Generalized muscular stiffness, fasciculations, and myokymia of peripheral nerve origin.
TL;DR: The muscular stiffness and continual EMG activity were abolished by curare but persisted during spinal anesthesia and after peripheral nerve blocks, suggesting that the syndrome was due to isolated, spontaneous, peripheral nerve hyperactivity.
Abstract: THE PERIPHERAL nerve disorders, unlike central nervous system and muscle diseases, have not been widely recognized as causes of generalized muscular stiffness. Isaacs,1,2in 1961 and 1967, reported three patients with an entity of generalized muscular stiffness, fasciculations, continual electromyographic (EMG) activity at rest and depressed deep tendon reflexes. The muscular stiffness and continual EMG activity were abolished by curare but persisted during spinal anesthesia and after peripheral nerve blocks, suggesting that the syndrome was due to isolated, spontaneous, peripheral nerve hyperactivity. Isaacs also discovered that diphenylhydantoin (DPH) induced a substantial and sustained decrease in the muscular stiffness. Similar cases were reported by Mertens and Zschocke3and by Levy et al,4both groups confirming the effects of spinal anesthesia and curare. Mertens and Zschocke3also found carbamazepine as effective as DPH in treatment. Sig wald et al,5Gardner-Medwin and Walton,6and Hughes and
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TL;DR: In “dystrophic” mice, many spinal root axons are bare and closely apposed to one another in midroot, and impulses arise in the spinalRoot axons of dystrophic mice both spontaneously and as a result of cross‐talk between single fibers.
Abstract: In "dystrophic" mice, many spinal root axons are bare and closely apposed to one another in midroot. The direction of nerve impulse traffic in lubosacral spinal nerve roots was determined by biphasic recording of spontaneous activity. In normal mice, impulse traffic in dorsal and ventral roots is directed toward and away from the spinal cord, respectively. However, in spinal root fibers of dystrophic mice, impulses also originate in midroot and are propagated toward both the spinal cord and the periphery. Impulses originate in midroot as single isolated events, in bursts at frequencies of up to 100 Hz, or as continuous activity persisting for several minutes in single fibers. Ectopically arising activity in some single fibers is consistently associated with transmission of an impulse in another fiber past the site of origin of the ectopically arising impulse. Thus impulses arise in the spinal root axons of dystrophic mice both spontaneously and as a result of cross-talk between single fibers.
168 citations
TL;DR: It is concluded that in at least some cases the direction of ephaptic transmission is from bare axon to myelinated axon, and that there may be multiple sites of spontaneous ectopic excitation in single dystrophic mouse spinal root axons.
Abstract: 1. Ephaptic transmission was observed between spontaneously active single nerve fibres in the spinal nerve roots of dystrophic mice. 2. In the five ephaptically interacting pairs of fibres studied in detail, the conduction velocities in the exciting fibres were < 1 m/sec and the conduction velocities in the excited fibres were 2-10 m/sec in the immediate vicinity of the ephapses at 26-28 degrees C. 3. Membrane current analysis suggested that conduction was continuous in the exciting fibres. In some cases conduction away from the ephapse in the excited fibre was saltatory in at least one and possibly in both directions of transmission. 4. It is concluded that in at least some cases the direction of ephaptic transmission is from bare axon to myelinated axon. 5. Transmission time across the ephapses, measured as the interval between peaks of inward membrane current in exciting and excited fibres, was less than or equal to microseconds-240 microseconds. 6. Ephaptic transmission is not necessarily contingent upon the direction of propagation of the impulse in the exciting fibre. 7. Ephaptic transmission between two fibres can remain stable at frequencies of at least 70 Hz. 8. There may be multiple sites of spontaneous ectopic excitation in single dystrophic mouse spinal root axons. An impulse traversing a site of ectopic excitation may incite a subsequent burst of impulses to arise from that site following a delay of more than 100 msec.
163 citations
TL;DR: Spontaneous and associated hyperkinetic facial movements and contracture which follow injury to the seventh cranial nerve or arise without known previous injury (cryptogenic hemifacial spasm) are pathological motor phenomena not found in the distribution of other cranial or somatic motor nerves.
Abstract: Spontaneous and associated hyperkinetic facial movements and contracture which follow injury to the seventh cranial nerve (postparalytic hemifacial spasm) or arise without known previous injury (cryptogenic hemifacial spasm) are pathological motor phenomena not found in the distribution of other cranial or somatic motor nerves. The commonly expressed hypotheses of pathogenesis--aberrant regeneration and fiber excitation by false synapse formation (ephapses) at the site of injury--cannot account for all aspects of these phenomena or for the uniqueness of such movements to the distribution of the seventh nerve. The suggestion is made that the existing diversity of facial motor behavior, which encompasses voluntary, emotional, and especially automatic, associated, and reflexive movements, is based on a unique central organization that sets it apart from other motor groups. I hypothesize that because of this organization, the changes following axonal injury--which include selective deafferentation, glial response, axonal sprouting, functional reconnection, and hyperexcitability from dendritic spike generation--can unmask and augment automatic, associated, and reflexive movements already present in the facial neuronal network to result in facial hyperkinesia.
129 citations
TL;DR: The myokymia described here is of interest not only because of its genetic association with a movement disorder, but also because the muscle findings support a peripheral basis for the muscle movements.
118 citations
TL;DR: Two members of a family with a neuropathy resembling Charcot‐Marie‐Tooth disease were unable to relax their muscles after voluntary contraction, and muscle spasm often outlasted voluntary contraction by 30 seconds or more before subsiding into myokymia and fasciculations.
Abstract: Two members of a family with a neuropathy resembling Charcot-Marie-Tooth disease were unable to relax their muscles after voluntary contraction. Muscle spasm often outlasted voluntary contraction by 30 seconds or more before subsiding into myokymia and fasciculations. The posture of the hand during muscle spasm resembled that of tetany, and Trousseau's and Chvostek's signs were present although no abnormality of calcium or magnesium metabolism could be demonstrated. Muscle spasms ceased during medication with carbamazepine, 600 mg daily. Nerve stimulation, electromyography, and regional neuromuscular blockade with curare indicated that the condition originated in peripheral nerve, while microneurographic recordings showed that sensory as well as motor fibers were hyperexcitable. Sural nerve biopsy revealed axonal degeneration involving myelinated and unmyelinated fibers. It was concluded that the neural hyperexcitability is caused by a membrane defect resulting in a low threshold for excitation throughout the length of the axon.
91 citations
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348 citations
Journal Article•
TL;DR: In this article, two patients with a syndrome of continuous muscle fibre activity were described and the site of the abnormal discharge localised to the motor nerve terminals, and the neurological nature of the disorder was confirmed.
Abstract: Twelve years ago two patients with a syndrome of continuous muscle fibre activity were described and the site of the abnormal discharge localised to the motor nerve terminals. These cases have been restudied electrophysiologically, by muscle histology and histochemistry and by motor nerve terminal and end-plate preparations. The neurological nature of the disorder is confirmed, and the relevant effectsof drugs acting on motor nerve terminals discussed. The original cases responded dramatically to diphenylhydantoinate, and one of the patients has improved to a point where he no longer requires therapy, thus confirming the acquired nature of the disorder.S. Afr. Med. J., 48, 1601 (1974).
329 citations
TL;DR: The original cases responded dramatically to diphenylhydantoinate, and one of the patients has improved to a point where he no longer requires therapy, thus confirming the acquired nature of the disorder.
Abstract: Twelve years ago two patients with a syndrome of continuous muscle fibre activity were described and the site of the abnormal discharge localised to the motor nerve terminals. These cases have been restudied electrophysiologically, by muscle histology and histochemistry and by motor nerve terminal and end-plate preparations. The neurological nature of the disorder is confirmed, and the relevant effectsof drugs acting on motor nerve terminals discussed. The original cases responded dramatically to diphenylhydantoinate, and one of the patients has improved to a point where he no longer requires therapy, thus confirming the acquired nature of the disorder.S. Afr. Med. J., 48, 1601 (1974).
324 citations
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