H-reflex Latency Research Articles

Normal range for H-reflex recording from the calf muscles.

This study was performed to derive the normal range for H-reflex latency, recording from the calf, on a large and varied subject population. Two hundred fifty-one asymptomatic subjects without risk factors for neuropathy were tested bilaterally. The results were analyzed to determine whether various demographic characteristics were associated with different results. A repeated measures analysis of variance was performed with the latency as the dependent variable and age, race, gender, body mass index (kg/m2), and height as the independent variables. A significance value of P < or = 0.01 level was used. Side-to-side variability was also examined, and, for this measure, a repeated measurements analysis was not necessary because there was only one measurement per subject; a simple analysis of variance was used. Age and height were noted to be associated with different mean latencies; race, gender, and body mass index were not. The mean H-reflex latency was 30.3 +/- 2.4 ms, and the upper limits of normal (mean + 2 SD) for the various categories of age and height ranged from 30.0 to 38.2 ms. In addition, the upper limits of normal were derived as the 97th percentiles of observed latency values. For all subjects taken together, this value was 35.0 ms, and, for the various subgroups, it ranged from 29.7 to 36.4 ms. Mean side-to-side variability was 0.2 +/- 1.0 ms, with an upper limit of normal of 2.2 ms as the mean + 2 SD or 2.0 ms as the 97th percentile.

Reproducibility of tendon jerk reflexes during a voluntary contraction

Objectives: The present study explored whether testing tendon jerks during voluntary contraction of the test muscle would improve reproducibility by effectively ‘clamping’ the excitability of the motoneurone pool at firing threshold.Methods: Tendon jerk reflexes of soleus, tibialis anterior and vastus lateralis and the soleus H reflex were recorded in 12 healthy subjects at rest and during voluntary contractions of 10–20% of maximum. Recordings were repeated 8–10 times in 5 subjects, in whom reflex symmetry was also determined.Results: Not all tendon jerk reflexes could be recorded at rest, and the variability of latency and amplitude was high. All reflexes could be recorded in each subject during contractions. The latency of tendon jerk reflexes decreased by approximately 2 ms during contractions, but H-reflex latency decreased by only 0.2–0.3 ms. For the tendon jerks, an asymmetry of >3.0 ms at rest and >2.5 ms contracting would be outside 3 SD of the normal mean. In repeat studies, the coefficient of variation of reflex latency was <4% for the tendon jerk.Conclusions: A voluntary contraction could potentiate the tendon jerk by a number of mechanisms, but the most important is probably enhancement of the excitability of the motoneurone pool. The present techniques should increase the value of tendon reflex testing when assessing possible peripheral nerve, plexus and root disturbances.

Body mass index effect on common nerve conduction study measurements.

This study was performed to determine whether there is a difference in nerve conduction study (NCS) measures based on body fat (body mass index; BMI). Two hundred fifty-three subjects had the following NCS tests performed on them: median, ulnar, peroneal, and tibial motor studies; median, ulnar, radial, and sural sensory studies; median and ulnar mixed nerve studies; and H-reflex studies. BMI was calculated as weight (kg) divided by height (m) squared. A repeated measures analysis of variance was run adjusting for age, sex, and height and using BMI as both a continuous variable and by dividing BMI into upper, middle, and lower thirds. The sensory and mixed nerve amplitudes correlated significantly (P < or = 0.01) with BMI for all nerves tested, with means being approximately 20-40% lower in the obese than in the thin subjects. No correlation was noted between BMI and nerve conduction velocity, H-reflex latency, or most of the other motor/sensory/mixed measures. The correlation between increased BMI and lower sensory/mixed nerve amplitudes should be taken into account in clinical practice.

Experimental jaw-muscle pain does not change heteronymous H-reflexes in the human temporalis muscle.

Muscle pain generally has an inhibitory effect on voluntary orofacial motor function. However, it is not known whether muscle pain causes direct or indirect changes in motoneuron excitability. In this study a monopolar needle stimulation technique was used to evoke the direct motor response (M-response) in the left masseter muscle and the heteronymous H-reflex in the left temporalis muscle as an indirect measure of motoneuron excitability. Series of 20 repeated electrical stimuli were delivered at 50% of maximal voluntary contraction (MVC) before, during, and after periods with experimental jaw-muscle pain in 11 healthy subjects. Pain was induced by standardized infusion of hypertonic (5%) saline into the mid-portion of the right masseter muscle. The mean pain intensity rating on a 100-mm visual analog scale was 42+/-5 mm. The short-latency responses (less than 6 ms) could be evoked in all subjects. Analysis of the latency and amplitude of the temporal H-reflex indicated no significant effect of jaw-muscle pain. The amplitude of the masseteric M-response was significantly smaller in the postpain condition than in the pain conditions (ANOVA, P=0.018), but no differences were found between the prepain and postpain conditions. In nine subjects, poststimulus periods (mean offset latency, 69.6+/-8.6 ms) with significantly (more than 50%) suppressed EMG activity were detected in the ipsilateral masseter muscle following the M-response (mean offset latency, 5.5+/-0.2 ms). These reflex responses did not show a systematic change during the pain conditions. In conclusion, acute contralateral jaw-muscle pain does not seem to modulate the motoneuron excitability as measured by the heteronymous H-reflex.

NECK RETRACTION INCREASED CERVICAL H-REFLEX AND DECREASED NECK PAIN.

1392 Neck exercises are the central treatment protocol for patients with neck pain. Extension, flexion or retraction movements have been prescribed based on patients self report of pain. The purpose of this study was to evaluate the use of the flexor carpi radialis (FCR) H-reflex in determining cervical root compression and decompression during neck retraction and correlate the finding with neck pain. Twelve subjects (20-40y) with confirmed symptoms of neck pain for more than 6 months volunteered for the study. The FCR H-reflex was elicited by electrical stimulation of the median nerve at the cubital fossa(0.5 ms., 0.2 pps at H-max) using bipolar surface electrodes. Signal was recorded from the FCR muscle using 500-2000 gain and 10-10,000 Hz bandpass. Pain intensity of the neck (evaluated by visual analog scale) and the H-reflex were recorded before and after A-upright sitting, B- 20min of reading and C- 20 repetitions of neck retractions. The peak to peak amplitude and the deflection latency were measured and averaged for 4 reflex representations. One way ANOVA and Spearman correlation were used for statistics. Results showed significant decrease in the H-reflex amplitude after reading and significant increase after neck retractions (p<0.001). No measurable changes were recorded in the H-reflex latency (p<0.34). Neck pain intensity was significantly increased after reading and decreased after neck retraction(p<0.001). Changes in the H-reflex amplitude and pain intensity during different testing conditions were strongly correlated (r=0.85- -0.82). These results imply a cervical root decompression during neck retractions and suggest it for effective therapy. They also confirm the objective utility of the FCR H-reflex for on line evaluation of patients with neck pain.

A new method for eliciting and studying H-reflexes in the human masseter

A non-invasive method is presented for transmuscular stimulation of the masseteric nerve, using a frame to apply a cathode to the mandibular notch and an anode to the inside of the mouth. The H-reflex response was recorded using surface, macro and single motor-unit (SMU) electromyography (EMG) from the masseter. The latency of the reflex response representing the H-reflex in SMUs was determined from the cumulative sum of the peristimulus time histogram. This latency was then corrected using a spike-trigger averaging technique, where the SMU spikes were used as triggers and the macro EMG recording as the source. SMU latencies for the H-reflex in masseter were in the range 5.9–8.8 msec, whereas H-reflex latencies for surface EMG varied between 5.4 and 6.4 msec.

Normal values of patellar and ankle tendon reflex latencies

The clinical value of latency measurement of tendon reflexes in neurological patients has been reported by several authors. However, normal values are not readily comparable. In the present study, latencies and amplitudes of patellar (PTR) and ankle tendon reflexes (ATR) were measured at rest and after facilitation in 102 normal controls. A manually operated reflex hammer, tipped with electrically conductive rubber, ensured an immediate start of the sweep of the oscilloscope. Latencies showed a significant correlation with height ( r = 070 for PTR and r = 072 for ATR, P < 0.0001) and to a lesser degree with age ( r = 016 and r = 0.30, P < 0.0001). While amplitudes were highly variable, rendering them less useful for diagnostic purposes, latencies showed minimal intra-individual variability (CV 15 and 08%, respectively). Correlation of ATR-latency with the H-reflex latency of the soleus muscle was very high ( r = 097, P < 0.0001). Comparison with three other hammer types yielded corresponding results with a hammer supplied with a piezo-electric element; however, significantly shorter latencies were found with a hammer with a microswitch, and with another hammer with a spring-contact, due to a delay from the tap on the tendon until the start of the sweep of the monitor.

Utility of H-reflex in the Diagnosis Cervical Radiculopathy

H-reflex is a kind of late respons which can be used for the proximal nerve conduction study. Also it is a useful and widely used nerve conduction technique es to look electrically at the monosynaptic reflex. Although recordable from all muscles theoretically, H-reflexes are most commonly recorded from the calf muscles following stimulation of the tibial nerve in the popliteal fossa. But in this study, We tried to establish the normal data and to evaluate the significance of the H-reflex study in cervical radiculopathy. H-reflexes were recorded from flexor carpi radialis (FCR) muscle, extensor carpi radialis (ECR) muscle, brachioradialis (BR) muscle, and abductor digiti minimi (ADM) muscle in 31 normal adults (62 cases) and 12 patients with cervical radiculopathy. The mean values of H-reflex latency in normal control group were msec in FCR; msec in ECR; msec in BR; msec in ADM. And the mean values of side to side difference of H-reflex latency were msec in FCR; msec in ECR; msec in BR; msec in ADM. Mean values of side to side differences of interlatency time were msec in FCR; msec in ECR; msec in BR; msec in ADM. Also, there were no significant differences in H-reflex latency between right and left side. H-reflex tests in patient group with cervical radiculopathy revealed abnormal findings in 11 out of 12 patients. These results suggest that H-reflex in the upper extremity would be helpful in the diagnosis of the cervical radiculopathy.

P135 Retest reliability in facial nerve conduction studies

The H-reflex on stimulation of the tibial nerve in the popliteal fossa is routinely used in the diagnosis of first sacral (S1) nerve-root radiculopathy. The H-reflex latency, however, is considered to lack sensitivity since a small change from the focal root pathology can be diluted in a relatively long reflex latency. We have studied the soleus H-reflex elicited by stimulation of the S1 nerve root at the S1 foramen. The normal values for the S1-foramen H-reflex have been reported in a previous study, but there are no definitive reports in patients with S1 radiculopathy. This study was undertaken to determine whether stimulating at the S1 nerve root can improve the utility of the H-reflex for detecting an S1-root lesion.A randomised paired-study design was utilised to evaluate two H-reflexes: one elicited with tibial nerve stimulation and one elicited with S1-root stimulation. Fifty-five patients with unilateral S1 radiculopathy, confirmed by clinical, electrodiagnostic and magnetic resonance imaging (MRI) evidences were studied. A high-voltage electrical stimulator was used to elicit H-reflexes bilaterally at the S1 foramen and L4/L5 spine level. Latencies were compared with previously generated normal values and similar responses from the asymptomatic leg, focussing on the interval between the peak of M- and H-waves (HMI).On the symptomatic side, 39 of the 55 patients had abnormal tibial H-reflex latencies and 54 patients had abnormal responses on S1-foramen stimulation (absent in 18; HMI prolonged >0.4 ms in 36). On the asymptomatic side, all 55 patients had normal tibial H-reflexes, and 52 had normal responses on S1-foramen stimulation. In three patients, the HMI was abnormal on S1-foramen stimulation. In 46 patients tested with L4/L5-level stimulation, H-reflex was present in 39 and absent in seven. The latency of the M-wave to S1 stimulation was normal.Abnormal S1-root H-reflexes reveal lesions at the S1 root in patients with normal tibial H-reflexes; therefore, enhancing diagnostic sensitivity. The appearance of the H-reflex to L4/L5-level stimulation in patient with absent H-reflex to S1-foramen stimulation further localises the site of S1 nerve-root lesion to the L5/S1 spine level. Thus, H-reflex to S1-root stimulation significantly increases the diagnostic sensitivity for S1 radiculopathy.In our study, the S1-root H-reflex with high-voltage electrical stimulation has shown greater sensitivity than the tibial H-reflex in evaluating S1 compressive radiculopathies. An abnormal S1-root H-reflex helps to localise the lesion to the S1 root in patients with concurrent abnormal tibial nerve H-reflex, which may increase diagnostic specificity.

Central H-reflex latency from S1 root stimulation. I. Intraspinal conduction time of S1 root

Central H-reflex latency from S1 root stimulation. I. Intraspinal conduction time of S1 root

Central H-reflex latency from S1 root stimulation. II. A highly sensitive test for S1 radiculopathy

Central H-reflex latency from S1 root stimulation. II. A highly sensitive test for S1 radiculopathy

Normal limits of side-to-side H-reflex amplitude variability

Our hypothesis was that side-to-side difference in the tibial H-reflex amplitude can aid in the diagnosis of unilateral S1 radiculopathy with an otherwise normal side-to-side H-reflex latency difference. We studied 47 healthy subjects, (mean ± SD, 35 ± 10 years) using methods similar to those described by Braddom and Johnson. Only those with side-to-side latency difference less than 1.5msec were included (n = 45). Current was increased in 0.5 to 1.0 mA increments until the H-reflex amplitude maximized and then fell; on each side the response with the maximal peak-to-peak amplitude was measured for peak-to-peak amplitude and onset latency. The amplitude on the side of the smaller response was expressed as a ratio of the contralateral amplitude; this mean value (±SD) was 0.74 ± 0.17. We conclude that a side-to-side amplitude ratio smaller than 0.4 (mean − 2 SD) in the face of a normal side-to-side latency difference is probably abnormal.

The relationship between estimates of Ia-EPSP amplitude and conduction velocity in human soleus motoneurons.

There are several parameters associated with motoneuron size, among which are the conduction velocity of the axon as well as the size of the excitatory postsynaptic potential (EPSP) induced by stimulation of Ia afferents in the corresponding muscle nerve. In particular, it has been established in animal experiments that small motoneurons with a low conduction velocity exhibit large Ia EPSPs, whereas large motoneurons with a high conduction velocity show small Ia EPSPs. Thus small motoneurons are recruited earlier than large ones. In this study, we investigated whether such a relationship between motoaxon conduction velocity and size of the Ia EPSPs could also be found for human soleus motoneurons. In total, 36 motor units from six healthy volunteers were activated by a slight voluntary contraction and exposed to 200 stimuli of the tibial nerve in the popliteal fossa. Stimuli were delivered using a special stimulus protocol ensuring a constant pre-stimulus spike density along with a constant rate of discharge of the investigated unit. From the stimulus-correlated spike train data a measure of Ia-EPSP amplitude was obtained, along with the single-unit H-reflex latency. Additionally, for each unit, the so-called surface macro EMG was recorded, which measures the complete electrical activity attributable to the unit investigated. From the macro EMB, the intramuscular delay from arrival of each action potential at the soleus muscle and the detection of the muscle-fiber action potential picked up by the recording needle electrode were measured. All single-unit H-reflex latencies were corrected for the corresponding intramuscular delays. From the corrected latencies, single-unit conduction velocities were obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

INTRAMUSCULAR RECORDING OF H-REFLEXES FROM MUSCLES OF THE POSTERIOR COMPARTMENT OF THE LOWER LEG

This study was designed to elucidate the role of different muscles of the posterior compartment of the lower leg in the generation of the surface-recorded H-reflex. H-reflexes were evoked through percutaneous stimulation of the posterior tibial nerve and recorded concurrently, using monopolar electrodes from the soleus (SOL), medial and lateral gastrocnemii (MG and LG), tibialis posterior (TP), flexor digitorum longus (FDL), and flexor hallucis longus (FHL). There were significant (P less than 0.01) differences in the amplitudes, latencies, and modified H:M ratios of the responses recorded from the different muscles. The SOL modified H:M ratios were consistently the highest (x = 1.02), while the H:M ratios for MG (x = 0.34) and LG (x = 0.37) were consistently the lowest. Latencies of H-reflexes obtained from proximal recording sites (x = 29.2 ms) were significantly shorter than those from the most distal site (x = 31.5 ms). These results establish the contribution made by various deep and superficial muscles to the conventionally recorded H-reflex and help explain the differences in H-reflex amplitudes and latencies when recordings are made from different sites.

The Inverse Relationship Between Nonverbal Intelligence and the Latency of the Hoffmann Reflex from the Right and Left Thenar Muscles in Right- and Left-Handed Subjects

The relationship between nonverbal reasoning ability and the latency of the Hoffmann (H) reflex was studied in right- and left-handed subjects. The nonverbal reasoning ability was assessed by the Cattell's Culture Fair Intelligence test. Hand preference was assessed by the Edinburgh Handedness Inventory. Hoffmann reflex was recorded from thenar muscles of the right and left thumbs. In left-handers (total sample), IQ was found to be significantly and negatively linearly related to the H-reflex latency from the left side. In strong left-handers, there was a significant negative linear relationship between IQ and the H-reflex latency from right and left sides, but with a higher correlation for the left side. In weak left-handers, IQ did not show any significant relation to the H-reflex latencies from the right and left sides. In right-handers (total sample), there was a significant negative linear correlation between IQ and the H-reflex latency from the right side. In right-handed women without familial sinistrality (FS-), IQ was found to be inversely related to the H-reflex latency from the right and left side, but with a higher correlation for the right side. In right-handed women with FS, IQ did not show any significant relation to the H-reflex latency from the right and left sides. In right-handed men with right eye preference and FS-, IQ was found to be negatively linearly related to the H-reflex latency from the right and left sides equally. In right-handed men with right eye FS+, mixed eye FS-, +, mixed eye-right foot (FS-), mixed eye-mixed foot, and left eye preference there was no significant relationship between IQ and the H-reflex latency from the right and left sides. Only in strong left-handers there was a significant, positive linear correlation between IQ and the right minus left (R-L) difference of latencies. The H-reflex latency from the right and left sides was not significantly correlated with the R-L difference of latencies in left-handers. In right-handed women with right eye preference FS-, and in right-handed men with right eye preferences FS-, The H-reflex latency from the right side was found to be positively linearly correlated with the R-L difference of latencies. In right-handed women FS+, and in right-handed men FS+, and mixed or left eye preference, the H-reflex latency from the left side was found to be negatively linearly related to the R-L difference of latencies.(ABSTRACT TRUNCATED AT 400 WORDS)

The Relationship of Latency Characteristics of the Hoffmann Reflex From the Right and Left Thenar Muscles To Serum Testosterone Levels in Right-Handed Male and Female Subjects

The latency characteristics of the Hoffmann reflex from the right and left thenar muscles were analyzed in right-handed young men and women relative to serum testosterone levels. There was no correlation between the H-reflex latencies and serum testosterone levels in the female subjects. In the male subjects, the H-reflex latencies from the right and left sides were found to be negatively linearly related to the serum testosterone levels. The right minus left latencies were found to be inversely correlated with serum testosterone levels in women; there was no correlation between these variables in men. It was also established that the right-left differences in the H-reflex latencies were directly related to the degree of the right-hand preference in the female subjects. It was concluded that testosterone may, at least, contribute to the spinal-motor lateralization in women, but not in men. The results were also discussed with regard to the testosterone hypothesis of cerebral lateralization, sex-related differences, hand preference, hand skill, and intelligence.

The flexor carpi radialis H-reflex in polyneuropathy: relations to conduction velocities of the median nerve and the soleus H-reflex latency.

In 80 controls latencies of flexor carpi radialis (FCR) and in 94 controls latencies of soleus H-reflexes correlated well with length of the extremity, body height and age. Multiple regression equations using latency as a variable dependent on age and body height can be best used in practice when both reflexes are employed for demonstration of proximal pathology. The majority (69%) of 93 patients with various polyneuropathies showed abnormalities in both reflexes illustrating that proximal nerve segments are frequently involved. Four per cent had abnormal FCR H-reflexes with normal soleus H-reflexes whereas the reverse was found in 19% of the patients. Abnormal FCR H-reflexes occurred with normal motor and sensory conduction velocities in the peripheral part of the median nerve in 14%, whereas the reverse was seen in 12%, indicating that FCR H-reflex examination is a valuable supplement to conventional conduction studies for detection of electrophysiologically existing pathology.

Tendon vibration-induced inhibition of human and cat triceps surae group I reflexes: Evidence of selective Ib afferent fiber activation

In humans, prolonged vibration of the Achilles tendon produced transient depression or abolition of the soleus H-reflex. Recovery of the electrical reflex threshold to previbration values at a constant lower stimulus intensity usually occurred between 10 to 55 min. Electrical stimulation at higher multiples of the reflex threshold produced reflex EMG amplitudes more immediately comparable to previbration controls. When postvibration H-reflexes were completely abolished, poststimulus averaging of voluntarily maintained tonic EMG activity showed evidence of inhibition at a 46-ms latency in contrast to a 32-ms previbration H-reflex latency. In cat, observation of H-reflexes were rare, but stimulus-evoked changes in EMG activity mimicked the postvibration depression seen in humans. Ventral root postvibration reflexes from triceps surae varied in magnitude but were usually depressed or abolished at 1.0 to 1.2 times the electrical reflex threshold. These responses returned to previbration control amplitudes within 20 to 35 min. Magnitude of depression and time to recovery were dependent on the intensity of the electrical stimulus. In five experiments, depression of postvibration reflex activity and recovery were accompanied by gradual recovery in amplitude of the group I volley to previbration amplitudes. Elevated group Ia axonal electrical thresholds, monitored from seven isolated units, were observed to recover to previbration values in parallel with postvibration reflex recovery to control amplitudes. At electrical stimulus intensities greater than 1.4 times the reflex threshold, postvibration reflex responses were often potentiated, probably reflecting posttetanic potentiation of group Ia pathways activated at their higher axonal thresholds. In two observations, postvibration Ib axonal electrical thresholds did not change. Overall, the findings supported the proposal that postvibration depression of soleus H-reflexes in humans or cats is caused by both disfacilitation and autogenetic inhibition due to withdrawal of Ia afferent activation and increased selectivity of Ib afferent fiber stimulation, respectively.

The H-reflex of the flexor carpi radialis muscle; a study in controls and radiation-induced brachial plexus lesions.

H-reflexes of the flexor carpi radialis muscle were studied in 52 controls and 25 cancer patients with radiation-induced brachial plexopathy. It was found that H-reflex conduction velocity (H-RCV) decreased with increasing age. This was not true for H-reflex latency (H-RL) and inter-latency times. There were no H-RCV and latency differences between age-matched male and female subjects. In the affected arm the reflex was absent in nine patients and delayed in 16 patients in whom H-RCV was decreased in 13 patients. Three patients showed large H-RL differences which were also notable features in median nerve disease in the region of the brachial plexus.

Effect of height on nerve conduction velocity

The effect of height on nerve conduction velocity (NCV) was studied in 41 normal subjects. Peroneal and sural NCV correlated inversely with height and with estimated axonal length, whereas median motor and sensory NCV failed to show any significant relationship to height. These findings are consistent with the hypothesis of abrupt distal axonal tapering in the lower extremities. Recognition of height effect in the legs is clinically significant, since diagnostic sensitivity of NCV determinations is improved when corrected for height differences. Multiple regression equations derived from the sample data allow satisfactory estimation of peroneal NCV, sural NCV, H-reflex latency, and F-wave latency from height (or axonal length), age, and other important predictors.