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H Feistner

Publications and source records attributed to H Feistner.

At least 19 recordsLinked to original sources
PubMed2000

Frontal-executive dysfunction in early onset cerebellar ataxia of Holmes' type.

We report the case of a 29-year-old male patient with cerebellar ataxia of Holmes' type. The combination of progressive cerebellar ataxia and hypogonadotrophic hypogonadism is a rare distinctive syndrome which was first described by Holmes in 1907. Early diagnosis is desirable because replacement of testosterone may allow normal sexual development. MRI showed severe combined superior vermian and cerebellar hemisphere atrophy. Comprehensive neuropsychological testing pointed to a more widespread cerebellar mediated functional CNS involvement in the earlier stages of this ataxic syndrome than previously described in mentally not retarded subjects.

Adult↗
PubMed2000

Mitochondrial complex I deficiency in a female with multiplex arthrogryposis congenita.

A 10-year-old female with arthrogryposis multiplex congenita is presented. Clinical, neurophysiologic, and histologic findings suggested a mild myopathy. The analysis of enzymatic activity in the homogenate and of mitochondrial function in saponin-permeabilized fibers from the muscle biopsy revealed an approximately twofold-decreased specific activity of the NADH:CoQ oxidoreductase (complex I of the mitochondrial respiratory chain) that was compensated for by an increased number of mitochondria. The complex I deficiency was also detected in cultivated skin fibroblasts of the patient. The observed defect of mitochondrial oxidative phosphorylation in arthrogryposis multiplex congenita may be of pathogenetic relevance.

Arthrogryposis↗
PubMed2000

Mitochondrial DNA abnormalities in skeletal muscle of patients with sporadic amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis is a neurodegenerative disease affecting the anterior horn cells of the spinal cord and cortical motor neurons. Previous findings have suggested a specific impairment of mitochondrial function in skeletal muscle of at least a limited number of patients. Applying flavoprotein/NAD(P)H autofluorescence imaging of mitochondrial function in saponin-permeabilized muscle fibres, we detected a heterogeneous distribution of the respiratory chain defect among individual fibres in muscle biopsies of patients (11 out of 17) with sporadic amyotrophic lateral sclerosis (SALS). These findings correlate with the presence of cytochrome c oxidase (COX)-negative muscle fibres detected histologically. We established the molecular basis for the decreased activities of NADH:CoQ oxidoreductase and COX in SALS muscle. In the skeletal muscle of the investigated patients, diminished levels (13 out of 17) or multiple deletions (one out of 17) of mitochondrial DNA (mtDNA) were observed. These alterations of mtDNA seem to be related to decreased levels of membrane-associated mitochondrial Mn-superoxide dismutase. Our results support the viewpoint that an oxygen radical-induced impairment of mtDNA is of pathophysiological significance in the aetiology of at least a subgroup of patients with SALS.

Adult↗
PubMed1999

Visualization of defective mitochondrial function in skeletal muscle fibers of patients with sporadic amyotrophic lateral sclerosis.

The mitochondrial function in skeletal muscle was investigated in skeletal muscle biopsies of 26 patients with sporadic amyotrophic lateral sclerosis (ALS) and compared with investigations of 28 age-matched control muscle samples and biopsies of 6 patients with spinal muscular atrophy (SMA) and two patients with Tay-Sachs disease. In comparison to the control, SMA and Tay-Sachs biopsies, we observed in the ALS samples a significant about two-fold lower activity of complex I of mitochondrial respiratory chain. To visualise the distribution of the mitochondrial defect in skeletal muscle fibers we applied confocal laser-scanning microscopy and video fluorescence microscopy of NAD(P)H and fluorescent flavoproteins. The redox change of mitochondrial NAD(P)H and flavoproteins on addition of mitochondrial substrates, ADP, or cyanide were determined by measurement of fluorescence intensities with dual-photon UV-excitation and single-photon blue excitation. In skeletal muscle fibers of ALS patients with abnormalities of mitochondrial DNA (multiple deletions, n=1, or lower mtDNA levels, n=14) we observed a heterogeneous distribution of the mitochondrial defects among individual fibers and even within single fibers. In some patients (n=3) a mitochondrial defect was also detectable in cultivated skin fibroblasts. These findings support the viewpoint that the observed impairment of mitochondrial function in muscle of certain ALS patients is caused by an intrinsic mitochondrial defect which may be of pathophysiological significance in the etiology of this neurodegenerative disease.

Adult↗
PubMed1999

Characterisation of paired-pulse transcranial magnetic stimulation conditions yielding intracortical inhibition or I-wave facilitation using a threshold-hunting paradigm.

Short-interval, paired-pulse transcranial magnetic stimulation (TMS) is usually used to demonstrate intracortical inhibition. It was shown recently that with short-interval, paired-pulse TMS a facilitation - called intracortical I-wave facilitation - can also be demonstrated. It was the aim of this study to investigate which stimulus conditions lead to intracortical inhibition and what conditions yield an intracortical I-wave facilitation in a hand muscle of normal subjects. Paired-pulse TMS responses with an interstimulus interval of 1.2 ms were obtained from the abductor digiti minimi muscle of four normal subjects. A threshold-hunting paradigm with hunting through first or second stimulus variation was used to obtain a curve of threshold-pair strengths. All subjects showed two branches of stimulus interaction on this diagram. If the first stimulus of a threshold pair was below approximately 65% of resting motor threshold it modified the response primarily due to the second stimulus through intracortical inhibition. However, if the first stimulus of a threshold pair exceeded approximately 65% of resting motor threshold it became responsible for the spinal action-potential initiation. The subsequent second stimulus served as a "booster" for the ongoing intracortical I-wave activity, making it impossible to observe the intracortical inhibition evoked by the first stimulus.

Action Potentials↗
PubMed1999

Effects of the amplitude threshold on the separability of neuropathic and myopathic from normal EMG using parameters of the turns/amplitude analysis.

OBJECTIVE: In this study, the relationship between the amplitude threshold used for the determination of the turns of the electromyographic (EMG) interference pattern and the parameters of the turns/amplitude analysis was examined. It was investigated whether the discrimination of myopathic and neuropathic from normal muscles could be optimized by an appropriate amplitude threshold. METHODS: The interference patterns of the tibialis anterior muscle of 15 patients with myopathies, 30 patients with neuropathies and 56 controls were recorded, using concentric needle electrodes. A computer program performed the Willison analysis, systematically varying the amplitude threshold between 10 microV and 200 microV. RESULTS: Amplitudes as well as the number of turns per second were non-linearly related to the amplitude threshold. The reduction of the amplitude threshold to 30 microV resulted in a clearly better separation of the distributions of the number of turns of neuropathic, myopathic and normal EMG, compared to the traditional threshold value of 100 microV. The distributions of amplitude values, however, were not affected. The distance between the turns parameter distributions of neuropathic patients and controls and between the distributions of myopathic patients and controls, expressed by the Kolmogoroff-Smirnov distance, had a maximum at 30 microV. CONCLUSIONS: For the turns/amplitude analysis of the tibialis anterior muscle an amplitude threshold of 30 microV should be selected.

Adult↗
PubMed1998

Impairment of mitochondrial function in skeletal muscle of patients with amyotrophic lateral sclerosis.

In skeletal muscle homogenates of 14 patients with sporadic amyotrophic lateral sclerosis, an approximately twofold lower specific activity of NADH:CoQ oxidoreductase in comparison to an age matched control group (n=28) was detected. This finding was confirmed by a detailed analysis of mitochondrial oxidative phosphorylation in skeletal muscle using saponin-permeabilized muscle fibers. (i) A significantly lowered maximal glutamate+malate and pyruvate+malate supported respiration of saponin-permeabilized fibers was detected in the patients group. (ii) Titrations with the specific inhibitor of NADH:CoQ oxidoreductase amytal revealed a higher sensitivity of respiration to this inhibitor indicating an elevated flux control coefficient of this enzyme. (iii) Applying functional imaging of mitochondria using ratios of NAD(P)H and flavoprotein autofluorescence images of saponin-permeabilized fibers we detected the presence of partially respiratory chain inhibited mitochondria on the single fiber level. A secondary defect of mitochondrial function due to the neurogenic changes in muscle seems to be unlikely since no mitochondrial abnormalities were detectable in biopsies of patients with spinal muscular atrophy. These results support the viewpoint that an impairment of mitochondria may be of pathophysiological significance in the etiology of amyotrophic lateral sclerosis.

Adult↗
PubMed1998

Common peroneal nerve palsy caused by a ganglion. Case report.

A common peroneal nerve palsy caused by a ganglion cyst is a rare entity. A 48-year old man was referred with a six year history of intermittent pain that had resulted in a complete palsy of the common peroneal nerve. A magnetic resonance (MR) scan showed compression of the nerve by a ganglion, which was excised and the nerve was released. Three months later the lost muscle function had returned completely.

Ganglia↗
PubMed1997

Application of inhibitor titrations for the detection of oxidative phosphorylation defects in saponin-skinned muscle fibers of patients with mitochondrial diseases.

Inhibitor titrations were applied to characterize functional changes in mitochondrial energy metabolism in the skeletal muscle of patients with mitochondrial diseases. For this we titrated the maximal mitochondrial respiration rate of saponin-skinned muscle fibers isolated from the skeletal muscle biopsy with the specific inhibitors of mitochondrial oxidative phosphorylation complexes I, IV and V-rotenone, azide and oligomycin. For three patients with deletions of mitochondrial DNA and one patient with a complex I deficiency the titrations revealed at rather normal respiration activities of saponin-skinned fibers significant differences to healthy controls: (i) The inhibitor titration curves of the affected enzyme were much steeper and (ii) for almost complete inhibition of respiration a smaller amount of the inhibitor is necessary. The detailed analysis of the titration curves within the framework of metabolic control theory indicated elevated flux control coefficients of the respective complex of respiratory chain. On the other hand, for one patient with a mitochondrial DNA depletion syndrome, decreased respiration activities of skinned fibers but no redistribution of flux control was observed. We conclude, therefore, that application of inhibitor titrations and the quantitative description of the titration curve can be a valuable approach to elucidate functional defects of mitochondrial oxidative phosphorylation.

Adult↗
PubMed1997

Plasticity and function--the fate of a free, neurovascular muscle graft ten years post-reconstruction.

A 16-year-old female sustained a subtotal amputation of the left thigh. Debridement resulted in a bone and soft-tissue defect of 20 cm in length. The whole quadriceps muscle was lost, and the knee joint was open. The femur was stabilized by transfer of corticocancellous bone grafts. A latissimus dorsi muscle was harvested and transferred to reconstruct the lost quadriceps muscle. The thoracodorsal nerve was coaptated to the motor branch of the femoral nerve. The years after trauma, the muscle provides excellent motor function. EMG evaluation reveals no sign of denervation; macro-electromyography reveals only a moderate enlargement of motor units. There is recruitment of all motor units. Maximum voluntary torque of the transplanted muscle has decreased, compared to the contralateral rectus femoris. Histologic evaluation demonstrates a normal skeletal muscle with typical fiber distribution. These results indicate complete adaptability of the muscle at an atypical site, with a high degree of functional and structural plasticity of the skeletal muscle. The decreased voluntary torque of the transferred latissimus dorsi depends on the lower, total-fiber, cross-sectional area--the result of a parallel fiber structure.

Adolescent↗
PubMed1997

[Use of automatic, computer-assisted EEG analysis in clinical practice].

Digital EEG-recorders are being increasingly accepted for clinical routine application, thereby offering the possibility for an automated computerised EEG evaluation. This paper presents the results of a corresponding computer programme developed in our group. Based on 313 clinical routine-EEG we compared the computer reports to the visual EEG-interpretations and obtained the following result: Background activity is reliably detected with a rate comparable to a human interpreter. Similar results were observed with focussed pathological activity. Intermittent activity (Parenrhythmia, dysrhythmia) however lacks a sufficiently high score of correct evaluation and requires further development. Epileptiform potentials, especially spikes, are detected with high sensitivity, however, at the cost of low specificity, and are therefore still in need of further improvement.

Cerebral Cortex↗
PubMed1997

[Surgical decompression of bilateral, compression-induced damage to the posterior interosseous nerve. A case report].

Bilateral posterior interosseous nerve palsy is a rare case of radial nerve entrapment. The patient is unable to extend the fingers in the metacarpophalangeal joints. Extension of the interphalangeal joints is preserved due to the intrinsic muscles. Neither the extensor carpi radialis longus and brevis muscles are affected nor the brachioradialis muscle. However, extension of the wrist may be weak. There is no sensory loss. The neurophysiological examination underlines the clinical findings. In our case compression is caused by the arcade of Frohse and the vessels of the recurrent radial artery. A good recovery of nerve function is seen after surgical decompression.

Decompression, Surgical↗
PubMed1996

A trend-detection algorithm for intraoperative EEG monitoring.

Intraoperative EEG-monitoring needs to discriminate random fluctuations from real systematic variations (trends). This task is made more difficult by several types of artifacts. With the goal of supporting visual EEG evaluation, a new trend-detection algorithm is presented which is based on spectral analysis and a post-processing dynamic linear model, the latter introduced by Harrison and Stevens. A gradient value provided by this model is exploited to determine the onset and relative extent of an existing trend. Artifacts are detected by several threshold measures for the original signal and its first derivative. The system was validated using a set of intraoperative EEGs recorded during carotid endarterectomy.

Algorithms↗
PubMed1995

Laser-excited fluorescence studies of mitochondrial function in saponin-skinned skeletal muscle fibers of patients with chronic progressive external ophthalmoplegia.

The functional behavior of mitochondria in skeletal muscle of patients with chronic progressive external ophthalmoplegia was studied by laser-excited fluorescence measurements of NAD(P)H and flavoproteins in saponin-skinned fibers. Variations in the mitochondrial content and the presence of partially respiratory chain-inhibited mitochondria can be detected using this novel method.

DNA, Mitochondrial↗
PubMed1995

Comparison of single motor unit responses to transcranial magnetic and peroneal nerve stimulation in the tibialis anterior muscle of patients with amyotrophic lateral sclerosis.

Responses of single tibialis anterior motor units to transcranial magnetic stimulation and to a synchronized Ia volley evoked by peripheral nerve electrical stimulation were obtained in amyotrophic lateral sclerosis (ALS) patients and normal controls. Whereas the units of normal subjects exhibited rather stereotyped short-latency spike density peaks in response to both types of stimulus, the responses of ALS patient units were much less uniform. All ALS patient units exhibited a response to the synchronized Ia volley indistinguishable from that of normal subjects, indicating that the investigated spinal motoneurons are capable of normal excitatory responses in ALS patients. More than half of the ALS patient units responded to the transcranial magnetic stimulus with prolonged spike-density peaks appearing at a latency consistent with the notion that these pathological peaks are evoked by some relatively hyperexcitable structures presynaptic to the corticomotoneurons.

Adult↗
PubMed1994

Correlations between size parameters and the amplitude of the excitatory postsynaptic potential evoked by magnetic brain stimulation in human hand muscle motoneurons.

According to the size principle for motoneurons one would expect that an excitatory stimulus given to a motoneuronal pool should evoke small excitatory postsynaptic potentials (EPSPs) in large and large EPSPs in small motoneurons of the pool. In this study this expectation was tested for the motoneuron pool of the first dorsal interosseus muscle of man excited by a magnetic stimulus given to the contralateral motor cortex. In total, 60 first dorsal interosseus motor units from three healthy volunteers were investigated. For each unit the EPSP size induced by the magnetic brain stimulus was assessed indirectly through a cross correlation of magnetic brain stimuli with motor unit discharges during a slight voluntary contraction. In addition to the indirect measurement of EPSP size, three indicators of motoneuronal size were obtained for each unit: the area the macroelectromyogram (Macro EMG) of the unit encloses with the baseline, the peak-to-peak amplitude of the Macro EMG, and the "true" latency from the magnetic stimulus to the motor unit which in turn provides an indirect estimate for the conduction velocity of the motoneuronal axon. It was found that all three measures of motoneuron size were significantly negatively correlated with the estimates of EPSP amplitude. Such significant negative correlations were found not only in the pooled data but also in the data from each subject individually. These correlations reveal that a magnetic brain stimulus induces small EPSPs in large and large EPSPs in small motoneurons of the first dorsal interosseus muscle of man.

Adult↗
PubMed1994

Quantification of D- and I-wave effects evoked by transcranial magnetic brain stimulation on the tibialis anterior motoneuron pool in man.

Transcranial stimulation in man evokes multiple descending volleys in the spinal cord giving rise to multiple subpeaks in a peri-stimulus-time histogram (PSTH) obtained from a cross-correlation of motor unit discharges with transcranial stimuli. The first volley is termed the D wave, as it is assumed to be evoked by direct excitation of pyramidal tract neurons, whereas the subsequent I waves appear to be generated by indirect excitation of the pyramidal tract neurons via cortical interneurons. It was the aim of this study to obtain an estimate of the effect induced by multiple volleys evoked by transcranial magnetic stimulation on the entire motoneuron pool of the tibialis anterior in awake subjects. A considerable part of a particular motoneuron pool was investigated by sampling responses of a large number (at least 19) from each muscle investigated. In total, three tibialis anterior muscles from three normal volunteers were studied. From each of the 63 units included in this study, a PSTH to 100 transcranial magnetic stimuli and a PSTH to 100 electrical stimuli given to the peroneal nerve were compiled. From the motor unit response to the peripheral nerve stimulation, the latency of the single-unit H reflex peak was obtained. This yielded, the timing of the subpeaks in response to the magnetic stimulation relative to the timing of the H reflex of the same unit, thus eliminating the influence of the peripheral conduction time from the motoneuron to the recording electrode. It was found that 50 (79%) of the motor units exhibited at least two subpeaks in response to the cortical stimulus.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗