppler sonography system. ICP (mmHg) was measured using an epidural probe. After baseline measurements, a bolus of 3 micrograms/kg sufentanil was injected, and all parameters were continuously recorded for 30 min. The patients were assigned retrospectively to the following groups according to their blood pressure responses to sufentanil: group 1, MAP decrease of less than 10 mmHg, and group 2, MAP decrease of more than 10 mmHg. RESULTS: Heart rate, arterial blood gases, and esophageal temperature did not change over time in all patients. In 18 patients, MAP did not decrease after sufentanil (group 1). In 12 patients, sufentanil decreased MAP > 10 mmHg from baseline despite norepinephrine infusion (group 2). ICP was constant in patients with maintained MAP (group 1) but was significantly increased in patients with decreased MAP. Vmean did not change with sufentanil injection regardless of changes in MAP. CONCLUSIONS: The current data show that sufentanil (3 micrograms/kg intravenous) has no significant effect on middle cerebral artery blood flow velocity and ICP in patients with brain injury, intracranial hypertension, and controlled MAP. However, transient increases in ICP without changes in middle cerebral artery blood flow velocity may occur concomitant with decreases in MAP. This suggests that increases in ICP seen with sufentanil may be due to autoregulatory decreases in cerebral vascular resistance secondary to systemic hypotension.     

The pentoxifylline and corglycon treatment of patients with circulatory encephalopathy against a background of atherosclerotic lesions of the major cerebral arteries

As many as 34 patients having stage II-III atherosclerotic dyscirculatory encephalopathy with coexisting ischemic heart disease in the presence of stenosing and occlusive lesions of major brain arteries were evaluated for effects pentoxiphyllin and corglycon on the clinical course of this medical condition as well as systemic and cerebral haemodynamics. In this series, 82.7 percent of patients derived benefit from a single intravenous infusion of pentoxiphyllin and corglycon and course treatment with these drug preparation that was evidenced by an improvement in the parameters of systemic and cerebral hemodynamics and regression of neurologic symptomatology. The results of the studies made permit recommending pentoxiphyllin in combination with corglycon for treatment of those DE patients with eukinetic and hypokinetic types systemic haemodynamics, whereas pentoxiphyllin alone--for those with hyperkinetic type of haemodynamics, taking into consideration its cardiodepressive effects.     

Dynamics of local cerebral blood flow in patients with contusion and compression of the brain in the postoperative period

Study of local cerebral blood flow and PO2 in 19 patients with contusion of the brain after they had undergone surgery with removal of intracranial hematoma showed that posthypohyperemia developed in the previously compressed area of the brain which led to the formation of multiple hemorrhages along the vessels and consequent decrease in local blood flow later. It was assumed that the level of hyperemia in stability of general arterial pressure reflects the degree of tissue acidosis which grows with an increase in intracranial pressure. Early operative intervention for correcting the brain compression is most effective in such conditions.     

Computer image analysis of brain CT images for discriminating hypodense cerebral lesions in children

Nitric oxide (NO) was detected by chemiluminescence in exhaled air from awake humans, anaesthetized rabbits, guinea pigs, germ-free rats and conventional rats. Rabbits exhibited the highest concentrations, followed by guinea pigs, humans and rats. There was no significant difference between germ-free rats and control rats. The authenticity of NO was confirmed in cold-trap experiments. Intravenous administration of inhibitors of NO synthase (0.01-300 mg kg-1) to guinea pigs dose dependently reduced NO concentrations in exhaled air with the following potency order: L-N omega-nitro-arginine-methylester > asymmetric NG,NG-dimethyl-L-arginine-dihydrochloride = L-NG-mono-methyl -arginine = L-N5- (1-iminoethyl)-ornithine = aminoguanidine > L-canavanine. The effect of the NO synthase inhibitors was partly or fully reversed by L-arginine (1 g kg-1 i.v.), and L-arginine per se induced a significant increment of NO in exhaled air. In rats, L-N omega-nitro-arginine-methylester was considerably less potent than in guinea pigs. The concentration of NO in exhaled air increased 3-fold when changing from in situ blood auto-perfusion of rabbit lungs to in situ perfusion with saline medium. Addition of L-N omega-nitro-arginine-methylester to the saline perfusion medium evoked a reduction of NO concentrations in the air from the ventilated perfused lungs. Perfusion of lungs with Ca(2+)-free medium induced significant decrements in NO concentrations in exhaled air, an effect partly reversed upon reintroducing Ca2+ into the medium. In conclusion, NO was detected in exhaled air from humans and animals by chemiluminescence.(ABSTRACT TRUNCATED AT 250 WORDS)