Comparison of the effects of barbiturate, benzodiazepine and ketamine on visual evoked potentials in rabbits.

The aim of this study was to compare the effects of barbiturate, benzodiazepine and ketamine on flash-evoked potentials (F-VEP) in adult rabbits. A total of 36 animals were studied, 16 after pentobarbital endovenous (EV) infusion, 10 after midazolam EV administration, and 10 after ketamine EV infusion. Pentobarbital induced triphasic F-VEP, first negative (N1), second positive (P1), third negative (N2) waves, all with large amplitudes and P1 with well-defined morphology. Mean P1 latency was 33ms. Midazolam induced similar but less defined triphasic waves, with mean latency of 27ms. Ketamine induced poliphasic and poorly defined F-VEP, with mean first positive (P1) latency of 27ms. Statistical analysis showed more elongated latency for the pentobarbital group than the midazolam and ketamine groups. The results of this study suggest that the pharmacological effects of pentobarbital and midazolam on GABA neurotransmission in rabbit visual cortex may be different; another neurotransmission system, possibly cholinergic, may be involved. The ketamine effect seen in rabbit visual cortex seems to be different from pentobarbital and midazolam.

Multimodal evoked potentials and the ovarian cycle in young ovulating women.

There is controversy over how hormonal conditions influence cerebral physiology. We studied pattern-shift visual evoked potentials (PS-VEP), brain stem auditory evoked potentials (BAEP) and short-latency somatosensory evoked potentials (SSEV) in 20 female volunteers at different phases of the menstrual cycle (estrogen phase, ovulatory day and progesterone phase). Statistical analysis showed decreased latencies for P100 (PS-VEP), N19 and P22 (SSEV) waves in the progesterone phase compared with the estrogen phase. There was no significant difference between the estrogen and the ovulation day values. Comparing the three above stages, there were no significant differences in the brainstem auditory evoked potentials. The reduction of the latencies of the potentials generated in multisynaptic circuits provides the first consistent neurophysiological basis for a tentative comprehension of human pre-menstrual syndrome.

Ulnar-to-median nerve anastomosis in the forearm. Review and report of 2 new cases.

The ulnar-to-median nerve anastomosis in the forearm is a very rare occurrence, not mentioned in many anatomical text books. We found only 4 cases cited in medical literature. Here we describe 2 new cases, for which diagnosis was suspected when the compound muscle action potential of the abductor pollicis brevis muscle (APB), obtained by maximal stimulation of the median nerve at the elbow, was lower than that obtained at the wrist. The diagnosis was confirmed by stimulation of the ulnar nerve at the elbow, which evoked a compound muscle action potential of the APB with a clear negative initial deflection without volume-conducted potential.

Silent period in carpal tunnel syndrome.

The silent period is a misunderstood electrophysiological phenomenon leading to several different hypotheses explaining its electrogenesis. It has been studied by different authors and different methodologies giving a wide variability of results, therefore an exact pattern of its normal values does not exist. This work was undertaken to define the normal morphology and duration of the silent period obtained by supramaximal stimulus of the median nerve, during maximum isometric effort of the abductor pollicis brevis muscle against resistance, using 20 adult volunteers without neurological alterations. The normal median duration was 104.6 milliseconds. The same methodology was applied to 20 hands from 20 patients with carpal tunnel syndrome. The silent period showed many types of morphological alterations, but the major alteration observed was a tendency to temporal elongation. No correlation between the severity of the carpal tunnel syndrome and the silent period alterations were observed.

Test of a new technique for the diagnosis of carpal tunnel syndrome.

Several new techniques for carpal tunnel syndrome diagnosis have been developed in the last few years. This work tests a technique that compares the distal motor latency of the median nerve to the second lumbrical muscle (2L) with the distal motor latency of the ulnar nerve to the interossei muscle (INT). Results from 40 normal hands give the superior limit of the normal difference (2L-INT) as 0. 26 ms (&xmacr;+3 SD). In 55 hands with different levels of carpal tunnel syndrome, this new technique was more sensitive and accurate than the conventional test which uses the distal motor latency of the median nerve to the abductor pollicis brevis muscle (APB), especially in the less severe cases. With the absence of the compound muscle action potentials of the APB muscle caused by severe thenar atrophy, it is much easier to obtain the potential from the 2L muscle. We concluded that this is a sensitive, simple, rapid, and non-invasive new technique, and therefore, it should be incorporated as part of the routine ENMG procedures for carpal tunnel syndrome diagnosis.

[Is the metabolic response self-limited in head trauma? Analysis of acute phase proteins and glycemia]. / A resposta metabólica ao trauma cranioencefálico é autolimitada? Análise das proteínas de fase aguda e glicemia.

There are many reports supporting a self-limitation mechanism involved with hypermetabolic response after severe cranial injury. It was proposed a study with severe head injury patients, in three stages of the evolution. The first 7 days after admission (moment 1-M1), the second three days latter (M2) and the last 7 days after the first (M3). Among male patients with severe head injury, attended between January 1992 and December 1993 in University Hospital of Botucatu, UNESP, were selected 28 male patients, with Glasgow severity scale between 4 and 6, with pO2 < 70 mm Hg, weighting 60 kg or more. Among these patients, 6 finished the study, including analysis of the excretion of N, acute phase proteins, glycemia, triglycerides and amine nitrogen. During the study there were no changes in nitrogen balance and there was a decrease in protein C-reative. Glycemia tends to fall within two weeks after injury. The authors make some considerations about possible mechanisms involved in brain modulation associated with the period of dependence of hypermetabolism and hypercatabolism after closed brain injury. There are some evidences that the brain responds to head trauma with a gobal non specific way, which tends to be reorganized beyond the first two weeks after lesion. The study does not show any influence of the type and severity of head trauma.

[Evoked potentials in neurocysticercosis]. / Potenciais evocados na neurocisticercose.

In 25 patients with cysticercosis of central nervous system, classified in two clinical forms, benign and malign, evoked potentials were obtained. Normal exam was found in 9 cases with the benign form. From 4 patients with malign clinical presentations, 2 had multiple abnormalities of the evoked potentials, and F wave alterations (mixed pattern). The authors suggest that this mixed pattern may be indicative of severe prognosis.

[Control of supply and use of energy substrates in the encephalon]. / Controle do fornecimento e da utilização de substratos energéticos no encéfalo.

Although accounting for 2% of body weight, brain has one of the greatest metabolic rates compared with other organs and systems. The energy metabolic consum is expended mainly in the maintenance of ionic gradient, essential to neuronal activity. Brain receives energy substrates from circulation, with interference of blood brain barrier (BBB). Glucose is the main substrate and has a metabolic rate so high as 150 g/day (0.7 mM/G/min). At cellular level, metabolism of glucose seems to be controlled by phosphofructokynase. If the cellular level were high enough, manose and other products like fructose 1,6 biphosphate, pyruvate, lactate and acetate can be used in the place of glucose. Lactate, when oxyded, consums at least 21% of the cerebral needs of O2. In ischemia and inflammatory infections, brain tissue produces lactate instead of use it. Ketone bodies reduce cerebral needs of glucose; in view of the disturbances that occur in cerebral production of succinyl CoA and guanosine 3 phosphate (GTP), they must be considered as complementary substrate but not as an alternative one. Although they can be metabolized, there are no evidences that brain could produce energy from systemic free fatty acids, even when hypoglicemia is present. Ethanol and glycerol are considered only at experimental level. Brain uptake of aminoacids occur better for long chain aminoacids, specially valine. The aminoacids that are synthetised in the brain (aspartate, gluconate and alanine) show the lower absortion rates. All aminoacids should be oxided to CO2 and H2O. Even when glucose consum is reduced to 30%, aminoacid accounts for only 10% of the energetic expenditure of the brain. To maintain cerebral glucose and oxygen supply to the brain, blood flow must be at least 800 ml/min. The regulation of supply and consumption of energy substrate by the brain is changed in few situations. Among them, are included the oxidation of lactate immediately before milk diet early in development and utilization of ketone bodies at the beginning of lactation. This review includes a brief discussion about the relevance of glucose as the main energy substrate for cerebral tissue in different ages and ischemia or hypoxia.

[Cerebral glucose metabolism in craniocerebral trauma: an evaluation]. / Metabolismo da glicose cerebral no trauma crânio-encefálico. Uma avaliação.

The authors give a general overview on the cerebral glucose metabolism, with special reference to brain injury, including intake, blood-brain barrier properties for glucose transport, oxidative metabolism and energetic needs during the head trauma. The evidences of the presence of ischemia and hypoxia in those situations and the relationships with the cerebral glucose metabolism are discussed. They point to the several explanations for hyperglicemia present up to 10 days after admission in brain injury, relating to the energetic needs at different phases of head trauma recovery. Some considerations are made about the lack of evidences on increase in glucose consumption or lactate production when hyperglycemia occurs in association with brain damage and ischemia caused by head trauma. The brain capacity to compensate metabolic disturbances is discussed. Some questions are made about current indications for restriction of glucose infusion in pacients who are in catabolic phase and need to spare their body protein pool. At the same way, the polemic about previous hyperglycemia and cerebral injury is revised. Some considerations are made about the moment to introduct increases in glucose administration.

[Diphenylhydantoin poisoning in monotherapy and in combination with other antiepileptic drugs]. / Intoxicação por difenilhidantoína em monoterapia e em combinação com outros anticonvulsivantes.

It was determined the serum concentration of phenytoin in 100 patients from July 1979 to July 1984. Among those, 67.3% as monotherapy and 32.7% as polytherapy. With monotherapy we found increased concentration of phenytoin (greater than 24 mg/l) in 3.3% and side effects in 0.4%. The patients treated with combination of two or more antiepileptic drugs showed increased concentration of phenytoin in 9.1% and side effects in 4.6%. Toward side effects, there were no difference between the many associations of two or more drugs. The data reinforce conviction that we must first attempt to reach the upper therapeutic threshold before we try the use of two or more distinct drugs.

Intoxicaçäo por difenilhidantoína: em monoterapia e em combinaçäo com outros anticonvulsivantes / Diphenylhydantoin intoxication in monotherapy and in combination with other antiepiletic drugs

Entre julho de 1979 e julho de 1984 foram determinadas as concentraçöes plasmáticas de difenilhidantoína de 1.000 pacientes que faziam uso do medicamento como única droga ou em associaçäo com outros anticonvulsivantes. Sob monoterapia encontramos um percentual de 3,3% com níveis séricos acima de 24mg/1 e 0,4% com sinais clínicos de efeitos colaterais. Entre os pacientes em utilizaçäo de associaçäo medicamentos foi determinada elevaçäo dos níveis séricos de difenilhidantoína em 9,1% dos pacientes e sinais clínicos de intoxicaçäo em 4,6%. Näo foi constatado predomínio de qualquer das diferentes associaçöes medicamentosas na frequência de sinais clínicos de intoxicaçäo. Os ddados reforçam a assertiva de que devemos esgotar todas as possibilidades de controle com uma única droga, antes de tentar a utilizaçäo de um segundo medicamento

[Contraceptive methods and epilepsy. Consideration on its physiopathogenesis]. / Métodos contraceptivos e epilepsia. Considerações sobre a fisiopatogenia.

The authors present six cases of patients with catamenial epilepsy, that use contraceptive methods (hormonal and intrauterine device). A critical report of the physiopathogenic aspects of hormones and epilepsy is also made. The authors conclude that: 1 - It seems there is no doubt about the influence of sexual hormones in epilepsy. 2 - There is no previsibility about the consequence of the use of contraceptives (hormonal and IUD) in patients with catamenial epilepsy. 3 - Further studies are still necessary to demonstrate the risk factors of contraceptive methods in epileptic patients.

[Clinical study of catamenial epilepsy: significance of the presence of a previous cerebral lesion]. / Estudo clínico da epilepsia catamenial: significado da presença de lesão cerebral prévia.

Four hundred thirty one epileptic patients, aged 10 years or more old, have been studied in the neurology clinic of Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da U.S.P., from February to July, 1981. The authors selected 119 patients aged between 13 to 45 years, that presented periodic menstrual bleeding and at least, one epileptic seizure a month. The patients were divided in two groups, the first constituted of 36 patients with catamenial seizures and the second one with 83 patients showing non catamenial seizures. The authors compare the number of pictures suggestive of "organic lesions" found in both groups. The statistical analysis shows that there are no differences between the two groups. The authors registered the EEG findings of these patients.

[Clinical study of catamenial epilepsy: clinical types of epileptic crises]. / Estudo clínico da epilepsia catamenial: tipos clínicos das crises epilépticas.

Four hundred thirty one epileptic patients, aged 10 years or more old, have been studied in the neurology clinic of Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da U.S.P., from February to July, 1981. The authors selected 119 patients aged between 13 to 45 years, that presented periodic menstrual bleeding and at least, one epileptic seizure a month. The patients were divided in two groups, the first constituted of 36 patients with catamenial seizures and the second one with 83 patients showing non catamenial seizures. It was determined a prevalence coefficient of 105.9/1000. The authors classify the clinical types of epileptic seizures found in patients with catamenial epilepsy and compare them with those occurred in a group of patients on menacme. The statistical analysis shows that there are no differences between the two groups.

Metodos contraceptivos e epilepsia: consideracoes sobre a fisiopatogenia. / Contraceptive methods and epilepsy: considerations on the physiopathogenis

Os autores apresentam seis casos ilustrativos de pacientes em uso de metodos contraceptivos hormonais e DIU (dispositivo intrauterino). E feita tambem uma revisao critica dos aspectos fisiopatogenicos. Os autores concluem que: 1 - Parece nao haver duvidas sobre a influencia dos hormonios ovarianos na epilepsia. 2 - Nao ha previsibilidade quanto as consequencias do uso de contraceptivos (hormonais e DIU) em pacientes com epilepsia catamenial. 3 - Ha necessidade ainda de estudos complementares que elucidem melhor os fatores de risco na utilizacao de metodos contraceptivos pelas pacientes epilepticas

Estudo clinico da epilepsia catamenial. Tipos clinicos das crises epilepticas. / Clinical study of catamenial epilepsy: clinical types of epileptic crisis

Foram atendidas 431 pacientes epilepticas com idades acima de 10 anos, no periodo de fevereiro a julho de 1981 no ambulatorio de Neurologia do H.C.F.M.R.P. Destas, foram selecionadas 119 pacientes com idade de 13 a 45 anos e/ou fluxo mentrual periodico e pelo menos uma crise epileptica ao mes. As pacientes foram separadas em dois grupos, o primeiro constituido de 36 pacientes com diagnostico de epilepsia catamenial e o segundo com 83 pacientes que apresentavam epilepsia nao catamenial. Determinamos um coeficiente de prevalencia de 105,9/1000 para a epilepsia catamenial.Classificamos os tipos clinicos de crises epilepticas ocorridas em pacientes com epilepsia catamenial e comparamos com as ocorridas em pacientes na menacme

Estudo clinico da epilepsia catamenial. Significado da presenca de lesao cerebral previa. / Clinical study of catamenial epilepsy: significance of the presence of previous cerebral lesion

Foram atendidas 431 pacientes epilepticas com idades acima de 10 anos, no periodo de fevereiro a julho de 1981 no ambulatorio de Neurologia do H.C.F.M.R.P. Destas, foram selecionadas 119 pacientes con idades de 13 a 45 anos e/ou fluxo mentrual periodico e pelo menos uma crise epileptica ao mes. As pacientes foram separadas em dois grupos, o primeiro constituido de 36 pacientes com diagnostico de epilepsia catamenial e o segundo com 83 pacientes que apresentavam epilepsia nao catamenial.Confrontamos a percentagem de quadros clinico-laboratoriais sugestivos de lesao "organica", encontradas nos dois grupos. Anotamos os achados eletrencefalograficos das pacientes estudadas