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Biomedical subjects

R Benecke

Publications and source records attributed to R Benecke.

At least 163 records · Page 9Linked to original sources
PubMed1980

The value of electrophysiological examination of the flexor carpi ulnaris muscle in the diagnosis of ulnar nerve lesions at the elbow.

The aim of the present study was to answer the question whether electrophysiological examination of the m.flexor carpi ulnaris, especially of the distal latency (stimulation point 2 cm above the sulcus ulnaris) to this muscle, represents a valid procedure for the localisation of an ulnar nerve lesion at the elbow. In 64 patients, a total of 68 ulnar nerve lesions at the elbow were subjected to conventional clinical and electrophysiological examinations. A pathologically prolonged distal latency to m.flexor carpi ulnaris (> 4.0 ms) was found in 82.4% of the patients. In terms of their value in the topo-diagnosis of an ulnar lesion, measurement of the distal latency to m.flexor carpi ulnaris and conventional analysis of trans-sulcal motor conduction velocity of the fibres to the hypothenar muscles yield equivalent information. However, evaluation of the distal latency to m.flexor carpi ulnaris is not only subject to fewer sources of error but is also technically much easier to perform. In the localisation of a clinically suspected ulnar nerve lesion at the elbow, we therefore suggest that the electrophysiological investigation should commence with an examination of the distal latency to m.flexor carpi ulnaris.

Adolescent↗
PubMed1980

The distal sensory nerve action potential as a diagnostic tool for the differentiation of lesions in dorsal roots and peripheral nerves.

On the basis of the conception that, in preganglionic lesions, peripheral sensory nerve fibers should remain intact, the question arises whether evaluation of distal sensory nerve action potentials can be helpful in differentiating between cervical dorsal root and peripheral nerve lesions. Amplitudes of sensory nerve action potentials (SNAP) and corresponding distal sensory conduction velocities (SCV) of the median and ulnar nerves were measured in 194 patients with distal sensory impairment and in 20 control subjects. In dorsal root lesions attributable to degenerative changes of cervical spines and/or discs, SNAP and SCV were within the normal range. In peripheral nerve lesions, located in the brachial plexus, or at the elbow or wrist, diminished SNAP amplitudes and/or slowing of SCV were found. It is concluded that in patients with sensory deficit in the hands recordings of SNAP make a differentiation between lesions of dorsal roots and peripheral nerves possible.

Action Potentials↗
PubMed1979

Electromyographic examination of gluteal muscles in the differential diagnosis of lumbar herniated discs.

The aim of the present investigation was to establish the value of gluteal muscles (m.gluteus medius, GME; m.gluteus maximus, GMX) as segmental reference muscles in the topical diagnosis of lumbar root compression syndromes. The methodological rationale consisted in determining the frequency with which denervation potentials could be recorded in the GME and GMX of patients with clinically and electromyographically well-defined monosegmental or bisegmental lumbar root compression syndromes. Of the L5-syndromes (N=36), 81% revealed denervation potentials in GME, but only 6% in GMX. Of the S1 syndromes (N=26), 63% exhibited denervation potentials in GMX and 32% in GME. L5 syndromes showed a better correlation of positive findings to GME than S1 syndromes to GMX. As far as the differential diagnosis is concerned, the advantages of recording EMG from GME and GMX are two-fold: (a) the immediate certainty of excluding a peripheral nerve lesion and (b) a reduction in the incidence of false negative findings.

Adult↗
PubMed1977

Tetanus toxin induced actions on spinal Renshaw cells and Ia-inhibitory interneurones during development of local tetanus in the cat.

In anaesthetized cats the activities of Renshaw cells (RCs) and Ia-inhibitory interneurones (IaINs) were recorded during the accumulation of tetanus toxin in the spinal cord following injection into the gastrocnemius muscle. The early response of the RCs increased during the period of development of local tetanus. With some cells there was a subsequent decrease in the early response in later periods of the observation time (16-44 hrs after intramuscular injection). The effects on the spontaneous activity of the RCs were in good correspondence to those on the early response. The hyperactivity of the RCs is proposed to be mediated mainly via disinhibited cholinergic gamma-motoneurones using muscarinic postsynaptic receptors. The "pause" which follows the early response and the recurrent inhibition of IaINs was not reduced during the development of local tetanus. These results indicate that the central action of tetanus toxin in local tetanus does not consist of a general loss of postsynaptic inhibition. It is suggested that tetanus toxin acts mainly on synaptic elements of the alpha- and gamma-motoneurones or on presynaptic nerve terminals in their vicinity. In later periods of disturbing influence on the cholinergic transmission at Renshaw cells seems to occur.

Animals↗
PubMed1977

Effects of type A botulinum toxin on the cholinergic transmission at spinal Renshaw cells and on the inhibitory action at Ia inhibitory interneurones.

1. The central action of botulinum toxin A (BTA) on the cholinergic transmission at Renshaw cells (RCs) and on the RC-induced inhibition of Ia inhibitory interneurones (IaINs) was studied in anaesthetized cats. BTA was administered by application directly into the spinal cord, injection into a ventral root (L7) and/or injection into the triceps surae (GS) muscle. 2. A direct application of BTA into the spinal cord led to a decrease of the early and the late response of RCs. 3. When the neurotoxin was injected into the GS muscle, the RC activity remained unaffected during the test period (33-46 h after application). 4. No effect appeared up to 10 h after an injection into the ventral root L7. 5. The RC-induced inhibition on IaINs, when tested in animals with local botulismus, remained intact during the test period. 6. From the present results it is suggested that on the spinal level the central action of botulinum toxin predominantly passes on the motoneurones.

Action Potentials↗
PubMed1975

Recurrent inhibition of individual Ia inhibitory interneurones and disinhibition of their target alpha-motoneurones during muscle stretches.

The effects of ramp stretches applied to triceps surae muscle on the discharge patterns of single Ia inhibitory interneurones, monosynaptically invaded from various nerves, were studied in either decerebrate or anesthetized cats. Interneurones which received direct excitatory Ia input from the stretched muscle exhibited augmented activity both during the dynamic and static phase of stretch, which was, however, interrupted by a transient inhibitory influence during the dynamic phase of stretch. The influences on Ia inhibitory interneurones, monosynaptically invaded from hamstring or tibial nerve, were exclusively inhibitory. These stretch-induced inhibitions were better demonstrable in decerebrate than in anesthetized preparations. The timing of the discharge patterns of additionally recorded Renshaw cells during stretch, and the disappearance or reduction of the above described inhibitory effects after administration of DHE, strongly support the idea that these inhibitory actions are caused by Renshaw inhibition. In Ia inhibitory interneurones, monosynaptically activated from the antagonistic peroneal nerve, stretch induced also pronounced inhibitory effects, which were most probably caused by mutual inhibition between Ia inhibitory interneurones. The suppression of agonistic Ia inhibitory interneurone activity below the tonic resting activity corresponded to an enhancement of the monosynaptic reflex amplitude of the antagonistic motoneurone pool. The findings suggest that normal orthodromic activation of Renshaw cells, and consequently the recurrent inhibition of the Ia inhibitory interneurones, is predominantly linked with rapid phasic, rather than slow tonic, motoneuronal firing. The functional role of this mechanism for the performance of rapidly alternating movements and the damping of ballistic agonist contractions is discussed.

Animals↗