Disease relevance of H-Reflex

• Reciprocal inhibition of the H-reflex showed a decrease in the amount of inhibition in all the patient groups and a facilitation of the H-reflex during the 3rd period of inhibition in the patients with spasmodic torticollis or generalized dystonia [1].
• We studied reciprocal inhibition of H-reflexes in the forearm flexor and extensor muscles in 14 patients with spastic hemiplegia secondary to a focal cerebral lesion and 14 normal volunteers [2].
• RESULTS: During spinal shock, the loss of tendon tap reflexes and flaccid muscle tone were associated with low persistence of F-waves and loss of flexor reflexes, whereas H-reflexes were already elicitable [3].
• The recovery curve of the H-reflex was normal in patients with writer's cramp or blepharospasm, but showed an increase of the physiologic recovery at a 200 msec delay in patients with spasmodic torticollis or generalized dystonia [1].
• Baseline H-reflex amplitude was increased in both contusion groups at 4 weeks and showed a positive linear correlation with serotonin immunoreactivity [4].

Psychiatry related information on H-Reflex

• Effect of 5-hydroxytryptophan on H-reflex recovery curves in normal subjects and patients with affective disorders [5].
• 4. A single stimulus (2-3 X sensory threshold) to the superficial (cutaneous) branch of the radial nerve at the wrist failed to produce inhibition of the flexor H reflex [6].
• The aim of the present study was to investigate the modulations in amplitude of H reflexes elicited in a hand muscle, the flexor pollicis brevis, during the performance of a choice reaction time (RT) task in which this muscle was directly involved [7].

High impact information on H-Reflex

• Other abnormalities included long-latency responses in the extremities in 2 patients, release of H-reflexes from flexor hallucis brevis muscle in 2 patients, and an Hmax/Mmax ratio of 98% in 2 patients [8].
• In the former cases, the size of the H' reflex evoked by the same conditioning H1 discharge was further depressed after L-acetylcarnitine, pointing to a potentiating effect of the drug on Renshaw cells; in the latter cases no such effect was seen [9].
• Soleus H-reflex tests in causalgia-dystonia compared with dystonia and mimicked dystonic posture [10].
• In one patient, we repeated the H-reflex tests twice after withdrawal of levodopa [11].
• Baclofen abolished the concomitantly recorded H-reflex and markedly suppressed the P wave amplitude and area [12].

Chemical compound and disease context of H-Reflex

• The excitability curve of the H reflex conditioned by stimulation of a mixed nerve was studied in eight Parkinsonism patients, before and after L-dopa therapy [13].
• The effect of lumbar intrathecal fentanyl on reported pain, nociceptive flexor withdrawal reflexes, a monosynaptic motor arc (H-reflex), and supraspinal effects such as miosis, nausea, respiratory depression was evaluated [14].
• Nitrous oxide depresses the H-reflex in children with cerebral palsy [15].
• Before baclofen, H reflex was present in 5 patients (H(max)/M(max) from 0.23 to 0.84) and absent in one who had infantile neuroaxonal dystrophy [16].
• The percent of the unconditioned reflex amplitude for reflex activation history and the maximum H-reflex were decreased at 25 and 45 min post effusion as compared to measures taken at baseline, post needle stick, and post lidocaine (P<0.05) [17].

Biological context of H-Reflex

• Effects of intrathecal fentanyl and lidocaine on somatosensory-evoked potentials, the H-reflex, and clinical responses [18].
• The H-reflex of the flexor carpi radialis is easily obtainable and can be recorded by a simple nerve conduction technique detailed in this communication [19].
• Trial-to-trial fluctuations in H-reflexes and motor evoked potentials in human wrist flexor [20].
• A long lasting inhibition (greater than 8 s) of the soleus Hoffmann reflex (H-reflex) was evoked by a preceding soleus H-reflex, by a brief voluntary ankle flexor or extensor muscle contraction or by a tap applied to the Achilles tendon [21].
• In family 1 both patients had a late-onset phenotype with preservation of knee and ankle jerks, lack of cardiomyopathy, and preserved H reflex [22].

Anatomical context of H-Reflex

• The H-reflex recovery curve was obtained after stimulation of the median nerve at the elbow and recording from the flexor carpi radialis [23].
• In 6 healthy volunteers, stimulation of the median nerve at the elbow elicited H-reflexes in muscles innervated by the ulnar nerve (flexor digitorum profundus of the 4th and 5th digits of the hand) as well as the median nerve (flexor carpi radialis) [24].
• Peripheral inhibition of the flexor H reflex was produced by motor threshold stimulation with a single shock of the radial nerve supplying the extensor muscles [25].
• Spinal cord excitability was tested by eliciting the H-reflex in a finger flexor muscle (flexor digitorum superficialis) in humans looking at goal-directed hand actions presented on a TV screen [26].
• Intrathecal baclofen did not modify the amount of monosynaptic facilitation of the soleus H-reflex brought about by stimulation of the femoral nerve [27].

Associations of H-Reflex with chemical compounds

• After smoking the nicotine-containing cigarettes, the subjects showed a reduction of the H reflex recovery cycle [28].
• 2. Distinct differences were observed between the modifications of the test reflex and those of the reference H-reflex during both tonic and phasic voluntary contractions [29].
• 3. Injections of lobeline at doses sufficient to evoke respiratory discomfort lasting 25-32 s (37-73 microgram kg-1) increased the size of the H reflex in soleus with an onset latency of about 10 s and lasting about 20 s [30].
• The effects of subarachnoid injection of Conray (methylglucamine iothalamate) and its dimer (methylglucamine locarmate) in various concentrations were compared using electrophysiological monitors of the cortical evoked response (CER) and the H-reflex [31].
• Effects of propofol on H-reflex in humans [32].

Gene context of H-Reflex

• Abnormalities in CMCT may be the third electrophysiological diagnostic criterion in FA, after reduced amplitude of nerve action potentials and absent H reflex [33].
• Dopa-responsive dystonia and normalization of soleus H-reflex test results with treatment [11].
• As hypothesised, slopes of linear regressions fitted to H-reflex versus EMG data were independent of gravity for walking and running (ANOVA, P > 0.8) [34].
• However, abolition of the H reflex and F waves during REM sleep has also been reported [35].
• 1. H reflexes were elicited in the small muscles of the foot in the canine and human during passive locomotor-like rotation of the shank about the ipsilateral knee [36].

Analytical, diagnostic and therapeutic context of H-Reflex

• In this study, nitric oxide synthase immunohistochemistry supported by nicotinamide adenine dinucleotide phosphate diaphorase histochemistry was used to demonstrate the nitric oxide synthase immunoreactivity in the monosynaptic Ia-motoneuron pathway exemplified by structural components of the afferent limb of the soleus H-reflex in the dog [37].
• After intrathecal injection both the specific NMDA antagonist (-)-2-amino-7-phosphonoheptanoate and pentamidine dose-dependently reduced the magnitude of the polysynaptic flexor reflex without affecting the monosynaptic H-reflex [38].
• F response and H reflex for monitoring nerve block during epidural analgesia with ropivacaine [39].
• CONCLUSIONS: Significant improvements in SST and SLR result from low volume epidural injection of Marcaine, with questionable prolongation of the H-reflex to the gastrocnemius-soleus complex on the affected side [40].
• The median nerve of the subjects at the cubital fossa was electrically stimulated (0.5 msec; 0.2 pulses per second [pps] at H-max), whereas the flexor carpi radialis muscle H-reflex was recorded by electromyography [41].

References