0000000000121633
AUTHOR
Roland Besser
No evidence for efficacy of intrathecal verapamil in the treatment of tonic-clonic status epilepticus
In two patients with refractory generalized tonic-clonic status epilepticus, 15 mg of the calcium antagonist verapamil was given by suboccipital intrathecal administration. During a 2–6-h observation period, seizure frequency did not decrease. However, in one patient, verapamil induced severe hypotension. Subsequent thiopental anesthesia suppressed convulsions immediately. Our results indicate that, in contradistinction to animal studies with different administration techniques, intrathecal administration of verapamil does not produce any anticonvulsant effect in humans.
Cranial nerve function in workers exposed to polychlorinated dioxins and furans
OBJECTIVE: To look for possible effects of polychlorinated dioxins and furans (PCDD/F) on cranial nerve function. MATERIAL AND METHODS: Clinical and neurophysiological examinations [visual and brainstem auditory evoked potentials (VEP and BAEP), blink reflex] in 121 PCDD/F exposed workers of one pesticide producing plant. RESULTS: BAEP abnormalities were more frequent in workers with chloracne (6 of 33 workers, 18.2%) than in those without chloracne (7 of 84, 8.3%), but this was not statistically significant (chi2: 2.33). VEP abnormalities were seen in one worker with and two without chloracne. Clinically visual functions were normal except in one worker, who was amaurotic since birth. Blin…
Der Effekt von Neostigmin an der motorischen Endplatte beim Intermediärsyndrom der Alkylphosphatvergiftung
A patient with severe organophosphate intoxication received Neostigmine 1 mg IV during the intermediate syndrome. This dose resulted clinically and neurophysiologically in a marked deterioration of neuro-muscular transmission. This effect of neostigmine on the neuromuscular block during the intermediate syndrome (deterioration) differs from its effect on a similar pattern (improvement), which is seen in the delayed neuropathy following organophosphate exposure. The administration of therapeutic doses of cholinesterase inhibitors in patients with a reduced safety margin due to inhibition of endplate acetylcholinesterase may be dangerous.
Effects of Neuromuscular Blocking Agents on Neuronal Nicotine Receptors of Motor Nerves: Blockade of Nicotinic Autofacilitation and Backfiring
ABSTRACT Tubocurarine reduced (60%) [3H]acetylcholine release from the isolated rat phrenic nerve at concentrations of 1 or 10 μM, but blocked backfiring of the phrenic nerve occuring after partial blockade of cholinesterase already at a concentration of 100 nM. The distinct potency of tubocurarine suggests differences between the presynaptic nicotine receptors mediating autofacilitation of release and preterminal nicotine receptors mediating backfiring of the motor nerve or a low agonist concentration at the latter receptors. The new neuromuscular blocking agents atracurium, pancuronium and vecuronium less effectively reduced [3H]acetylcholine release than tubocurarine indicating a lower a…
Somatosensory evoked potentials aiding the diagnosis of brain death.
SEP were recorded in 14 patients, who fulfilled the clinical and electroencephalographic criteria of brain death. The results are compared with the respective ones in healthy subjects. Beside the absence of cortical N 20 in each brain dead patient, reduction of amplitude or absence of near field negativity (N 13b) from upper neck regardless of the position of the reference electrode represents the predominant result. The near field potential from the lower neck (N 13a) was unaffected. The counterpart in the far field potential recorded from F z was amplitude reduction of P 13. These results suggest that the dissociation of N 13a and N 13b can confirm the diagnosis of brain death. Moreover t…
Impaired neuromuscular transmission during partial inhibition of acetycholinest-erase: The of stimulus-induced antiromic backfiring in the generation of the decrement-increment phenomenon
Neuromuscular transmission was studied in the rat phrenic nerve-hemidiaphragm preparation with acetylcholinesterase (AChE) partially inactivated. Enzyme inhibition resulted in (1) increased single-twitch tension of the diaphragm; (2) compound muscle action potential (CMAP) containing repetitive discharges; (3) stimulus-induced antidromic backfiring (SIAB) seen in the phrenic nerve; and (4) repetitive nerve stimulation (RNS) eliciting a decrement-increment (D-I) phenomenon (i.e., amplitude reduction maximal with the second CMAP). Using a high-calcium and low-magnesium solution, SIAB and the decrement of the second CMAP during RNS were intensified, whereas closely spaced trains and (+)-tubocu…
Efficacy of obidoxime in human organophosphorus poisoning: determination by neuromuscular transmission studies.
Six patients with organophosphorus compound intoxications developed an intermediate syndrome (weakness and fasciculations) and obidoxime was given on eight occasions. The efficacy of the acetylcholinesterase (AChE) reactivator was monitored electrophysiologically by neuromuscular transmission studies using single and repetitive nerve stimulation (20 and 50 Hz) and the activity of the serum (butyryl) cholinesterase (ChE). Dramatic electrophysiologic improvement was seen when obidoxime was given early within 12 h in 3 patients, although evidence of AChE inhibition did not subside completely. When administration of obidoxime was delayed 26 h or more after intoxication on five occasions, electr…
A quantitative study of the pancuronium antagonism at the motor endplate in human organophosphorus intoxication
Nine patients with organophosphorus (OP) intoxication developing neuromuscular transmission defects were given pancuronium 1, 2, or 4 mg intravenously (IV). Thirteen patient controls with hypoxic encephalopathy received similar dosages. The responses were monitored electrophysiologically using single and repetitive nerve stimulation (20 and 50 Hz). In OP patients, pancuronium did not alter the amplitude of the single CMAP, whereas its repetitive discharges were reduced. Severe neuromuscular blocks were reversed only partially by pancuronium 4 mg. In less severe blocks, 1 and 2 mg resulted in marked improvement. In the patient controls, pancuronium 4 mg induced a severe neuromuscular block b…
End-plate dysfunction in acute organophosphate intoxication.
Acute organophosphate intoxication resulting from suicide attempts in 14 patients produced a series of electrophysiologic abnormalities that correlated with the clinical course. Spontaneous repetitive firing of single evoked compound muscle action potentials (CMAP) was the earliest and most sensitive indicator of the acetylcholinesterase inhibition. A decrement of evoked CMAP following repetitive nerve stimulation was the most severe abnormality. At the height of the intoxication no CMAP was evoked after the first few stimuli. The decrement-increment phenomenon occurred only at milder stages of intoxication and its features are characteristic of acetylcholinesterase inhibition. These electr…
Pancuronium improves the neuromuscular transmission defect of human organophosphate intoxication.
Two patients with acute severe organophosphate intoxication showed (1) single evoked compound muscle action potentials (CMAP) with repetitive discharges and (2) prominent decremental responses of CMAP with 20 and 50 Hz supramaximal nerve stimulation. Following the intravenous injection of single small doses of pancuronium, marked improvement in these abnormalities occurred and persisted for several hours. We postulate that the physiologic improvement following low-dose pancuronium results from blockade of acetylcholine receptors, especially those located on the terminal axon responsible for antidromic backfiring.
Increased risk of sensory neuropathy in workers with chloracne after exposure to 2,3,7,8-polychlorinated dioxins and furans
Objective - The existence of a peripheral neuropathy after exposure to polychlorinated dioxins (PCDD) is still discussed, as studies concerning dioxin effects on the peripheral nervous system are rare and contradictory. Material and methods - Clinical and neurophysiological examinations (motor conduction velocity of the peroneal nerve, sensory conduction velocities of the sural and ulnar nerves) were made in 156 dioxin exposed workers (42 with, 114 without cloracne) from one pesticide producing plant. Because of known risk factors for peripheral neuropathy, 7 workers with and 28 without cloracne were excluded from further analysis. Results - Workers with chloracne had a significantly higher…
Backfiring of the isolated rat phrenic nerve does not collide with impulse propagation following repetitive nerve stimulation at 1-50 Hz.
Acetylcholinesterase inhibition with neostigmine in the isolated rat phrenic nerve-hemidiaphragm preparation induced axonal backfiring and repetitive compound muscle action potentials following single nerve stimulation. The duration of backfiring and the repetitive compound muscle action potentials did not exceed 55 ms. With repetitive nerve stimulation at frequencies ranging from 1 to 50 Hz, backfiring was present only with the first stimulus and the amplitude of the second compound muscle action potential was maximally reduced, while the subsequent responses recovered gradually. However, the amplitudes of the concommitant antidromic nerve action potentials remained unchanged during the en…
Combined therapy with acyclovir and adenosine arabinoside in herpes simplex encephalitis.
We report a case of herpes simplex encephalitis (HSE) with initial coma and severe left-sided hemiparesis in which combined treatment with adenine arabinoside and acyclovir was followed by complete recovery. This favorable result is discussed in view of the literature of HSE treatment including experimental studies on antiviral activity of both drugs. Combined treatment may be useful in severe cases of HSE.
Successful treatment of HSV encephalitis during pregnancy.
A propos d'une femme presentant une grossesse de 23 semaines. Description des signes cliniques et electroencephalographiques. Les effets de l'aciclovir sur l'encephalite et sur l'evolution de la grossesse sont etudies
High pancuronium sensitivity of axonal nicotinic-acetylcholine receptors in humans during organophosphate intoxication.
The effect of low-dose pancuronium on neuromuscular transmission was studied in 2 patients during the early and late stages of severe organophosphate intoxication. Single evoked compound muscle action potentials (CMAP) were followed by repetitive discharges and a decrement-increment (D-I) phenomenon with 10-, 20-, and 50-Hz supramaximal nerve stimulation. Intravenous pancuronium, 1 mg, abolished the D-I phenomenon, while the repetitive discharges of the CMAP were only partially reduced. It is postulated, that the disappearance of the D-I phenomenon with persistence of the CMAP repetitive discharges results from blockade of nicotinic-acetylcholine receptors located on the terminal axon respo…