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Biomedical subjects

A C Ludolph

Publications and source records attributed to A C Ludolph.

125 records · Page 7Linked to original sources
PubMed1989

[Electromagnetic stimulation of the nervous system. I. Normal values in the central nervous system and a comparison with electric stimulation].

After non-invasive stimulation of the motor cortex by brief electromagnetic pulses evoked potentials were biolaterally recorded in 29 healthy individuals. Normal values for the following target muscles were calculated: abductor pollicis brevis (APB), biceps brachii (BIC), tibialis anterior (TIB) and extensor digitorum brevis (EDB). In a subgroup (N = 12) results for APB and EDB were compared with those obtained by electrical stimulation techniques.

Adult↗
PubMed1989

[Electromagnetic stimulation of the nervous system. II. Normal values in the peripheral nervous system and comparison with electrical stimulation methods].

In 15 healthy subjects we stimulated the peripheral nervous system by a brief intense magnetic field and recorded evoked muscle potentials from peripheral muscles. Latencies were compared with those obtained by conventional electrical stimulation techniques. Amplitudes of muscle responses after magnetic stimulation were often smaller than those obtained after electrical stimulation; however, latencies were comparable at all stimulation sites.

Adult↗
PubMed1988

A clinical neurophysiologic study of tropical spastic paraparesis.

During a field study in the Seychelles Islands, 19 patients with tropical spastic paraparesis (TSP) were evaluated electrophysiologically. Methods of assessment included motor and sensory nerve conduction studies, electromyography, and analysis of the somatosensory evoked potentials after stimulation of the tibial and median nerves. The results showed that the most prominent feature of the disease, a spastic paraparesis, is accompanied by subclinical involvement of spinal sensory pathways and a comparatively minor peripheral sensorimotor polyneuropathy.

Electromyography↗
PubMed1988

Chronic ergotamine abuse: evidence of functional impairment of long ascending spinal tracts.

22 migraine patients with a history of chronic ergotamine abuse were compared with 12 patients with a similar intake of dihydroergotamine. The study of somatosensory-evoked potentials showed that 50% of the patients with a history of ergotamine abuse had increased central conduction times after stimulation of the tibial nerve. Corticomotoneuronal latencies obtained by noninvasive electrical stimulation of the motor cortex were normal in 5 patients. The functional sensory deficits were not related to clinical impairment and were more frequently observed in patients with a comparatively high mean daily and cumulative intake.

Adult↗
PubMed1988

[Function of the long spinal cord pathways in cervical spinal stenosis--an electrophysiologic study].

Cervical spinal stenosis is radiologically defined by a reduced inner diameter (X less than 13 mm) of the cord canal and in most cases etiologically connected with spondylosis. The following study describes the results of non-invasive assessment of the long ascending and descending spinal tracts in 12 patients. The long ascending spinal tracts were examined by spinal and cortical SEP after stimulation of the tibial nerve; for the assessment of the descending spinal tracts motor responses of the tibial anterior muscle were recorded after non-invasive stimulation of the motor cortex. Clinically symptomatic patients (N = 2) exhibited clear-cut functional motor and sensory deficits of the central pathways. In asymptomatic patients (N = 10) corticomotoneuronal latencies to the lower limbs were increased in 8 cases. In comparison, increased central sensory latencies were found in 9/10. In conclusion, the studies showed that the technique of non-invasive stimulation of the motor cortex may play a role in the detection of subclinical lesions of the long descending motor tracts due to a chronic mechanical irritation.

Cerebral Cortex↗
PubMed1988

[Methodology and normal values for the recording of evoked muscle potentials following stimulation over motor roots].

In 28 healthy subjects the peripheral nervous system was stimulated with brief high-voltage condenser discharges over the vertebral column. Latencies were correlated with the length of the extremity. The following normative data were obtained: M. biceps brachii 5.2 ms (SD 0.37 ms), M. abductor pollicis 14.2 ms (SD 0.86 ms), M. tibialis anterior 16.2 ms (SD 1.0 ms), M. extensor digitorum brevis 25.0 (SD 1.3 ms). Comparison of these latencies with those obtained by F-wave studies support the idea that motor roots are stimulated by this method.

Electric Stimulation↗
PubMed1988

[Findings in the peripheral motor system following stimulation of the motor nerve roots: polyradiculitis, amyotrophic lateral sclerosis and polyneuropathy].

The peripheral nervous system was stimulated over the vertebral column by brief, high-voltage condenser discharges. Potentials from proximal and distal muscles were recorded. We examined healthy subjects (N = 28), patients suffering from ALS (N = 5), from polyradiculitis (N = 6), and polyneuropathies (N = 8). In ALS latencies were slightly (in most cases less than 20%), in polyradiculitis latencies were markedly increased (30-40% on average). The latencies of patients suffering from polyneuropathies showed a variable pattern of vulnerability. Moreover, we could show that this method is frequently capable to quantify deficits in the peripheral nervous system when F-waves are absent.

Amyotrophic Lateral Sclerosis↗
PubMed1987

Guam amyotrophic lateral sclerosis-parkinsonism-dementia linked to a plant excitant neurotoxin.

The decline in the high incidence of amyotrophic lateral sclerosis, parkinsonism, and Alzheimer-type dementia among the Chamorro population of the western Pacific islands of Guam and Rota, coupled with the absence of demonstrable viral and hereditable factors in this disease, suggests the gradual disappearance of an environmental factor selectively associated with this culture. One candidate is seed of the neurotoxic plant Cycas circinalis L., a traditional source of food and medicine which has been used less with the Americanization of the Chamorro people after World War II. Macaques were fed the Cycas amino acid beta-N-methylamino-L-alanine, a low-potency convulsant that has excitotoxic activity in mouse brain, which is attenuated by N-methyl-D-aspartate receptor antagonists. These animals developed corticomoto-neuronal dysfunction, parkinsonian features, and behavioral anomalies, with chromatolytic and degenerative changes of motor neurons in cerebral cortex and spinal cord. In concert with existing epidemiological and animal data, these findings support the hypothesis that cycad exposure plays an important role in the etiology of the Guam disease.

Amino Acids, Diamino↗
PubMed1987

Non-invasive assessment of the pyramidal tract and motor pathway of primates.

Non-invasive direct stimulation of the motor cortex of cynomolgus monkeys has been used to assess in awake and anesthetized animals the central and peripheral conduction times of the motor pathway and to measure the latencies of the descending spinal volley of the pyramidal tracts. Repetitive stimulation failed to induce convulsive activity or detectable pathological changes. Peripheral latencies were comparable with those obtained from F-wave analysis. Central conduction times for corticospinal tracts regulating the upper and lower limbs were 2.7 msec and 5.4 msec, respectively, the estimated conduction velocity (67.5 m/sec) corresponding to results obtained by invasive methods. These studies provide a new and apparently safe technique to assess non-invasively the functional status of the central motor pathway in primates, a method that might also find utility in clinical practice.

Animals↗
PubMed1987

Studies on the aetiology and pathogenesis of motor neuron diseases. 1. Lathyrism: clinical findings in established cases.

Lathyrism is a toxic disease of the motor system constantly associated with primary consumption of the seed of Lathyrus sativus (chickling or grass pea). Neurological examination was performed on 38 affected subjects drawn from four regions of the Indian subcontinent endemic for lathyrism. All showed a consistent and largely symmetric pattern of neurological deficit similar to that displayed by 5 Europeans with longstanding lathyrism now living in Israel. Hallmarks of lathyrism include a pyramidal pattern of motor weakness combined with greatly increased tone in the thigh extensors and adductors and in the gastrocnemius muscles so that the more severely affected walk on the balls of their feet with a lurching scissoring gait. Extensor plantar responses are uniformly present in such cases, and the knee and ankle tendon reflexes are exaggerated and often clonic. Hoffmann signs and exaggerated biceps and/or triceps tendon jerks are also found in the most severely affected. Sensory signs are absent, although perverse sensations in the legs are frequently reported at the onset. Walking difficulties commonly begin suddenly but may also appear subacutely or insidiously. Some individuals experience partly reversible symptoms suggestive of a diffuse CNS excitation of somatic, motor and autonomic function.

Adult↗
PubMed1987

[Methodology and normal values in recording evoked motor potentials following transcranial stimulation in the human].

Electric non-invasive stimulation of the motor cortex was performed in 19 healthy subjects. Muscle responses were recorded with surface electrodes from the abductor, pollicis brevis and anterior tibial muscle. The mean central motor latencies for pathways regulating the function of the upper limbs was 4.5 msec (standard deviation 0.5 msec), the corresponding latency for the lower limbs was 9.6 msec (standard deviation 1.2 msec). The reproducibility of latencies and configuration of the potentials obtained indicates that the method described can be used as a reliable method in the diagnosis of affections of the motor system.

Electric Stimulation↗
PubMedDate not supplied

Functional deficits of central sensory and motor pathways in patients with cervical spinal stenosis: a study of SEPs and EMG responses to non-invasive brain stimulation.

The central conduction time of the descending and ascending fibers of the spinal cord were examined in patients with radiologically defined cervical spinal stenosis (antero-posterior diameter of the spinal canal less than 13 mm). Nineteen patients were examined, only 4 of whom showed clinical signs of spastic weakness or ataxia. The electromyographic response after non-invasive stimulation of the leg area of the motor cortex was delayed in 13 of the 15 clinically unaffected patients. The central latency (N21-P39) of the somatosensory evoked response after stimulation of the tibial nerve (tibialis SEP) was increased in 12 of the 15 individuals. The 4 patients with clinical signs showed abnormal latencies with both methods. The use of both techniques for the examination of the function of the spinal cord revealed increased latencies in the central motor and/or sensory pathways in all patients. The technique of non-invasive stimulation of the corticospinal system therefore provides an additional tool to detect and quantify subclinical and clinically apparent lesions in patients with defined cervical spinal stenosis.

Central Nervous System↗
PubMedDate not supplied

Open magnetic and electric graphic analysis.

The OMEGA software provides an analysis platform for user-independent, fast, and reproducible multimodal data analysis in one single software environment. Synergetic interactions pursued between the two functional imaging techniques fMRI and MEG use the morphological MRI recording as a basis for a common coordinate frame. In this way, direct interchange, comparison, and integration among the results of the different modalities have become feasible. The fMRI data analysis provides information about the localization of functional activity with low temporal resolution, whereas the MEG recording complements the corresponding time evolution with a high temporal resolution. The implementation of OMEGA allows the analyst to receive comprehensive MEG/fMRI results in a matter of minutes after the measurements have been completed. With OMEGA, the clinical researcher gets comprehensive information in a quick and standardized approach about the sites and the time course of neurological activation, which is useful for clinical applications and diagnostics.

Algorithms↗
PubMedDate not supplied

Transcranial magnetic stimulation: influence on plasma levels of hormones of the anterior pituitary gland and of cortisol?

To assess possible side effects of transcranial magnetic stimulation on the release of anterior pituitary gland hormones three different examinations on 10 males were performed following a standardized protocol. Plasma levels of prolactin, FSH, LH, hGH and cortisol were determined before and after stimulation. Cortical stimulation had no specific influence on the plasma levels of the hormones examined.

Adult↗
PubMedDate not supplied

Corticomotoneuronal latencies after non-invasive stimulation of the motor cortex in adrenomyeloneuropathy and adrenoleukodystrophy: results in patients and their relatives.

Corticomotoneuronal latencies after non-invasive stimulation of the motor cortex were studied in two patients with adrenomyeloneuropathy (AMN), in one patient with adrenoleukodystrophy (ALD), in two obligate heterozygotes, and in three clinically not affected sisters of the patients with AMN. Corticomotoneuronal latencies were prolonged in the patients as well as in obligate female carriers, but normal in the clinically and biochemically not affected relatives. The noninvasive cortex stimulation was found to be a sensitive method to detect clinical and subclinical deficits in patients and heterozygous carriers.

Adolescent↗