Resumo em Inglês:
The author studies the significance of the accurate test of vibration sense for the diagnosis of some diseases of the nervous system. This work is divided into three main parts. First part - After reviewing the medical literature on the nature, pathways and physiopathology of the vibration sense, the author states the following conclusions : 1. Pallesthesia is an inespecific type of sensation. 2. The receptors for vibratory stimuli include both the superficial structures designed to record the cutaneous deformation, and the end-organs located in the muscles, ligaments, joints and periosteum. 3. On the light of more recent experimental work, carried on by neuro-physiologists and clinical neurologists, it becomes evident that the muscle spindles are the end-organs mostly concerned in the reception of vibratory stimuli. 4. These facts lead to the conclusion that vibration sense impulses run in the spinal cord by tactile and proprioceptive pathways. There are reasons to believe that lesions of the dorsal funiculi are more apt to interfere with the conduction of vibratory stimuli. 5. The dissociation between pallesthesia (lost or impaired) and joint sense (impaired or normal), frequently met with in several nervous diseases, must be ascribed to the fact that injury of nerve fibers lengthens the refractory period; the vibratory stimuli, which normally are transmitted almost in the limit of nerve fiber ability, are thus summed up and does not evoke the vibratory sensation any more. 6. The prevalence of kinesthesic over pallesthesic disturbances, which is said to occur in lesions of parietal lobes, can be explained by the discriminative character of the former type of sensation, as well as by a wider bilateral cortical representation of the vibration sense pathways. Second part - The analysis of variance of the vibratory perception thresholds measured with the "Bio-thesiometer" in 55 normal subjects lead the author to the following conclusions: 1. The vibration perception thresholds show wide variations according to the bodily area which is tested. 2. The variations of the vibration perception thresholds among subjects, although great, are lesser than the changes among bodily areas. 3. Among the bodily areas studied, the fingers and toes were the most sensitive to vibratory stimuli. 4. The vibration perception thresholds in the head are very high and are prone to great individual variations. 5. The least individual variations were shown by the bodily areas more sensitive to vibratory stimuli. 6. All these facts point to the selection of the fingers and toes as the bodily areas more suitable for the quantitative test of pallesthesia, with diagnostic purposes or to estimate the course of nervous diseases. 7. The variations of the vibration perception thresholds during regular time intervals (3 days) have not been significant in relation to the variations among bodily areas and subjects. 8. The average vibration perception thresholds of the left side of the body were lesser than those of the right side, although only in the great toes the difference was statistically significant. 9. It has been statistically proved that the method used in this work is a trustful procedure for the quantitative study of vibration sense. Third part - The study of 126 cases of nervous diseases due to lesions of various topographies, using the same quantitative method, allowed the following conclusions: 1. Vibration sense can be the only form of sensation impaired in several kinds of nervous diseases. 2. The quantitative test of pallesthesia has great semiotic significance since the increase of the vibration perception thresholds can be the only sign of damage of the sensory pathways. 3. Dissociation between pallesthesia and kinesthesia can be observed in several nervous diseases and as well in peripheral as in central lesions. 4. In cases of diabetic neuropathy the impairment of vibration sense is frequent and sometimes very conspicuous; it bears a close relation to the severeness of the whole neurologic picture. 5. In cases of herniated nucleus pulposus the test of vibration sense can cooperate in the diagnosis of the side of the protrusion. However, it must be emphasized that the changes in pallesthesia have not, in such cases, the semiotic significance which some authors have assigned to them. 6. In the subacute combined degenerations of the spinal cord, with constitutional or acquired achlorhydria, the test of vibration sense is imperative, owing to the early and marked impairment of this form of sensation. The quantitative method can disclose, in several cases, the existence of pallesthesic changes not shown by routine procedures, particularly those involving the upper limbs. 7. In poliradiculoneuritis the vibration sense is deeply impaired, even in the upper limbs, where other forms of sensation can be normal by routine examination. 8. In trigeminal nerve lesions the quantitative test of vibration sense is of little semiotic significance, owing to the great variability of the thresholds in the head and to the frequent confusion between vibration and auditory senses. In the four cases tested the increase of the thresholds was slight, even in two cases with associated facial palsy. 9. In cases of parietal lobe injuries, including two cases of hemisphe-rectomy, the impairment of vibration sense is remarkable and coincident or not with changes in the joint sense. 10. In other diseases of the nervous system, the quantitative test of vibration sense has proved worthful for the diagnosis, either as a positive or sometimes as a negative finding.
