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Biomedical subjects

C H Lücking

Publications and source records attributed to C H Lücking.

At least 55 records · Page 3Linked to original sources
PubMed1999

Facial nerve dysfunction in hereditary motor and sensory neuropathy type I and III.

Facial nerve function was studied in 19 patients with hereditary motor and sensory neuropathy type I (HMSN I) and 2 patients with hereditary motor and sensory neuropathy type III (HMSN III, Déjérine-Sottas), and compared to that in 24 patients with Guillain-Barré syndrome (GBS). The facial nerve was stimulated electrically at the stylomastoid fossa, and magnetically in its proximal intracanalicular segment. Additionally, the face-associated motor cortex was stimulated magnetically. The facial nerve motor neurography was abnormal in 17 of 19 HMSN I patients and in both HMSN III patients, revealing moderate to marked conduction slowing in both the extracranial and intracranial nerve segments, along with variable reductions of compound muscle action potential (CMAP) amplitudes. The facial nerve conduction slowing paralleled that of limb nerves, but was not associated with clinical dysfunction of facial muscles, because none of the HMSN I patients had facial palsy. Conduction slowing was most severe in the HMSN III patients, but only slight facial weakness was present. In GBS, conduction slowing was less marked, but facial weakness exceeded that in HMSN patients in all cases. We conclude that involvement of the facial nerve is common in HMSN I and HMSN III. It affects the intra- and extracranial part of the facial nerve and is mostly subclinical.

Adult↗
PubMed1999

Quantitative sudomotor axon reflex test (QSART): a new approach for testing distal sites.

The quantitative sudomotor axon reflex test (QSART) is a useful tool in the evaluation of C-fiber function. Because many neuropathies show a length-dependent loss of nerve function, a new capsule was designed for distal performance of the QSART, allowing measurements on fingers and toes. We investigated 20 healthy volunteers and 15 patients with insulin-dependent diabetes mellitus and normal sensory nerve conduction studies. A QSART was performed on the forearm and on the thumb. The groups showed no differences in the QSARTs on the forearm, but the sweat volume on the thumb was significantly lower in patients. Calculation of the forearm/finger ratio reduced the interindividual variation and showed the highest sensitivity for detecting C-fiber dysfunction in the patient group. We conclude that the distal measuring device and the forearm/finger ratio are more sensitive tools for the early detection of distal-onset neuropathies than are the commonly used proximal testing sites.

Adult↗
PubMed1999

Facial palsy in Heerfordt's syndrome: electrophysiological localization of the lesion.

Heerfordt's syndrome is characterized by fever, uveitis, swelling of the parotid gland, and facial nerve palsy and represents a variety of neurosarcoidosis. Since the first description of the syndrome, discussion about the lesion site has been controversial and has included the assumption of direct nerve compression by parotid gland swelling or a lesion within the facial canal in light of observations of accompanying taste disturbance. We report on a 26-year-old man with typical Heerfordt's syndrome who developed bilateral facial nerve palsy. Electrical and magnetic stimulation of the whole facial motor path provided strong evidence for a pathological process that: (i) began in the cerebellopontine angle; (ii) spread distally into the facial canal; and (iii) could be characterized by proximal demyelination. The patient recovered completely within 6 weeks under immunosuppressive therapy with steroids.

Adult↗
PubMed1999

Involvement of cranial muscles and high intermuscular coherence in orthostatic tremor.

Electromyographic recordings were conducted from limb, trunk, and cranial muscles in 6 patients with orthostatic tremor. Spectral analysis revealed a high-frequency tremor not only in the muscles of the limbs and trunk, but also in cranial muscles. The cross spectra were analyzed between various pairs of muscles that displayed a high-frequency tremor pattern. The resulting peak correlations were uniformly very high (near one) suggesting a high level of coherence. The involvement of cranial muscles suggests that supraspinal mechanisms are involved in the generation of orthostatic tremor. The high intermuscular coherence between all muscles indicates the existence of either a unique oscillator that generates tremor in all involved muscles on both sides of the body or a linking mechanism probably at a supraspinal level. The high-frequency tremor was only found when the muscles were contracted isometrically, irrespective of body posture. Thus, tremor generation might be more closely linked to mechanisms responsible for isometric force control than to those involved in stance regulation.

Aged↗
PubMed1999

The role of higher-order motor areas in voluntary movement as revealed by high-resolution EEG and fMRI.

In the human motor cortex structural and functional differences separate motor areas related to motor output from areas essentially involved in higher-order motor control. Little is known about the function of these higher-order motor areas during simple voluntary movement. We examined a simple finger flexion movement in six healthy subjects using a novel brain-imaging approach, integrating high-resolution EEG with the individual structural and functional MRI. Electrical source reconstruction was performed in respect to the individual brain morphology from MRI. Highly converging results from EEG and fMRI were obtained for both executive and higher-order motor areas. All subjects showed activation of the primary motor area (MI) and of the frontal medial wall motor areas. Two different types of medial wall activation were observed with both methods: Four of the subjects showed an anterior type of activation, and two of the subjects a posterior type of activation. In the former, activity started in the anterior cingulate motor area (CMA) and subsequently shifted its focus to the intermediate supplementary motor area (SMA). Approximately 120 ms before the movement started, the intermediate SMA showed a drop of source strength, and simultaneously MI showed an increase of source strength. In the posterior type, activation was restricted to the posterior SMA. Further, three of the subjects investigated showed activation in the inferior parietal lobe (IPL) starting during early movement preparation. In all subjects showing activation of higher-order motor areas (anterior CMA, intermediate SMA, IPL) these areas became active before the executive motor areas (MI and posterior SMA). We suggest that the early activation of the anterior CMA and the IPL may be related to attentional functions of these areas. Further, we argue that the intermediate part of the SMA triggers the actual motor act via the release of inhibition of the primary motor area. Our results demonstrate that a noninvasive, multimodal brain imaging technique can reveal individual cortical brain activity with high temporal and spatial resolution, independent of a priori physiological assumptions.

Adult↗
PubMed1999

Diagnosis of tachycardia syndromes associated with orthostatic symptoms.

The postural tachycardia syndrome (POTS) is characterized by excessive tachycardia only in upright position without evidence of a cardiac or metabolic disease in combination with orthostatic symptoms like dizziness, lightheadedness or syncope but without relevant falls in blood pressure. The cause is unknown. A specific diagnostic marker has not been found so far. Eighteen patients with typical symptoms of POTS were examined. They underwent standard autonomic function tests with continuous measurement of heart rate (HR) and blood pressure. All fulfilled the inclusion criteria of pathologically increased HR activation during passive tilt or standing over 90 seconds. The upper limits of normal were based on data from 137 healthy volunteers between 18 and 85 years of age. Actively standing up induced more POTS-typical HR increases and lead to more consistent results than passive tilt. HR responses during Valsalva manoeuvre and deep breathing were normal in all except one patient each, indicating that assessment of HR during these tests does not contribute to the diagnosis of POTS. Frequency of symptoms reducing overall well-being and the degree of impairment of life quality by symptoms typical of POTS were measured with a self-assessment scale. The majority of patients reported a permanent reduction of overall well-being and a relevant impairment of life quality due to dizziness, tachycardia, and syncopes. This underlines the importance of considering POTS as a differential diagnosis of orthostatic syndromes and the necessity of treating it adequately.

Adolescent↗
PubMed1999

Brain imaging in a patient with hemimicropsia.

Hemimicropsia is an isolated misperception of the size of objects in one hemifield (objects appear smaller) which is, as a phenomenon of central origin, very infrequently reported in literature. We present a case of hemimicropsia as a selective deficit of size and distance perception in the left hemifield without hemianopsia caused by a cavernous angioma with hemorrhage in the right occipitotemporal area. The symptom occurred only intermittently and was considered the consequence of a local irritation by the hemorrhage. Imaging data including a volume-rendering MR data set of the patient's brain were transformed to the 3-D stereotactic grid system by Talairach and warped to a novel digital 3-D brain atlas. Imaging analysis included functional MRI (fMRI) to analyse the patient's visual cortex areas (mainly V5) in relation to the localization of the hemangioma to establish physiological landmarks with respect to visual stimulation. The lesion was localized in the peripheral visual association cortex, Brodmann area (BA) 19, adjacent to BA 37, both of which are part of the occipitotemporal visual pathway. Additional psychophysical measurements revealed an elevated threshold for perceiving coherent motion, which we relate to a partial loss of function in V5, a region adjacent to the cavernoma. In our study, we localized for the first time a cerebral lesion causing micropsia by digital mapping in Talairach space using a 3-D brain atlas and topologically related it to fMRI data for visual motion. The localization of the brain lesion affecting BA 19 and the occipitotemporal visual pathway is discussed with respect to experimental and case report findings about the neural basis of object size perception.

Adult↗
PubMed1999

A software for recording and analysis of human tremor.

For many diseases various methods for the diagnosis and treatment monitoring are available. Presently, such methods are not established for an investigation of tremor diseases, although the different forms of tremor are common neurological symptoms and occur frequently in various neurological diseases and also other conditions. We developed an easy-to-use application for tremor-analysis and recording, running under MS-Windows, that allows us to investigate different forms of tremor by advanced mathematical methods of time series analysis. The application is also applicable for users who are not familiar with these kind of advanced data analysis methods. It provides tools for the diagnosis and treatment monitoring under laboratory conditions, based on previously developed and established methods of spectral and cross spectral analysis of tremor and electromyographic time series.

Electronic Data Processing↗
PubMed1999

Side-to-side correlation of muscle activity in physiological and pathological human tremors.

OBJECTIVE: Many tremors occur always or often bilaterally. The question arises whether this could be explained by a common source or commonly transmitting pathways or by bilaterally represented, independent structures with the same oscillatory properties. A similar tremor frequency does not provide sufficient information to clarify this question. METHODS: We analyze coherencies between surface electromyographies (EMG) to investigate if bilateral physiologic (PT), essential (ET), Parkinsonian (PD) and orthostatic (OT) tremors originate from a common source for both sides of the body. We show that commonly used techniques to test whether coherencies are significant could lead to false positive results for tremor EMGs. A new estimation procedure is proposed to test EMG tremor time series on their linear independence. We apply this test to bilateral tremors. RESULTS: All measured EMG-pairs in OT (n = 7) were highly coherent between both sides with reproducible coherency values of up to 0.99. All other investigated tremors, i.e. PT and enhanced physiological tremors (EPT, n = 117), ET (n = 76) and PD resting and postural tremors (n = 70) do not show a significant side-to-side correlation. CONCLUSIONS: This finding shows that the pathophysiologies of OT and other pathological tremors are definitely different. Either they have different origins or different kinds of transmitting pathways. The proposed method might also be used to investigate other electrophysiological data and is a helpful, easy to use investigation for a daily clinical routine.

Computer Simulation↗
PubMed1999

Impairment in preattentive visual processing in patients with Parkinson's disease.

We explored the possibility of whether preattentive visual processing is impaired in Parkinson's disease. With this aim, visual discrimination thresholds for orientation texture stimuli were determined in two separate measurement sessions in 16 patients with idiopathic Parkinson's disease. The results were compared with those of 16 control subjects age-matched and 16 young healthy volunteers. Discrimination thresholds were measured in a four-alternative spatial forced-choice paradigm, in which subjects judged the location of a target embedded in a background of distractors. Four different stimulus configurations were employed: (i) a group of vertical targets among horizontal distractors ('vertical line targets'); (ii) targets with varying levels of orientation difference on a background of spatially filtered vertically oriented noise ('Gaussian filtered noise'); (iii) one 'L' among 43 '+' signs ('texton'), all of which assess preattentive visual processing; and (iv) control condition, of one 'L' among 43 'T' distractors ('non-texton' search target), which reflects attentive visual processing. In two of the preattentive tasks (filtered noise and texton), patients with Parkinson's disease required significantly greater orientation differences and longer stimulus durations, respectively. In contrast, their performance in the vertical line target and non-texton search target was comparable to that of the matched control subjects. These differences were more pronounced in the first compared with the second session. Duration of illness and age within the patient group correlated significantly with test performance. In all conditions tested, the young control subjects performed significantly better than the more elderly control group, further indicating an effect of age on this form of visual processing. The results suggest that, in addition to the well documented impairment in retinal processing, idiopathic Parkinson's disease is associated with a deficit in preattentive cortical visual processing.

Adult↗
PubMed1999

Alexithymia and attachment representation in idiopathic spasmodic torticollis.

We investigated alexithymia and the mental representation of attachment in idiopathic spasmodic torticollis (IST). It was hypothesized a) that alexithymia in IST is more prevalent than in a nonclinical control group and b) that significant correlations emerge between alexithymia and a dismissing attachment representation. Twenty patients with IST and 20 healthy controls matched for age and sex were administered the Toronto Alexithymia Scale (TAS-20) and the Adult Attachment Interview (AAI). Attachment was classified using the Attachment Interview Q-sort. IST patients scored significantly higher on the measure of alexithymia than subjects in the comparison group. In IST a dismissing attachment representation was significantly more frequent than in the control group. Across the total sample, externally oriented thinking correlated positively with dismissing attachment, and both externally oriented thinking and difficulty communicating feelings (two of the three subscales of the TAS-20) correlated inversely with secure attachment. Alexithymia is more prevalent in IST than in normals. As was hypothesized, alexithymia in adults is significantly interrelated with the mental representation of attachment.

Adult↗
PubMed1999

Multimodality monitoring during passive tilt and Valsalva maneuver under hypercapnia.

In occlusive cerebrovascular disease cerebral blood flow (CBF) autoregulation can be impaired and constant CBF during fluctuations in blood pressure (BP) cannot be guaranteed. Therefore, an assessment of cerebral autoregulation should consider not only responsiveness to CO2 or Diamox. Passive tilting (PT) and Valsalva maneuver (VM) are established tests for cardiovascular autoregulatory function by provoking BP changes. To develop a comprehensive test for vasomotor reactivity with a potential increase of sensitivity and specificity, the authors combined these maneuvers. Blood pressure, corrected to represent arterial pressure at the level of the circle of Willis, middle cerebral artery Doppler frequencies (DF), heart rate (HR) and endtidal partial pressure of CO2 (PtCO2) were measured continuously and noninvasively in 81 healthy subjects (19-74 years). Passive tilt and Valsalva maneuver were performed under normocapnia (mean, 39 + 4 mmHg CO2) and under hypercapnia (mean, 51 + 5 mm Hg CO2). Resting BP, HR, and DF increased significantly under hypercapnia. Under normocapnia and hypercapnia, PT induced only minor, nonsignificant changes in mean BP at the level of the circle of Willis compared to baseline (normocapnia: + 2 + 15 mm Hg; hypercapnia: -3 +/- 13 mm Hg). This corresponded with a nonsignificant decrease of the mean of DF (normocapnia: -4 +/- 11%; hypercapnia -6 +/- 12%). Orthostasis reduced pulsatility of BP by a predominantly diastolic increase of BP without significant changes in pulsatility of DF. Valsalva maneuver, with its characteristic rapid changes of BP due to elevated intrathoracic pressure, showed no significant BP differences in changes to baseline between normocapnic and hypercapnic conditions. Under both conditions the decrease in BP in phase II was accompanied by significantly increased pulsatility index ratio (PIDF/PIBP). Valsalva maneuver and PT as established tests in autonomic control of circulation provoked not only changes in time-mean of BP but also in pulsatility of BP. The significant increase in pulsatility ratio and decrease of the DF/BP ratio during normocapnia and hypercapnia indicated preserved CBF autoregulation within a wide range of CO2 partial pressures. Hypercapnia did not significantly influence the autoregulatory indices during VM and PT. Physiologically submaximally dilated cerebral arterioles can guarantee unchanged dynamics of cerebral autoregulation. Combined BP and MCA-DF assessment under hypercapnia enables investigating the effect of rapid changes of blood pressure on CO2-induced predilated cerebral arterioles. Assuming no interference of hypercapnia-induced vasodilation, VM, with its rapid, distinct changes in BP, seems especially to be adequate provocation for CBF autoregulation. This combined vasomotor reactivity might provide a more sensitive diagnostic tool to detect impaired cerebral autoregulation very early.

Adult↗
PubMed1998

Central mechanisms in human enhanced physiological tremor.

The sites of the central nervous structures involved in enhanced physiological tremor (EPT) are still unclear. The syndrome of persistent mirror movements (PMM) is characterized by abnormal bilateral corticospinal projections. If a supraspinal mechanism is involved in EPT, the activity of EPT should be coherent between both sides in subjects with this abnormality. We investigated three PMM subjects and three normal controls. Focal transcranial magnetic stimulation (TMS) resulted in contralateral hand muscle responses in the controls. The PMM subjects, in contrast, had bilateral responses. Similarly, long-latency reflexes (LLR) in PMM could be recorded bilaterally, while the control subjects showed responses only on the stimulated side. EPT was evoked by intravenous salbutamol. EMG time series were recorded bilaterally from the wrist extensor muscles and cross spectra were calculated. If there was a significant right-left-coherence, phase analysis was performed. No control subject showed a significant right-left-coherence of tremor activity. In contrast, a significant coherence was found in PMM between 8 and 12 Hz. When the mechanical tremor frequency of one hand was reduced by loading, coherences and phase spectra of the EMGs remained unchanged. By comparing the results from TMS, LLR and cross spectral analysis we come to the conclusion, that the 8 to 12 Hz component of EPT is transmitted transcortically, most likely originating from two separate generators for both sides.

Adult↗
PubMed1998

Involvement of the esophagus in the cramp-fasciculation syndrome.

A 35-year-old male patient presented with symptoms of a cramp-fasciculation syndrome, but also reported difficulties swallowing. Esophageal manometry showed spontaneous nonperistaltic contractions, pathologically increased amplitudes and duration of the contractile complexes, and an asynchronous propagation. Electromyographic evidence of fasciculations in the sternocleidomastoid and pectoralis muscles was found. Apparently all types of peripheral motor fibers can be involved in this heterogeneous syndrome, including cranial motor nerves, the vagal nerve, and enteric motor fibers of the gastrointestinal tract.

Adult↗
PubMed1998

Absence of transcallosal inhibition following focal magnetic stimulation in preschool children.

Focal transcranial magnetic stimulation of the hand-associated motor cortex was used to study normal healthy preschool children (n = 7; mean age, 4.6 years) and adults (n = 7; mean age, 29.4 years) under the conditions of standardized tonic voluntary contraction of small hand muscles. Callosally mediated inhibitory as well as corticospinally mediated inhibitory and excitatory motor effects were investigated. Although children had no detectable transcallosal inhibition, their corticospinally mediated postexcitatory silent period was present (mean, 140.8 +/- 30.2 msec). It was significantly shorter than in adults (mean, 192.5 +/- 32.0 msec). The motor thresholds of the cortically elicited muscle responses, measured as the lowest stimulus intensity, were significantly higher in children (mean, 89 +/- 5%) than in adults (mean, 46 +/- 6%). The corticomuscular latency of transcranially elicited motor responses revealed no difference between children and adults. These observations may reflect maturation processes in the motor system. Maturation of at least some direct corticospinal fibers occurs early in life and is followed by that of intracortical excitatory and inhibitory connections. The maturation of functionally competent callosal connections appears to occur after the age of 5 years.

Adult↗
PubMed1998

Diagnostic and pathophysiological aspects of psychogenic tremors.

Psychogenic tremor has become a rare movement disorder. Twenty-five patients from our movement disorder unit presented either with obviously nonorganic body shaking during stance or with extremity tremors. A sudden onset and a variable but rarely remitting course of the condition was common. The "coactivation sign of psychogenic tremor" and absent finger tremor were the most consistent criteria to separate them from organic tremors. Quantitative analysis of tremor shows decreasing amplitudes in most organic tremors when the extremity is loaded with additional weights. In contrast, we found an increase of tremor amplitude for most of the cases with psychogenic tremor. This might be caused by increased coactivation to maintain the oscillation. These clinical and electrophysiological features suggest a clonus mechanism induced by coactivation as the pathophysiological basis of psychogenic extremity tremor. Psychiatric evaluation did not show overt signs of hysteria for the majority of the patients. However, we found depression and functional somatic or psychosomatic conditions to be frequent among the patients. A reduced ability to cope with stressful situations may play a significant role. The clinical course of the condition is usually far from benign. We conclude that psychogenic tremor can be positively diagnosed by means of neurologic signs in the majority of patients and is not only a diagnosis of exclusion. The poor outcome makes early and serious neuropsychiatric attempts at therapy necessary.

Adaptation, Psychological↗