Intermediate myasthenia syndrome following acute organophosphates poisoning-an analysis of 21 cases

1998 ◽  
Vol 17 (1) ◽  
pp. 40-45 ◽  
Author(s):  
Fengsheng He ◽  
Haibing Xu ◽  
Fukuang Qin ◽  
Li Xu ◽  
Jinxiang Huang ◽  
...  
Keyword(s):  
Action Potentials ◽  
Neuromuscular Junctions ◽  
Cranial Nerves ◽  
Respiratory Muscles ◽  
Acetylcholinesterase Activity ◽  
Acute Poisoning ◽  
Muscular Weakness ◽  
Repetitive Nerve Stimulation ◽  
Pesticide Mixtures ◽  
Limb Muscles

1 Twenty-one cases out of 272 patients of acute organophosphates poisoning were diagnosed as intermediate syndrome (IMS) with a prevalence at 7.7%. The responsible OP insecticides included parathion, omethoate and some OP containing pesticide mixtures. IMS occurred mainly in severe OP poisoning patients who recovered from the acute cholinergic crisis at 7-75 h after the onset of acute poisoning. 2 Muscular weakness appeared in the following three categories of muscles: (1) neck flexors and proximal limb muscles; (2) muscles innervated by motor cranial nerves and/or (3) respiratory muscles. Blood acetylcholinesterase activity was persistently inhibited. Electroneuromyography (ENMG) with repetitive nerve stimulation (RNS) at frequencies of 20 Hz or 30 Hz in seven patients showed decrements of common muscle action potentials during the presence of myasthenia in five patients and became normal when their muscle strength recovered. 3 Mild IMS recovered within 2-7 days and had a favorable prognosis. Severe IMS patients with respiratory paralysis needed immediate endotracheal intubation and mechanical ventilation. Recovery of weakness of the respiratory muscles and proximal limb muscles took longer, the slowest being 30 days. Four of the patients died of respiratory paralysis and the fatality rate was 19%. 4 The mechanism of IMS remains to be further investigated. The RNS/ENMG changes indicate a post-synaptic block at the neuromuscular junctions. 5 In order to promote the recognition of this syndrome, we proposed to name the syndrome as Intermediate Myasthenia Syndrome (IMS).

scholarly journals Changes in miniature endplate potential frequency during repetitive nerve stimulation in the presence of Ca2+, Ba2+, and Sr2+ at the frog neuromuscular junction.

1981 ◽  
Vol 77 (5) ◽  
pp. 503-529 ◽  
Author(s):  
J E Zengel ◽  
K L Magleby
Keyword(s):  
Nerve Stimulation ◽  
Transmitter Release ◽  
Neuromuscular Junctions ◽  
Fourth Power ◽  
Bathing Solution ◽  
Frog Neuromuscular Junction ◽  
Repetitive Nerve Stimulation ◽  
Time Constants ◽  
Endplate Potential ◽  
Induced Changes

Miniature endplate potentials (MEPPs) were recorded from frog sartorious neuromuscular junctions under conditions of reduced quantal contents to study the effect of repetitive nerve stimulation on asynchronous (tonic) quantal transmitter release. MEPP frequency increased during repetitive stimulation and then decayed back to the control level after the conditioning trains. The decay of the increased MEPP frequency after 100-to 200-impulse conditioning trains can be described by four components that decayed exponentially with time constants of about 50 ms, 500 ms, 7 s, and 80 s. These time constants are similar to those for the decay of stimulation-induced changes in synchronous (phasic) transmitter release, as measured by endplate potential (EPP) amplitudes, corresponding, respectively, to the first and second components of facilitation, augmentation, and potentiation. The addition of small amounts of Ca2+ or Ba2+ to the Ca2+-containing bathing solution, or the replacement of Ca2+ with Sr2+, led to a greater increase in the stimulation-induced increases in MEPP frequency. The Sr-induced increase in MEPP frequency was associated with an increase in the second component of facilitation of MEPP frequency; the Ba-induced increase with an increase in augmentation. These effects of Sr2+ and Ba2+ on stimulation-induced changes in MEPP frequency are similar to the effects of these ions on stimulation-induced changes in EPP amplitude. These ionic similarities and the similar kinetics of decay suggest that stimulation induced changes in MEPP frequency and EPP amplitude have some similar underlying mechanisms. Calculations are presented which show that a fourth power residual calcium model for stimulation-induced changes in transmitter release cannot readily account for the observation that stimulation-induced changes in MEPP frequency and EPP amplitude have similar time-courses.

The Extraocular Muscles and Diplopia

2014 ◽  
pp. 124-161
Author(s):  
Shirley H. Wray ◽  
Shirley H. Wray
Keyword(s):  
Eye Movements ◽  
Nerve Palsy ◽  
Neuromuscular Junctions ◽  
Cranial Nerves ◽  
Abducens Nerve ◽  
Extraocular Muscles ◽  
Oblique Muscle ◽  
Oculomotor Nerve Palsy ◽  
Subjective Complaint ◽  
Oculomotor Nuclei

deals with action and innervation of the extraocular muscles. In their intact state, the extraocular muscles and the cranial nerves that innervate them are responsible for every movement of the eyes signaled by the cortex. Diplopia, or double vision, is the commonest subjective complaint associated with a lesion affecting the extraocular muscles, their neuromuscular junctions, the oculomotor nuclei or nerve, or pathways in the brainstem that maintain alignment of the eyes. The diplopia history focuses on distinguishing monocular from binocular diplopia and the diplopia examination pays attention to head position, ocular alignment, and the range of eye movements during monocular and binocular viewing as keys to diagnosis. Diplopia with full eye movements is fully discussed. Four illustrative cases are presented: episodic diplopia due to ocular myasthenia gravis; a case of esotropia (paresis of the lateral rectus with inward deviation of the eye) due to an abducens nerve palsy; a case of exotropia (paresis of the medial rectus with outward deviation of the eye) due to a fascicular oculomotor nerve palsy; and a case of hypertropia (vertical misalignment of the eyes due to paresis of the superior oblique muscle vs. skew deviation) caused by a post-traumatic trochlear nerve palsy.

Action potentials of accessory respiratory muscles in dogs

1960 ◽  
Vol 199 (3) ◽  
pp. 569-572 ◽  
Author(s):  
T. Ogawa ◽  
N. C. Jefferson ◽  
J. E. Toman ◽  
T. Chiles ◽  
A. Zambetoglou ◽  
...  
Keyword(s):  
Action Potentials ◽  
Respiratory Muscles ◽  
Transversus Abdominis ◽  
Intercostal Muscles ◽  
Intrinsic Muscle ◽  
Internal Oblique ◽  
Accessory Respiratory Muscles

Among 30 so-called accessory respiratory and other muscles tested, the presence of rhythmic respiratory impulses was found in 12. Both expiratory and inspiratory impulses were detected in certain muscles, in others only in- or expiratory ones. The muscles with most frequent inspiratory impulses were the intercartilaginous intercostal muscles, the intrinsic muscle of the larynx and the nostril; those with expiratory impulses were abdominis, external and internal oblique, transversus abdominis, scalenus anterior, and lower interosseous intercostal muscles.

Responses of bulbospinal and laryngeal respiratory neurons to hypercapnia and hypoxia

1985 ◽  
Vol 59 (4) ◽  
pp. 1201-1207 ◽  
Author(s):  
W. M. St John ◽  
A. L. Bianchi
Keyword(s):  
Spinal Cord ◽  
Recurrent Laryngeal Nerve ◽  
Phrenic Nerve ◽  
Action Potentials ◽  
Respiratory Muscles ◽  
Laryngeal Nerve ◽  
Respiratory Neurons ◽  
Peripheral Chemoreceptor ◽  
Medullary Respiratory Neurons ◽  
Neuronal Groups

The purpose was to evaluate activities of medullary respiratory neurons during equivalent changes in phrenic discharge resulting from hypercapnia and hypoxia. Decerebrate, cerebellectomized, paralyzed, and ventilated cats were used. Vagi were sectioned at left midcervical and right intrathoracic levels caudal to the origin of right recurrent laryngeal nerve. Activities of phrenic nerve and single respiratory neurons were monitored. Neurons exhibiting antidromic action potentials following stimulations of the spinal cord and recurrent laryngeal nerve were designated, respectively, bulbospinal or laryngeal. The remaining neurons were not antidromically activated. Hypercapnia caused significant augmentations of discharge frequencies for all neuronal groups. Many of these neurons had no change or declines of activity in hypoxia. We conclude that central chemoreceptor afferent influences are ubiquitous, but excitatory influences from carotid chemoreceptors are more limited in distribution among medullary respiratory neurons. Hypoxia will increase activities of neurons that receive sufficient excitatory peripheral chemoreceptor afferents to overcome direct depression by brain stem hypoxia. The possibility that responses of respiratory muscles to hypoxia are programmed within the medulla is discussed.

Coupling of Calcium Homeostasis to Axonal Sodium in Axons of Mouse Optic Nerve

2002 ◽  
Vol 88 (2) ◽  
pp. 802-816 ◽  
Author(s):  
Yakov Verbny ◽  
Chuan-Li Zhang ◽  
Shing Yan Chiu
Keyword(s):  
Optic Nerve ◽  
Calcium Homeostasis ◽  
Action Potentials ◽  
Calcium Influx ◽  
Repetitive Nerve Stimulation ◽  
Strongly Coupled ◽  
Sodium Load ◽  
Calcium Clearance ◽  
Calcium Dyes ◽  
Ionophore Monensin

Axonal populations in neonatal and mature optic nerves were selectively stained with calcium dyes for analysis of calcium homeostasis and its possible coupling to axonal Na. Repetitive nerve stimulation causes a rise in axonal [Ca2+]i the posttetanus recovery of which is impeded by increasing the number of action potentials in the tetanus. This effect is augmented in 4-aminopyridine (4-AP; 1 mM), which dramatically increases the calcium and presumably sodium load during the tetanus. Increasing axonal [Na]i with the Na-ionophore monensin (4–50 μM) and ouabain (30 μM) retards posttetanus calcium decline, suggesting that efficient calcium clearance depends on a low level of axonal [Na]i. Posttetanus calcium clearance is not affected by K-mediated depolarization. To further examine coupling between axonal [Na]i and [Ca2+]i, the resting axonal [Ca2+]i was monitored as axonal [Na+]i was elevated with ouabain, veratridine, and monensin. In all cases, elevation of axonal [Na+]i evokes a calcium influx into axons. This influx is unrelated to activation of calcium channels but is consistent with calcium influx via reversal of the Na/Ca exchanger expected as a consequence of axonal [Na+]i elevation. In conclusion, this study demonstrates that calcium homeostasis in the axons of the optic nerve is strongly coupled to axonal [Na+]i in a manner consistent with the Na/Ca exchanger playing a major role in extruding calcium following nerve activity.

scholarly journals Congenital myasthenic syndrome due to a TOR1AIP1 mutation: a new disease pathway for impaired synaptic transmission

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Judith Cossins ◽  
Richard Webster ◽  
Susan Maxwell ◽  
Pedro M Rodríguez Cruz ◽  
Ravi Knight ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Synaptic Transmission ◽  
Muscle Weakness ◽  
Nuclear Membrane ◽  
Nerve Stimulation ◽  
Neuromuscular Junctions ◽  
Synaptic Function ◽  
Inherited Disorders ◽  
Repetitive Nerve Stimulation ◽  
Nuclear Membrane Protein

Abstract Congenital myasthenic syndromes are inherited disorders characterized by fatiguable muscle weakness resulting from impaired signal transmission at the neuromuscular junction. Causative mutations have been identified in genes that can affect the synaptic function or structure. We identified a homozygous frameshift deletion c.127delC, p. Pro43fs in TOR1AIP1 in two siblings with limb-girdle weakness and impaired transmission at the neuromuscular synapse. TOR1AIP1 encodes the inner nuclear membrane protein lamin-associated protein 1. On muscle biopsy from the index case, lamin-associated protein 1 was absent from myonuclei. A mouse model with lamin-associated protein 1 conditionally knocked out in striated muscle was used to analyse the role of lamin-associated protein 1 in synaptic dysfunction. Model mice develop fatiguable muscle weakness as demonstrated by using an inverted screen hang test. Electromyography on the mice revealed a decrement on repetitive nerve stimulation. Ex vivo analysis of hemi-diaphragm preparations showed both miniature and evoked end-plate potential half-widths were prolonged which was associated with upregulation of the foetal acetylcholine receptor γ subunit. Neuromuscular junctions on extensor digitorum longus muscles were enlarged and fragmented, and the number of subsynaptic nuclei was significantly increased. Following these findings, electromyography was performed on cases of other nuclear envelopathies caused by mutations in LaminA/C or emerin, but decrement on repetitive nerve stimulation or other indications of defective neuromuscular transmission were not seen. Thus, this report highlights the first nuclear membrane protein in which defective function can lead to impaired synaptic transmission.

Three-Dimensional Computer Reconstruction of the Distribution of Neuromuscular Junctions in the Thyroarytenoid Muscle

1983 ◽  
Vol 92 (5) ◽  
pp. 424-429 ◽  
Author(s):  
Leslie T. Malmgren ◽  
Marc Rosen ◽  
Richard R. Gacek
Keyword(s):  
Computer Graphics ◽  
Neuromuscular Junctions ◽  
Three Dimensional ◽  
Acetylcholinesterase Activity ◽  
Blocking Agent ◽  
Precise Knowledge ◽  
Autopsy Specimen ◽  
Dimensional Distribution ◽  
Motor End Plates ◽  
Thyroarytenoid Muscle

Microinjections of botulinum toxin have recently been shown to be effective in the treatment of strabismus, and it has also been suggested that microinjections of this myoneural blocking agent might be of value in the treatment of spastic dysphonia. The success of such a microinjection technique would rely on a precise knowledge of the distribution of myoneural junctions in the thyroarytenoid muscle. In view of this potential application as well as the need for such information in reinnervation procedures, we have used computer graphics to reconstruct the three-dimensional distribution of motor end-plates in the thyroarytenoid muscle. Three cat and one human (fresh autopsy specimen) larynges were frozen and sectioned on a cryostat. Serial sections were then processed for the histochemical localization of acetylcholinesterase activity to demarcate the neuromuscular junctions. An X-Y digitizer was used to reference the position of the motor end-plates in each serial section, and the three-dimensional distribution of the neuromuscular junctions was reconstructed on a computer graphics terminal. The results are discussed in regard to their applicability to clinical treatment of spastic dysphonia and other disorders of Phonation.

scholarly journals Electrodiagnostic Examination of the Tibial Nerve in Clinically Normal Ferrets

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Ezio Bianchi ◽  
Daniela Callegari ◽  
Manuela Ravera ◽  
Maurizio Dondi
Keyword(s):  
Action Potentials ◽  
Motor Nerve ◽  
Neuromuscular Disorders ◽  
Low Frequency ◽  
Mustela Putorius ◽  
Repetitive Nerve Stimulation ◽  
Motor Nerve Conduction ◽  
Clinically Normal ◽  
Minimum Latency ◽  
Muscular Action

Tibial nerves of 10 normal domestic ferrets (Mustela putorius furo) were evaluated by means of electrodiagnostic tests: motor nerve conduction studies (MNCSs), supramaximal repetitive nerve stimulation (SRNS),Fwaves, and cord dorsum potentials (CDPs). Values of conduction velocity, proximal and distal compound muscular action potentials, and amplitudes of MNCS were, respectively, 63.25 7.56 m/sec, 10.79 2.75 mV, and 13.02 3.41 mV. Mean decrements in amplitude and area of compound muscular action potentials of wave 9 with low frequency SRNS were 0.3 3.83% and 0.1 3.51%. The minimum latency of theFwaves and theFratio were, respectively, 8.49 0.65 ms and 1.92 0.17. Onset latency of CDP was 1.99 0.03 ms. These tests may help in diagnosing neuromuscular disorders and in better characterizing the hindlimb paresis reported in many ferrets with systemic illnesses.

scholarly journals Oxime and atropine failure to prevent intermediate syndrome development in acute organophosphate poisoning

2013 ◽  
Vol 70 (4) ◽  
pp. 420-423 ◽  
Author(s):  
Slavica Vucinic ◽  
Biljana Antonijevic ◽  
Nela Ilic ◽  
Tihomir Ilic
Keyword(s):  
Total Dose ◽  
Key Management ◽  
Cranial Nerves ◽  
Respiratory Muscles ◽  
Organophosphate Poisoning ◽  
Organophosphate Insecticide ◽  
Delayed Treatment ◽  
Medical Institutions ◽  
Exact Etiology ◽  
Pralidoxime Methylsulphate

Introduction. Intermediate syndrome (IMS) was described a few decades ago, however, there is still a controversy regarding its exact etiology, risk factors, diagnostic parameters and required therapy. Considering that acute poisonings are treated in different types of medical institutions this serious complication of organophosphate insecticide (OPI) poisoning is frequently overlooked. The aim of this paper was to present a case of IMS in organophosphate poisoning, which, we believe, provides additional data on the use of oxime or atropine. Case report. After a well-resolved cholinergic crisis, the patient developed clinical presentation of IMS within the first 72 h from deliberate malathion ingestion. The signs of IMS were weakness of proximal limb muscles and muscles innervated by motor cranial nerves, followed by the weakness of respiratory muscles and serious respiratory insufficiency. Malathion and its active metabolite were confirmed by analytical procedure (liquid chromatography-mass spectrometry). Pralidoxime methylsulphate, adiministered as a continuous infusion until day 8 (total dose 38.4 g), and atropine until the day 10 (total dose 922 mg) did not prevent the development of IMS, hence the mechanical ventilation that was stopped after 27 h had to be continued until the day 10. Conclusion. Continuous pralidoxime methylsulphate infusion with atropine did not prevent the development of IMS, most likely due to the delayed treatment and insufficient oxime dose but also because of chemical structure and lipophilicity of ingested OPI. A prolonged intensive care monitoring and respiratory care are the key management for the intermediate syndrome.

Two Cases of Organophosphate Poisoning with Development of Intermediate Syndrome

1990 ◽  
Vol 9 (3) ◽  
pp. 187-189 ◽  
Author(s):  
M. Karademir ◽  
F. Ertürk ◽  
R. Koçak
Keyword(s):  
Conventional Therapy ◽  
Respiratory Muscles ◽  
Respiratory Support ◽  
Organophosphate Poisoning ◽  
Delayed Neuropathy ◽  
Organophosphorus Poisoning ◽  
Limb Muscles ◽  
Support Recovery ◽  
Carbamate Pesticide

Two cases of intermediate syndrome caused by organophosphorus poisoning are reported. Trichlorfon, propoxur (a carbamate pesticide) and fenthion were ingested in both attempts at suicide. After successful conventional therapy during the cholinergic phase, but before the time when the onset of delayed neuropathy might be expected, an intermediate syndrome developed. It affected the proximal limb muscles, neck flexors and respiratory muscles 2 d after pesticide ingestion. The two patients needed respiratory support. Recovery from the intermediate syndrome was complete in both patients, although one subsequently developed delayed neuropathy.

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