[Pseudo-conduction block in nonsystemic vasculitic neuropathy]. / Pseudobloqueo de conducción en vasculitis aislada del sistema nervioso periférico.

SUMMARY: Introduction. Nonsystemic vasculitic neuropathy (NSVN) is an inflammatory disorder of the vasa nervorum which usually is expressed as a mononeuritis multiplex. We present a patient with NSVN with histological confirmination focused on the neurophysiological findings at the early stages. CASE REPORT: A 36 years-old woman presented with paresthesia and weakness in her right hand followed by left footdrop. The first neurophysiologic examination showed low amplitude of the right median nerve (RMN) CMAP with proximal stimulation. A second examination showed signs of axonal damage in several nerves, including the RMN. CONCLUSIONS: The acute ischemic damage of a nerve can give a pattern of conduction block in the electroneurographic study as in the RMN of the presented case. This phenomenon is referred as "pseudo-conduction block", since it is transient and evolves towards a definite pattern of axonal neuropathy. When a vasculitic neuropathy is suspected, repeated neurophysiologic studies are necessary in order to ensure a proper (appropriate) characterization of the lesional patterns.

[Physiopathology and recording techniques of the ocular movements]. / Fisiopatología y técnicas de registro de los movimientos oculares.

A number of functional systems are involved in the control of eye movements. The vestibulo-ocular and optokinetic reflexes are automatic responses that compensate for the movements of the head and those of the visual environment in order to stabilize the retinal image on a given fixation point. The saccadic movements are quick displacements of fixation from one to another point in the visual field. The smooth pursuit movements consist in the gaze following a moving target. Finally, there are some involuntary movements of very small amplitude during fixation maintenance. Each functional modality of movement depends on specific neuronal circuits that work in a coordinated manner for encoding the contraction of the oculomotor muscles to reach an adequate position at every moment. These neuronal systems can be altered by many neurological processes of different kinds and localizations, causing a broad variety of oculomotor disturbances. The most salient aspects of the physiopathology and the recording systems of eye movements are reviewed.

[Electromyographic signal processing and analysis methods]. / Métodos de procesamiento y análisis de señales electromiográficas.

Clinical electromyography is a methodology for recording and analysing the bioelectrical activity of the skeletal muscle tissue in order to diagnose neuromuscular pathology. The possibilities of application and the diagnostic performance of electromyography have evolved parallel to a growing understanding of the properties of electricity and the development of electrical and electronic technology. The first commercially available electromyography equipment for medical use was introduced in the middle of the 20th century. It was based on analog electronic circuits. The subsequent development of digital technology made available more powerful and accurate systems, controlled by microprocessors, for recording, displaying, storing, analysing, and classifying the myoelectric signals. In the near future, it is likely that advances in the new information and communication technologies could result in the application of artificial intelligence systems to the automatic classification of signals as well as expert systems for electromyographic diagnosis support.

[Clinical and neuropathological study of two brothers with Cockayne syndrome]. / Estudio clínico y neuropatológico en dos hermanos con síndrome de Cockayne.

INTRODUCTION: Cockayne syndrome (CS) is a rare autosomal recessive disease which is characterized by physical and mental retardation, progressive neurological disfunction, photosensitivity and other cutaneous features. Usually they present ophthalmologic abnormalities as well as other heterogenous clinical, radiological and pathologic features as leucodistrophy and calcifications in central nervous system and segmental demyelination in peripheral nervous system. CLINICAL CASES: Two brothers, sons of healthy unrelated parents, are presented. The first patient was referred at 8 months of age because of psychomotor retardation and the second one at 5 months old because of a cataract. At the age of 2 years both presented a complex clinical picture with photosensitivity, growth and mental retardation, peripheral neuropathy, neurosensorial deafness, and cerebral atrophy and calcifications in neuroimaging diagnosis tests. In the following years the older brother presented signs of renal failure, cataracts and retinopathy, and died at 9 years old because of a respiratory infection. The neuropathologic study showed a discrete neuronal loss and diffuse demyelination with calcium deposits in cerebral white matter and basal ganglia. Today the second patient is 8 years old and shows a clinical course similar to that of his brother. CONCLUSIONS: Clinical, radiologic and pathologic features in our patients support the diagnosis of CS type II.

Quantification of jiggle in real electromyographic signals.

Two parameters have been defined for quantifying jiggle: normalized consecutive amplitude differences (CAD) and the cross-correlational coefficient of consecutive discharges (CCC). In real recordings, artifacts from several sources may increase the variability of these parameters as they were originally defined. Two methodological modifications designed to overcome such a limitation are proposed: estimation of baseline fluctuation from segments of the recording free from nearby concurrent motor unit potentials (MUPs), and waveform alignment of consecutive discharges by correlation maximization (CM). The results obtained by the original and modified methods were compared for MUPs from normal subjects and patients with amyotrophic lateral sclerosis and chronic neurogenic diseases. With the modified method, CAD and CCC showed fewer extreme values and less scatter. The number of successfully aligned MUPs with the CM method was 18.8% higher (n = 394; Chi-square = 54.6; P < 0.001), including irregular and unstable MUPs. The proposed modifications improve our capability to quantify the jiggle of real signals and reduce the necessity of manual interventions although low-interference recordings and operator supervision are still required.

[Multiple sclerosis and epileptic seizures]. / Esclerosis múltiple y crisis epilépticas.

INTRODUCTION: Although epileptic seizures are uncommon in multiple sclerosis they are more prevalent than in the general population, which supports an aetiological relationship. Similarly in a considerable proportion of patients with multiple sclerosis and epileptic seizures, alterations in magnetic resonance and electroencephalogram studies which could be correlated with the clinical features of epilepsy were observed. Nevertheless, it is difficult to establish definite clinical characteristics in these patients since the underlying pathogenic mechanisms are poorly understood and there is great variability with regard to the type of seizure, point at which this occurs during the course of the disease, degree of recurrence and other aspects. CLINICAL CASE: We report the clinical, electroencephalographical and neuroimaging findings of seven patients with multiple sclerosis who had epileptic seizures and those in whom there was no evidence of other potentially epileptogenic pathology. In two patients the epileptic seizures formed part of the first episode of their illness. One patient presented more than one type of epileptic seizure. These seizures were generalized in two cases, partial sensory and/or motor with secondary generalization in three, simple partial motor in one and partial complex in two. The epileptic seizures coincided with other clinical features of episodes in three cases and the electroencephalogram showed anomalies in five cases. CONCLUSIONS: The findings observed were of a wide variety, as was found in other reported series. We point out certain correlations between the clinical data, magnetic resonance and electroencephalogram which may help to orientate the management of these patients.

[Unilateral asterixis associated with anatomic cerebral lesions]. / Asterixis unilateral asociada a lesiones anatómicas cerebrales.

Three patients with unilateral asterixis associated with different vascular lesions of thalamus, basal ganglia and internal and external capsules of contralateral hemisphere are described. Unilateral asterixis is a highly indicative sign of focal cerebral lesion. Its pathophysiology is still unknown. It has been postulated that asterixis is a myoclonic phenomenon resulting from malfunction within neuronal circuits of central nervous system responsible for the active maintenance of posture.

Disturbed hypothalamic-pituitary axis in idiopathic recurring hypersomnia syndrome.

Disturbed function of the hypothalamic-pituitary axis at adrenal and thyroid levels was found during an episode of hypersomnia in the idiopathic recurring hypersomnia syndrome. These endocrinological abnormalities, abolished ACTH and cortisol responses to insulin-induced hypoglycemia and absent TSH response to TRH, normalised thereafter in the symptom-free interval. These data support the hypothesis that Kleine-Levin syndrome is related to an intermittent hypothalamic dysfunction.

[Reflex sympathetic dystrophy. A new manifestation of Lyme disease?]. / Distrofia simpática refleja. Nueva manifestación de la enfermedad de Lyme?

Several syndromes derived from the involvement of central and peripheral nervous system and meninges have been reported in the infection by Borrelia burgdorferi. The features of autonomic nervous system involvement have received a marginal attention. Reflex sympathetic dystrophy is an autonomic picture characterized by regional sympathetic hyperactivity which has not been associated with Lyme disease. We report a 16-year-old female with clinical, radiological and scintigraphic features consistent with reflex sympathetic dystrophy. The usual causes of this syndrome were ruled out and antibodies against Borrelia burgdorferi were detected by immunofluorescence, enzyme immunoassay and Western blotting. Specific IgG and IgM levels had a progressive increase during three months. In Lyme borreliosis causes of false positives were excluded. Antigen-antibody bands were detected in increasing number during the evolution, using sonicates of B. burgdorferi and patient's sera with the Western blotting technique. Our data suggest that reflex sympathetic dystrophy is another type of nervous system involvement in the multifaceted Lyme borreliosis.

Cluster headache and intercalated seizures in a young man: therapeutic effectiveness of flunarizine.

A young man suffering from both cluster headache and epilepsy is reported. Since the age of 37 he had recurrent generalized tonic-clonic seizures; one year later cluster headache attacks began. Neurological examination, standard laboratory tests and CT-scan were normal. The EEG showed medium-voltage sharp waves, not blocking upon eye opening, over the right parieto-temporal region. Flunarizine was added to his phenytoin therapy; it controlled both paroxysmal disorders. After six months, flunarizine was discontinued and during a one year follow-up the patient remained symptom-free. This calcium channel blocker can be regarded as an ideal drug in patients suffering from both cluster headache and epilepsy; it controls this headache syndrome and is a useful add-on to standard anti-convulsant therapy.