Senescence and Deep Tendon Reflex W

With increasing age, various changes occur in the human nervous system. These structural and functional changes may result in a number of neurologic signs commonly found during the examination of elderly people. Often such signs occur in the absence of any discernable neurological disease. For this reason, they are usually attributed entirely to advanced uncomplicated aging, or senescence.

Reflex testing ranks as the premier objective measure of nervous system integrity (2:28). Moreover, it has been observed that reflex findings may change with normal aging.

A number of authors, for example, have found that a reduction or loss of the ankle jerk is a normal senescent variant (2:21). Furthermore, research has suggested that the incidence of absent ankle jerks rises steadily with advancing age (1:71). One proposed explanation for the areflexia is elongation of the Achilles tendon due to shortening of the muscle (1:21).

These studies, however, have not all been in complete accord (1:21). Jenkyn and Reeves note a high degree of variation in the frequency of observed normal responses (2:29). This they attribute to factors such as different study populations, testing techniques, and, perhaps, to intercurrent subclinical illness (2:28).

DeVries et al. suggests that this variability might be caused by differences in the activity history of the subjects tested (1:71). Considerable evidence supports the hypothesis th

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ey tried to point out that the result was smaller than that measured by previous studies, they could not ignore the fact that it did exist (1:78). Finally, since it had been suggested that the number of muscle spindles may decrease in old age, mechanically and electrically elicited reflexes were compared (1:79). DeVries et al. postulated that agerelated losses in the function of the fusimotor system should introduce a greater agegroup difference in a mechanically elicited monosynaptic response than when the response is elicited electronically and, therefore, effectively bypasses the spindle system (1:79). Since no significant age difference was found between the two different methods of eliciting reflexes, it was concluded that the muscle spindles were not involved (1:7980). Rather, the authors suggest that physical activity may be as important in maintaining the normal function of the nervous system as it is in the maintenance of structure and function in muscle (1:79). While their theory may be tenable, it also seems logical that some muscle spindle activity would decrease with advancing age. In another study, Koceja also investigated neuromuscular changes with age (3:245). He examined human soleus motoneuron excitabil
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Approximate Pages = 6 (250 words per page)

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