Comparison of monosynaptic and polysynaptic Ia reflexes in the evaluation of hyporeflexia.
Explore the source record for details and available documents.
Humans↗
Biomedical subjects
G Deuschl
Publications and source records attributed to G Deuschl.
Neuroleptic malignant syndrome: observations on altered consciousness.
A young man with a previously untreated schizophrenia developed a neuroleptic malignant syndrome (NMS) on the second day of neuroleptic treatment. The dominant symptom was deep coma. The NMS occurred on the second day of neuroleptic therapy with rapidly progressing mental deterioration, temperature elevation, and extrapyramidal signs. After anticholinergics were injected the patient regained consciousness. This suggests that a cholinergic hyperactivity in the central nervous system (rather than hyperthermia) is responsible for the disturbance of consciousness in NMS. The experimental evidence that central cholinergic systems are stimulated by neuroleptics is discussed. It is concluded that anticholinergics might be helpful in treating coma during NMS.
Adult↗
[SPECT studies with 99mTc-HMPAO in Huntington's chorea patients].
Huntington's chorea is an autosomal dominant inherited disease with a chronic course and atrophy of the corpus striatum. PET examination shows reduced glucose metabolism in the caudate nucleus. We examined seven patients with Huntington's chorea by SPECT, using 99mTc-HMPAO. All patients had cortical defects of varying severity. In addition, five patients showed increased uptake in the region of the caudate nucleus. The specific tracer uptake due to the metabolic processes in the region of the caudate nucleus in Huntington's chorea is discussed.
Caudate Nucleus↗
Essential tremor: electrophysiological and pharmacological evidence for a subdivision.
Forty five patients with essential tremor have been investigated by means of clinical examination, polygraphic EMG records and testing of long-latency reflexes. Clinically there were no differences between the patients, whereas the electrophysiological investigations suggested two subtypes. One group of patients may be characterised by normal long-latency reflexes and synchronous tremor bursts in antagonists or activity of the antigravity muscle alone. The second group had abnormal long-latency reflexes and reciprocal EMG activity in antagonists. It is suggested that these two groups represent distinct subgroups of essential tremor. Patients of the first group responded well to propranolol, whereas those of the second group did not.
Electrophysiology↗
[Orthostatic tremor: clinical aspects, pathophysiology and therapy].
Orthostatic tremor is characterized by its isolated occurrence in leg and trunk muscles during standing with undisturbed sitting, lying and walking. In a female patient with this tremor syndrome the basic electrophysiological feature of muscle activity was a 16 Hz, highly synchronized tremor in all leg muscles and sometimes in the arm muscles. This rhythmic EMG activity however, was not restricted to stance but occurred during all kinds of muscle activation in sitting, lying or standing positions, despite only standing was accompanied by a subjective sensation of unsteadiness and falling to the ground. Mechanical tremor analysis at the patella revealed an additional 8 Hz tremor caused by alternating large and small amplitudes of the 16 Hz tremor bursts. The occurrence of the 8 Hz tremor was much more related to the feeling of unsteadiness than the 16 Hz tremor. Single motor units mostly fired at a frequency of 8 Hz, but only at the time of tremor bursts. Hence the 16 Hz-pattern may not be explained as the result of a pure motoneuronal abnormality. There were no indications for abnormal reflexes contributing to tremor genesis. A fixed time relation of the tremor bursts in different muscles has been found suggesting a common generator within the CNS for the tremor. After successfully treatment with Primidon the pattern of muscle activation was normalized during sitting and lying, however, during standing and walking the 16 Hz tremor was still present. We believe that an unknown central oscillator is causing the tremor and central structures which are involved in stance regulation have a predominant access to switch on this oscillator.
Diagnosis, Differential↗
Long-latency responses in human thenar muscles mediated by fast conducting muscle and cutaneous afferents.
Electrical stimulation of median nerve at the wrist near motor threshold evokes two distinct reflexes in voluntarily innervated thenar muscles. The first is the Hoffmann reflex (HR) and the second is the long-latency reflex (LLR). Stimulation of the motor branch of the median nerve at the thenar sub-threshold for motor fibers evokes the same pattern suggesting that group IA muscle afferents are mediating the LLR. Stimulation of pure cutaneous afferents evokes a LLR of similar latency without a preceding HR. Statistical analyses of the reflex latencies of HR and LLR are in favor of a fast conduction velocity for the cutaneous afferents involved. Hence for muscular and cutaneous LLR a long-lasting central conduction time has to be assumed.
Adolescent↗
Effect of stereoencephalotomy on long-latency EMG responses and motor control of arm movements in Parkinson's syndrome.
Explore the source record for details and available documents.
Diencephalon↗
Single preganglionic sympathetic neurons of the cat branch intraspinally and project through different rami communicantes albi--a retrograde double labelling study with fluorescent tracers.
Evidence is presented that in lumbar segments of the cat, two neighbouring rami communicantes albi (white rami, WR) may contain axons of one and the same preganglionic sympathetic neurone (PSN). This was shown with bisbenzimide (Bb) and propidium iodide (PI) applied in the same cat to the central cut ends of two WR (PI to WRL1, Bb to WRL2). PSN, double labelled from both these sites, were observed in the intermediolateral and intercalate nuclei of the L1 segment. It is postulated that axons of PSN branch intraspinally and project through different WR.
Animals↗
Cytoarchitectonic organization of lumbar preganglionic sympathetic neurons in the cat.
The location and dendritic projection of lumbar preganglionic sympathetic neurons (PSN) has been investigated in the cat. Horseradish peroxidase was either injected into lumbar paravertebral ganglia or directly applied to a lumbar ramus communicans albus. PSN were regularly found in the lateral funiculus and in the intermediate area of the ipsilateral spinal cord. They were concentrated in different nuclei: nuclei intermediolateralis pars principalis (IMLp) and pars funicularis (IMLf), nucleus intercalatus (IC) and medially near the central channel. Inconsistently, some PSN were observed in the ventral horn. Dendrites extending over a few soma were found in nearly all PSN, thus allowing description of the main dendritic projections of the preganglionic nuclei. Sometimes axons of IMLp and IC neurons could be traced into the ventral roots. In the IMLp the PSN were arranged in round clusters (up to 30 cells), which regularly followed each other in rostrocaudal direction. These clusters increased their mediolateral diameter from L1 to L4. Many cells distributed their dendrites longitudinally within the IMLp, but dendritic projections into the dorsal horn, the intermediate area and into the lateral funiculus were also frequently observed. The IMLf consisted of a few PSN only. These neurons were located in the tissue spaces between axon bundles and mediolaterally arranged, pointing towards the IMLp. The PSN of the IC were mediolaterally oriented and arranged in transverse bands extending from the lateral horn to the dorsal aspects of the central channel. All cells had mediolaterally oriented dendrites which sometimes crossed the spinal cord midline in case of the medially located neurons. The dendrites of the laterally located cells projected very often into the dorsal horn. In the medial region the PSN covered a narrow area extending from the dorsal aspects of the central channel in a ventrolateral direction up to the level of the ventral commissure. The neurons were localized in clusters and mediolaterally or longitudinally oriented. Dense clusters consisting of round cells were prevalent in the ventrolateral position. The dendrites had a rostrocaudal and mediolateral orientation and, in case of the dorsomedially located cells, sometimes crossed the spinal cord midline. The main dendritic projection areas of the different preganglionic nuclei have been compared with the location of the terminal fields of descending supraspinal and propriospinal systems and of primary afferents. It has been considered that this structural arrangement would allow for intricate interaction of the various systems with subpopulations of PSN. Thus each preganglionic nucleus might integrate specific neuronal information.
Animals↗
Mental retardation, acromegalic face, and megalotestes in two half-brothers: a specific form of X-linked mental retardation without fra(X) (q)?
We describe a family with two half-brothers affected with severe mental retardation. The phenotype in the affected individuals is characterized by apparent acromegaly, profound mental retardation, and hyperactivity. The mother has analogous but less severe facial anomalies and mild mental impairment. Screening for fra(X) (q) was negative in peripheral lymphocytes using methotrexate for fra(X) enhancement. The clinical findings in our patients are similar to those described by Fryns et al. [1986] in two patients with acquired lesions of the central nervous system. CT investigations in one of our patients showed areas of hyperdensity in the pontine region and a small subarachnoid cyst. The pedigree suggests X-linked inheritance. The association of apparent acromegaly, CNS anomalies, megalotestes, and mental retardation in this family supports the hypothesis that a distinct syndrome may exist with phenotype anomalies more severe than those characteristic for the Martin-Bell syndrome but without fragile X.
Abnormalities, Multiple↗
Frontal and parietal components of enhanced somatosensory evoked potentials: a comparison between pathological and pharmacologically induced conditions.
Pathologically enhanced somatosensory evoked potentials (giant SEPs) were recorded in 10 patients with cortical myoclonus of various origins. With non-cephalic reference electrodes a giant frontal negativity corresponding to normal N30 was found over the contra- and ipsilateral hemispheres which was not simply a phase reversal of the well-known enhanced parietal P25. The preceding far-field P14, parietal N20 and frontal P22 were of normal size. A similar result was found when SEPs were studied during the action of etomidate, an ultrashort-acting non-barbiturate hypnotic which produced a marked increase of the parietal P25 and frontal N30 after intravenous administration. These increased components, on the other hand, were abolished when recording was repeated immediately after application of electroconvulsive shock whereas P14, N20, and P22 remained more or less unchanged in both conditions. Our results indicate that there are neuronal elements in the sensorimotor cortex which are more resistant to influences such as narcotic drugs and seizure activity than others, being highly modifiable by these alterations. It is speculated whether these highly modifiable cortical systems are those in which giant SEPs, as well as pharmacologically increased SEP components, arise.
Adolescent↗
The relations between long-latency reflexes in hand muscles, somatosensory evoked potentials and transcranial stimulation of motor tracts.
In 15 normal subjects the latency of electrically elicited long-latency reflexes (LLRs) of thenar muscles was compared with somatosensory evoked potentials (SEPs) after median nerve stimulation and with the latencies of thenar muscle potentials after transcranial stimulation (TCS) of the motor cortex. Assuming a transcortical reflex pathway the intracortical relay time for the LLR was calculated to be 10.4 +/- 1.9 msec (mean +/- S.D.) or 8.1 +/- 1.6 msec depending on the experimental conditions. The duration of the cortical relay time is not correlated with the peripheral or central conduction times, with body size or arm length. If the LLRs of hand muscles are conducted transcortically the long duration of the cortical relay time suggests a polysynaptic pathway.
Adult↗
Differences of cortical activation in spontaneous and reflex myoclonias.
Frontal and parietal components of somatosensory evoked potentials (SEPs) following median nerve stimulation and scalp potentials preceding myoclonic jerks (jerk-locked averaging, JLA) were compared in 6 patients with cortical reflex myoclonus. Giant potentials were found over the parietal cortex in both conditions. Prominent frontal activity was detected following median nerve stimulation which, however, was absent in jerk-locked averages. Therefore an identical generator of the giant SEP and the JLA is unlikely. As the frontal component is lacking in jerk-locked averaging, the spontaneous jerks produced in our experimental paradigm are believed to be due to spontaneous hyperactivity of the parietal cortex rather than to pathologically enhanced transcortical reflexes.
Adolescent↗