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1.
Maximum conduction velocities of compound-action potentials of the infraorbital (ION) and palpebral (PN) nerves were determined by averaging potentials evoked and recorded through subcutaneous needle electrodes. The specificity of the stimulating and recording sites was verified by recording before and after cutting the nerves. Conduction times for orthodromically and antidromically conducted potentials of the ION were essentially the same. The unipolarly recorded antidromic compound-action potentials of the ION were of higher peak-to-peak amplitude and were more reliably recorded than were the bipolarly recorded orthodromic action potentials. Areas of cutaneous innervation were not found for the PN. Neuromuscular blockade eliminated the volume-conducted muscle action potentials that were recorded after PN stimulation, allowing triphasic nerve action potentials to be recorded unobscured. Mean conduction velocities were: ION = 83.9 +/- 3.5 m/s; PN = 56.4 +/- 2.8 m/s. Distributions of the external diameters of myelinated fibers within the ION and the PN were determined.  相似文献   

2.
Compound-action potentials (CAP) were recorded directly from the surface of fascicles of the distal portion of the saphenous nerve (SN) of dogs in situ. Potentials were evoked through needle electrodes and were recorded through bipolar stainless steel electrodes. Stimuli of 10-microseconds duration and of 0.4 +/- 0.15-mA amplitude evoked a monophasic CAP. Sensory conduction velocities of afferent fibers, the action potentials of which contributed to this evoked compound potential, ranged from 62.4 +/- 2.8 m/s for the most rapidly conducting fibers to 30.5 +/- 2.4 m/s for the least rapidly conducting fibers. Stimuli of 25-microseconds duration and of 2.2 +/- 0.8-mA amplitude evoked a second, longer latency CAP in addition to the first CAP. Sensory conduction velocities of afferent fibers, the action potentials of which contributed to this evoked compound potential, ranged from 20.4 +/- 2.9 m/s for the most rapidly conducting fibers to 13.7 +/- 1.0 m/s for the least rapidly conducting fibers. Low-amplitude, negative peaks were recorded between the first and second major potentials elicited by the longer duration stimuli. Stimuli of still longer duration and higher currents induced contractions of the caudal part of the sartorius muscle by current spread in 9 of 12 dogs. In 3 dogs, a third monophasic CAP was evoked, having a maximal conduction velocity of 1.7 +/- 0.2 m/s. After section of the distal portion of the SN on one side in each of 2 dogs, an absence of signs of sensory deficit was found on clinical neurologic examination. The area of cutaneous innervation of the cranial branch of the distal portion of the SN was determined electrophysiologically.  相似文献   

3.
Brain stem and cerebrocortical potentials were evoked by electrical stimulation of the infraorbital nerve of dogs and recorded through needle electrodes placed adjacent to the contralateral parietal bone. Five individual, short latency peaks were recorded in each averaged trigeminal nerve-evoked potential and were identified as I, II (A and B), III (A and B), PI (A, B, and C), and NI. Mean peak latencies +/- 1 SD were as follows: I = 0.9 +/- 0.1 ms, IIA = 1.7 +/- 0.1 ms, IIB = 2.5 +/- 0.1 ms, IIIA = 3.6 +/- 0.15 ms, IIIB = 4.1 +/- 0.2 ms, PIA = 5.2 +/- 0.15 ms, PIB = 6.4 +/- 0.2 ms, PIC = 7.3 +/- 0.3 ms, and NI = 11.0 +/- 0.6 ms. Trigeminal nerve-evoked potentials recorded through needle electrodes were essentially the same as potentials evoked by direct stimulation of the infraorbital nerve and recorded directly from the dura mater overlying the contralateral rostral suprasylvian gyrus. The specificity of the stimulating site was verified by recording before and after the infraorbital nerve was cut proximal to the stimulating site.  相似文献   

4.
Normal values for motor conduction in the tibial, ulnar and fibular nerves of dogs have been determined using a new method for recording and analysing evoked motor potentials. The use of an alligator clip as a roving surface electrode for recording, and a personal computer to analyse the evoked potentials has facilitated faster and more reproducible motor conduction studies. Compound muscle action potential (CMAP) and motor nerve conduction velocity data are in good agreement with previous studies. Normal values for CMAP area, residual latency and proximal to distal ratios for CMAP area and amplitude are presented for the first time.  相似文献   

5.
After the ulnar nerve was surgically transected, nerve conduction velocity in the distal segment and the evoked motor unit potential (EMUP) from the interosseous muscle were recorded until neuromuscular transmission failed. In five of the six dogs in the experiment, functional conduction ceased by 4.8 days, as determined by failure of both proximal and distal stimulation of the distal segment to evoke a muscle response. From the time of section until neuromuscular failure, the nerve conduction velocity remained unchanged. The amplitude of the EMUP from the interosseous muscle, however, decreased markedly during this time. Changes in other features of the EMUP are also presented. Fibrillation (denervation) potentials did not appear until the first day that muscle response could not be detected by stimulating the nerve. These data present a principle which would enable a determination of relative extent and progression of peripheral nerve damage.  相似文献   

6.
A technique for measuring motor nerve conduction velocities (NCV) in sheep was developed using 15 clinically normal ewes. Mean ±SD values were determined for the radial (76.3±12.5 m/s), peroneal (103.9±12.7 m/s), and tibial (98.6±13.1 m/s) nerves. The recording needle electrode was located in the extensor carpi radialis, tibialis cranialis, and gastrocnemius muscles, respectively. Latencies, amplitudes and durations of the proximal and distal evoked compound muscle action potentials are given. To investigate further the unexpectedly high NCVs calculated for the peroneal and tibial nerves, analogous stimulating and recording electrode sites were used in 7 clinically normal dogs. The corresponding canine peroneal (88.1±8.3 m/s) and tibial (89.2±12.4 m/s) NCVs were higher than the standard sciatic-tibial NCV recorded from the interosseous Myelinated nerve fiber diameters were measured on semithin transverse sections of peroneal and tibial nerve specimens taken from a clinically normal ewe and bitch. A possible explanation for the relative species difference in the proximal peroneal and tibial NCV values is the presence of fibers in both the peroneal and tibial nerves of the sheep which were as much as 3 wider than the largest fibers found in the dog.  相似文献   

7.
The aim of this study was to develop a technique for recording electrical activity of the equine cerebral cortex following application of a noxious electrical stimulus to the maxillary branch of the trigeminal nerve in order to investigate trigeminal nerve neurophysiology in control and headshaking horses. Triphasic somatosensory evoked potentials (SEPs) were recorded using subcutaneous needle electrodes in four control and four headshaking horses under general anaesthesia. Dural electroencephalography electrodes were used to record SEPs in one further control and one further headshaking horse. Headshaking horses appeared to have decreased middle latency and inter-peak intervals following stimulation of the trigeminal nerve compared with control horses, supporting abnormal trigeminal nerve physiology in equine headshaking.  相似文献   

8.
Lateral thoracic nerve reflex latencies values were measured in ponies using a simple, non-invasive technique. The reflex was elicited using an external triggering hammer attached to an electrodiagnostic unit. The resulting evoked, compound muscle action potentials were recorded with electrodes, which were placed over the 6th ribs or 11th rib level with the axilla. Two superimposed repeats of 4 signal-averaged sweeps of 50 or 100 milliseconds were recorded and the estimated reflex pathway was measured for each subject in order to calculate the reflex latencies and latency velocities. Mean left and right 6th rib peak latencies were not significantly different from each other ( P = .609), but left 6th rib latencies were shorter than those recorded from the 11th rib ( P < .0001), substantiating the existence of an indirect (central) pathway to the reflex. The calculated left and right 6th rib latency velocities were not significantly different from each other ( P = .58) but left 6th rib latency velocities were different from left 11th rib ( P = .009). The calculated latency velocities were within the broad range for corticospinal tract motor conduction velocities and comparable to magnetic motor evoked latency velocities. The use of lateral thoracic reflex latency measurements to objectively identify the site of spinal cord lesions is discussed.  相似文献   

9.
The motor cortex was transcranially and peripheral nervous structures (motor roots, plexus, peripheral nerves) were percutaneously stimulated by magnetic pulses in awake dogs and in dogs awaking from general anesthesia. The compound muscle action potentials were recorded by surface or needle electrodes. The central motor conduction time as an information about central motor tracts was obtained by subtracting the peripheral latency from the corticomuscular latency. The peripheral latency was assessed by high voltage electrical and magnetic stimulation of motor roots and by the F-wave technique. The motor conduction velocity of the tibial nerve was measured by percutaneous magnetic and by electrical stimulation and the resulting values were compared.  相似文献   

10.
The influence of stimulation site and voltage on amplitude, wave form, conduction time, and velocity of sensory action potentials in the ulnar and radial nerves was evaluated in 25 healthy dogs. A 5-fold increase in stimulation voltage above threshold caused a 300% increase in the amplitude of evoked sensory nerve potentials. An additional 2-fold increase in stimulation voltage (to 10 times threshold) resulted in an additional 40% increase in amplitude. An absolute saturation voltage was not found. Latency velocity was increased by increasing stimulation voltage, but conduction velocity was not affected. Multicomponent nerve action potentials were frequently found at the proximal recording sites. The number of components was not affected by stimulation voltage. Proximal displacement of the stimulation site resulted in an increase in amplitude of the nerve action potentials, increased latency velocity, and fewer components; conduction velocity was not affected. As a consequence of these findings, preference was given to simultaneous recording at 2 sites along the nerve, stimulation at the more proximal stimulation site distal to the carpus, and stimulation voltages between 5 and 10 times the threshold. The occurrence of multicomponent wave forms, the absence of an absolute saturation voltage, and the lowering of the number of components by proximal displacement of the site of stimulation may all be related to the relatively small number of sensory nerve fibers that can be activated at the stimulation site.  相似文献   

11.
Eleven ponies and 13 horses were used to develop a technique for determining conduction velocity for the radial and median nerves and establishing normal limits for these values. One pony was euthanatized to determine the course of the radial and the median nerves. From this dissection, both proximal and distal stimulation sites for the radial and the median nerves were selected, as well as areas for recording muscle evoked responses from the abductor digiti I longus (extensor carpi obliquus) and the radial head of the deep digital flexor muscles. The other ten ponies and the horses were used in studies on the stimulation of the nerves and recording of muscle evoked responses from which conduction velocity could be calculated. Conduction velocities for the radial and the median nerves were calculated and recorded.  相似文献   

12.
Spinal conduction velocities of the fastest afferent fibers of the spinal cord were calculated from the onset latencies of averaged evoked responses elicited by stimulation of the tibial nerve sensory afferent fibers and were recorded at various sites on the spinal cord. Locations for stimulation and recording electrodes were identified. Waveforms, mean amplitudes, and duration of the evoked spinal potentials were described. The mean conduction velocity of the spinal cord afferents at T12-T13 was 74.25 m/s with a SD of +/- 9.81 m/s. The mean conduction velocity of the spinal cord afferents, determined at the cisterna magna, was 80.66 m/s with a SD of +/- 11.50 m/s. This is a slight increase over the spinal conduction velocity at T12-T13 (P = 0.05).  相似文献   

13.
Supramaximal percutaneous nerve stimulation was used in motor nerve conduction velocity studies conducted in ten middle-aged, clinically normal dogs. Dogs were separated into two groups; dogs in one group weighted less than or equal to 7.5 kg and dogs in the other group weighted greater than or equal to 15.9 kg. Mean values and SEM were recorded for radial (72.1 +/- 1.9 m/s), median 65.6 +/- 2.1 m/s), ulnar (58.9 +/- 1.0 m/s), tibial (68.2 +/- 1.4 m/s), and peroneal (79.8 +/- 1.8 m/s) nerves. Values for latency, amplitude, and duration for proximal and distal evoked potentials were recorded. Analysis of mean nerve conduction velocity values for all nerves between the two groups indicated no statistical difference (P greater than 0.05). However, the two groups were statistically different (P less than 0.05) when values for distal latency and measurements of nerve length were compared. These data suggest that if latency is substituted for velocity measurements, various populations of dogs must be considered to clarify interpretation.  相似文献   

14.
OBJECTIVE: To investigate the value of nasopharyngeal and tracheal recordings of somatosensory evoked potentials (SSEP) in anesthetized dogs. ANIMALS: 10 healthy mixed-breed dogs (5 males and 5 females). PROCEDURE: Square-ware electrical stimuli (50 microseconds duration, 4Hz) were delivered through bipolar surface electrodes to the median nerve of the right forelimb with 7 to 12 mA constant current. The SSEP were recorded with soft electrodes placed on the epipharynx and dorsal wall of the trachea, respectively. Traditional scalp and neck recordings of SSEP were also performed, using SC-inserted needle electrodes. The potentials recorded dorsally and ventrally from the neuraxis were compared to assess the application of these signals for intraoperative neurophysiologic monitoring. RESULTS: Electrical stimulation of the median nerve resulted in multiphasic potentials recorded from all 4 recording sites. Latency and phase shifts were observed between the far-field potentials placed ventrally and dorsally from the neuraxis. CONCLUSIONS AND CLINICAL RELEVANCE: Potentials recorded with nasopharyngeal and tracheal electrodes are regarded suitable for intraoperative neurophysiologic monitoring in anesthized dogs.  相似文献   

15.
This study has been carried out to determine the effect of neutral position, hyperextension and hyperflexion of the tarsal joint on the tibial nerve, motor action potential latency and tarsal canal compartment pressure in dogs with the aid of electrophysiological and anatomical methods. Totally twenty healthy mongrel dogs were used. Latency of motor nerve action potential (MNAPL) studies of tibial nerve via surface stimulating and needle recording electrodes was performed on right hind limbs of all the dogs. The compartment pressures of the tarsal canal with the pressure transducer were determined from both limbs from ten of the dogs. In one dog, tarsal regions of both left and right limbs were demonstrated using magnetic resonance imaging (MRI). Two dogs were euthanatized and tarsal regions of the dogs were sectioned for correlative anatomy. Nerve conduction studies showed that the MNAP latency of the tibial nerve were 3.55 +/- 0.097 ms, 3.76 +/- 0.087 ms and 3.39 +/- 0.097 ms in neutral, hyperextension and hyperflexion positions, respectively. Hyperflexion of the tarsal joint caused prolongation of the MNAP latency of the tibial nerve with the highest pressure value being determined in tarsal canal. From the anatomical viewpoint, the distance between the flexor hallucis longus muscle and the superficial digital muscle was the shortest during hyperflexion and the plantar branch of saphenous artery, lateral and medial plantar nerves located more laterally in cadaver and MR imaging sections. As a result of this study, it is thought that tarsal region diseases as well as long time splint in the hyperflexion position as applied in the Ehmer sling can affect the compartment pressure and nerve tension because of occupying in the tarsal canal. Raising pressure and nerve stretching in the tarsal canal compartment could cause deficiencies in the conduction velocity of the tibial nerve. This might be a result of tarsal tunnel syndrome in the dog. Clinicians could consider this syndrome in cases of tarsal region diseases as well as application of long time splint in hyperflexion of tarsal joints in dogs.  相似文献   

16.
Compound motor-nerve action potentials evoked by supramaximal stimulation of the proximal and distal aspects of the tibial nerve were evaluated in chickens 1 to 15 weeks old. Motor-nerve conduction velocity increased from a mean of 22.6 m/s at week 1 to a mean of 52.7 m/s at week 15. The increase in conduction velocity was greatest for the first few weeks, and reached a plateau at 10 weeks. Subcutaneous limb temperature, limb length, and proximal latency measurements also increased with age; however, distal latency measurements were not significantly influenced by age. A quadratic equation was calculated to predict mean motor-nerve conduction velocity for maturing chickens.  相似文献   

17.
Spinal-evoked potentials were recorded from 2 litters of clinically normal mixed-breed dogs between 35 and 300 days of age. Summated responses to tibial nerve stimulation were recorded from percutaneous needle electrodes placed at L7-S1, L4-5, T13-L1, C7-T1, and the cisterna cerebellomedullaris. The ulnar nerve was stimulated with recordings at C7-T1 and the cisterna cerebellomedullaris. Amplitudes did not change significantly with age, but were significantly (P less than 0.05) different between various recording sites. On day 35, segmental and overall (L7-cisterna cerebellomedullaris) conduction velocities were less than half of the adult values. Spinal cord conduction velocities increased with age, reaching adult values at approximately 9 months of age. It was determined that quadratic equations best predicted the conduction velocities during maturation.  相似文献   

18.
In 25 adult dogs of various breeds, recurrent laryngeal nerve fibers were electrically stimulated at 2 points along their extralaryngeal course. Evoked compound muscle action potentials were recorded in the ipsilateral intrinsic laryngeal muscles, using a percutaneous needle electrode. Latencies, amplitudes, and durations were measured. Latencies were correlated with neck length (r = 0.88 on left and 0.82 on right). Five of the dogs were euthanatized, and the nerve length between the 2 stimulating needle electrodes was measured; calculated conduction velocities (mean +/- SD) were 55 +/- 6 m/s (left) and 57 +/- 6 m/s (right). In 38 additional canine cadavers, the lengths of the exposed left and right recurrent laryngeal nerves were correlated with neck length (r = 0.44 on left and 0.56 on right). A linear regression model is proposed for predicting normal latencies, despite variations in neck length among different breeds of dogs.  相似文献   

19.
Averaged evoked potentials were recorded from the scalp of 22 dogs after repetitive stimulation of the pudendal nerve. Four experimental procedures were used: (1) percutaneous needle-stimulating electrodes with dogs tranquilized with xylazine; (2) percutaneous needle-stimulating electrodes with dogs tranquilized with acepromazine; (3) percutaneous needle-stimulating electrodes with dogs anesthetized with alpha-chloralose; and (4) Sherrington type stimulating electrodes applied directly to nerves with dogs anesthetized with alpha-chloralose. The average evoked potentials were similar with all treatments. Three peaks (N1, P1, and N2) with consistent latency and amplitude were generally present, followed by additional peaks with variable latencies and amplitudes. The mean latency for N1 after direct stimulation was significantly longer than the mean latency for N1 in the 3 other groups (95% confidence intervals). There were no other significant differences in mean latencies among groups for any of the peaks.  相似文献   

20.
Using a signal-averaging system, potentials evoked by stimulation of nerves in the limbs or tail of dogs were recorded through needle electrodes placed adjacent to the vertebral column. Cord dorsum potentials (consisting of a small triphasic wave followed by a large negative peak and a subsequent slow positive phase) were recorded at the level of the lumbar enlargement after stimulating nerves in the pelvic limb or tail, and at the cervical enlargement after forelimb nerve stimulation. Ascending volleys were recorded from appropriate levels of the spinal cord or from regions of the cauda equina. After forelimb nerve stimulation, a large slow potential, reflecting activation of an unidentified neuronal pool, was recorded at the level of the first cervical vertebra. Percutaneously recorded potentials were closely similar to those recorded directly from the dura mater, suggesting that the method accurately recorded spinal cord electrical events and, therefore, might be of use in studying clinical or experimental spinal cord disease.  相似文献   

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