Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 20
Filtrar
1.
J Obstet Gynaecol ; 24(4): 387-91, 2004 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-15203577

RESUMEN

The aim of this study was to establish a population-based incidence of severe acute maternal morbidity (SAMM) in hypertensive pregnancies and to assess if substandard care was unique to cases of SAMM and mortality or whether it was apparent in uncomplicated pregnancies as well. The population-based incidence of hypertension was 12%. Using defined criteria for SAMM, the incidence of SAMM was 3/1000 deliveries. The MMR was 42/100000 deliveries, i.e. SAMM is seven times greater than the mortality. Substandard care was similar in cases of SAMM and mortality and uncomplicated hypertensive patients. Audit of SAMM is informative, can be conducted more frequently, and in small sample population groups. It also allows interviews of patients, hence problems of inefficient documentation is obviated.


Asunto(s)
Hipertensión/epidemiología , Servicios de Salud Materna , Área sin Atención Médica , Complicaciones Cardiovasculares del Embarazo/epidemiología , Enfermedad Aguda , Adulto , Parto Obstétrico/estadística & datos numéricos , Países en Desarrollo , Femenino , Humanos , Hipertensión/etiología , Hipertensión/patología , Incidencia , Auditoría Médica , Embarazo , Complicaciones Cardiovasculares del Embarazo/etiología , Complicaciones Cardiovasculares del Embarazo/patología , Índice de Severidad de la Enfermedad , Sudáfrica/epidemiología
2.
J Obstet Gynaecol ; 23(6): 596-8, 2003 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-14617457

RESUMEN

Acute trauma is not all that uncommon in pregnancy. It accounts for 15% of non-obstetric maternal deaths. Moreover, about 15% of acute spinal cord injuries involve young women of childbearing age (Gilson et al., 1995). Most of the existing literature on spinal cord injury in pregnancy is concerned with the management of patients with pre-existing lesions; very few articles deal with acute injuries. We report the management of a case of acute spinal cord injury in the third trimester of pregnancy and review the major clinical issues associated with such cases.


Asunto(s)
Hemiplejía/complicaciones , Complicaciones del Embarazo/terapia , Traumatismos de la Médula Espinal/complicaciones , Heridas por Arma de Fuego/complicaciones , Adulto , Traumatismos del Brazo/complicaciones , Traumatismos del Brazo/terapia , Cesárea , Tratamiento de Urgencia , Femenino , Hemiplejía/terapia , Humanos , Traumatismos Mandibulares/complicaciones , Traumatismos Mandibulares/terapia , Traumatismos del Cuello/complicaciones , Traumatismos del Cuello/terapia , Embarazo , Tercer Trimestre del Embarazo , Atención Prenatal , Traumatismos de la Médula Espinal/terapia , Heridas por Arma de Fuego/terapia
3.
BJOG ; 110(10): 889-93, 2003 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-14550357

RESUMEN

OBJECTIVE: To assess whether severe acute maternal morbidity (SAMM, 'near misses') can be used as a surrogate of an analysis of maternal deaths to describe the pattern of severe maternal disease and avoidable factors related to it. DESIGN: Prospective, descriptive study. SETTING: A SAMM and maternal mortality audit was conducted in three clearly defined geographical areas, consisting of rural and urban settings in South Africa. POPULATION: Indigent black African pregnant women. METHOD: Cases of SAMM and maternal deaths were collected in the areas and a comparison was made of the disease profiles and avoidable factors, missed opportunities and substandard care. MAIN OUTCOME MEASURES: The proportion of primary obstetric causes and avoidable factors in women with SAMM and maternal deaths, and the mortality indices of the primary obstetric causes of death and organ system dysfunction. RESULTS: A total of 423 women with SAMM and 128 maternal deaths were collected over two years. Demographic factors were similar between the groups except that significantly more maternal deaths had not attended any antenatal care. The primary obstetric causes of SAMM and maternal death did not correlate. The four most common causes of SAMM were complications of hypertension (27.2%), postpartum haemorrhage (18.0%), antepartum haemorrhage (12.8%) and abortion (11.3%), whereas the four most common causes of maternal death were non-pregnancy related sepsis (26.6%), complications of hypertension (23.4%), pre-existing medical disease (14.1%) and abortion (10.9%). The types of avoidable factors were similar between both groups although administrative factors occurred significantly more frequently in the maternal death group as did poor problem identification and monitoring. CONCLUSION: Review of SAMM gives a different disease pattern to that obtained from maternal death audits. However, in diagnosing inadequacies in the health system, similar information was obtained.


Asunto(s)
Mortalidad Materna , Complicaciones del Embarazo/mortalidad , Adulto , Causas de Muerte , Femenino , Humanos , Auditoría Médica , Embarazo , Estudios Prospectivos , Salud Rural , Sudáfrica , Salud Urbana
4.
BJOG ; 109(5): 509-13, 2002 May.
Artículo en Inglés | MEDLINE | ID: mdl-12066939

RESUMEN

OBJECTIVE: To investigate the effect of chronic oxygen therapy in fetuses with absent end diastolic flow in the umbilical artery assessed by doppler analysis at 24-30 weeks of gestation. DESIGN: A double-blind, randomised control trial was performed with patients blindly allocated to receive humidified oxygen or humidified air. SETTING: A tertiary referral hospital in South Africa. PARTICIPANTS: Thirty-two women who presented between 24 and 30 weeks of gestation with a confirmed finding of absent end diastolic flow in the umbilical artery. METHODS: After randomisation patients were allocated to receive a 40% mixture of humidified oxygen or humidified air from uniform coloured gas cylinders which were marked either 'a' or 'b' All women received betamethasone from 27 weeks of gestation on a weekly basis. Cardiotocographs were used from 28 weeks of gestation; after 28 weeks of gestation an amniocentesis was considered to confirm fetal maturity. Women were expected to breath the allocated gas continuously apart from meals and visits to the toilet. MAIN OUTCOME MEASURES: Survival of the fetus was the main outcome measure with secondary outcome measures documenting improvement in the fetal condition in utero. RESULTS: There were 16 women randomised to receive oxygen and 16 to receive air. There were nine survivors in the oxygen group (56.3%) and six in the air group (37.5%) (relative risk 1.5, 95% confidence interval 0.7-3.2). There was a nonsignificant increase in mean birthweight in the oxygen group (858.3 grammes vs 774.4 grammes) and a nonsignificant increase in mean duration of treatment in the oxygen group (12.8 days vs 10.4 days). CONCLUSION: This study did not demonstrate that chronic oxygen therapy provides any benefits to compromised fetuses between 24 and 30 weeks of gestation. Larger studies with sufficient power are necessary to assess whether oxygen therapy can reduce perinatal mortality by a clinically useful amount in this group of patients.


Asunto(s)
Enfermedades Fetales/terapia , Oxígeno/administración & dosificación , Arterias Umbilicales/fisiopatología , Cardiotocografía/métodos , Intervalos de Confianza , Diástole , Método Doble Ciego , Femenino , Muerte Fetal , Enfermedades Fetales/fisiopatología , Edad Gestacional , Humanos , Evaluación de Resultado en la Atención de Salud , Embarazo , Resultado del Embarazo , Flujo Sanguíneo Regional , Ultrasonografía , Arterias Umbilicales/diagnóstico por imagen
5.
Best Pract Res Clin Obstet Gynaecol ; 15(4): 563-81, 2001 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-11478816

RESUMEN

The incidence of acute renal failure in pregnancy has decreased. This decrease is less marked in developing countries in which resources are more scarce. The clinical diagnosis of acute renal failure is crude due to the variability of clinical signs and the late occurrence of basic biochemical abnormalities. Obstetric and gynaecological diseases are found among the traditional pre-renal, intra-renal and post-renal causes of acute renal failure. The cornerstone of management is the identification of high-risk cases and the prevention of acute renal failure by maintaining intravascular volume. The evidence for the efficacy of other prophylactic medical interventions, such as the use of loop diuretics, mannitol, low-dose dopamine and others, is poor. Management of established acute renal failure includes restoration of intravascular volume, treatment of any reversible causes, especially pregnancy complications such as pre-eclampsia, strict fluid balance and correction of any electrolyte abnormality or metabolic acidosis. Dialysis is a supportive measure until the kidneys recover.


Asunto(s)
Lesión Renal Aguda/terapia , Oliguria/terapia , Complicaciones del Embarazo/terapia , Embarazo de Alto Riesgo , Lesión Renal Aguda/diagnóstico , Lesión Renal Aguda/etiología , Adulto , Factor Natriurético Atrial/uso terapéutico , Cardiotónicos/uso terapéutico , Enfermedad Crítica , Diuréticos Osmóticos/uso terapéutico , Dopamina/uso terapéutico , Femenino , Fluidoterapia , Humanos , Manitol/uso terapéutico , Oliguria/diagnóstico , Oliguria/etiología , Embarazo , Complicaciones del Embarazo/diagnóstico , Complicaciones del Embarazo/etiología , Pronóstico , Diálisis Renal , Desequilibrio Hidroelectrolítico/etiología , Desequilibrio Hidroelectrolítico/terapia
6.
Cephalalgia ; 19(6): 566-74, 1999 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-10448543

RESUMEN

The purpose of this study was (i) to compare a range of stress-related personality traits, including defense and coping mechanisms, of migraine patients (n = 23) with those of tension headache patients (n = 18) and dermatologically afflicted, but otherwise healthy, controls (n = 22), and (ii) to compare their state anxiety and other moods before, during, and after the presentation of a psychological stressor (mental arithmetic). For all three groups, mental arithmetic induced a significant increase in state anxiety and mood disturbance, followed by a subsequent decrease during recovery. Migraine patients were not found to have a higher disposition for anxiety, depression, or rigidity than tension headache patients or controls. Between the headache groups no differences in the use of defense and coping mechanisms were found. Compared to the control group, however, both migraine patients and tension headache patients were more inclined to use internally focused defense mechanisms and less inclined to seek social support when confronted with a problem. The psychological reaction of migraine patients to mental stress hardly differed from tension headache and control subjects. Compared to the control subjects, however, both groups of headache patients exhibited a diminished recovery from feelings of vigour, depression, and fatigue due to the stress induced. It is suggested that this distinct psychological reaction to stress of headache patients versus healthy control subjects is related to the more internally focused defense style of the headache sufferers. Thus, in contrast to previous results, this study does not present evidence of a migraine personality. It suggests the development of specific personality characteristics as a consequence of suffering from episodic headache.


Asunto(s)
Identidad de Género , Trastornos Migrañosos/psicología , Personalidad , Rol del Enfermo , Estrés Psicológico/complicaciones , Adaptación Psicológica , Adolescente , Adulto , Ansiedad/diagnóstico , Ansiedad/psicología , Mecanismos de Defensa , Depresión/diagnóstico , Depresión/psicología , Femenino , Humanos , Control Interno-Externo , Persona de Mediana Edad , Inventario de Personalidad , Cefalea de Tipo Tensional/psicología
7.
Br J Obstet Gynaecol ; 105(9): 985-90, 1998 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-9763050

RESUMEN

OBJECTIVE: To test the application of a clinical definition of severe acute maternal morbidity. DESIGN: A one-year prospective descriptive multi-centre study. SETTING: Kalafong and Pretoria Academic hospitals, catering for the delivery of indigent women in the Pretoria Health Region. METHODS: A 'near-miss' describes a patient with an acute organ system dysfunction, which if not treated appropriately, could result in death. The case notes of women fitting this definition and all maternal deaths were analysed and compared. OUTCOME MEASURE: Determine the primary obstetric factors and the organ systems that failed. Identification of episodes of sub-standard care and missed opportunities. Results One hundred and forty-seven near misses and 30 maternal deaths were identified. The commonest reasons for a near-miss were: emergency hysterectomy in 42 women (29%); severe hypotension in 40 (27%); and pulmonary oedema in 24 (16%). The most common initiating obstetric conditions were hypertension in 38 women (26%); haemorrhage in 38 (26%); and abortion or puerperal sepsis in 29 (20%). The primary obstetric factors amongst the maternal deaths were: hypertension (33%); sepsis (27%); and maternal medical diseases (17%) in 10, 8 and 5 women respectively. Sub-standard care was identified in 82 cases. Breakdown in the health care administration was identified in 33, and patient-orientated missed opportunities on 34 occasions. CONCLUSION: The definition of severe acute maternal morbidity identified nearly five times as many cases as maternal death. This definition allows for an effective audit system of maternal care because it is clinically based, the definition is robust and the cases identified reflect the pattern of maternal death.


Asunto(s)
Complicaciones del Embarazo/diagnóstico , Atención Prenatal/normas , Calidad de la Atención de Salud , Femenino , Maternidades/normas , Humanos , Mortalidad Materna , Auditoría Médica , Proyectos Piloto , Embarazo , Complicaciones del Embarazo/mortalidad , Estudios Prospectivos , Sudáfrica/epidemiología
8.
Hum Genet ; 102(4): 464-6, 1998 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-9600245

RESUMEN

Hereditary paroxysmal ataxia, or episodic ataxia (EA), is a rare, genetically heterogeneous neurological disorder characterized by attacks of generalized ataxia. By direct sequence analysis, a different missense mutation of the potassium channel gene (KCNA1) has been identified in three families with EA.


Asunto(s)
Ataxia/genética , Mutación Puntual/genética , Canales de Potasio con Entrada de Voltaje , Canales de Potasio/genética , Sustitución de Aminoácidos/genética , Cromosomas Humanos Par 12/genética , Femenino , Heterocigoto , Humanos , Canal de Potasio Kv.1.1 , Masculino , Linaje
9.
Headache ; 38(4): 270-80, 1998 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-9595866

RESUMEN

This study aimed at the combined assessment of the serotonergic and sympathetic nervous system reactions of migraine patients before, during, and after the induction of mental stress in order to detect the possible role of these reactions in inducing a migraine attack. The responses to mental stress of the migraine patients were compared to a group of patients suffering from tension headache and a control group. Activation of the sympathoadrenomedullary system due to mental stress was successfully induced in the migraine patients (n = 23), in the tension headache patients (n = 18), and in the control group (n = 22). The results of this study present evidence of increased cardiovascular activity in migraine patients as compared to nonmigraineurs. However, no evidence was found of a specific serotonergic, sympathoadrenomedullary, or cerebrovascular response of migraine patients to mental stress as compared to nonmigraineurs.


Asunto(s)
Catecolaminas/sangre , Trastornos Migrañosos/sangre , Trastornos Migrañosos/fisiopatología , Serotonina/sangre , Estrés Psicológico/sangre , Estrés Psicológico/fisiopatología , Adolescente , Adulto , Plaquetas/química , Presión Sanguínea , Femenino , Frecuencia Cardíaca , Humanos , Persona de Mediana Edad , Trastornos Migrañosos/psicología , Músculos/fisiopatología , Arterias Temporales/fisiopatología
10.
Br J Obstet Gynaecol ; 104(10): 1180-3, 1997 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-9332997

RESUMEN

OBJECTIVE: To assess the effect of low dose dopamine on the urine output in postpartum pre-eclamptic or eclamptic women with oliguria. DESIGN: A double blind, randomised controlled study. SETTING: The high care area of the labour ward in a teaching hospital. SAMPLE: Forty postpartum pre-eclamptic women with oliguria, defined as < 30 mL/hour, who have not responded to a 300 mL crystalloid fluid challenge. INTERVENTION: Dopamine was infused at a rate of 1 to 5 microg/kg per minute, or sterile water was given as placebo in the same dilution. MAIN OUTCOME MEASURE: Urine output, blood pressure and pulse was measured for six hours before and for six hours after the intervention. RESULTS: Women who received dopamine (344 mL over 6 hours) showed a clinically and statistically significant (P = 0.0014, Mann-Whitney U test) higher median urine output compared with those receiving placebo (135 mL over 6 hours) for the duration of therapy. The respective 95% confidence intervals were 212.3 to 712.7 mL compared with 73.8 to 244.7 mL. No differences in blood pressure or pulse were found between the two groups. CONCLUSIONS: The use of low dose dopamine in a labour setting improved urine output in postpartum pre-eclamptic women with oliguria who had not responded to a single fluid challenge without a detrimental effect on the blood pressure or pulse.


Asunto(s)
Dopamina/administración & dosificación , Oliguria/tratamiento farmacológico , Preeclampsia/orina , Adulto , Método Doble Ciego , Femenino , Humanos , Infusiones Intravenosas , Oliguria/orina , Atención Posnatal , Periodo Posparto , Embarazo , Resultado del Embarazo
11.
Am J Med Genet ; 70(4): 444-7, 1997 Jun 27.
Artículo en Inglés | MEDLINE | ID: mdl-9182789

RESUMEN

In medical genetics, several systems are used to classify and code genetic disorders for the purpose of automated registration. In the Netherlands, a genetic diagnosis code system has been developed that links a unique four-digit code to a principal description and all current synonyms. The main goal of this coding system is to enable nationwide uniformity of coding, without losing access to information stored in the past, identified by the ICD/BPA code (the International Classification of Diseases as adapted by the British Paediatric Association) and/or the MIM code (McKusick's classification in Mendelian Inheritance in Man). To this effect, the Dutch diagnosis code is cross-referenced with the 2 pre-existing classification systems. Developments in medical genetics make regular updates of all coding systems necessary. In the Netherlands, new diagnosis codes are assigned centrally to preserve uniformity and distributed periodically to all 8 clinical genetic centers. Diagnosis codes are assigned in numerical order of inclusion, enabling quick and easy updates. It is possible to include subclassifications of disorders according to pattern of inheritance, gene location, and gene mutations and to cover all disorders and disorder subtypes which are not clearly distinguished by the 2 pre-existing classification systems. The architecture of the coding system is suitable for international use. It offers a practical solution for clinical geneticists in need of a coding system suitable for clinical use. The use of the diagnosis code will also facilitate reliable comparison of data and nationwide genetic epidemiological studies.


Asunto(s)
Anomalías Congénitas/clasificación , Enfermedades Genéticas Congénitas/clasificación , Sistema de Registros/clasificación , Anomalías Congénitas/diagnóstico , Anomalías Congénitas/patología , Enfermedades Genéticas Congénitas/diagnóstico , Enfermedades Genéticas Congénitas/patología , Humanos , Registros Médicos , Estudios Multicéntricos como Asunto , Países Bajos/epidemiología , Sistema de Registros/estadística & datos numéricos , Síndrome , Organización Mundial de la Salud/organización & administración
13.
Br J Obstet Gynaecol ; 103(6): 518-22, 1996 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-8645642

RESUMEN

OBJECTIVE: To establish the antihypertensive properties of intravenous nimodipine used to treat eclamptic patients. To assess the effects of intravenous nimodipine on oxygen delivery and consumption. DESIGN: A prospective observational study. SETTING: The Maternity Centre Obstetric Intensive Care Unit, Groote Schuur Hospital. PARTICIPANTS: Four unselected patients presenting with proteinuric hypertension and seizures. METHODS: Haemodynamic observations were obtained by a radial artery catheter and right heart catheterisation with a pulmonary artery flow directed thermodilution catheter. Observations were obtained prior to and after the administration of nimodipine. RESULTS: A significant reduction in mean arterial pressure occurred in all patients after administration of nimodipine. This was due to a significant reduction in systemic vascular resistance. Neither oxygen delivery to the tissues nor peripheral oxygen consumption changed significantly during nimodipine infusion. No adverse effects related to the use of nimodipine were documented. CONCLUSIONS: Nimodipine is an effective vasodilator. There may be a role for nimodipine as a single agent for the management of eclampsia.


Asunto(s)
Eclampsia/tratamiento farmacológico , Hemodinámica/efectos de los fármacos , Nimodipina/administración & dosificación , Respiración/efectos de los fármacos , Vasodilatadores/administración & dosificación , Adulto , Presión Sanguínea/efectos de los fármacos , Eclampsia/fisiopatología , Femenino , Humanos , Hipertensión/tratamiento farmacológico , Infusiones Intravenosas , Embarazo , Estudios Prospectivos , Resultado del Tratamiento
15.
Exp Brain Res ; 81(1): 95-106, 1990.
Artículo en Inglés | MEDLINE | ID: mdl-2394234

RESUMEN

A new technique is described for recording the activity of single motor units in human or monkey hand muscles. A pair of microwire electrodes is introduced into the muscle using a fine needle. After insertion, the needle can be completely removed, leaving the recording microwires in situ. The method allows stable recording of a motor unit during natural movement of the hand and fingers. The identity of a given single motor unit was reflected in the form and amplitude of the motor unit-triggered average (MU-TA), derived by averaging the unrectified surface EMG recorded from the muscle with discharges of the motor unit. The MU-TA of a given unit remained constant despite variations in the form and size of its action potential. Inspection of successive MU-TAs increased confidence that records were taken from one and the same unit over long recording periods. Control experiments in human first dorsal interosseous showed that the peak-to-peak amplitude of the MU-TA was highly correlated with both the twitch force (r = 0.65-0.92, mean 0.82, six subjects) and force threshold (r = 0.62-0.93, mean 0.83) of a given unit. Similar findings were obtained for human abductor pollicis brevis (AbPB) motor units. In the monkey, AbPB motor units which were recruited early in a precision grip task and which discharged steadily during the grip had smaller MU-TAs than late-recruited, phasic units. The combination of methods described in this paper enable a single motor unit to be identified and recognised. The relative size of the unit, which is an important parameter in most motor unit studies, can be reliably estimated from the amplitude of the MU-TA. This allows indirect assessment of motor unit size in a free-to-move animal.


Asunto(s)
Mano/inervación , Neuronas Motoras/fisiología , Potenciales de Acción/efectos de los fármacos , Animales , Electrodos Implantados , Electrofisiología , Humanos , Macaca nemestrina , Músculos/inervación , Músculos/fisiología
16.
J Physiol ; 413: 351-78, 1989 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-2600855

RESUMEN

1. The possibility that the discharge pattern of monkey corticomotoneuronal cells influences the degree to which they facilitate their target hand muscles was tested by compiling spike-triggered averages of EMG recorded from these muscles. 2. Records were made from area 4 corticomotoneuronal cells in three conscious macaque monkeys while they performed a precision grip between index finger and thumb. Simultaneous EMG recordings were made from up to six different intrinsic hand muscles. Twenty cells which produced clear post-spike facilitation of one or more muscles were selected for further analysis. 3. Spikes recorded from these cells were grouped according to the occurrence of a previous spike in the periods 0-10 ms, 10-20 ms, and so on up to 60-70 ms before the trigger spike. The post-spike period in which no additional spikes were allowed to fall was kept at either 12.5 or 25 ms. 4. Spikes selected in this way produced a transient facilitation of their target muscle EMG activity. The peak amplitude of this facilitation was normalized as a percentage of modulation of the background EMG level. The background level was determined from a period in the average to which the cell could not have contributed, because of the post-trigger spike interval. We verified that the percentage of modulation was not influenced by the overall level of EMG activity, since, for a given interval, the modulation was the same whether the relevant spikes were selected during periods of high- or low-level EMG activity. 5. The relative amplitude of the post-spike facilitation (i.e. the percentage of modulation) showed marked variation with interspike interval. A full analysis was completed for seventeen neurones. Spikes with the shortest intervals (less than 10 ms) usually produced the strongest effects, and evidence is presented that this was due to temporal summation and facilitation at the corticomotoneuronal synapse. Mid-range intervals (10-40 ms) were generally far less effective, although they constituted the highest proportion of cell activity. 6. A striking finding was the strong facilitation generated by the longer interspike intervals (40-70 ms). Although the absolute size of this post-spike effect was much smaller than that of the shortest intervals, its percentage of modulation was similar. It is suggested that this enhanced facilitation results from a combination of lower frequency discharge among the active motoneurones, and increased synchrony in the corticomotoneuronal input to them. 7. All of the above results were confirmed by examining cross-correlations between single corticomotoneuronal cells and single motor units in their target muscle.(ABSTRACT TRUNCATED AT 400 WORDS)


Asunto(s)
Mano , Corteza Motora/fisiología , Neuronas Motoras/fisiología , Músculos/fisiología , Médula Espinal/fisiología , Animales , Vías Eferentes/fisiología , Electromiografía , Macaca nemestrina
17.
Neurosci Lett ; 77(1): 113-8, 1987 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-3601210

RESUMEN

The functional connections between corticospinal neurones and motor units of the monkey's hand muscles were investigated by constructing cross-correlograms of activity recorded from pyramidal tract neurones and from single motor units in the contralateral thenar muscles during performance of a precision grip between thumb and index finger. Only those neurones which produced postspike facilitation of the surface-recorded electromyogram (EMG) of these muscles were selected for analysis. Positive correlations were observed for 11/15 selected neurones, and the form of the correlation was suggestive of monosynaptic action. Corticospinal cells which produced a correlation peak often did so with all concurrently-sampled motor units.


Asunto(s)
Músculos/inervación , Neuronas/fisiología , Animales , Electromiografía , Electrofisiología , Mano , Macaca nemestrina
18.
Exp Brain Res ; 66(3): 621-37, 1987.
Artículo en Inglés | MEDLINE | ID: mdl-3038586

RESUMEN

Corticomotor (CM) neurones were identified in three conscious macaque monkeys by the presence of post-spike facilitation (PSF) in spike-triggered averages of e.m.g. recorded from intrinsic hand and forearm muscles during performance of a precision grip task. Post-spike effects were compared with those produced by single-pulse intracortical microstimulation (ICMS), with strengths of 4-20 microA, delivered at the site of 47 CM cells. Most muscles facilitated by a CM cell were also facilitated by ICMS at the site of the cell. ICMS effects were stronger: at 10 microA, the amplitude of ICMS-evoked facilitation was on average 2.8 times greater than PSF, and 6.9 times greater at 20 microA. Onset latency of ICMS-evoked facilitation was consistently longer (by 1.7 and 1.3 ms at 10 and 20 microA respectively) than PSF, and it is suggested that this results from the indirect, trans-synaptic excitation of CM cells by ICMS. Post-spike suppression was rarely seen (7/421 compared to 105/421 cases of PSF). In contrast, suppression and facilitation were equally common in response to ICMS. The synaptic mechanisms underlying these effects were explored in 5 anaesthetised macaque monkeys. ICMS facilitated a greater proportion of the tested muscles than did the CM cell recorded at the stimulus site. The results suggest the juxtaposition in the motor cortex of CM neurones with different 'muscle fields'. The merits of STA and ICMS for exploring cortical organisation are discussed.


Asunto(s)
Corteza Motora/fisiología , Músculos/inervación , Tractos Piramidales/fisiología , Animales , Mapeo Encefálico , Estimulación Eléctrica , Antebrazo , Mano , Macaca nemestrina , Tiempo de Reacción/fisiología , Sinapsis/fisiología , Transmisión Sináptica
19.
J Physiol ; 381: 529-49, 1986 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-3625544

RESUMEN

1. Post-spike facilitation of e.m.g. activity by monkey motor cortex neurones has been investigated in different hand and forearm muscles. 2. Seventy-eight neurones were recorded concurrently with between five and ten different muscles. Forty-seven neurones were identified as cortico-motor by the presence of post-spike facilitation in the spike-triggered average of at least one of the tested muscles. 3. All forty-seven cortico-motor neurones showed clear increases in activity during performance of a precision grip task by the monkey, and all of them were co-activated with the sampled muscles. 4. To assess the divergence of facilitation from a single cortico-motor neurone to different muscles, spike-triggered averages were constructed with all of the concurrently recorded muscles. The number of muscles in the sample, and the number of muscles showing post-spike facilitation, were corrected by excluding any post-spike facilitation which could have arisen by cross-talk between the different pairs of e.m.g. electrodes. 5. Most cortico-motor neurones produced post-spike facilitation in a restricted number of tested muscles. The mean number of post-spike facilitation-bearing muscles per cortico-motor cell rose from 1.4 +/- 0.5 (S.D.) when five muscles were sampled to 2.0 +/- 1.5 when ten were sampled. On average, each cortico-motor neurone produced post-spike facilitation in 27% of the tested muscles. Only three of forty-seven cortico-motor neurones gave post-spike facilitation in half or more of the tested muscles. 6. The distribution pattern of post-spike facilitation among the muscles sampled with a given cortico-motor neurone was not altered when the spike-triggered averages were constructed from cortico-motor cell and e.m.g. activity recorded during two different phases of the precision grip task, or during performance of a quite different, power grip, task. 7. Cortico-motor cells which produced post-spike facilitation in two or more different muscles often did so in muscles with synergistic functions. 8. It is suggested that cortico-motor neurones may contribute to relatively independent finger movements by virtue of their selective facilitation of hand muscles leading to a fractionated pattern of muscle activity.


Asunto(s)
Mano/fisiología , Corteza Motora/fisiología , Músculos/fisiología , Neuronas/fisiología , Tractos Piramidales/fisiología , Potenciales de Acción , Animales , Antebrazo/fisiología , Macaca nemestrina , Movimiento , Factores de Tiempo
20.
J Physiol ; 381: 497-527, 1986 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-3625543

RESUMEN

1. The method of spike-triggered averaging has been used to detect a direct influence of pyramidal tract neurones on the activity of hand and forearm muscles in conscious monkeys trained to perform repetitive movements of the hand and fingers. Gross electromyograms (e.m.g.s) from individual muscles were rectified and synchronously averaged with respect to the discharge of single, antidromically identified pyramidal tract cells in the 'hand' area of the pre-central gyrus. 2. The presence in an average of a post-spike facilitation which could be revealed reproducibly from successive epochs of recording and was clearly larger than the biggest fluctuations seen in pseudo-randomly triggered averages of the same e.m.g. data, was taken to indicate a direct cortico-motoneuronal excitatory influence. 3. 55% of cortical neurones analysed showed post-spike facilitation in one or more recorded muscle and 7% showed post-spike suppression. In terms of the total number of muscle-neurone combinations analysed, the proportions showing post-spike effects were 18 and 1% respectively. These figures have been influenced by the pre-selection of neurones for analysis according to restrictive criteria. The neurones selected (a) were recorded at cortical loci where weak intracortical microstimulation could evoke finger movements, (b) could be activated antidromically at short latency by medullary pyramidal tract stimulation, (c) showed natural discharge activity which was clearly modulated in relation to voluntary finger movements, and (d) were located in the anterior bank of the central sulcus. The results provide some evidence to vindicate these criteria. 4. The strongest post-spike facilitation observed had a peak which was 42% higher than the average pre-spike level of e.m.g. activity, but most were within the range 5-20%. Facilitation peaks below about 3% could not have been resolved from the 'noise' in the averages. The mean latency from cell discharge in the cortex to the start of the post-spike facilitation was 11.2 ms (range 7.4-17.2) for intrinsic hand muscles and 9.8 ms (range 4.1-15.0) for forearm muscles. These latencies were compared with the latencies of responses to intracortical microstimulation and to stimulation of the medullary pyramidal tract. 5. Evidence was obtained suggesting that the latency for cortico-motoneuronal activation of an individual motor unit was commonly subject to considerable variability and that different motor units of a muscle could be facilitated by the one cortical neurone at different latencies. These factors are thought to contribute to an elongation of the time course of post-spike facilitation.(ABSTRACT TRUNCATED AT 400 WORDS)


Asunto(s)
Mano/fisiología , Músculos/fisiología , Tractos Piramidales/fisiología , Potenciales de Acción , Animales , Femenino , Antebrazo/fisiología , Macaca nemestrina , Masculino , Neuronas Motoras/fisiología , Movimiento , Factores de Tiempo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA