Effect of chronic renal failure, dialysis and transplantation on motor nerve conduction velocity in children. (17/366)

Ulnar and peroneal motor nerve conduction volocities (MNCVs) were measured in 47 children in a dialysis-transplantation program. Mean peroneal MNCV was significantly decreased from normal in children with mild renal failure (serum creatinine concentration, 1.5 to 2.9 mg/dl), whereas ulnar MNCV was significantly decreased only when the serum creatinine value was at least 9 mg/dl. Both ulnar and peroneal MNCVs remained unchanged during long-term hemodialysis or peritoneal dialysis; however, after individual dialyses ulnar MNCV increased. After renal transplantation ulnar MNCV returned to normal within a year and peroneal MNCV within 3 years. Before dialysis was required and during long-term dialysis most plasma magnesium values were elevated; ionized calcium activity was decreased in about 50% of determinations. After transplantation and the concentration of divalent cations rapidly returned to normal. These children differed from adults studied in that (a) there was no correlation between severity of renal failure and MNCV, (b) long-term dialysis did not improve MNCV and (c) peroneal velocities did not recover for 3 years after transplantation.  (+info)

Dose-response and onset/offset characteristics of rapacuronium. (18/366)

BACKGROUND: A rigorous study of the dose-response relation of rapacuronium has, to our knowledge, yet to be performed. In addition, there is little information available regarding the onset or offset profile of rapacuronium when administered in subparalyzing doses. These issues necessitate further study. METHODS: Forty-seven adult patients, American Society Anesthesiologists physical status I or II, were studied. Tracheal intubation was accomplished without muscle relaxants. Anesthesia was maintained with use of nitrous oxide, propofol, and alfentanil. The electromyogram of the first dorsal interosseous muscle was measured using a monitor. Single stimuli at 0.10 Hz were administered. A single dose of rapacuronium was administered. After log-dose or logit transformation of the data, the best-fit line of regression was determined using the method of least squares. For each subject, the authors estimated the 50% effective dose (ED50) and 95% effective dose (ED95) from the Hill equation using the slope obtained from regression analysis. The onset times to 50 and 90% of peak effect were estimated in a subset of 10 individuals in which peak twitch depression decreased to the range of 90-99%. RESULTS: The calculated ED50 and ED95 values for rapacuronium were 0.39 +/- 0.08 (SD) and 0.75 +/- 0.16 mg/kg, respectively. After a single ED95 dose, 90% of the drug's peak effect was evident in 77 +/- 17 s. After this dose, rapacuronium has a clinical duration of 6.1 +/- 1.1 min. CONCLUSIONS: The authors found the ED95 of rapacuronium to be substantially less than suggested by previous estimates. Rapacuronium has an onset profile that is not different from that previously reported for succinylcholine. The rate of spontaneous recovery was faster after rapacuronium than the authors previously observed after mivacurium administration but was slower than after succinylcholine, using an identical protocol.  (+info)

Neuromuscular monitoring at the orbicularis oculi may overestimate the blockade in myasthenic patients. (19/366)

BACKGROUND: In most publications about myasthenia, monitoring neuromuscular blockade during anesthesia is recommended. In healthy patients, the relation of blockade between muscles has been established, but there is little information about the relation in myasthenic patients. Our objective was to investigate whether the relation between the orbicularis oculi and adductor pollicis muscles is the same in healthy patients and myasthenic patients. METHODS: After anesthesia was induced with 4-6 mg/kg thiopental and 2 microg/kg fentanyl, followed by 2% sevoflurane and 60% nitrous oxide in oxygen, 10 healthy patients and 10 myasthenic patients received 0. 025 and 0.01 mg/kg vecuronium, respectively. Neuromuscular monitoring was performed with use of accelerometry at the orbicularis oculi and the adductor pollicis muscles by stimulating the temporal branch of the facial nerve and the ulnar nerve. RESULTS: The relation of blockade between these two muscles was not the same in healthy patients and myasthenic patients: in healthy patients, the maximum neuromuscular blockade with 0.025 mg/kg vecuronium was less in the orbicularis oculi than in the adductor pollicis (median 72% vs. 91%; P < 0.05); in contrast, in myasthenic patients, the blockade with 0.01 mg/kg vecuronium was greater in the orbicularis oculi than in the adductor pollicis (median 96% vs. 62%; P < 0.05). CONCLUSION: Neuromuscular monitoring at the orbicularis oculi may overestimate blockade in myasthenic patients. Extubation must be performed when the muscle most sensitive to neuromuscular blocking agents is recovered. Therefore, neuromuscular monitoring at the orbicularis oculi is recommended to avoid persistent neuromuscular blockade in patients with myasthenia gravis.  (+info)

The protective effect of procaine blocking on nerve-electrophysiological study during operation. (20/366)

OBJECTIVE: To clinically evaluate the protective effect of procaine blocking on nerves. METHODS: Electrophysiological examination before and after procaine blocking was conducted on 32 nerves during operation, 18 of which were donor nerves and 14 were injured ones. RESULTS: The latency of somatosensory evoked potentials (SEPs) was lengthened (15.30%) and the amplitude was lowered (18.47) after procaine blocking. Compared with the values before procaine blocking, the differences were significant (P < 0.01 and P < 0.05, respectively). SEP waves disappeared after procaine blocking in some cases (28.13%). CONCLUSION: Latency of SEP is lengthened and amplitude is lowered after procaine blocking. In some cases, SEPs even disappear.  (+info)

Tension distribution to the five digits of the hand by neuromuscular compartments in the macaque flexor digitorum profundus. (21/366)

The macaque flexor digitorum profundus (FDP) consists of a muscle belly with four neuromuscular regions and a complex insertion tendon that divides to serve all five digits of the hand. To determine the extent to which compartments within FDP act on single versus multiple digits, we stimulated the primary nerve branch innervating each neuromuscular region while recording the tension in all five distal insertion tendons. Stimulation of each primary nerve branch activated a distinct region of the muscle belly, so that each primary nerve branch and the muscle region innervated can be considered a neuromuscular compartment. Although each neuromuscular compartment provided a distinct distribution of tension across the five distal tendons, none acted on only one digital tendon. Most of the distribution of tension to multiple digits could be attributed to passive biomechanical interactions in the complex insertion tendon, although for the larger compartments a wider distribution resulted from the broad insertion of the muscle belly. Nerve ligations excluded contributions of spinal reflexes or distal axon reflexes to the distribution of tension to multiple digits. We conclude that the macaque FDP consists of four neuromuscular compartments, each of which provides a distinct distribution of tension to multiple digits.  (+info)

Stimulus-response functions of slowly adapting mechanoreceptors in the human glabrous skin area. (22/366)

1. Single unit impluses were recorded from the ulnar and median nerves of awake human subjects with tungsten electrodes inserted percutaneously in the upper arm. 2. One hundred and one slowly adapting receptors with receptive fields in the glabrous skin area were studied. The units were classified as type SA-I and type SA-II largely on the basis of their responses to lateral stretching of the skin. Eighty-eight receptors did not respond to this type of stimulus (type SA-I), whereas thirteen receptors readily responded to stretching (type SA-II), AND OFTEN EXHIBITED DIRECTIONAL SENSITIVITY. 3. The SA-I receptors showed no spontaneous discharge, and the discharge pattern was mostly rather irregular, whereas most of the SA-II receptors had a spontaneous discharge, and a very regular discharge pattern. 4. The conduction velocities of the afferent were all in a A alpha range. The mean value for the SA-I receptors was 58-7 plus or minus 2-3m/sec, and for the SA-II receptors 45.3 plus or minus 3.6 m/sec. 5. The neural response to stimuli of varying skin indentation amplitudes was analyzed. The threshold for a dynamic response ranged for the SA-I receptors from 0.15 to 1.35 mm and for the SA-II receptors from 0.25 to 0.95 mm. The threshold for a static discharge ranged for the SA-I receptors from 0.25 to more than 2.0 mm and for the SA-II receptors from 0.55 to 1.65 mm. 6. The stimulus-response functions were analysed for 25 SA-I receptors and 2 SA-II receptors. A hyperbolic log tangent function was the best description when the neural response was defined as the total number of impluses evoked by a stimulus of 1 sec duration. When only the static part of this type of plot was analyzed, a power function was a very good description for many units, but other functions (linear, logarithmic exponential, log tanh) were equally good or better for many units. This was also the dase when the mean impulse frequency of the sustained discharge was defined as a measure of the neural response. These two latter types of plots were clearly negatively accelerating, the exponent of the power function being 0.66 (mean).  (+info)

Surgical management of Guyon's canal syndrome, an ulnar nerve entrapment at the wrist: report of two cases. (23/366)

Guyon's canal syndrome, an ulnar nerve entrapment at the wrist, is a well-recognized entity. The most common causes that involve the ulnar nerve at the wrist are compression from a ganglion, occupational traumatic neuritis, a musculotendinous arch and disease of the ulnar artery. We describe two cases of Guyon's canal syndrome and discuss the anatomy, aetiology, clinical features, anatomical classification, diagnostic criteria and treatment. It is emphasized that the knowledge of both the surgical technique and anatomy is very important for a satisfactory surgical result.  (+info)

Sabin attenuated LSc/2ab strain of poliovirus spreads to the spinal cord from a peripheral nerve in bonnet monkeys (Macaca radiata). (24/366)

Vaccine-associated paralytic poliomyelitis is a serious concern while using the live attenuated oral polio vaccine for the eradication of poliomyelitis. The bonnet monkey model of poliovirus central nervous system (CNS) infection following experimental inoculation into the ulnar nerve allows the comparative study of wild-type and attenuated poliovirus invasiveness. Dosages >/=10(4) TCID(50) of Mahoney strain of poliovirus type 1 [PV1(M)] result in paralysis. In contrast, even with 10(7) TCID(50) of Sabin attenuated strain of poliovirus type 1 (LSc/2ab), no paralysis occurs, but virus spreads into the CNS where viral RNA is found in spinal cord neurons. While wild-type PV1(M) viral RNA replicates in neurons (and possibly in glial cells) and in cells around vessel walls, which may be mononuclear or endothelial cells, attenuated viral RNA is detected only in neurons. Systemic viraemia and gastrointestinal virus shedding occurs only in PV1(M)-infected animals. While a systemic serologic response is detected in both groups of animals, cerebrospinal fluid antibodies are detected only in animals infected with PV1(M). Both the PV1(M) and LSc/2ab strains spread to the cervical spinal cord and then to the lumbar spinal cord following ulnar nerve inoculation. Neuronophagia and neuronal loss are only seen in PV1(M)-infected monkeys in whom clinical paralysis is observed. Infection with LSc/2ab does not result in neuronophagia, neuronal loss or clinical paralysis. Spread of attenuated poliovirus in spinal cord neurons without causing paralysis following inoculation into the ulnar nerve is an important finding.  (+info)