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Biomedical subjects

C Z Hong

Publications and source records attributed to C Z Hong.

At least 19 recordsLinked to original sources
PubMed1991

All peroneal motoneurons of the rat survive crush injury but some fail to reinnervate their original targets.

This is a quantitative study of the motoneuronal population of the rat's common peroneal nerve following severe crush injury of the sciatic nerve or its component branches. The crush was performed unilaterally under anesthesia for 60 seconds with hemostat jaws covered with tubing to form a smooth, 2 mm long, injured zone. Recovery from injury was allowed for 14 to 188 days. It was measured behaviorally using the sciatic functional index (SFI) and electrophysiologically by comparing the conduction velocity and amplitudes of evoked muscle action potentials prior to injury, and again after injury just before the nerve was labeled with horseradish peroxidase (HRP), and/or its wheat germ agglutinin conjugate (WGA-HRP), 48-72 hours before sacrifice. The motoneurons were retrogradely labeled on both sides so that the uninjured side might serve as a control. On the injured side the nerves were labeled either distal or proximal to the crush site. The tibialis anterior muscles on both sides were removed and weighted. Spinal segments L2 to L6 were cut in serial, frozen cross-sections. HRP reaction products were formed using TMB as the chromogen. The normal peroneal nerve was found to contain 634 +/- 26 motoneurons (22 cases). The number of motoneurons labeled 5-15 mm distal to the injury site (22 cases) was 535 +/- 69 or 84.4% of normal. In 12 cases in which the nerve was labeled 5 mm proximal to the injury normal population numbers (648 +/- 30) were found. These counts demonstrated that the unlabeled 15.6% in the distal labeled cases had not vanished as a result of cell death. Instead, the unlabeled group was composed mainly of small motoneurons whose axons probably had not regenerated distal to the crushed zone. Mean soma size of injured neurons increased to maximum 3-6 weeks after injury and then gradually decreased in size over the following weeks to nearly normal values. This transient increase in size was due to two factors: 1) soma swelling in response to axonal injury, and 2) absence of many small motoneurons, presumably gamma-motoneurons, which were either incapable of, or prevented from, regenerating beyond the injury zone long after larger motoneurons had reinnervated their targets. SFI scores, muscle weights, and amplitude ratios of evoked potentials recovered to control values by 70-80 days post-injury. Conduction velocities remained 20-25% below normal at the end of 80 days.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Effects of a topically applied counterirritant (Eucalyptamint) on cutaneous blood flow and on skin and muscle temperatures. A placebo-controlled study.

This study was designed to investigate the effects of a new product of counterirritant, Eucalyptamint, on the cutaneous circulation and on skin and muscle temperatures. Ten normal subjects (six males and four females, with an average age of 34 +/- 6 yr) were involved in this study. Eucalyptamint was applied to the anterior forearm skin of one side, and placebo was applied to the contralateral forearm. The subjective feelings, cutaneous blood flow, and skin temperature were measured before and periodically (5-min intervals) after the application of the compound. Muscle temperature was measured before and 30 min after the application of the Eucalyptamint. There was no significant effect on the subjective sensation. However, there were statistically significant (P less than 0.05) increases in cutaneous blood flow (up to 4 times base-line) and skin temperatures (up to 0.8 degrees C higher than base-line) after the application of Eucalyptamint with the effects lasting up to 45 min after the application. The muscle temperature was also increased (0.4 degrees C) significantly (P less than 0.05) 30 min after application of the Eucalyptamint. There were no significant changes in the placebo application. The results of this study suggested that the new product of counterirritant, Eucalyptamint, produced significant physiologic responses that may be beneficial for pain relief and/or useful to athletes as a passive form of warm-up.

Adult↗
PubMed1991

Reversible nerve conduction block in patients with polyneuropathy after ultrasound thermotherapy at therapeutic dosage.

This study investigated the effect of ultrasound on nerve conduction in patients with polyneuropathy. Eight able-bodied controls (Group C) and 16 patients with clinical and physiologic evidence of polyneuropathy were tested. Eight patients (Group NP) had no aching pain symptoms; eight patients (Group P) had severe aching pain, burning sensation, unpleasant tingling, and/or hyperesthesia in the lower extremities. For two minutes, therapeutic ultrasound in doses of 0.5, 1.0, and 1.5W/cm2 were applied over the anterior surface of the leg along the pathway of the deep peroneal nerve. Peroneal nerve conduction studies were performed before, during, and after ultrasound treatment. The compound muscle action potential (CMAP) was recorded from the extensor digitorum brevis muscle. Nerve conduction studies on all eight patients in Group P revealed a significant decrease (41.4% and 44% reduced for doses of 1.0W/cm2 and 1.5W/cm2, respectively; p less than .05) in amplitude of CMAP (from baseline to the first negative peak), and an increase (6.4% and 6.7% increased for doses of 1.0W/cm2 and 1.5W/cm2, respectively; p less than .05) in proximal latency one minute after ultrasound application with a dose of 1.0 or 1.5W/cm2, but not with a dose of 0.5W/cm2 (p greater than 0.1). Changes returned to pretreatment values within five minutes of cessation of ultrasound therapy. In Groups C and NP, there were no significant changes in amplitudes of CMAP or proximal latency before, during, or after ultrasound therapy at a dose of 0.5, 1.0, or 1.5W/cm2. It was concluded that ultrasonic therapy with therapeutic dosage may cause a reversible conduction block on patients with painful polyneuropathy.

Action Potentials↗
PubMed1991

Conduction of the dorsal digital branches of the radial nerve to the long finger.

Orthodromic conduction of the radial nerve digital branches to the third digit from the anatomic snuffbox has rarely been described. This paper describes a technique for measuring conduction of the lateral and medial digital branches of the radial nerve to the third digit at a distance of 10cm from the base of the digit to the anatomic snuffbox. An evoked response from the lateral digital branch was recorded in each of the 56 nerves tested. Responses had an average latency of 2.10 +/- .18msec. Responses from the medial digital branches of the nerve were obtained in only 55% of the 49 nerves tested. Responses had an average latency of 2.11 +/- .21msec. When no appreciable response was recorded at the anatomic snuffbox from the medial digital branch, a response was recorded from the ulnar nerve at the volar wrist at 14cm.

Action Potentials↗
PubMed1990

Short-term exposure to a 1.5 tesla static magnetic field does not affect somato-sensory-evoked potentials in man.

The literature is contradictory regarding the effect of static magnetic fields on the function of the central nervous system of mammals. Since human subjects are exposed to intense static magnetic fields during magnetic resonance imaging, it is important to determine if the static magnetic field adversely affects the nervous system of man. Therefore, somato-sensory evoked potentials (SEPs) elicited from median nerve stimulation were measured in 11 normal subjects before and during short-term exposure to a 1.5 Tesla static magnetic field. Specially modified instrumentation was used to record SEPs that were unperturbed by the static magnetic field. There were no statistically significant differences in the N20 or P25 latencies or in the amplitude from N20 negative peak to P25 positive peak of the SEPs obtained before compared to those recorded during exposure to the static magnetic field. In addition, there were no changes in the waveforms associated with exposure to the static magnetic field. We conclude that short-term exposure to a 1.5 Tesla static magnetic field does not affect SEPs (i.e., nerve conduction and synaptic transmission were within normal limits) in normal human subjects.

Adult↗
PubMed1990

Local steroid injection: its effect on the recovery of nerve conduction in experimental neuropathy.

This study was designed to investigate the effectiveness of local steroid injection on the recovery of nerve conduction in acute compression neuropathy. Experimental neuropathy with complete conduction block was produced by mechanical compression of the caudal nerves of 24 rats. Five days after compression, the compression site was injected with 0.2 mL Dexamethasone acetate (8 mg/mL suspension) in eight rats (group A), and 0.2 mL normal saline in another eight rats (group B). The remaining eight rats (group C) received no injection. Motor nerve conduction velocity (NCV) over the compressed segment, as well as amplitude of the evoked compound muscle action potential (CMAP) recorded from the segmental tail muscles, were measured before nerve compression and three times per week after nerve compression. The recovery rates of NCV of the caudal nerve were not significantly different among the three groups. The recovery rate of amplitude of CMAP in group A was significantly higher than that in groups B or C (p less than 0.01). However, there was no significant difference in recovery rate of the amplitude of CMAP between groups B and C. It is concluded that local steroid injection to the site of nerve compression may facilitate the recovery of nerve conduction block but not the recovery of demyelinative lesion.

Action Potentials↗
PubMed1989

Increased skin temperature after vibratory stimulation.

The skin temperature effect of vibratory stimulation was studied in 28 healthy subjects. Vibration (50 Hz or 100 Hz) was applied to the volar surface of the left forearm for 15 min. Skin temperature of the bilateral forearms was measured before and immediately after cessation of vibration and at 5 and 10 min postvibration. Vibration at 100 Hz for 15 min on all 28 subjects was associated with a temperature increase of 4.20 +/- 0.79 degrees F that was significantly (P less than 0.01) higher than that in the controls (0.38 +/- 0.33 degrees F). Skin temperature decreased to previbration levels by 50 min of postvibration. The 11 subjects who received 50-Hz vibration for 15 min showed a skin temperature increase (0.75 +/- 0.23 degrees F) in the vibrated forearm significantly (P less than 0.01) higher than that in the control forearm (0.11 +/- 0.17 degrees F). All measurements decreased to previbration skin temperatures by 10-min postvibration. Vibration at 100 Hz also produced skin erythema in all subjects, whereas 50-Hz vibration produced no erythema. The mechanism by which 100-Hz vibration relieves pain is largely unclear, but it could be associated with increased skin temperature and erythema.

Adult↗
PubMed1989

Peroneal nerve entrapment at the knee localized by short segment stimulation.

The purpose of this study was to evaluate the usefulness of short segment stimulation (SSS) of the peroneal nerve at the knee in order to localize the site of compression and/or entrapment of the nerve. Eighteen patients with suspected peroneal nerve palsy and 28 controls were studied by SSS of the peroneal nerve across the knee. Compound muscle action potentials (CMAPs) were obtained from the extensor digitorum brevis muscle after successive supramaximal stimuli of the nerve at 2 cm intervals, starting 4 cm distal (D4 and D2) and ending 6 cm proximal (P2, P4, and P6) to the fibular head prominence (P). In patients the average conduction times from D2 to P, P to P2, and P2 to P4 were significantly (P less than 0.05) longer and the average amplitude of CMAPs at P, P2, P4, and P6 significantly (P less than 0.05) lower than those of controls. Fourteen patients showed statistically significant reduction in amplitude and prolongation of conduction time in one or more short segments. Three patients had prolongation of conduction time only and one patient had reduction in amplitude only. When nerve conduction of the entire 10-cm segment across the knee was tested by the conventional method, only nine showed reduction in amplitude from proximal stimulation, or slowing of motor conduction velocity across the 10-cm segment or both. It was concluded that the SSS technique is a sensitive and reliable procedure for the detection of mild compression or entrapment of the peroneal nerve around the knee.

Action Potentials↗
PubMed1989

Electrophysiologic recovery of acute conduction block of rat tail nerve.

The recovery of experimental compression neuropathy with prolonged conduction block of the caudal nerve was studied electrophysiologically in 48 adult Sprague-Dawley albino rats divided equally into six groups. The pressure applied in groups A, B, C, D, E, and F was approximately 20kg/cm2 for 20 minutes, 20kg/cm2 for 10 minutes, 20kg/cm2 for 5 minutes, 10kg/cm2 for 20 minutes, 20kg/cm2 for 10 minutes, and 10kg/cm2 for 5 minutes, respectively. The motor nerve conduction velocity (NCV) and the amplitude of the evoked compound muscle action potential (CMAP) were measured before and periodically after nerve compression. The period of initial complete block was significantly longer in the high pressure groups than in the lower ones, and also significantly longer in the nerves compressed for 20 minutes than for those compressed for five or ten minutes. Thus, the severity of conduction block seems to be related to both pressure and duration of compression. Once the conduction block began to recover, the recovery rate of conduction block (recovery rate of amplitude ratio of CMAP, proximal/distal) was not significantly different. The recovery rate of demyelinative lesion (NCV recovery rate) was also not significantly different among the six groups. The degree of compression seems to determine the severity of the initial conduction block, but not the subsequent recovery rate of conduction.

Action Potentials↗
PubMed1989

Early smooth horizontal eye movement: a favorable prognostic sign in patients with locked-in syndrome.

Locked-in Syndrome (LIS) is a rare clinical entity consisting of quadriplegia, paralysis of lower cranial nerves, mutism, and bilateral paresis of horizontal gaze. The prognosis is usually poor. Most patients who do survive have severe residual impairment or develop chronic LIS. Review of the literature shows that recovery has been reported but not systematically studied, particularly with respect to early prognostic signs. We report a case of LIS with bilateral pontine infarctions shown by MRI. Severe neurological deficits included quadriplegia, paresis of horizontal gaze, facial paralysis, and bulbar palsy. Horizontal eye movements were present and smooth by the second week after onset. The patient had almost full functional motor recovery within four months, after a comprehensive rehabilitation program. Fourteen other reported cases of LIS with full recovery had documented recovery of lateral gaze in the early stage. In addition, smooth horizontal gaze is the most frequent activity in incomplete LIS. Early recovery of horizontal eye movement may indicate that the brain lesion is limited and may be a good prognostic sign in LIS.

Adult↗
PubMed1988

Learning ability of young rats is unaffected by repeated exposure to a static electromagnetic field in early life.

Infant albino rats were exposed to a static electromagnetic field of 0.0 Tesla (control) or 0.5 Tesla (experimental) for 14 postnatal days. Following a 1-month rest period, the experimental (13 males and 10 females) and control (11 males and 14 females) rats were trained on four successive reversals of a position habit in a single-unit enclosed T-maze that was adapted for the use of escape-avoidance of mild foot shock as a motive. There was no significant difference in learning ability between the experimental and control groups in terms of total (initial combined with repetitive) errors committed over the four reversal problems. While the females tended to make more errors than the males, this difference was likewise insignificant.

Age Factors↗
PubMed1988

Averaged F-wave conduction velocity of peroneal nerve.

Averaged F-wave conduction velocities (a-FWCV) of peroneal nerve were measured on 38 healthy volunteers and 22 patients with clinical and electromyographic evidence of unilateral L5 or L5 + S1 radiculopathy. The peroneal nerve was stimulated supramaximally at the fibular head and the compound muscle action potential was recorded from the extensor digitorum brevis muscle. Averaged tracings from 32 consecutive stimuli were obtained. The averaged F-wave latency (Fp) and M-wave latency (Mp) were measured from the stimulating artifact to the peak of the waves. The distance (D) between the stimulating point and the T12 spinous process was measured. The value of a-FWCV was calculated as 2D/(Fp-Mp-1) m/second. In normal subjects, the average value of a-FWCV was 56 +/- 4, and there was no significant difference between males and females, nor between the right and left sides. The differences among the tests administered at different times on the same subject were also statistically insignificant. Of the 22 patients, 17 had subnormal value of a-FWCV if the lower normal limits were defined as mean minus 2.5 SD (i.e., 46 m/second) calculated from the normal control value. However, only one of them had subnormal value of FWCV calculated by the conventional method (without averaging technique). All the patients with two root (L5 + S1) involvement had subnormal a-FWCV. It is concluded that the a-FWCV is a more sensitive measure than the conventional FWCV in the assessment of L5 radiculopathy.

Adult↗
PubMed1988

Averaged axillary F-loop latency of median and ulnar nerves.

Axillary F-loop latencies (AFLL) were measured on median and ulnar nerves of 54 normal volunteers. The median and ulnar nerves were stimulated at the wrist and at the axilla 25cm distal to the sternal notch. The compound muscle action potentials were recorded from thenar and hypothenar muscles. Averaged tracings from 32 consecutive stimuli at the wrist were obtained. The averaged F-wave latencies were measured to the peak (Fwp) of the averaged F-wave. The M-wave latencies from wrist and axilla stimulation were measured to the onset of the wave (Mw and Ma, respectively). The averaged AFLL (a-AFLL) was calculated as (Fwp + Mw)-2 Ma. The average values of a-AFLL were 14.12 +/- 0.88msec for median nerve, and 13.97 +/- 0.90msec for ulnar nerve. There was no significant difference between male and female subjects, nor between the right and left sides. Seven subjects with EMG evidence of C8 or C8 to T1 radiculopathy, although manifesting normal AFLL gauged by the regular method (ie, measured to the onset of the shortest F-wave latency among eight tracings), had significantly longer "averaged AFLL" in both median and ulnar nerves of the affected side than the a-AFLL obtained from the normal side. It is concluded that the a-AFLL is a more sensitive measure than the "regular AFLL" in the assessment of proximal nerve lesion (especially C8 or C8 to T1 radiculopathy).

Adult↗
PubMed1988

Electrophysiologic studies of the median nerve and its palmar cutaneous branches after nerve grafting.

Electromyography (EMG) and nerve conduction studies were performed on a patient with an incomplete lesion of the median nerve involving the motor fibers to the thenar muscles, the palmar cutaneous branches, and the sensory fibers to the index finger. The studies were done before, and 13 weeks, 16 weeks, and one year after grafting. The preoperative electrodiagnostic evaluation showed abnormalities involving the median motor fibers and the palmar cutaneous branch. Electromyography of the opponens pollicis and abductor pollicis brevis before surgery showed severe active denervation. Thirteen weeks after nerve grafting, the median motor distal latency was prolonged and the amplitude of the evoked potential of the median motor and index finger digital sensory nerves were decreased. At 16 weeks, both the latency and amplitude showed improvement, as did EMG of the affected muscles. One year later, the electrophysiologic findings were normal except for a slightly prolonged median motor distal latency. Clinical and functional improvement after grafting correlated well with the electrophysiologic findings. We conclude that EMG and nerve conduction studies are useful tools for following the progression of recovery after nerve grafting.

Action Potentials↗
PubMed1988

Ultrasound thermotherapy effect on the recovery of nerve conduction in experimental compression neuropathy.

Bilateral tibial nerves of 18 albino rats were mechanically compressed between knee and ankle. Beginning on the fifth day after compression, ultrasound thermotherapy of 0.5 or 1.0watt/cm2 was applied over the area of nerve compression in one limb for one minute three times per week. The other side (control) was not treated. Motor distal latency (DL), motor nerve conduction velocity (NCV) of the segment with nerve compression, and amplitude of the evoked compound muscle action potential (ACMAP) were measured before and immediately after nerve compression and two or three times per week after compression. The recovery rates of NCV and ACMAP of the tibial nerve treated with ultrasound of 0.5watt/cm2 were significantly faster than those of the control nerve. There was no significant change in the recovery rate of DL. However, if ultrasound of 1.0watt/cm2 was applied, the recovery rate of ACMAP of the treated nerve was slower than that of the control nerve. There were no significant changes in the recovery rates of DL and NCV. Low doses of ultrasound thermotherapy may facilitate recovery of compression neuropathy, but higher doses may induce an adverse effect.

Action Potentials↗
PubMed1987

Rehabilitation in dual disability of hemiplegia and upper extremity amputation: two case reports.

Dual disability involving amputation and hemiplegia is relatively rare. The vast majority of these cases involve lower extremity amputations. In this report two patients sustained a right-sided hemiplegia complicating an old left upper extremity amputation. Through the comprehensive rehabilitation program these two patients were able to make gains, especially in some activities of daily living and in lower extremity functions. Since some of the upper extremity activities, such as dressing or bathing, could not be accomplished, it appears that patients with upper extremity amputation who have a contralateral hemiplegia have a poorer prognosis for achieving functional independence than patients with lower extremity amputation and similar neurologic loss.

Amputation, Surgical↗
PubMed1987

Static magnetic field influence on human nerve function.

In an attempt to understand the possible neural mechanism mediating the effects of a static magnetic field (SMF), nerve conduction velocity (NCV) and excitability index (EI), measured as the ratio of the amplitude of the submaximally evoked compound muscle action potential during or after magnetic exposure to that before exposure from the same intensity of stimulation of the motor nerve, were studied on ten normal volunteers (aged 17 to 39), when the nerve was exposed to an SMF of 1 tesla (T) for 15 seconds. NCV and EI were measured before, during (5, 10, and 15 sec) and three minutes after magnetic exposure. Both NCV and EI were measured on median nerve in all ten subjects, the peroneal nerve in seven subjects, while the ulnar nerve was measured for only EI in eight subjects. There was no significant change in NCV over the segment exposed to the magnetic field. However, EI was significantly increased during the magnetic exposure in all three nerves. The effects were observed as early as five seconds after exposure and disappeared by three minutes after exposure. It is concluded that the excitability of the motor nerve is increased when it is exposed to an SMF with a density of 1T.

Action Potentials↗