Anthropogenic and natural impacts in the marine area of influence of the Grijalva - Usumacinta River (Southern Gulf of Mexico) during the last 45 years.

The development of the Grijalva-Usumacinta river basin exerts modifications on its discharge area. A sediment core was studied to reconstruct environmental changes and trace element contamination status during the past 45 years. 210Pb-derived mass accumulation rates indicate higher sediment input to the area since 1995, related to increased precipitation and floodings in the catchment area. Sediments show finer particles from the late 1970s on, likely related to dams construction upriver and/or land use changes. Heavy metal enrichment factors (EF < 2) suggest minimum contamination. Benthic foraminifera and redox-sensitive - elements (As, Ba, Co, Cr, Cu, Ni, Pb, V and Zn) indicate the sediments before 2000 were deposited under oxygenated conditions. Afterwards, environmental conditions changed and benthic foraminifera and dinocysts assemblages changed suggesting eutrophication and lower oxygen conditions during the last 20 years. Monitoring should be continued to assess eutrophication/hypoxic/pollution trends that could become deleterious to the marine biota.

Neurophysiological monitoring of lumbosacral spinal roots during spinal surgery: continuous intraoperative electromyography (EMG).

INTRODUCTION: Neurophysiological monitoring during spinal surgery reduces the associated neurological complications. Continuous EMG recording has developed an useful technique for spinal root monitoring PATIENTS AND METHODS: Fifty four patients who underwent surgery for several lumbosacral spinal lesions (low and high degree spondylolisthesis, spinal stenosis, degenerated or herniated lumbar discs) were studied to evaluate the effectiveness of continuous EMG recording in monitoring spinal root function during surgery. Electrical root or screw stimulation was also performed in nine of them. To correlate surgical spinal root lesion with a precise EMG injury activity an animal study with 5 pigs was performed; lesion was produced by prolonged spinal root traction. RESULTS: In the porcine group EMG discharges lasting longer than one minute after cessation of root traction was noted in 74% of spinal root levels (neurotonic discharges or pseudo-rhythmic activity in 70% of the cases). Spinal root lesion was demonstrated through EMG three weeks after surgery. In the patient group pathological-significant EMG activity was not recorded in any case during monitoring. Mechanical or chemical root stimulation during surgery produced brief lasting EMG bursts of no pathological significance. Only a patient developed a mild acute L5-S1 radiculopathy after surgery (1 false negative) and post-operative deficit was not observed in the rest. Electrical stimulation of spinal roots and screws allowed to identify root level and prove the adequate placement of screws. CONCLUSION: Spontaneous and evoked EMG recordings are simple techniques that provide continuous information about lumbosacral spinal roots function throughout surgery.

[A neurophysiological study of the alterations to the central and peripheral nervous systems in Friedreich's ataxia]. / Estudio neurofisiológico de las alteraciones del sistema nervioso central y periférico en la ataxia de Friedreich.

INTRODUCTION: Friedreich's ataxia (FA) is the most common type of early-onset hereditary ataxia, starting during childhood and adolescence. Both the central and peripheral nervous systems are compromised. AIM. To describe the alterations found in the neurophysiological examination and their relation with the degree of disability and the time the disease lasts. PATIENTS AND METHODS: We examined 26 patients diagnosed with FA by means of a genetic study with multimode evoked potentials, transcranial magnetic stimulation, peripheral nerve conductions and a study of small myelinated-unmyelinated sensory fibres using quantitative sensory tests (thermotest). RESULTS: Peripheral sensory potentials, somatosensory potentials and motor responses with transcranial stimulus were pathological in all patients. From the early stages of the disease there were both peripheral sensory neuropathy and alterations of the somatosensory potentials and motor responses with transcranial stimulus in the lower limbs. Alterations in the somatosensory potentials in the upper limbs and the motor responses obtained by transcranial stimulus were related with the degree of disability. Brainstem and visual potentials were altered in 16 and 28% of cases, respectively; only reduced amplitude of the P100 was related with the degree of disability. In the thermotest, 50% of the patients showed alterations. CONCLUSIONS: Increased disability in patients with FA is related with the progressive involvement of the somatosensory and pyramidal pathways. Although traditionally reports have claimed that the thick myelinated fibres are the ones involved in FA, we found alterations in the small calibre fibres in half the patients.

Estudio neurofisiológico de las alteraciones del sistema nervioso central y periférico en la ataxia de Friedreich / Europhysiological study of the alterations to the central and peripheral nervous systems in Friedreich´s ataxia

Introducción. La ataxia de Friedreich (AF) es la ataxia hereditaria más frecuente de comienzo en la infancia y adolescencia. Existe una afectación de los sistemas nervioso central y periférico. Objetivo. Describir las alteraciones de la exploración neurofisiológica y su relación con el grado de discapacidad y la duración de la enfermedad. Pacientes y métodos. Se exploró a 26 pacientes diagnosticados de AF mediante un estudio genético con potenciales evocados multimodales, estimulación magnética transcraneal, conducciones nerviosas periféricas y estudio de fibras sensitivas mielínicas finas-amielínicas mediante tests sensitivos cuantitativos (termotest). Resultados. Los potenciales sensitivos periféricos, los potenciales somatosensoriales y las respuestas motoras con estímulo transcraneal fueron patológicas en todos los pacientes. Desde las fases iniciales de la enfermedad existía tanto una neuropatía sensitiva periférica como alteraciones de los potenciales somatosensoriales y respuestas motoras con estímulo transcraneal en los miembros inferiores. Las alteraciones de los potenciales somatosensoriales en los miembros superiores y las respuestas motoras mediante el estímulo transcraneal se relacionaron con el grado de discapacidad. Los potenciales troncoencefálicos y visuales estaban alterados en el 16 y 28% de los casos, respectivamente; sólo la reducción de amplitud de la P100 se relacionó con el grado de discapacidad. El 50% de los pacientes presentó alteraciones en el termotest. Conclusión. El aumento de discapacidad en los pacientes con AF se relaciona con la progresiva afectación de las vías somatosensorial y piramidal. Aunque se ha descrito clásicamente que en la AF están afectadas las fibras mielínicas gruesas, encontramos una alteración de las fibras de pequeño calibre en la mitad de los pacientes

Introduction. Friedreich’s ataxia (FA) is the most common type of early-onset hereditary ataxia, starting during childhood and adolescence. Both the central and peripheral nervous systems are compromised. Aim. To describe the alterations found in the neurophysiological examination and their relation with the degree of disability and the time the disease lasts. Patients and methods. We examined 26 patients diagnosed with FA by means of a genetic study with multimode evoked potentials, transcranial magnetic stimulation, peripheral nerve conductions and a study of small myelinated-unmyelinated sensory fibres using quantitative sensory tests (thermotest). Results. Peripheral sensory potentials, somatosensory potentials and motor responses with transcranial stimulus were pathological in all patients. From the early stages of the disease there were both peripheral sensory neuropathy and alterations of the somatosensory potentials and motor responses with transcranial stimulus in the lower limbs. Alterations in the somatosensory potentials in the upper limbs and the motor responses obtained by transcranial stimulus were related with the degree of disability. Brainstem and visual potentials were altered in 16 and 28% of cases, respectively; only reduced amplitude of the P100 was related with the degree of disability. In the thermotest, 50% of the patients showed alterations. Conclusions. Increased disability in patients with FA is related with the progressive involvement of the somatosensory and pyramidal pathways. Although traditionally reports have claimed that the thick myelinated fibres are the ones involved in FA, we found alterations in the small calibre fibres in half the patients

[Mitochondrial respiratory chain diseases. Evaluation and variability in 52 patients]. / Enfermedades de la cadena respiratoria mitocondrial. Evaluación y variabilidad en 52 pacientes.

INTRODUCTION: Clinical, electrophysiological, genetic and biochemical deficiencies variability were evaluated in 52 patients diagnosed of mitochondrial respiratory chain diseases (MRCD). PATIENTS AND METHODS: 26 men and 26 women, aged 19 to 79 years, were tested by clinical examination, electrophysiological techniques, muscle biopsy and genetic and biochemical studies. RESULTS: The patients were classified into seven phenotypes: myopathy, chronic progressive external ophthalmoplegia, progressive ophthalmoplegia plus ataxia, Kearns-Sayre syndrome, mitochondrial encephalomyopathy with lactic acidosis and stroke episodes (MELAS), myoclonic encephalopathy with ragged-red fibers (MERRF), and encephalopathies. Each phenotype may begin by different ways. The electromiography showed myopathy in 39 cases and various types of neuropathy in 10. Ragged-red COX negative fibers or widespread electron microscopic abnormalities were found in 47 cases. Simple deletions, multiple deletions and three different point mutations were observed. Deficiency of complexes I, II, III and IV were found alone or in different associations. CONCLUSIONS: MRCD shows wide variations in clinical, genetic and biochemical studies. Some patients with nonspecific manifestations, mainly of central nervous system, need careful attention and to be on account of diagnostic suspicion.

Enfermedades de la cadena respiratoria mitocondrial. Evaluación y variabilidad en 52 pacientes / Mitochondrial respiratory chain diseases. Evaluation and variability in 52 patients

Introducción. La variabilidad clínica, electrofisiológica, de las deficiencias bioquímicas y genéticas se evaluó en 52 pacientes diagnosticados de enfermedades de la cadena respiratoria mitocondrial (ECRM). Pacientes y métodos. Se evaluó a 26 hombres y 26 mujeres, de edades comprendidas entre 19 y 79 años, mediante exploración clínica, técnicas electrofisiológicas, biopsia de músculo y estudios bioquímico y genético. Resultados. Se clasificó a los pacientes en siete fenotipos: miopatía, oftalmoplejía externa progresiva crónica, oftalmoplejía progresiva plus con ataxia, síndrome de Kearns-Sayre, encefalomiopatía mitocondrial con acidosis láctica y episodios de ictus (MELAS), encefalopatía mioclónica con fibras rojo rasgadas (MERRF) y encefalopatía. Cada fenotipo puede debutar de forma diferente. La electromiografía mostró miopatía en 39 casos y diferentes tipos de neuropatía en 10. En 47 casos se puso de manifiesto la presencia de fibras rojo rasgadas COX negativas o alteraciones mitocondriales prominentes al microscopio electrónico. Se observaron deleciones simples y múltiples, así como tres mutaciones puntuales diferentes. Se encontraron deficiencias de los complejos I, II, III y IV aisladas o en diferentes asociaciones. Conclusiones. Las ECRM muestran grandes diferencias entre ellas en los estudios clínicos, bioquímicos y genéticos. Algunos pacientes con manifestaciones inespecíficas, principalmente del sistema nervioso central, requieren una atención cuidadosa y que se plantee la sospecha diagnóstica de ECRM (AU)

Introduction. Clinical, electrophysiological, genetic and biochemical deficiencies variability were evaluated in 52 patients diagnosed of mitochondrial respiratory chain diseases (MRCD). Patients and methods. 26 men and 26 women, aged 19 to 79 years, were tested by clinical examination, electrophysiological techniques, muscle biopsy and genetic and biochemical studies. Results. The patients were classified into seven phenotypes: myopathy, chronic progressive external ophthalmoplegia, progressive ophthalmoplegia plus ataxia, Kearns-Sayre syndrome, mitochondrial encephalomyopathy with lactic acidosis and stroke episodes (MELAS), myoclonic encephalopathy with ragged-red fibers (MERRF), and encephalopathies. Each phenotype may begin by different ways. The electromiography showed myopathy in 39 cases and various types of neuropathy in 10. Ragged-red COX negative fibers or widespread electron microscopic abnormalities were found in 47 cases. Simple deletions, multiple deletions and three different point mutations were observed. Deficiency of complexes I, II, III and IV were found alone or in different associations. Conclusions. MRCD shows wide variations in clinical, genetic and biochemical studies. Some patients with nonspecific manifestations, mainly of central nervous system, need careful attention and to be on account of diagnostic suspicion (AU)

Aportaciones del estudio neurofisiológico en el diagnóstico de un paciente con temblor ortostático / The contributions of a neurophysciological study in the diagnosis of patient with orthostatic tremor

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[Hypokalemic periodic paralysis: exercise test]. / Paralisis periódica hipopotasémica: prueba de ejercicio.

INTRODUCTION: Periodic paralyses are illnesses related with the dysfunction of the ionic pathways of the muscle fibre membrane. Neurophysiological diagnosis by means of a conventional electromyogram (EMG) is rather unsatisfactory when exploring patients in the asymptomatic phase, since they often display unspecific changes. Furthermore, it does not identify the alterations in muscular excitability. The exercise test consists in determining the variation in the area or the amplitude of the muscular action potential, which is obtained through electrical stimuli that are repeated periodically for several minutes after having carried out local exercise with the explored muscles. It is a simple technique that enables us to achieve a significant reduction in the area or amplitude of the action potential (more than 40% or 50% with regard to the basal value) in certain diseases produced by ionic pathway dysfunction, while the patient is in the asymptomatic phase. CLINICAL CASES: We report the cases of three patients diagnosed as suffering from hypokalemic periodic paralysis. During the asymptomatic phase, the EMG revealed characteristic myopathic changes in only one case and unspecific alterations in the other two. Nevertheless, the exercise test that was also performed during the asymptomatic phase showed a characteristic pathological response in the three patients. CONCLUSION: The exercise test is a technique that indirectly shows up the progressive loss of muscle fibre membrane excitability and helps diagnosis in asymptomatic patients.

Parálisis periódica hipopotasémica: prueba de ejercicio / Hypokalemic periodic paralysis: exercise test

Introducción. Las parálisis periódicas son enfermedades relacionadas con la disfunción de los canales iónicos de la membrana de la fibra muscular. El diagnóstico neurofisiológico mediante el electromiograma (EMG) convencional es poco satisfactorio cuando se explora al paciente en la fase asintomática, ya que muestra con frecuencia cambios inespecíficos. Además, no identifica las alteraciones en la excitabilidad muscular. La prueba de ejercicio consiste en determinar la variación del área o la amplitud del potencial de acción muscular que se obtiene mediante estímulos eléctricos que se repiten periódicamente durante varios minutos, tras haber realizado un ejercicio local con los músculos explorados. Es una técnica sencilla que permite objetivar una reducción significativa de la amplitud o del área del potencial de acción (de más del 40 por ciento o del 50 por ciento respecto al valor basal) en determinadas enfermedades producidas por una disfunción de los canales iónicos, mientras el paciente se encuentra en fase asintomática. Casos clínicos. Presentamos tres pacientes diagnosticados de parálisis periódica hipopotasémica. Durante la fase asintomática, se encontraron cambios miopáticos característicos en el EMG sólo en un caso y alteraciones inespecíficas en los dos restantes. Sin embargo, la prueba de ejercicio que se realizó también en la fase asintomática mostró una respuesta patológica característica en los tres pacientes. Conclusión. La prueba de ejercicio es una técnica que permite objetivar indirectamente la pérdida progresiva de la excitabilidad de la membrana de la fibra muscular y contribuye al diagnóstico de los pacientes asintomáticos (AU)

[Orthostatic postural tachycardia: study of 8 patients]. / Taquicardia postural ortostática: estudio de ocho pacientes.

The occurrence of syncopal episodes is a very frequent event. In the absence of a structural systemic or cardiac disease, syncope is resulting of an anomalous cardiovascular response neurally mediated by the autonomic nervous system. It is the final common manifestation of different abnormal mechanisms and is frequently precipitated by orthostatism. Orthostatic intolerance syndrome refers to the development of symptoms during the upright posture that disappear in supine position. Tachycardia may be one of the clinical features of the syndrome. During orthostatic stress a hyperadrenergic response, with maintained increment of heart rate and associated symptoms, is developed. Changes in blood pressure may be diverse and in some cases hypotension and syncope occurs. Eight patients with symptoms of orthostatic intolerance who underwent autonomic evaluation and were diagnosed from postural tachycardia are presented. In all the cases an abnormal increment of heart rate during tilting was found and it was associated to hyperadrenergic symptoms. Evidence of restricted sympathetic impairment was observed in six cases with distal reduction of sudomotor function and abnormal adrenergic response during Valsalva manoeuvre. Symptoms disappeared or mostly subsided with pharmacological (amitriptyline in one case, phenobarbital in another one and non-cardioselective beta-blockers in six patients) and non-pharmacological treatment. In further examinations heart rate and blood pressure were normal.

[Prevalence of alcoholism in the population attending a urban health center]. / Prevalencia de alcoholismo entre la población que acude a un centro de salud urbano.

OBJECTIVE: To find out the prevalence of alcoholism among those attending an urban Health Centre. To establish the level of concordance between the CAGE and MALT-O tests in the detection of alcoholism and to assess the effectiveness of the joint use of the above tests. DESIGN: Observational, crossover study. SITE. San Ignacio de Loyola Health Centre (Cuenca). PARTICIPANTS: A sample of 499 people of both sexes and over 18 years old was chosen from among the people attending the Centre. Systematic sampling from a random starting-point was used. MAIN MEASUREMENTS AND RESULTS: Each person was interviewed with a questionnaire containing the CAGE and MALT-O items and sociodemographic data. The person who gave at least two positive answers in both tests was considered an alcoholic. A total of 402 filled-in questionnaires were returned. 27 people were found to have two or more positive items, which mean a 6.7% prevalence of alcoholism (CI 95% = 4.2-9.1). This broke down into a prevalence of 1.33% among women and 13.63% among men (p < 0.0001). The concordance level, determined by the Kappa coefficient, between the two tests was 0.29 (CI 95% = 0.11-0.47). CONCLUSIONS: The prevalence of alcoholism found is greater than in other national studies on the out-patient population, although it continues to be low in comparison with several foreign surveys. On the other hand, we seem to gain nothing in the detection of alcoholism by adding the MALT-O to the CAGE test, even when the concordance level between the two tests has come out low.