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PubMed2001

The stiff-man syndrome and related disorders.

The stiff-man syndrome (SMS) is characterised by rigidity and spasm of predominantly axial and proximal limb muscles. The cause of the condition is unknown but the finding of antibodies to glutamic acid decarboxylase (GAD) in approximately 60% of patients has suggested an autoimmune basis. Pathological findings are limited to a small number of cases which are reviewed in this paper. In some, evidence of an inflammatory aetiology has been found, and there appears to be overlap with progressive encephalomyelitis with rigidity (PER) which may present with a similar clinical picture. The spontaneous muscle activity in SMS and PER is of central origin, related to release of polysynaptic spinal and brainstem reflexes. The SMS is readily distinguished from the continuous muscle activity, spasm and cramps of Isaac's syndrome and neuromyotonia which originate in the peripheral nervous system. Fasciculations, myokymia, myotonia and complex repetitive discharges are characteristic of these peripheral neuromuscular disorders.

Encephalomyelitis↗
PubMed1995

Mechanisms in motor neurone disease: clues from genetic studies.

Motor neurone disease is a rapidly progressive neurodegenerative disorder, characterized by muscular weakness and wasting with fasciculation and by spasticity. While most cases are sporadic, approximately 10% are inherited in an autosomal dominant mode. Recently, mutations in the gene encoding the free-radical scavenging enzyme superoxide dismutase-1 have been found to segregate with the disorder in 20% of familial cases. This is an exciting development, as free radical damage has long been implicated in the pathogenesis of motor neurone disease and it raises the possibility of novel therapeutic approaches in this otherwise fatal condition.

Brain↗
PubMed2003

Heat cramps: fluid and electrolyte challenges during tennis in the heat.

Sweat losses during tennis can be considerable. And while most players make a genuine effort to stay well hydrated to maintain performance and reduce the risk of heat illness, regular and copious water intake is often not enough. Besides an extraordinary water loss, extensive sweating can lead to a concomitant large electrolyte deficit too--particularly for sodium. Although a variety of other mineral deficiencies and physiological conditions are purported to cause muscle cramps, evidence suggests that, when a tennis player cramps in warm to hot weather, extensive and repeated sweating during the current and previous matches and a consequent sodium deficit are usually the primary contributing factors. Heat cramps often begin as subtle "twitches" or fasciculations in one or more voluntary muscles and, unless treated, can rapidly progress to widespread debilitating muscle spasms that leave an afflicted player on the court writhing in pain. If sufficient preventive measures are taken well before and during play, such cramping is avoidable in most cases. Appropriate and sufficient salt and fluid intake will enhance rehydration and fluid distribution throughout a player's body, so that heat cramps can be completely averted, even during long matches in the most challenging environments.

Dehydration↗
PubMed2001

The Drosophila neuregulin vein maintains glial survival during axon guidance in the CNS.

Neuron-glia interactions are necessary for the formation of the longitudinal axon trajectories in the Drosophila central nervous system. Longitudinal glial cells are required for axon guidance and fasciculation, and pioneer neurons for trophic support of the glia. Neuregulin is a neuronal molecule that controls glial survival in the vertebrate nervous system. The Drosophila protein Vein has structural similarities with Neuregulin. We show here that Vein functions like a Neuregulin to maintain glial cell survival. We present direct in vivo evidence at single-cell resolution that Vein is produced by pioneer neurons and maintains the survival of neighboring longitudinal glia. This mechanism links axon guidance to control of glial cell number and may contribute to plasticity during the establishment of normal axonal trajectories.

Animals↗
PubMed1988

Brainstem auditory evoked potentials after irradiation of nasopharyngeal carcinoma--report on two cases with myelopathy of the brainstem.

Brainstem auditory evoked potentials (BAEP) were recorded in two patients with nasopharyngeal carcinoma (NPC) irradiated 14 and three years ago respectively and compared with 15 healthy controls. The patients had features of post-irradiation myelopathy of the brainstem with reduced gag reflex, unilateral vocal cord paralysis and fasciculation of the tongue. The first patient had a blind left eye. The second patient had quadriparesis. All ears revealed post-irradiation otitis media changes and mixed deafness. BAEP was not recognizable in the left ear of the first patient and was normal in the left ear of the second patient. Simultaneous electrocochleogram and BAEP were recorded from the right ear of the first case. The wave I-V latency interval were prolonged in both right ears. In the absence of local recurrence and brain secondaries, these BAEP changes are attributed to the post-irradiation myelopathy of brainstem.

Brain Stem↗
PubMed1996

Experimental study on neurorrhaphy of the recurrent laryngeal nerve in dogs.

The effectiveness of anastomosis of a divided recurrent laryngeal nerve was evaluated in six adult mongrel dogs. Videolaryngoscopy and evoked compound muscle action potentials in the intrinsic laryngeal muscles were performed at six months and the posterior cricoarytenoid muscles and recurrent laryngeal nerves were processed for histomorphometric studies. Recovery of compound muscle action potentials in all re-innervated muscles and histomorphometric findings confirmed a good grade of axonal regeneration. The most significant histomorphometric changes observed were: a reactive hypertrophy of type I fibres in the posterior cricoarytenoid muscles of the re-innervated side, and a high nerve fibre density in the distal stump to the anastomosis. However, incomplete recovery of motion and fasciculated movements of the re-innervated vocal folds were observed. Reduction of effective motor units in the re-innervated muscles might be a factor that cause incomplete restoration of vocal fold movements.

Action Potentials↗
PubMed1988

An unusual subacute progressive motor neuronopathy with myasthenia-like features.

The initial presentation and clinical course of this 60-year old woman suggested a diagnosis of myasthenia gravis. The subsequent development of tongue fasciculations and the lack of response to treatment made a diagnosis of amyotrophic lateral sclerosis (ALS) more likely despite the presence of conjugate gaze paresis and the absence of many of the typical clinical and electromyographic (EMG) findings seen in this condition. The pathological findings were consistent with either a motor neuronopathy or an unusual variant of ALS. We review the clinical and pathological features of this unusual case in this report.

Amyotrophic Lateral Sclerosis↗
PubMed1984

The natural history of Machado-Joseph disease. An analysis of 138 personally examined cases.

We have examined 138 cases of a disorder previously described in people of Portuguese origin and which has received many names. By computer analysis of 46 different items of a standardized neurological examination carried out in each patient, we have been able to delineate the main components of the clinical presentation, to conclude that the marked variability in clinical expressions does not negate the homogeneity of the disorder, and to describe the natural history of this entity which should be called, for historical reasons, "Machado-Joseph Disease". This hereditary disease has an autosomal dominant pattern of inheritance, presenting as a progressive ataxia with external ophthalmoplegia, and should be classified within the group of "Ataxic multisystem degenerations". When the disease starts before the age of 20, it may present with marked spasticity, of a non progressive nature but often so severe that it can be accompanied by "Gegenhalten" countermovements and dystonic postures but little frank dystonia. There are few true extrapyramidal symptoms except akinesia. When the disease starts after the age of 50, the clinical spectrum is mostly that of an amyotrophic polyneuropathy with fasciculations accompanying the ataxia. For all the other cases the clinical picture is a continuum between these two extremes, the main determinant of the clinical phenotype being the age of onset and a secondary factor, the place of origin of the given kindred. The ataxic and amyotrophic components are clearly progressive with time in contrast to the spasticity component. Although the majority of known cases are of Portuguese origin, this is not obligatory. The next research endeavour should be a search for the chromosomal site of the gene, using molecular biology technology such as those for recombinant DNA.

Adolescent↗
PubMed1986

The concurrence of multiple sclerosis and amyotrophic lateral sclerosis.

We report the clinical and pathological findings of the unusual combination of two idiopathic central nervous system diseases, multiple sclerosis and amyotrophic lateral sclerosis in a 56 year old physician with a twenty-seven year history of a disease initially characterized by relapses and remissions, followed by an eight year quiescent period. During the last year of life there was rapid deterioration with development of generalized weakness, atrophy, weight loss and fasciculations of body and tongue, and associated difficulty with swallowing and sudden respiratory failure. The autopsy confirmed characteristic "burned out" plaques of multiple sclerosis and anterior horn cell and axonal degeneration of amyotrophic lateral sclerosis.

Amyotrophic Lateral Sclerosis↗
PubMedDate not supplied

Stratification of α ganglion cells and ON/OFF directionally selective ganglion cells in the rabbit retina.

The correlation between cholinergic sensitivity and the level of stratification for ganglion cells was examined in the rabbit retina. As examples, we have used ON or OFF alpha ganglion cells and ON/OFF directionally selective (DS) ganglion cells. Nicotine, a cholinergic agonist, depolarized ON/OFF DS ganglion cells and greatly enhanced their firing rates but it had modest excitatory effects on ON or OFF alpha ganglion cells. As previously reported, we conclude that DS ganglion cells are the most sensitive to cholinergic drugs. Confocal imaging showed that ON/OFF DS ganglion cells ramify precisely at the level of the cholinergic amacrine cell dendrites, and co-fasciculate with the cholinergic matrix of starburst amacrine cells. However, neither ON or OFF alpha ganglion cells have more than a chance association with the cholinergic matrix. Z -axis reconstruction showed that OFF alpha ganglion cells stratify just below the cholinergic band in sublamina a while ON alpha ganglion cells stratify just below cholinergic b . The latter is at the same level as the terminals of calbindin bipolar cells. Thus, the calbindin bipolar cell appears to be a prime candidate to provide the bipolar cell input to ON alpha ganglion cells in the rabbit retina. We conclude that the precise level of stratification is correlated with the strength of cholinergic input. Alpha ganglion cells receive a weak cholinergic input and they are narrowly stratified just below the cholinergic bands.

Action Potentials↗
PubMedDate not supplied

The number, morphology, and distribution of retinal ganglion cells and optic axons in the Australian lungfish Neoceratodus forsteri (Krefft 1870).

Australian lungfish Neoceratodus forsteri may be the closest living relative to the first tetrapods and yet little is known about their retinal ganglion cells. This study reveals that lungfish possess a heterogeneous population of ganglion cells distributed in a horizontal streak across the retinal meridian, which is formed early in development and maintained through to adult stages. The number and complement of both ganglion cells and a population of putative amacrine cells within the ganglion cell layer are examined using retrograde labelling from the optic nerve and transmission electron-microscopic analysis of axons within the optic nerve. At least four types of retinal ganglion cells are present and lie predominantly within a thin ganglion cell layer, although two subpopulations are identified, one within the inner plexiform and the other within the inner nuclear layer. A subpopulation of retinal ganglion cells comprising up to 7% of the total population are significantly larger (>400 microm2) and are characterized as giant or alpha-like cells. Up to 44% of cells within the retinal ganglion cell layer represent a population of presumed amacrine cells. The optic nerve is heavily fasciculated and the proportion of myelinated axons increases with body length from 17% in subadults to 74% in adults. Spatial resolving power, based on ganglion cell spacing, is low (1.6-1.9 cycles deg(-1), n = 2) and does not significantly increase with growth. This represents the first detailed study of retinal ganglion cells in sarcopterygian fish, and reveals that, despite variation amongst animal groups, trends in ganglion cell density distribution and characteristics of cell types were defined early in vertebrate evolution.

Amacrine Cells↗
PubMed1998

Temporary colonization of the site of lesion by macrophages is a prelude to the arrival of regenerated axons in injured goldfish optic nerve.

In crushed goldfish optic nerve, regenerating axons cross the site of lesion within 10 days following injury. Some 30 days later, Schwann cells accumulate at the lesion, where they myelinate the new axons. In this study, we have used immunohistochemistry and electron microscopy to examine the cellular environment of the crush site prior to the establishment of Schwann cells in order to learn more about the early events that contribute to axonal regeneration. During the first week following injury, macrophages enter the site of lesion and efficiently phagocytose the debris. The infiltration of macrophages precedes the arrival of regenerating axons that abut and surround these phagocytes. Based on EM morphology and phagocytic capacity, macrophages of the type observed at the site of lesion are not present in the degenerating distal nerve segment, where debris clearance is shared between conventional microglia and astrocytes over a period of several weeks. During this period, axon bundles emerging distally from the injury zone become enwrapped by astrocyte processes, thereby re-establishing the characteristic fascicular cytoarchitecture of the optic nerve. The process of fasciculation also leads to the displacement of myelin debris to the margins of the fiber bundles, where it is trapped by the astrocytes. Our results suggest that the early robust appearance of macrophages at the lesion, and their effectiveness as phagocytes compared with the microglia distally, may contribute to the vigorous axonal regeneration across the crush, beyond which axons--excepting the pioneers--extend through newly formed debris-free channels delineated by astrocyte processes.

Animals↗
PubMedDate not supplied

Physiological roles of axonal ankyrins in survival of premyelinated axons and localization of voltage-gated sodium channels.

440 kD ankyrin-B and 480/270 kD ankyrin-G are membrane skeletal proteins with closely related biochemical properties yet distinctive physiological roles in axons. These proteins associate with spectrin-actin networks and also bind to integral membrane proteins including the L1 CAM family of cell adhesion molecules and voltage-gated sodium channels. 440 kD ankyrin-B is expressed with L1 in premyelinated axon tracts, and is essential for survival of these axons, at least in the case of the optic nerve. 440 ankyrin-B may collaborate with L1 in transcellular structures that mediate axon fasciculation and mechanically stabilize axon bundles, although these proteins may also be involved in axon pathfinding. Ankyrin-B (-/-) mice exhibit loss of L1 from premyelinated axon tracts and a similar, although much more severe, phenotype to L1 (-/-) mice and humans with L1 mutations. Ankyrin-B and L1 thus are candidates to collaborate in the same structural pathway and defects in this pathway can lead to nervous system malformations and mental retardation. 480/270 kD ankyrin-G are highly concentrated along with the L1CAM family members neurofascin and NrCAM at nodes of Ranvier and axon initial segments. Voltage-gated sodium channels bind directly to ankyrins, and are likely to associate in a ternary complex containing neurofascin/NrCAM, and ankyrin-G. Mice with ankyrin-G expression abolished in the cerebellum exhibit loss of ability of Purkinje neurons to fire action potentials, as well as loss of restriction of neurofascin/NrCAM to axon initial segments. Ankyrin-G thus is a key component in assembly of functional components of the axon initial segment and possibly the node of Ranvier.

Animals↗
PubMedDate not supplied

A temporospatial map of adhesive molecules in the organ of Corti of the mouse cochlea.

In the nervous system, several classes of cell-surface and extracellular matrix molecules have been implicated in processes such as neural growth, fasciculation, pathfinding, target recognition and synaptogenesis, which require cell-to-cell or cell-to-substrate binding. In the developing mouse cochlea, little is known about the types of cell-surface and extracellular matrix molecules existing along the neural growth paths or their possible roles in development. Whole mount and sectioned cochlear tissue were immunolabeled for six different adhesive molecules - neural cell adhesion molecule (NCAM), polysialic acid (PSA), neural cell adhesion molecule L1, E-cadherin, syndecan-1 and tenascin-C. A temporospatial map of adhesive molecule distribution in the basal turns of the mouse cochlea was generated. Distributions of adhesive molecules were compared to each other and to the known progress of neural development in the region. This comparison demonstrated differences in the complements of adhesive molecules between the inner and outer hair cell regions, and variations in the expressions of adhesion molecules among different types of nerve fibers. In addition, developmental changes in the adhesive environment around and beneath the outer hair cells coincided with the known timing of the appearance of morphologically defined efferent synapses. These observations raise the possibility that molecular differences at the cell surface of inner and outer hair cells are one way that ingrowing neurites distinguish different environments to determine their growth routes and synaptic partners in the cochlea. In addition these observations demonstrate the potential for differential signaling of afferent and efferent innervation by altering the microenvironments in which synapses are formed.

Animals↗
PubMed1997

Neuromuscular transmission and its pharmacological blockade. Part 2: Pharmacology of neuromuscular blocking agents.

Clinically, neuromuscular blockade is induced with either depolarizing or non-depolarizing relaxants. Suxamethonium is the only depolarizing relaxant still in use. It is hydrolysed in the plasma by pseudo-cholinesterase (plasma cholinesterase). In some patients and in particular diseases the plasma cholinesterase activity is low and hence the effect of suxamethonium prolonged. Suxamethonium is characterized by side-effects such as myalgia, fasciculations and increase in intraocular, intracranial and intragastric pressure. More serious adverse reactions are masseter muscle spasm and potassium release, in patients with some neuromuscular diseases and increase in extrajunctional acetylcholine receptors. As non-depolarizing muscle relaxants benzylisoquinolines and steroidal compounds are mainly used. Each relaxant has its own pharmacological characteristics. The effect of most relaxants depends on liver and renal function because the pharmacokinetic behaviour is strongly dependent on these organs. Also, acid base balance disturbances, change in temperature, and neurological diseases have an effect on the profile of the relaxants. A number of drugs (anaesthetics, antibiotics, antiepileptics, etc.) have an effect on neuromuscular transmission, and thus interact with the relaxants. Some non-depolarizing relaxants cause histamine release and cardiovascular effects.

Body Temperature↗
PubMed2002

Motor unit hyperexcitability in amyotrophic lateral sclerosis vs amino acids acting as neurotransmitters.

OBJECTIVES: Electrophysiological studies of amyotrophic lateral sclerosis (ALS) patients reveal not only lower motor neuron involvement, but also widespread signs of its hyperexcitability. They might be the consequence of changes in the level of amino acids acting as neurotransmitters. MATERIAL AND METHODS: Electrophysiological examination of 31 patients with sporadic ALS was performed. A hyperexcitability index (HI) was created to describe the amount of double discharges, fasciculation potentials or 'giant' F-waves. Glutamate, aspartate, glycine and GABA concentration in serum and cerebrospinal fluid (CSF) were estimated, using the high performance liquid chromatography technique. RESULTS: The electrophysiological studies revealed marked variability in HI in the patients group. HI did not correlate with duration of the disease and the degree of disability expressed with Norris score, as well as with the level of excitatory or inhibitory amino acids in the body fluids. CONCLUSION: Hyperexcitability of the motor unit observed in ALS is not directly related to changes in serum and CSF level of amino acids acting as neurotransmitters.

Adult↗
PubMed2003

Searching for modulating effects of SCA2, SCA6 and DRPLA CAG tracts on the Machado-Joseph disease (SCA3) phenotype.

CONTEXT: Machado-Joseph disease (MJD/SCA3) is an autosomal dominant cerebellar ataxia of adult onset. The variability in age at onset and the complex and heterogeneous neurologic findings indicate that MJD, caused by a major gene, is modulated by modifier factors. OBJECTIVE: To study if the polymorphic CAG repeats at other loci (namely, SCA2, SCA6 and DRPLA) thus acted as modifier factors of this disease. DESIGN: Case-control. SETTING: Ambulatory care in a referral center. PATIENTS: A convenience sample of 39 unrelated, Brazilian patients with MJD. MAIN OUTCOME MEASURES: age of onset, anticipation, clinical subtypes and neurological findings. RESULTS: Fasciculations were associated with CAG repeat length of the long SCA2 allele (Mann-Whitney U-test, P < 0.03, after Bonferroni procedure). Other measures (age of onset, anticipation, clinical types and other neurological signs) were not associated with CAG repeat length of SCA2, SCA6 and DRPLA genes. CONCLUSIONS: The present results show that the CAG tract of SCA2 gene interferes with MJD phenotype. Further studies, with patients of other origins and with typing of other (CAG)n loci, are necessary.

Age of Onset↗
PubMed2003

Severe cognitive and motor coordination deficits in tenascin-R-deficient mice.

The extracellular matrix molecule tenascin-R (TN-R), predominantly expressed in the central nervous system, has been implied in a variety of functions, e.g. during myelination, cerebellar neurite fasciculation and hippocampal long-term potentiation. In this study, we investigated in detail the impact of TN-R deficiency on the living animal by analyzing the behavior of TN-R-deficient mice. The general state, gross sensory functions, reflexes and motoric capabilities appeared normal. In contrast, motor coordination on the rota-rod was compromised in these mice, indicating a deficit in cerebellar functions. In the open field and the hole board, the mutants interact differently with their environment, probably due to differences in their exploratory behavior. TN-R-deficient mice were able to learn a reference memory task in the Morris water maze. In contrast to wild-type mice, the mutants displayed an alternative strategy; swimming around the pool using a stereotypical circling pattern, crossing all possible platform positions after relocation of the escape platform (reversal). These results, confirmed by relocating the platform in the center of the pool, suggest that TN-R-deficient mice may be impaired in constructing a goal-independent representation of space. In addition, a two-way active avoidance test (shuttle box) revealed a severe deficit in associative learning in TN-R-deficient mice. Our results support important functions of TN-R in vivo in the central nervous system, in particular in the cerebellum and the hippocampus.

Animals↗