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American Journal of Physiology. Heart... Jan 2011This study was undertaken to elucidate the role played by transient receptor potential A1 channels (TRPA1) in activating the muscle reflex, a sympathoexcitatory drive...
This study was undertaken to elucidate the role played by transient receptor potential A1 channels (TRPA1) in activating the muscle reflex, a sympathoexcitatory drive originating in contracting muscle. First, we tested the hypothesis that stimulation of the TRPA1 located on muscle afferents reflexly increases sympathetic nerve activity. In decerebrate rats, allyl isothiocyanate, a TRPA1 agonist, was injected intra-arterially into the hindlimb muscle circulation. This led to a 33% increase in renal sympathetic nerve activity (RSNA). The effect of allyl isothiocyanate was a reflex because the response was prevented by sectioning the sciatic nerve. Second, we tested the hypothesis that blockade of TRPA1 reduces RSNA response to contraction. Thirty-second continuous static contraction of the hindlimb muscles, induced by electrical stimulation of the peripheral cut ends of L(4) and L(5) ventral roots, increased RSNA and blood pressure. The integrated RSNA during contraction was reduced by HC-030031, a TRPA1 antagonist, injected intra-arterially (163 ± 24 vs. 95 ± 21 arbitrary units, before vs. after HC-030031, P < 0.05). Third, we attempted to identify potential endogenous stimulants of TRPA1, responsible for activating the muscle reflex. Increases in RSNA in response to injection into the muscle circulation of arachidonic acid, bradykinin, and diprotonated phosphate, which are metabolic by-products of contraction and stimulants of muscle afferents during contraction, were reduced by HC-030031. These observations suggest that the TRPA1 located on muscle afferents is part of the muscle reflex and further support the notion that arachidonic acid metabolites, bradykinin, and diprotonated phosphate are candidates for endogenous agonists of TRPA1.
Topics: Analysis of Variance; Animals; Ankyrins; Calcium Channels; Hindlimb; Isothiocyanates; Male; Muscle Contraction; Muscle, Skeletal; Neurons, Afferent; Rats; Rats, Sprague-Dawley; Reflex; Sympathetic Nervous System; TRPA1 Cation Channel; TRPC Cation Channels
PubMed: 21076024
DOI: 10.1152/ajpheart.00547.2009 -
The American Journal of Physiology Aug 1994Reflex response of cardiac sympathetic nerve activity (CSNA) during static contraction of the triceps surae muscle was studied using anesthetized cats. A 1-min...
Reflex response of cardiac sympathetic nerve activity (CSNA) during static contraction of the triceps surae muscle was studied using anesthetized cats. A 1-min contraction was evoked by stimulating the peripheral ends of the cut L7 and S1 ventral roots. CSNA increased 48 +/- 13% immediately after the onset of contraction, which was abolished by cutting the L4-S1 dorsal roots. This rapid increase in CSNA preceded rises in heart rate (13 +/- 1 beats/min) and arterial blood pressure (33 +/- 6 mmHg). When tension development was altered by changing the frequency of ventral root stimulation or the initial muscle length, the CSNA increase depended on the tension developed. Passive stretch of the muscle, which primarily activates mechanoreceptors, increased CSNA by 41 +/- 22%. When the contraction was sustained for 5 min, CSNA remained elevated throughout the contraction despite a fall in tension, suggesting that the later increase in CSNA is caused by factors other than a mechanical event of contraction (e.g., metabolic products). Thus it is suggested that cardiac sympathetic outflow is stimulated due to a reflex arising from the contracting muscle. The increase in CSNA at the initiation of contraction is likely to be caused by a reflex from muscle mechanoreceptors, which is followed by a subsequent increase due to a reflex from muscle metaboreceptors.
Topics: Animals; Cats; Denervation; Heart Conduction System; Heart Rate; Muscle Contraction; Paralysis; Physical Stimulation; Reflex; Spinal Nerve Roots; Sympathetic Nervous System
PubMed: 8067438
DOI: 10.1152/ajpheart.1994.267.2.H821 -
Muscle & Nerve Jan 1995This prospective study evaluated the extensor digitorum brevis deep tendon reflex (EDBR) in a normal population and in patients with L-5 and S-1 radiculopathies. There...
This prospective study evaluated the extensor digitorum brevis deep tendon reflex (EDBR) in a normal population and in patients with L-5 and S-1 radiculopathies. There were 88 subjects: 53 normals, 17 L-5, and 18 S-1 radiculopathy subjects. The clinical EDBR revealed a 91% specificity, with 18% sensitivity for L-5, and 11% for S-1. The electrodiagnostic EDBR yielded increased sensitivities of 35% for L-5 (P = 0.07) and 39% for S-1 (P = 0.04), with 87% specificity. H-reflexes showed 50% sensitivity for the S-1 group (P = 0.0006) and 91% specificity. EDBR latencies were significantly related to age and leg length (r2 = 0.46, P < 0.0001). Age alone explained 26% (P < 0.0001) of the EDBR variability and leg length 20% (P < 0.0001). EDBR clinical and electrodiagnostic reflexes have low sensitivities, high specificities, and do not discriminate L-5 from S-1 root involvement.
Topics: Adult; Aged; Aged, 80 and over; Electrodiagnosis; H-Reflex; Humans; Middle Aged; Muscles; Peripheral Nervous System Diseases; Reaction Time; Reference Values; Reflex; Sensitivity and Specificity; Spinal Nerve Roots; Toes
PubMed: 7799998
DOI: 10.1002/mus.880180108 -
Physical Medicine and Rehabilitation... Feb 2004The advent of equipment capable of performing SEPs, MEPs, and EMG in a multiplexed manner and in a timely fashion brings a new level of monitoring that far exceeds the... (Review)
Review
The advent of equipment capable of performing SEPs, MEPs, and EMG in a multiplexed manner and in a timely fashion brings a new level of monitoring that far exceeds the previous basic monitoring done with SEPs only. Whether this more comprehensive monitoring will result in greater protection of the nervous system awaits future analysis. In any event, monitoring of the spinal cord with SEPs is an accepted standard of care for cases that place the spinal cord at risk. Likewise, nerve root monitoring with EMG is a widely practiced form of monitoring and shows great benefit. MEPs and reflex monitoring, which address the descending pathways and the interneuronal connections, is efficacious in detecting abnormalities that may be missed by SEPs.
Topics: Electromyography; Evoked Potentials; Evoked Potentials, Somatosensory; H-Reflex; Humans; Monitoring, Intraoperative; Neurosurgical Procedures; Spinal Diseases; Spinal Nerve Roots
PubMed: 15029900
DOI: 10.1016/s1047-9651(03)00106-2 -
American Journal of Physiology. Renal... Sep 2012Increased abdominal muscle wall activity may be part of a visceromotor reflex (VMR) response to noxious stimulation of the bladder. However, information is sparse...
Increased abdominal muscle wall activity may be part of a visceromotor reflex (VMR) response to noxious stimulation of the bladder. However, information is sparse regarding the effects of cauda equina injuries on the VMR in experimental models. We studied the effects of a unilateral L6-S1 ventral root avulsion (VRA) injury and acute ventral root reimplantation (VRI) into the spinal cord on micturition reflexes and electromyographic activity of the abdominal wall in rats. Cystometrogram (CMG) and electromyography (EMG) of the abdominal external oblique muscle (EOM) were performed. All rats demonstrated EMG activity of the EOM associated with reflex bladder contractions. At 1 wk after VRA and VRI, the duration of the EOM EMG activity associated with reflex voiding was significantly prolonged compared with age-matched sham rats. However, at 3 wk postoperatively, the duration of the EOM responses remained increased in the VRA series but had normalized in the VRI group. The EOM EMG duration was normalized for both VRA and VRI groups at 8-12 wk postoperatively. CMG recordings show increased contraction duration at 1 and 3 wk postoperatively for the VRA series, whereas the contraction duration was only increased at 1 wk postoperatively for the VRI series. Our studies suggest that a unilateral lumbosacral VRA injury results in a prolonged VMR to bladder filling using a physiological saline solution. An acute root replantation decreased the VMR induced by VRA injury and provides earlier sensory recovery.
Topics: Abdominal Muscles; Animals; Electromyography; Female; Rats; Rats, Sprague-Dawley; Reflex; Replantation; Spinal Cord; Spinal Nerve Roots; Urinary Bladder; Urination
PubMed: 22696606
DOI: 10.1152/ajprenal.00094.2012 -
Journal of Musculoskeletal & Neuronal... Mar 2024To investigate changes in the H-reflex in patients with monoradiculopathies involving L5 or S1 levels by stimulating the sciatic nerve and recording simultaneously from...
OBJECTIVES
To investigate changes in the H-reflex in patients with monoradiculopathies involving L5 or S1 levels by stimulating the sciatic nerve and recording simultaneously from the tibialis anterior (TA), peroneus longus (PL), and soleus (S) muscles.
METHODS
Patients with unilateral radicular back pain with L5 or S1 root compression on MRI, participated in this cross-sectional study. The H-reflex over the TA, PL, and S muscles was simultaneously recorded by sciatic nerve stimulation. The H-reflex latency was compared with that of the contralateral extremity.
RESULTS
Fifty-eight patients (29 patients L5; 29 patients S1 radiculopathy) were included in the study. There were significant delays in the latency of the H-reflex over TA (30.95±2.31-29.21±1.4) and PL (31.05±2.85-29.02±1.99) muscles on the affected side in patients with L5 radiculopathy. However, the latency of the S H-reflex was similar on both sides. In contrast, in patients with S1 radiculopathy, there was a significant delay in the latency of soleus H reflex (32.76±3.45-29.9±3.19), while the significant delay was not detected in the TA and PL muscles. However, the cutoff values for the H-reflex latency of all muscles were not found to have clinical significance.
CONCLUSIONS
The study presents that the H-reflex study, recorded from the TA, PL, and S muscles by sciatic nerve stimulation, is of interest but has minimal contribution to radiculopathy diagnosis in conventional electrodiagnostic tests.
Topics: Humans; Radiculopathy; Spinal Nerve Roots; Cross-Sectional Studies; Muscle, Skeletal; H-Reflex
PubMed: 38427371
DOI: No ID Found -
Journal of Neurophysiology Oct 2017Botulinum toxin (Btx) is used in children with cerebral palsy and in other neurological patients to diminish spasticity and reduce the risk of development of...
Botulinum toxin (Btx) is used in children with cerebral palsy and in other neurological patients to diminish spasticity and reduce the risk of development of contractures. We investigated changes in the central gain of the stretch reflex circuitry in response to Btx injection in the triceps surae muscle in rats. Experiments were performed in 21 rats. Eight rats were a control group, and 13 rats were injected with 6 IU of Btx in the left triceps surae muscle. Two weeks after Btx injection, larger monosynaptic reflexes (MSR) were recorded from the left (injected) than the right (noninjected) L4 + L5 ventral roots following stimulation of the corresponding dorsal roots. A similar increase on the left side was observed in response to stimulation of descending motor tracts, suggesting that increased excitability of spinal motor neurons may at least partly explain the increased reflexes. However, significant changes were also observed in postactivation depression of the MSR, suggesting that plastic changes in transmission from Ia afferent to the motor neurons also may be involved. The data demonstrate that muscle paralysis induced by Btx injection is accompanied by plastic adaptations in the central stretch reflex circuitry, which counteract the antispastic effect of Btx. Injection of botulinum toxin into ankle muscles causes increased gain of stretch reflex. This is caused by adaptive changes in regulation of transmitter release from Ia afferents and increased excitability of spinal motor neurons.
Topics: Adaptation, Physiological; Animals; Botulinum Toxins; Ganglia, Spinal; Male; Motor Neurons; Muscle Contraction; Muscle, Skeletal; Rats; Rats, Sprague-Dawley; Reflex, Stretch
PubMed: 28724781
DOI: 10.1152/jn.00276.2017 -
Journal of Neurosurgery Jan 1997Myelopathy from cervical spondylosis is often accompanied by hyperreflexia of the upper-extremity deep tendon reflexes (DTRs). Reflexes such as the pectoralis jerk and...
Myelopathy from cervical spondylosis is often accompanied by hyperreflexia of the upper-extremity deep tendon reflexes (DTRs). Reflexes such as the pectoralis jerk and the deltoid jerk may only be apparent in the context of hyperreflexia. Although the nerve roots involved in the reflex arcs are well described, levels of cervical spinal cord compression that lead to the hyperreflexia are not as clear. This is of particular significance for patients with multilevel cervical spondylosis in determining the levels responsible for their symptoms. The authors examined 15 consecutive patients who presented for treatment of cervical myelopathy. The clinical examination was then correlated with levels of cervical spinal cord compression by cervical magnetic resonance imaging or computerized tomography with intrathecal contrast enhancement. The presence of a prominent pectoralis jerk was seen only in patients with spinal cord compression at the C2-3 and/or C3-4 levels (nine patients). No patient with compression at or below the C4-5 disc space without coexisting compression at a higher level had hyperactive pectoralis reflexes. This association between the C3-4 level and a hyperactive pectoralis reflex was significant (p < 0.004, Fisher's exact test). The deltoid reflex was tested in the last nine consecutive patients. It was present in patients with compression of the upper spinal cord at levels C3-4 and C4-5 (four of five patients) but appeared in only one of four patients with compression below C4-5. This association did not attain statistical significance. The presence of a hyperactive pectoralis reflex is specific for lesions of the upper cervical spinal cord. Examination of upper-extremity DTRs may be helpful in planning the appropriate levels for surgical decompression in patients with multilevel spondylosis and myelopathy.
Topics: Humans; Male; Pectoralis Muscles; Reflex, Babinski; Reflex, Stretch; Spinal Cord Compression
PubMed: 8988096
DOI: 10.3171/jns.1997.86.1.0159 -
PloS One 2019Posterior root-muscle (PRM) reflexes are short-latency spinal reflexes evoked by epidural or transcutaneous spinal cord stimulation (SCS) in clinical and physiological...
Posterior root-muscle (PRM) reflexes are short-latency spinal reflexes evoked by epidural or transcutaneous spinal cord stimulation (SCS) in clinical and physiological studies. PRM reflexes share key physiological characteristics with the H reflex elicited by electrical stimulation of large-diameter muscle spindle afferents in the tibial nerve. Here, we compared the H reflex and the PRM reflex of soleus in response to transcutaneous stimulation by studying their recovery cycles in ten neurologically intact volunteers and ten individuals with traumatic, chronic spinal cord injury (SCI). The recovery cycles of the reflexes, i.e., the time course of their excitability changes, were assessed by paired pulses with conditioning-test intervals of 20-5000 ms. Between the subject groups, no statistical difference was found for the recovery cycles of the H reflexes, yet those of the PRM reflexes differed significantly, with a striking suppression in the intact group. When comparing the reflex types, they did not differ in the SCI group, while the PRM reflexes were more strongly depressed in the intact group for durations characteristic for presynaptic inhibition. These differences may arise from the concomitant stimulation of several posterior roots containing afferent fibers of various lower extremity nerves by transcutaneous SCS, producing multi-source heteronymous presynaptic inhibition, and the collective dysfunction of inhibitory mechanisms after SCI contributing to spasticity. PRM-reflex recovery cycles additionally obtained for bilateral rectus femoris, biceps femoris, tibialis anterior, and soleus all demonstrated a stronger suppression in the intact group. Within both subject groups, the thigh muscles showed a stronger recovery than the lower leg muscles, which may reflect a characteristic difference in motor control of diverse muscles. Based on the substantial difference between intact and SCI individuals, PRM-reflex depression tested with paired pulses could become a sensitive measure for spasticity and motor recovery.
Topics: Adult; Female; H-Reflex; Humans; Male; Muscle, Skeletal; Reflex; Spinal Cord; Spinal Cord Injuries; Spinal Cord Stimulation; Young Adult
PubMed: 31877192
DOI: 10.1371/journal.pone.0227057 -
Journal of Neurology, Neurosurgery, and... Mar 1988Phasic stretch reflexes were evoked in the tibialis anterior (TA) muscle, by tapping the dorsal side of the foot with a hand-held reflex hammer. The responses were...
Phasic stretch reflexes were evoked in the tibialis anterior (TA) muscle, by tapping the dorsal side of the foot with a hand-held reflex hammer. The responses were recorded by means of surface electrodes. The TA reflex was examined in 70 healthy subjects and in 18 patients with L5 radicular compression. In 58 (83%) of the healthy subjects the reflex could be recorded bilaterally, in eight (11%) subjects no reflex was found on either side, and in four (6%) it was absent in one leg. Simultaneous recordings from the gastrocnemius-soleus showed that TA responses were not caused by volume conduction from that muscle. In the 18 patients with L5 radicular compression the TA reflex was absent on the affected side 13 times (72%) and present bilaterally in the other five cases. If asymmetry of the reflex (unilateral absence) is considered as a test for the presence of L5 radicular compression, the likelihood ratio for a positive test is 12.0, and for a negative test 0.3. The examination of the TA reflex is easily performed and can be useful in the diagnosis of L5 radicular compression.
Topics: Humans; Muscles; Nerve Compression Syndromes; Reaction Time; Reference Values; Reflex, Stretch; Spinal Nerve Roots; Tibial Nerve
PubMed: 3361331
DOI: 10.1136/jnnp.51.3.397