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PubMed1975

The effect of exogenous TSH and Achilles tendon reflex time in man.

The effect of exogenous thyrotropin (TSH) -- 3 X 10 IU daily -- on Achilles tendon reflex time (ART) was investigated in the group of 38 in-patients, treated for thyroid cancer. A significant shortening of ART was recorded in a subgroup of hypothyroid persons after the 2nd and 3rd dose of TSH. Moreover, a significant correlation was proved between initial values of ART and their changes after the 2nd and 3rd TSH injection in this group. No significant interrelationship was observed between changes of thyroid function and ART after TSH administration. In interpretation of this finding the possibility of direct effect of TSH on muscle metabolism in hypothyroid man should be considered.

Humans↗
PubMed1995

Early onset cerebellar ataxia with retained tendon reflexes: a clinical, electrophysiological and computed tomographic study.

Fourteen patients of Early Onset Cerebellar Ataxia with retained tendon reflexes (EOCA) were prospectively evaluated clinically, electorphysiologically and with CT scan. Their age and duration of symptoms were 18.6 +/- 8.3 years and 7.8 +/- 5.1 years respectively. High consanguinity (91.7%) and positive family history (76.9%) suggested autosomal recessive inheritance. Apart from cerebellar signs and brisk knee jerks in all, other important findings were abnormal ocular movements (mostly impaired saccades) in 92.8%, Babinski's sign (78.6%), brisk ankle jerks (64.3%), spasticity in lower limbs (50%) and impairment of proprioceptive sensations (50%). Neuropsychological tests, done in 12 patients, were abnormal in all. Abnormalities of electroneuromyographic studies were universal, motor conduction parameters (85.7%) being more affected than sensory (78.6%). One or more modalities of evoked potentials were abnormal in 71.4%, that of brainstem auditory evoked response being most frequent (50%), followed by posterior tibial somatosensory evoked potential (SSEP) (46.1%) and median SSEP and visual evoked potential (30.8% each). CT scan (n = 12) showed atrophy of brainstem (91.7%), cerebellar hemisphere and/or vermis (83.3%) and cerebral cortex (33.3%). There was no correlation between the duration of disease and degree of disability or abnormalities of nerve conduction and CT parameters. The rationality of the diagnosis of this recently recognised entity of 'EOCA' in Indian context is discussed.

Adolescent↗
PubMed1985

Achilles tendon reflexes and surface EMG activity during anticipation of a significant event and preparation for a voluntary movement.

Achilles tendon reflexes were evoked bilaterally during and shortly after an interstimulus-interval (ISI) of 4 s and expressed as percentages of an averaged control reflex. Surface EMG of the soleus muscles were recorded continuously during the ISI, and expressed as percentages of a control EMG level. Three types of tasks were introduced, according to a between subjects design. Condition I consisted of a guessing task, involving anticipation of the second stimulus (S2) and not requiring a motor response. Conditions II and III were a warned choice and simple RT task respectively, the motor response to S2 being a plantar flexion of either the left or right foot in Condition II, and a plantar flexion of the right foot in Condition III. The results can be stated as follows: 1. Anticipation of a stimulus is not sufficient for a reflex increase to occur during an ISI. Preparation for a movement seems to be a necessary condition. 2. The reflex increase during preparation is rather independent of the amount of selectivity in the preparatory process; simple and choice RT tasks yield similar results, although the mean RTs do differ. 3. A difference between the involved and non-involved legs in the simple RT task is not found in the present experiment, as opposed to other studies. The particular instruction given to the subjects could be of importance in producing this difference. 4. Reflex changes cannot simply be accounted for by changes in background EMG of the agonist, as the EMG time course shows no changes over time in either condition.

Journal Article↗
PubMed1986

Motor preparation and the Achilles tendon reflex: the role of background muscle tension.

The effects of instructed tension or relaxation of the soleus muscles on the amplitude of the Achilles tendon reflex were investigated. Reflexes were evoked during the foreperiod of a warned reaction time experiment with a plantar flexion of the right foot serving as the response, and during isometric contractions of the right soleus muscle at different low levels of tension. The tension levels were related to the subject's maximal voluntary contraction force. The results were comparable in the two tasks. When background muscle tension was present in the right leg the reflexes in that leg were depressed, whereas in the contralateral leg reflexes were increased. This difference in amplitude was roughly proportional to the amount of tension and independent of whether the antagonist muscle was also activated during the contraction. It was argued that the differential reflex effect found in the two soleus muscles during motor preparation need not be a reflection of a selective neural inhibition. It could also be explained by a reduced effectiveness of the tendon tap in stretching the muscle, due to stiffening of the muscle during contraction. It was concluded that during motor preparation, only reflex changes recorded in the absence of muscle tension can be considered reflections of subliminal changes in spinal reactivity.

Achilles Tendon↗
PubMed1977

Tendon reflex latencies in the upper extremity.

This study was aimed at establishing a baseline for the latency values of the biceps-brachii, triceps-brachii and brachioradialis tendon reflexes from the moment of elicitation by percussion of the tendon, to the appearance of the muscle action potential. The percussion hammer triggered the electronic sweep on the electromyograph oscilloscope, showing latency to the onset of the potential. Standard skin electrodes were used. Certain precautions were taken to avoid artifacts caused by skin movement. Thirty normal volunteer subjects, between the ages of 17 and 55 years, were examined. Biceps reflex latency values varied between 9 and 14 msec; with a mode of 11 msec and an average of 11 msec. Triceps latency values varied between 9 and 13 msec; with a mode of 11 msec and an average of 10 msec, and brachioradialis latency values varied between 13 and 20 msec, with a mode of 16 msec and an average of 16 msec.

Action Potentials↗
PubMed1990

Clinical and genetic heterogeneity in early onset cerebellar ataxia with retained tendon reflexes.

A clinical and genetic study was performed on 20 patients affected by early onset cerebellar ataxia with retained tendon reflexes (EOCA). Mean age at onset was 8.8 (SD 6.0) years. The frequency distribution of age of onset significantly differed from the normal distribution. Consanguinity rate was 16.7% and segregation ratio 0.164. As well as ataxia, which was a constant feature, there were signs of involvement of the cortico-spinal tracts and/or peripheral nerves in most patients. Results of neurophysiological studies were not homogeneous, nor were morphological findings of the sural nerve biopsy. The data suggest that EOCA may be genetically and clinically heterogeneous.

Adolescent↗
PubMed1979

Diabetic polyneuropathy. Corneal sensitivity, vibratory perception and Achilles tendon reflex in diabetics.

In a controlled study, corneal sensitivity, vibratory perception of the left index finger and great toe and achilles tendon reflex were examined in 100 diabetes patients and 100 controls. The result showed significantly reduced corneal sensitivity, vibratory perception and increased number of areflexi in the diabetic group. Furthermore, the decrease of corneal sensitivity, vibratory perception and presence of areflexi correlated well to one another and to age, duration of D. M. above 15 years and diabetic retinopathy. Significant intercorrelations suggest that a reduced corneal touch threshold forms part of a polyneuropathy in diabetes. A corneal hypesthesia cannot be considered a valuable index in screening a population for diabetes as previously has been suggested.

Achilles Tendon↗
PubMed1993

Reduced life expectancy in 40 cases of early onset cerebellar ataxia with retained tendon reflexes: a population-based study.

A survival analysis of 40 cases of early onset cerebellar ataxia (EOCA) with retained tendon reflexes was performed. They represent all cases of EOCA diagnosed between 1945 and 1990 among residents of a defined area of Northwestern Italy, followed up to December 31, 1990. The survival rates were respectively 92%, 87% and 77% at 10, 20 and 30-years, worse than expected in a disease which is usually considered benign. The relative death rate was 4 times higher than expected for the general population. Prognosis was significantly worse for males than for females, whereas the age of onset and the calendar year of onset did not affect survival.

Adolescent↗
PubMed1982

Effects of stimulus and task factors on Achilles tendon reflexes evoked early during a preparatory period.

The effects of intensity, duration and modality of a warning signal on tendon (T) reflexes evoked during the initial phase of a preparatory period of 4 sec were investigated. Reflexes were evoked simultaneously in both legs, from 0 to 350 msec after warning signal onset in steps of 50 msec. The required response was a planter flexion of the right foot. A facilitation of reflexes was seen within 150 msec after warning signal onset, showing a somewhat longer latency for visual as compared to auditory signals. An effect of intensity was found in the auditory modality only, where the louder of two warning signals yielded a clear peak at 100 msec while the softer stimulus caused no significant departure of Achilles tendon reflexes from baseline. The time course of facilitation in the auditory modality was influenced by warning signal duration as well, although this effect was only marginally significant. There were no effects of physical warning signal parameters on reaction time. A comparison with an experiment in which non-signal stimuli were presented alone, pointed to aspects of the preparatory process which were manifest at the spinal level as early as 200 msec after warning signal onset.

Achilles Tendon↗
PubMed2006

Kinematic quantitation of the patellar tendon reflex using a tri-axial accelerometer.

We designed a simple procedure based on the angular speed of the knee joint for quantitating the patellar tendon reflex. The angular speed of the knee joint is calculated from acceleration data generated in response to the tapping force applied to the patellar tendon with a customized tendon hammer and measured using a tri-axial accelerometer placed at the ankle joint. Data were collected and processed using a signal analyzer and a notebook PC. The results obtained using standard equipment were similar to those generated by more elaborate devices. For instance, the time delay (29.6+/-6.0 ms) and the acceleration time (150.8+/-19.5 ms) of the speed response were quite constant for all participants within the range of tapping forces normally applied during physical examinations. Representative relationships between the peak tapping force and the peak angular speed also closely fit with the exponential model (the average coefficient of determination, 0.70; range, 0.43-0.97). In contrast, the mean asymptotic value of the peak angular speed (Omega(pas)) was 160+/-67 degrees/s for spastic individuals, compared with only 72+/-21 degrees/s for healthy individuals. The important features of this method are portability, ease of use, and non-constraint of solicited reflex responses.

Adult↗
PubMed1993

Early onset cerebellar ataxia with retained tendon reflexes: prevalence and gene frequency in an Italian population.

A genetic epidemiologic analysis of early onset cerebellar ataxias (EOCA) with retained tendon reflexes was performed in a defined area of Northwestern Italy. Forty cases diagnosed from 1940 to 1990 were ascertained. The ascertainment probability was 85.7%. The segregation analysis (Weinberg's proband method and 'singles' method under incomplete ascertainment) is compatible with autosomal recessive inheritance. The point prevalence ratio was 1.0/100,000 population. The birth incidence rate was 1/48,000 live births. Gene frequency was estimated to be 1/218. The ratio of first-cousin marriages among parents of EOCA (4.5%) was lower than expected using Dahlberg's formula (8.9%).

Adolescent↗
PubMed1981

Comparison of monosynaptic tendon reflexes during preparation for ballistic or ramp movement.

Mechanism which underlie preparation for movement were studied in man using the method of 'monosynaptic tendon reflexes' during the preparatory period (PP) preceding the execution of ramp or ballistic tracking movements. Reflex reactivity is more important during the whole of the PP to a ramp rather than a ballistic movement; the increasing facilitation preceding the execution signal is greater and occurs earlier for the ramp than for the ballistic movement. These results were observed for 'fast' or 'slow' subjects in a reaction time task, but were more marked for the latter. On the one hand, preparation for movement is represented at the spinal level by a competition between activating influences, which allows for the speeding up of peripheral execution of central control, and inhibitory influences brought into play both by the need to suppress the movement until the execution signal and by the isolation of motor structures from postural proprioceptive servo-mechanisms. On the other hand, this preparation can imply a control of the level of activity in proprioceptive fusorial afferent pathways which depends on whether the movement to be executed is open-loop (ballistic) or closed (ramp). Comparison between the results obtained from fast and slow subjects underlines the importance of an active inhibitory process in spinal structures which would accompany temporal adjustment.

Female↗
PubMed1991

Early onset cerebellar ataxia with retained tendon reflexes. Clinical, electrophysiological and MRI observations in comparison with Friedreich's ataxia.

Fourteen patients with the clinical diagnosis of early onset cerebellar ataxia with retained tendon reflexes (EOCA) were examined and compared with 11 patients with Friedreich's ataxia (FA). The mean age of onset in EOCA was 15.9 +/- 6.0 yrs (FA: 14.0 +/- 5.7 yrs). Annual progression rate and the percentage of patients who were wheelchair-bound was lower in EOCA as compared with FA, although the difference did not reach statistical significance. The latency until becoming wheelchair-bound, however, was significantly longer in EOCA than in FA. The segregation ratio in EOCA was significantly lower than 0.25. Clinically, EOCA and FA patients presented with a progressive cerebellar syndrome. Associated symptoms, such as muscle wasting, sensory disturbances, foot deformity, scoliosis and electrocardiographic abnormalities were encountered less frequently in EOCA than in FA patients. The electrophysiological findings in EOCA were variable and pointed to axonal degeneration in peripheral nerves and central pathways. Posturographic measurements revealed a higher incidence of anteroposterior sway direction in EOCA as compared with FA, suggesting a cerebellar type of ataxia in EOCA. Eleven out of the 14 EOCA patients had cerebellar atrophy in MRI. The characteristic MRI finding in FA was upper cervical cord shrinkage and only minor atrophy of the cerebellum. The demonstration of cerebellar atrophy in the majority of EOCA patients supports the view that EOCA is distinct from FA. It is uncertain, however, whether EOCA is a homogenous disease entity or a group of phenotypically similar syndromes.

Action Potentials↗