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Biomedical subjects

P Fuhr

Publications and source records attributed to P Fuhr.

44 records · Page 3Linked to original sources
PubMed1991

Topographic maps of human motor cortex in normal and pathological conditions: mirror movements, amputations and spinal cord injuries.

We studied motor evoked potentials to transcranial magnetic stimulation in patients with unilateral upper limb amputations, complete T10-T12 spinal cord transection, and congenital mirror movements and in controls. Different muscles in the trunk and upper and lower extremities were evaluated at rest. In controls, muscles could be activated with stimulation of regions several centimeters wide. These areas overlapped extensively when muscles studied were from the same limb and shifted positions abruptly when muscles were from different limbs. Distal muscles were easier to activate than proximal muscles and normally evidenced exclusively a contralateral representation. Congenital defects in motor control in patients with mirror movements resulted in marked derangement of the map of outputs of distal hand muscles with enlarged and ipsilateral representations. Peripheral lesions, either acquired (amputations) or congenital (congenital absence of a limb), resulted in plastic reorganization of motor outputs targeting muscles immediately proximal to the stump. Central nervous system lesions (i.e., spinal cord injury producing paraplegia) also resulted in enlargement of the map of outputs targeting muscles proximal to the lesion. These results indicate that magnetic stimulation is a useful non-invasive tool for exploring plastic changes in human motor pathways following different types of injury.

Adult↗
PubMed1990

Electrocutaneous reflexes and multimodality evoked potentials in multiple sclerosis.

Electrical stimulation of the digital nerves of the index finger produces changes in the EMG signal during steady voluntary contraction of the first dorsal interosseous muscle. This electrocutaneous reflex (ECR) was studied in 90 patients classified into different categories according to diagnostic criteria for multiple sclerosis. In addition, pattern reversal visual evoked responses (VER), brainstem auditory evoked responses (BAER) as well as spinal and scalp recorded somatosensory evoked potentials (SSEP) were investigated by stimulating both the index finger and the posterior tibial nerve. The reflex response was altered uni- or bilaterally in 56 per cent of the patients and the abnormalities of the ECR were related to the categories of diagnostic probability. Pathological results were found in 28 per cent of the hands without clinical evidence of sensorimotor deficit. Although ECR abnormalities were often associated with clinical signs, significant correlation was found only with hyperreflexia and/or increased muscle tone in the corresponding upper limb. Pathological ECR were more common than pathological SSEPs with finger stimulation recorded under identical stimulus conditions. Fewer abnormalities were found by ECR testing than with VER, but the proportion of abnormal ECR was higher than that of BAER. ECR provides a valuable supplement to existing electrophysiological procedures for detecting lesions in the central nervous system.

Adolescent↗
PubMed1987

Detection threshold for percutaneous electrical stimuli: asymmetry with respect to handedness.

Sensory strength-duration curves were obtained using percutaneous true square-wave pulses ranging from 0.1 to 20.0 ms produced by an isolated constant current stimulator. In 119 healthy volunteers sensory thresholds were measured bilaterally by stimulating the distal phalange of the little finger. In order to examine the relationship of sensory threshold and handedness the latter was assessed by means of the Edinburgh Inventory. An asymmetry of sensory threshold was found for all the subjects and this was more pronounced with shorter stimuli. Of right-handers tested 73.5% had a lower threshold on the left side while 70.8% of left-handers had a lower threshold on the right side. Although threshold asymmetry is associated with handedness this is not necessarily due to cerebral lateralization.

Adolescent↗
PubMed1987

Electrocutaneous reflexes in upper limbs--reliability and normal values in adults.

The present study provides information as to both the range of normality and reliability of the electrocutaneous reflex (ECR) in upper limbs as a routine diagnostic procedure. Measurements were performed on 70 adult volunteers under optimized and standardized conditions. The mean latency was 40.3 +/- 3.2, 50.9 +/- 3.5 and 65.8 +/- 5.8 ms for E1, I1 and E2, respectively, and 21.9 +/- 1.6 ms for N22 of the cortical somatosensory-evoked potentials as recorded under identical stimulus conditions. Arm length represented the most important factor of interindividual variability while age was of minor and sex of no importance after normalization of the latencies for arm length.

Adult↗
PubMed1979

Evaluation of aortocoronary venous bypass grafting for prevention of cardiac arrhythmias.

The influence of ACB on cardiac arrhythmias was examined in 27 patients. Eight-hour Holter monitoring was performed 8 days preoperatively and 100 days postoperatively. Arrhythmias were divided into 3 groups (Class I: NSR +/- occasional APBs; Class II: less than five unifocal VPBs per minute; Class II: more than five VPBs per minute, multifocal VPBs, VPBs in a row or VT). Preoperative classification disclosed that 13 patients (48.1 per cent) were in Class I, six patients (22.2 per cent) were in Class II, and eight patients (29.6 per cent) were in Class III. The corresponding values after surgery were 10 patients (37.0 per cent), 13 patients (48.1 per cent), and four patients (14.8 per cent). These differences were not statistically significant (p less than 0.1). In view of the tendency of arrhythmias of Class III to improve after ACB, we feel that further investigations in this area are needed. At the present time ventricular arrhythmias alone constitute no indication for bypass surgery.

Adult↗
PubMedDate not supplied

Pathologic gambling in patients with Parkinson's disease.

Patients with Parkinson's disease frequently have depression, anxiety, and obsessive-compulsive disorder. We observed two patients who had episodes of pathologic gambling. At the same time, their Parkinson's disease deteriorated and they initiated self-medication with dopaminergic drugs. In both patients, signs were present of an addiction to dopaminergic medication. Pathologic gambling ceased in these patients after a few months. The significance of an insufficient dopaminergic reward system in patients with stereotypical addictive-like behavior (e.g., pathologic gambling) is discussed in this report. The most likely explanation for this newly recognized behavioral disorder in patients with Parkinson's disease is enhanced novelty seeking as a consequence of overstimulation of mesolimbic dopamine receptors resulting from addiction to dopaminergic drugs.

Antiparkinson Agents↗