Abnormal most-rapid isometric contractions in patients with Parkinson''s disease.

Fast isometric elbow flexor muscle contractions of specified amplitude in six normal subjects were compared with those of 11 patients with Parkinson's disease. Despite treatment, all patients exhibited deficits in this motor task. Three patients were able to produce rapid force pulses with normal contraction times, but the variability of their force responses was increased in comparison with the highly stereotyped responses produced by normal subjects. The other eight patients had prolonged contraction times and segmentation of the force profiles. The integrated area of the first agonist EMG burst and the rate of development of force (dF/dt) were less at any target level than what was needed to produce a fast response. The area of the EMG burst, however, did increase with target amplitude, and the relative increase of dF/dt, with target amplitude, was normal. It is concluded that the motor program subserving fast muscle contraction is preserved in Parkinson's disease, but its execution is characterised by improper scaling of motor output.     

Evoked isometric muscle contractions in myopathies: analysis of pathophysiological properties by different stimulus patterns

Isometric twitches of the adductor pollicis muscle following ulnar nerve stimulation were investigated in healthy subjects (n = 35) and patients with different types of myopathies (myotonic dystrophy, n = 19; limb girdle muscular dystrophy, n = 10; metabolic myopathy, n = 6). The changes within the rising part (i.e. within the contraction time, CT) of the isometric twitches after single stimuli were similar in myotonic and limb girdle dystrophies: the first part of CT, which lasts until the maximal contraction rate is achieved, was shortened, whereas the following second part of CT, which lasts until the maximal twitch force is achieved, was normal. In metabolic myopathies the first part was normal, whereas the second part was prolonged. The relaxation was prolonged in all types of myopathies, particularly in metabolic myopathies. Using double stimuli with short interstimulus intervals (ISI), the absolute refractory period of the muscle contraction (healthy subjects: 1.35 +/- 0.16 ms) was shortened in patients with myotonic dystrophy (1.02 +/- 0.11 ms). In the other types of myopathies, the absolute refractory period was only shortened provided that the single twitch force was clearly reduced. A similar dependence on a reduced single twitch force was also found with regard to the maximal force development with two stimuli and the corresponding ISI: the force contributed by a second stimulus was pathologically enhanced if the single twitch force was clearly reduced. The ISI related to the maximal force with two stimuli was shifted towards very short values (healthy subjects: 10.5 ms, myotonic dystrophy: 4.6 ms, limb girdle dystrophies: 5.0 ms). Our results can be attributed to altered kinetics of calcium release and uptake by the sarcoplasmic reticulum in myopathies.     

The efficacy of Cavain in patients suffering from anxiety

The therapeutical efficacy of Cavain should be proved in the treatment of patients suffering from abnormal anxiety, psychosomatic complaints and psychoreactive disorder. Thus two randomized groups of patients (26 each) were treated in double-blind technique with either 2 x 200 mg daily Cavain or placebo for a period of 28 days. Prior to the beginning of the investigations and within 14 days intervals the Hamilton Anxiety Scale (HAMA) and the Adjective Check List (Janke and Debus) were applied. The global therapeutical improvement and compatibility were documented after 14 and 28 days. A significant superiority of Cavain in comparison to placebo could be found. Cavain acted anxiolytically and promotive on the subjective vitality-related performance. Therapeutical conclusions are discussed.     

The heartbeat-evoked brain potential in patients suffering from diabetic neuropathy and in healthy control persons.

OBJECTIVES: Neurotransmission from the heart to the brain results in a heartbeat evoked potential (HEP). This potential appears as a positive waveform ranging from 250 to 600 ms after the onset of ventricular contraction. Only limited information exists as to what extent the HEP is sensitive to a dysfunction in cardio-afferent pathways. Thus, the HEP was studied in patients with autonomic diabetic neuropathy. METHODS: Twenty-five patients and a healthy control group of equal size participated. The HEP was obtained as the average over 1200 EEG sweeps (18 channels) sampled contingent upon the onset of ventricular contraction. A heartbeat attention task and a distraction task were employed. Patients answered a questionnaire pertaining to the frequency of subjective symptoms related to diabetic neuropathy. RESULTS: The HEP amplitude at frontal, central and temporal locations was significantly diminished in patients in the latency range of 280-330 ms. A significant correlation was found between the questionnaire score of subjective autonomic symptoms and the reduction in the HEP. CONCLUSIONS: We conclude that the HEP is sensitive to a comparably moderate abnormality in nerve function. Furthermore, we assume that the processing of subjective symptoms of the disease and the generation of the HEP share some common neuronal pathways.     

Neonatal seizures and severe hypotonia in a male infant suffering from a defect in peroxisomal beta-oxidation.

In this paper, we describe a baby male born to healthy non-consanguineous parents presenting at birth with hypotonia and seizures. Additional salient clinical features included the development of glaucoma, the absence of significant facial dysmorphism and the absence of liver enlargement or renal cysts. The patient died at the age of 3 months. At autopsy, liver fibrosis and kidney glomerulosclerosis were noted. Neuropathological findings included pachygyria of the olivary nuclei and cerebellar neuronal heterotopias. There was no evidence for a demyelinating process. Biochemically, the patient was found to have elevated plasma levels of very-long-chain fatty acids (VLCFA) and abnormal bile acid intermediates, whereas other indicators of peroxisomal function (plasmalogen biosynthesis and plasma pipecolic acid) were normal. Catalase staining of a liver biopsy specimen revealed peroxisomes to be present in normal numbers, although some were abnormally large. Trilamellar inclusions typical of a peroxisomal fatty acid oxidation defect were present in macrophages. Indeed, beta-oxidation of the very-long-chain fatty acid hexacosanoic acid (C26:0) was found to be strongly deficient. Fatty acyl-CoA oxidase activity in the patient's liver was normal, however. Furthermore immunocytochemical studies using antibodies against acyl-CoA oxidase, bifunctional protein and peroxisomal thiolase, revealed the normal localization of all three enzyme proteins within the peroxisomes. We suggest that our patient has a selective peroxisomal beta-oxidation defect, a recently identified heterogeneous group of early-onset peroxisomal disorders distinct from the Zellweger syndrome and other generalized peroxisomal disorders.     

Predictability of maximum voluntary isometric knee extension force from submaximal contractions in older adults

The purposes of this study were to develop and test a model describing the relationship between the central activation ratio (CAR; a measure of voluntary muscle activation) and percent maximum voluntary contraction (%MVC) force for old adults and to provide a method for more accurate determination of voluntary muscle activation failure. Twenty-one adults (ages 64-81) performed isometric testing of the quadriceps at 25%, 50%, 75%, and 100% MVC. During each contraction, a 100-HZ, 120-ms train of electrical pulses was delivered to the quadriceps muscle to quantify voluntary muscle activation. Similar to a young, healthy population (ages 20-35), a curvilinear relationship existed between the CAR and %MVC force for older adults. Predictions of subjects' MVCs using the linear model of CAR-%MVC force relationship generally demonstrated poor agreement with actual MVCs. Predictions of MVC from submaximal contractions (25%, 50%, and 75%) using a previously identified curvilinear young adult CAR-%MVC relationship were good [ICC (2,1): 0.81, 0.96, and 0.82, respectively]. Similar agreement was obtained from the curvilinear older adult CAR-%MVC relationship. These data suggest that the CAR-%MVC relationship is similar in young and older adult subjects and that curvilinear models of this relationship can predict MVC forces in older adults more accurately. Reexamination of the relationship between the CAR and %MVC force may allow a more accurate determination of how failure of voluntary muscle activation contributes to weakness in old adults.     

The therapy of families of patients suffering from schizophrenia

The development of pharmacotherapy, social psychiatry and the new patterns of comprehensive treatment of patients suffering from schizophrenia make most of psychiatrists believe that hospitalisations should be reduced to minimum. There has been a change in the roles and tasks of parents and spouses of the patients during their ambulatory therapy. Apart from outpatient clinics, daily wards, and hostels, there is a significant role of the therapy of families of the patients in the posthospital treatment. The patterns of schizophrenia as a disease and the relating indications concerning basic therapeutic management are of significant importance. The work presented here discusses two basic therapies of the families of patients suffering from schizophrenia, namely psychoeducation and systemic family therapy. The work draws attention to aims, forms and concepts of these therapies. However, an appropriate pharmacotherapy of patients suffering from schizophrenia is necessary regardless of their positive response to the families.     

Force sensation in isometric contractions: a relative force effect

A contralateral limb matching paradigm was employed to investigate the perception of isometric forces. Both force and branchial biceps and triceps EMG were recorded from each arm as subjects matched isometric contractions on the basis of equal sensation. It was found that smaller forces were consistently overestimated in magnitude and that the most accurate estimation of force occurred around the middle of the force domain. It is proposed that these results reflect the properties of the biceps muscle which is predominantly involved in gross motor activity.     

Recruitment stability in masseter motor units during isometric voluntary contractions

Recruitment of single motor units (SMUs) of the masseter muscle was studied using macro representation (MacroRep) as the indicator of motor unit size. When subjects followed a slow isometric force ramp, units were usually recruited in order of MacroRep size. However, pooling the data from repeated ramps in the same subject resulted in a weak relationship between MacroRep size and force recruitment threshold, probably due to marked variations in the relative contributions of the jaw muscles, and varying levels of cocontraction, in the development of total bite force in each ramp. The force recruitment thresholds of individual SMUs showed marked variability, but recruitment threshold stability was improved when expressed as a percentage of maximum surface electromyographic (SEMG) activity in the ipsilateral masseter. Therefore the SEMG recruitment threshold was concluded to be a more stable and accurate indicator of the SMU's position in the recruitment hierarchy in a given muscle. It was concluded that SMUs in masseter are recruited according to the size principle, and that when investigating recruitment in jaw muscles, SEMG recruitment threshold should be used in preference to force recruitment threshold. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:1290–1298, 1998.     

Sleep EEG with or without sleep deprivation? Does sleep deprivation activate more epileptic activity in patients suffering from different types of epilepsy?

A sleep EEG of 190 patients without sleep deprivation was recorded, followed by a sleep EEG after 24 h of sleep deprivation on the next day. The patients suffered from various types of epilepsy, in their routine EEGs no epileptic discharges were seen. Both sleep EEGs were recorded under the same antiepileptic drugs. A waking EEG was recorded immediately before each sleep EEG. The activation rates of epileptic activity in 52.6% (without sleep deprivation) and 53.2% (with sleep deprivation) of the patients showed no significant differences. Also on classifying the epileptic discharges no real difference was found between the 2 methods (generalized: 29.5 vs. 29.5%, generalized with lateral emphasis: 11.1 vs. 9.5%, focal: 12.1 vs. 14.2%). Only in the waking EEG, recorded immediately before the sleep EEG after sleep deprivation, a few more patients showed epileptic discharges (33.6 vs. 27.4%). Without there being any significant differences between the 2 methods there were some different results in comparing the EEG with the clinical findings: significantly more epileptic activity was shown in patients who had their first seizure before the age of 20 (55.6 and 55.6% vs. 26.3 and 31.6%), amongst females (59.8 and 61.9% vs. 45.2 and 44.1%), in awakening grand mal (= primary generalized tonic-clonic seizures, 76.5 and 70%) and in absences (69 and 72.4%). The higher activation rates in young subjects, in patients with a family history of seizures, with pathological neurological findings, mental retardation and delayed psychomotoric development in early childhood, were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sex differences in glycolysis during brief, intense isometric contractions

We have previously observed less muscle fatigue in women than men under conditions of intact circulation, but similar fatigue across the sexes during local ischemia. Thus, we hypothesized that women utilize their aerobic metabolic pathways to a greater extent than do men. To test this hypothesis, we examined the extent to which different pathways of intramuscular adenosine triphosphate (ATP) production were utilized by men and women during maximal voluntary isometric contractions. Force production during 15-s and 60-s contractions were recorded in parallel sessions. In one session, central activation was assessed with electrical stimulation. In the other, phosphorus magnetic resonance spectroscopy was used to quantify muscle oxidative capacity, and the contributions of glycolysis and oxidative phosphorylation to ATP synthesis during the 60-s contraction. Fatigue and central activation were similar in men and women during both the 15-s and 60-s contractions. The rate constants of phosphocreatine recovery following the 15-s contraction were similar in men and women, indicating similar oxidative capacities. Men exhibited greater acidosis and peak glycolytic rates compared with women during the 60-s contraction, with no differences observed in creatine kinase flux or the percent of oxidative capacity utilized. We conclude that men exhibit greater in vivo glycolysis during brief, intense isometric contractions. Although this metabolic difference did not contribute to any observable differences in fatigue in the present study, these results highlight a potentially important mechanism to explain sex-related differences in muscle function.     

Human muscle fascicle behavior in agonist and antagonist isometric contractions

Introduction: The aim of this study was to compare, at a given level of electromyographic (EMG) activity, the behavior of dorsiflexor and plantarflexor muscles as assessed via their architecture (pennation angle and fiber length) during agonist or antagonist isometric contractions. Methods: Real‐time ultrasonography and EMG activity of gastrocnemius medialis (GM) and tibialis anterior (TA) muscles were obtained while young males performed ramp isometric contractions in dorsi‐ and plantarflexion. Results: For both muscles, at a similar level of EMG activity, fiber length was longer, and pennation angle was smaller, during antagonist than during agonist contractions. Conclusions: These results indicate that, at similar levels of EMG activity, GM and TA muscles elicit a higher mechanical output while acting as an antagonist. These findings have important implications for muscle function testing. They show that estimation of antagonistic force using the common method based on the EMG/net torque relationship yields underestimated values. Muscle Nerve 45: 92–99, 2012     

Diogenes syndrome in patients suffering from dementia

Diogenes syndrome (DS) is a behavioral disorder of the elderly. Symptoms include living in extreme squalor, a neglected physical state, and unhygienic conditions. This is accompanied by a self-imposed isolation, the refusal of external help, and a tendency to accumulate unusual objects. To explore the phenomenon of DS in dementia we searched for the terms: “Diogenes syndrome, self-neglect, dementia. ” It has long been understood that individuals with dementia often become shut-ins, living in squalor, in the Eastern Baltimore study, dementia was present in 15% of the elderly cases with moderate and severe social breakdown syndrome; twice as many as in the general population of the same age group. Researchers have underlined the frequent presence of DS (36%) in frontotemporal dementia (FTD): different neuropsychological modifications in FTD may contribute to symptoms of DS. The initial treatment should be a behavioral program, but there is not sufficient information regarding pharmacological treatment of the syndrome.     

Amplitude of the surface electromyogram during fatiguing isometric contractions.

Five voluntee subjects held isometric handgrip contractions at specific submaximal tensions until the required tension could no longer be maintained. At the start of those contractions, the amplitude of the surface electromyogram (EMG) was linearly related to the tension exerted; the amplitude of the EMG increased linearly throughout these substained contractions by a constant amount--about 30% of the maximum. During sustained contractions, brief, intermittent maximal efforts showed that strength declined linearly at all tensions. At 25% maximal voluntary contraction (MVC), there was a linear fall in the EMG amplitude associated with the brief maximal efforts, but the fall in strength was more rapid than the fall in EMG amplitude. At 70% MVC, there was no fall in the EMG amplitude in response to the brief maximal efforts, while the muscle strength fell linearly.     

Rate of tension development in isometric contractions of a human hand muscle

The amplitude and rate of tension development during both electrical stimulation and voluntary activation of a human hand muscle were compared. The contractile responses from the first dorsal interosseous muscle of 14 normal human subjects were studied to provide the experimental data. At different forces less than 400g, under conditions of both electrical stimulation and voluntary contraction, force was directly proportional to speed of contraction. This linear relationship between the speed and force of contraction, as the proportion of active motor units varied, implies that these two parameters are similarly related in motor units of various sizes. In fast voluntary contractions, the rate of rise of tension at any given force level was greater than that observed in response to repetitive stimuli delivered to the motor nerve. Even at 200 and 500 impulses per second at maximal intensity, the speed of tension development was less than that found in fast voluntary contractions. The importance of asynchronous impulses and optimum discharge sequencing in generating a faster speed of tension development in fast voluntary contractions is underscored by these findings.     

Electromechanical changes during electrically induced and maximal voluntary contractions: Electrophysiologic responses of different muscle fiber types during stimulated contractions

The electrophysiologic and mechanical responses of a synergistic muscle group composed of different muscle fiber types were studied with respect to excitation frequency and muscle fatigue in five men. The force and evoked action potentials obtained from surface and intramuscular fine wire electrodes were recorded continuously during stimulated contractions of the gastrocnemius and soleus at 20, 50, and 80 Hz. The stimulus voltage was adjusted so that the force generated by high-frequency tetani (50 and 80 Hz) could initially match the force of maximal voluntary contractions (MVCs). The surface and intramuscular EMG signals were digitized at a sampling rate of 10 kHz with 16-bit fast A/D converters and stored on a floppy disk. The digitized data were then processed for every 5 s to calculate evoked potential amplitude and conduction time using an HP 9836 computer. Results indicated that after 30 s of high-frequency stimulation, significantly less force was generated than after a similar period of MVC. During this period of high-frequency force fatigue, considerably greater force was developed at 20-Hz stimulation. The excessive force loss during high-frequency tetanic contractions was accompanied by a marked reduction in the evoked potential amplitude and conduction time (prolongation of the M wave). The recording of intramuscular evoked potentials showed the gastrocnemius muscle to have greater reductions in these parameters. Our results support the hypothesis that force fatigue during high-frequency stimulation results from failure of electrical propagation due to reduced muscle membrane excitability. The observed muscle-fiber-dependent electrophysiologic responses may suggest that the metabolic profile of muscle fibers plays an important role in regulating the muscle membrane excitability during high-frequency stimulation.