Long-latency reflexes following electrical nerve stimulation. The Inter national Federation of Clinical Neurophysiology.
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Electric Stimulation↗
Biomedical subjects
G Deuschl
Publications and source records attributed to G Deuschl.
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↗
High penetrance and pronounced variation in expressivity of GCH1 mutations in five families with dopa-responsive dystonia.
We performed a clinical and molecular genetic analysis in members of five families with dopa-responsive dystonia. Four mutations were detected in the gene GCH1 that codes for GTP cyclohydrolase I. Two of these mutations, a delG309 in exon 1 and a C544T transition in exon 5, have not been described before. They result in inactivation of the enzyme by truncation. The remaining two mutations, both A to G transitions, a(-2)g in intron 1 and a(-2)g in intron 2, cause truncation by abnormal splicing. The genotype of family members was correlated to their clinical phenotype (obtained before molecular analysis). Clinical symptoms observed in the families included generalized and focal dystonia, abnormal gait, and subtle signs such as an abnormal writing test. High penetrance (0.8-1.0) was observed in four of five families if minor symptoms and signs were considered. A given mutation was more likely to cause symptoms in females than in males, thus confirming the well-established higher incidence of dopa-responsive dystonia in females than in males.
Adolescent↗
Geste device in tardive dystonia with retrocollis and opisthotonic posturing.
Retrocollis and opisthotonic posturing are typical clinical features of tardive dystonia and may be extremely disabling. We have treated five such patients with a custom-made mechanical device that delivers constant contact to the occiput and shoulders. All patients experienced relief and their walking improved. This geste device, working like a geste antagonistique, may be useful for the management of some patients with severe axial dystonia with retrocollis and back arching.
Adolescent↗
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↗
Severe bilateral tremor in a liver transplant recipient taking cyclosporine.
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Adult↗
Dose standardization of botulinum toxin.
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Animals↗
Consensus statement of the Movement Disorder Society on Tremor. Ad Hoc Scientific Committee.
This is a proposal of the Movement Disorder Society for a clinical classification of tremors. The classification is based on the distinction between rest, postural, simple kinetic, and intention tremor (tremor during target-directed movements). Additional data from a medical history and the results of a neurologic examination can be combined into one of the following clinical syndromes defined in this statement: enhanced physiologic tremor, classical essential tremor (ET), primary orthostatic tremor, task- and position-specific tremors, dystonic tremor, tremor in Parkinson's disease (PD), cerebellar tremor, Holmes' tremor, palatal tremor, drug-induced and toxic tremor, tremor in peripheral neuropathies, or psychogenic tremor. Conditions such as asterixis, epilepsia partialis continua, clonus, and rhythmic myoclonus can be misinterpreted as tremor. The features distinguishing these conditions from tremor are described. Controversial issues are outlined in a comment section for each item and thus reflect the open questions that at present cannot be answered on a scientific basis. We hope that this statement provides a basis for better communication among clinicians working in the field and stimulates tremor research.
Adult↗
Early-onset Alzheimer's disease due to mutations of the presenilin-1 gene on chromosome 14: a 7-year follow-up of a patient with a mutation at codon 139.
Mutations in the presenilin-1 gene (PS-1 gene) on chromosome 14 have recently been identified as a cause of familial early-onset Alzheimer's disease (EOAD). To our knowledge, only two German EOAD patients with mutations in the PS-1 gene have been identified thus far. Herein we report the case of a German EOAD patient with a family history of dementia and a missense mutation at codon 139 (M139V) of the PS-1 gene. The patient came to our clinic for the first time when he was 44 years old. During the following 7 years, his Mini-Mental State Examination (MMSE) score dropped from 24 to 0. Myocloni were an early neurological symptom that was already present during the first consultation. We could demonstrate that myoclonic activity was of cortical origin using a back-averaging method. Magnetic resonance imaging (MRI) revealed only slight changes in the early stage of the disease. Follow-up MRI studies showed progression of bitemporal ventricular enlargement and progressive frontal and temporal cortical atrophy. Although the majority of EOAD patients belong to the sporadic (non-genetic) type of AD, early-onset dementia, early myocloni and a familial history of AD should direct attention to the possibility of a genetic form of AD.
Adult↗
Cross-spectral analysis of physiological tremor and muscle activity. I. Theory and application to unsynchronized electromyogram.
We investigate the relationship between the extensor electromyogram (EMG) and tremor times series in physiological hand tremor by cross-spectral analysis. Special attention is directed to the phase spectrum and the effects of observational noise. We calculate the theoretical phase spectrum for a second-order linear stochastic process and compare the results to measured tremor data recorded from subjects who did not show a synchronized EMG activity in the corresponding extensor muscle. The results show that physiological tremor is well described by the proposed model and that the measured EMG represents a Newtonian force by which the muscle acts on the hand.
Biomechanical Phenomena↗
Cross-spectral analysis of physiological tremor and muscle activity. II. Application to synchronized electromyogram.
We investigated the relationship between synchronized muscle activity and tremor time series in (enhanced) physiological tremor by cross-spectral analysis. Special attention was directed to the phase spectrum and its potential to clarify the contribution of reflex mechanisms to physiological tremor. The phase spectra are investigated assuming that the electromyogram (EMG) synchronization was caused by a reflex or a central oscillator. Comparing these results to phase spectra of measured data, we found a significant contribution of reflexes. But reflexes only modify existing peaks in the power spectrum. The main agents of physiological tremor are an efferent pace and the resonant behavior of the biomechanical system.
Biomechanical Phenomena↗
Hemifacial spasm due to posterior fossa tumors: the impact of tumor location on electrophysiological findings.
Ephaptic transmission is one of the electrophysiological hallmarks of hemifacial spasm. It is generally accepted that in the majority of patients with idiopathic hemifacial spasm, microvascular compression of the facial nerve at the site where the nerve exits the brain stem is the underlying cause. Whether the actual site of the ephapse is at the site of the lesion or at a nuclear level due to hyperexcitability of the facial motor nucleus is still controversial. Rarely, hemifacial spasm may be due to space occupying lesions in the cerebellopontine angle or in the brain stem. We report the electrophysiological findings of four patients with hemifacial spasm due to extra-axial tumors in different locations of the posterior fossa. The location of the tumor was intrameatal in one patient, in the cerebellopontine angle in two patients and in the brain stem in another patient. Facial nerve motor neurographies including transcranial magnetic stimulation revealed abnormal findings in two patients. Selective stimulation of facial nerve branches demonstrated delayed (ephaptic) responses in all but one patient whose hemifacial spasm had disappeared after treatment with carbamazepine. The latencies of the delayed responses did not correlate with the tumor location. In sum, the site of ephaptic transmission cannot be reliably determined by latency measurements of the delayed response because of its variability which is probably caused by the different size and diameter of the axons participating in ephaptic transmission as well as by the extent of focal demyelination at the site of the lesion. A neuroradiological work up including MR imaging should be mandatory in all patients with hemifacial spasm because electrophysiological studies fail to differentiate between idiopathic and symptomatic hemifacial spasm.
Adult↗
Fast corticospinal system and motor performance in children: conduction proceeds skill.
Transcranial magnetic stimulation and motor performance tests were used to study the correlation between corticospinal maturation and actual motor performance in a group of young school children (n = 10, mean age = 7 years, age range = 6-9 years). The results were compared with normal adults (n = 10, mean age = 24 years, age range = 22-26 years). In children the central conduction time under the preinnervation condition of facilitation and the postexcitatory silent period was similar to that in adults. However, the central conduction time under relaxation, the latency jump (defined as the difference between the two preinnervation conditions), and the stimulus intensity were statistically different between children and adults (P < 0.01-0.001). Children did not reach the same level of performance as adults in any of the motor performance tasks (simple acoustic reaction time, tapping, ballistic movement, tracking, and diadochokinesis) (P < 0.05-0.01). The results indicate that at an early school age, children already possess mature fast corticospinal pathways able to access spinal motoneurons through the pyramidal tract. However, despite the partially adult-like level of neuronal maturation, young school children were not able to perform deliberate motor actions with the same proficiency as adults.
Adult↗
What is the optimal dose of botulinum toxin A in the treatment of cervical dystonia? Results of a double blind, placebo controlled, dose ranging study using Dysport. German Dystonia Study Group.
OBJECTIVES: Botulinum toxin injections have become a first line therapeutic approach in cervical dystonia. Nevertheless, published dosing schedules, responder rates, and frequency of adverse events vary widely. The present prospective multicentre placebo controlled double blind dose ranging study was performed in a homogenous group of previously untreated patients with rotational torticollis to obtain objective data on dose-response relations. METHODS: Seventy five patients were randomly assigned to receive treatment with placebo or total doses of 250, 500, and 1000 Dysport units divided between one splenius capitis (0, 175, 350, 700 units) and the contralateral sternocleidomastoid (0, 75, 150, 300 units) muscle. Assessments were obtained at baseline and weeks 2, 4, and 8 after treatment and comprised a modified Tsui scale, a four point pain scale, a checklist of adverse events, global assessment of improvement, and a global rating taking into account efficacy and adverse events. At week 8 the need for retreatment was assessed and then the code was unblinded. For those still responding, there was an open follow up until retreatment to assess the duration of effect. RESULTS: Seventy nine per cent reported subjective improvement at one or more follow up visits. Decreases in the modified Tsui score were significant at week 4 for the 500 and 1000 unit groups versus placebo (p<0.05). Additionally positive dose-response relations were found for the degree of subjective improvement, duration of improvement, improvement on clinical global rating, and need for reinjection at eight weeks. A significant dose relation was also established for the number of adverse events overall and for the incidence of neck muscle weakness and voice changes. CONCLUSION: Magnitude and duration of improvement was greatest after injections of 1000 units Dysport; however, at the cost of significantly more adverse events. Therefore a lower starting dose of 500 units Dysport is recommended in patients with cervical dystonia, with upward titration at subsequent injection sessions if clinically necessary.
Adult↗
Spontaneous and reflex activity of facial muscles in dystonia, Parkinson's disease, and in normal subjects.
OBJECTIVE: The blink rate is an index which can be easily obtained during the clinical examination, but it has not yet been properly standardised. The present study was undertaken to collect data on the age dependent development of this index and on possible abnormalities in Parkinson's disease and dystonia. METHODS: The blink rate and the rate of perioral movements were measured in 156 normal controls, 51 patients with Parkinson's disease, 48 patients with spasmodic torticollis, 14 patients with generalised dystonia, and 12 patients with focal hand or leg dystonias and have been correlated with the results of testing the orbicularis oculi reflex, the palmomental reflex, and the perioral reflex. RESULTS: No age related effects were found for the blink rate and perioral movements but all the reflexes showed age dependent variations. It is sufficient to measure the blink rate for one minute, provided standardised conditions are applied. Blink rate and perioral movement rate were positively correlated in patients and controls. The blink rate was significantly increased in spasmodic torticollis and decreased in Parkinson's disease. In generalised dystonia the blink rate was increased but in hand and leg dystonia the blink rate was normal. The reflex tests did not significantly differ between the subject groups except for the orbicularis oculi reflex, which was hyperexcitable in Parkinson's disease. CONCLUSION: Measuring the blink rate can assist the diagnosis of extrapyramidal disorders as a soft sign, but is not very sensitive. The group differences found indicate a decrease of the blink rate and perioral movements in hypokinetic and an increase in hyperkinetic extrapyramidal disorders such as spasmodic torticollis and generalised dystonias. This may be of interest for future pathophysiological studies.
Adult↗
Subacute combined degeneration: clinical, electrophysiological, and magnetic resonance imaging findings.
OBJECTIVE: Vitamin B12 deficiency is a systemic disease that often affects the nervous system. One of the most prevalent manifestations is subacute combined degeneration (SCD) of the spinal cord. To access the clinical, electrophysiological, and structural abnormalities associated with SCD, a study was conducted in nine patients. METHODS: Clinical, electrophysiological (electroneurography, somatosensory and motor evoked potentials), and MRI evaluations were performed in patients before and after treatment. RESULTS: The most prominent clinical and electrophysiological findings in all patients were dysfunctions of the posterior column. Corresponding hyperintense lesions in the posterior column of the spinal cord were found in two patients by T2 weighted MRI. Damage to the central motor pathway was identified in four patients. Demyelinating neuropathy was present in one patient and axonal neuropathy in four. All patients showed improvement of their symptoms after treatment with cobalamin. Abnormalities of the spinal cord on MRI disappeared early in recovery. Motor evoked potentials and median somatosensory evoked potentials typically normalised after treatment, whereas tibial somatosensory evoked potentials remained abnormal in most patients. CONCLUSIONS: Clinical, electrophysiological, and MRI findings associated with SCD in vitamin B12 deficiency are diverse. Thus vitamin B12 deficiency should be considered in the differential diagnosis of all spinal cord, peripheral nerve, and neuropsychiatric disorders.
Acute Disease↗
Acute therapy for cluster headache with sumatriptan: findings of a one-year long-term study.
The efficacy, safety, and tolerability of subcutaneous sumatriptan in the acute treatment of cluster headache were investigated in a multicenter study over a period of up to 1 year. A total of 2,031 attacks were evaluated in 52 patients. Therapy was successful in 88% of all attacks. Freedom from pain within 15 minutes in more than 90% of all attacks treated was reported by 42% of the patients, and no decline in efficacy occurred during the course of the study. Adverse events were reported by 62% of the patients.
Adult↗
[Psychosomatic aspects of idiopathic spasmodic torticollis. Results of a multicenter study].
Idiopathic spasmodic torticollis (IST) is one of the most frequent dystonic movement disorders. Its classification as a focal dystonia, as well as its treatment with botulinum toxin resulted in groups of patients being regularly seen by neurologic specialists. In a multicentre study, we investigated psychosocial changes, coping and psychopathology, and their interrelations with signs, symptoms and course. 256 patients were included in the study (59.3% women, 40.7% men). The mean age was 49.1 years. Rotating torticollis occurred more often than latero-retrocollis and antero-retrocollis. A family history of IST was seen in 3.1% of the total sample. 34% of the patients had additional dystonic symptoms. Most frequently, these affected the upper extremities (13%), less often the legs. 19.1% of the patients had experienced a period of complete remission. The General Symptom Index of the SCL 90-R in 27% of the patients ranged above the double standard deviation of the normal controls, indicating a clinically significant psychopathology.
Adaptation, Psychological↗