Page:WHR Rivers - Studies in Neurology - Vol 1.djvu/28

14 thinks about his sensations and the difference between normal and abnormal parts. In many cases it is necessary to obtain an introspective description or analysis of the sensations evoked; but we have attempted to keep this portion of our notes strictly separate from the records obtained with the various measurable tests.

Our aim has been to employ a series of tests which give measurable results without at the same time exhausting the patient, or demanding any but the smallest amount of introspection. The measurements so obtained are not compared with an absolute standard, but with the results yielded by the same tests on the normal half of the patient under identical conditions. Even on the normal side we do not attempt, in most instances, to discover the true threshold. We begin each series of observations on the unaffected half of the body with a test near the threshold value, but well within the patient's capacity. The abnormal parts are then examined with the same test, and, if a perfect series of answers cannot be obtained, the stimulus is increased until a threshold is reached, or, if this is not possible, until the task is at least many times easier than is necessary on the normal side. Thus, all our measurements are comparative, and each case yields its own standard. Otherwise such tests as the compasses, recognition of relative weight and size, and all attempts to estimate painful stimuli, are useless and fallacious for observations on the sick.

Sometimes, especially with lesions of the spinal cord, the opposite extremity to that mainly affected was also in a condition of abnormal sensibility, and it was impossible to obtain a standard for comparison from equivalent parts of the body. Under these circumstances we were obliged to compare the abnormal records with those from the hand or arm; such results must, however, be used with caution. No attention should be paid to the small variations in accuracy of response, and we have considered large differences only.

The examination was begun by obtaining from the patient a description of any abnormal sensations he may experience in the affected parts, such as pain, numbness or tingling. As these terms may imply in ordinary phraseology very different conditions, it is necessary to determine as exactly as possible in what sense they are used by the patient. "Numbness" may signify a "loss of feeling," or it may be used to describe, not a loss of function, but a positive abnormal sensation. Sometimes it may even signify inability to make delicate movements, especially in the fingers.

When spontaneous sensations exist, it is important to ascertain the conditions under which they occur, whether they are constant, and if they are aggravated by any external agent, such as contact, heat or cold.

We are accustomed to inquire if the patient has noticed at any time that he is unaware of the position in which the affected limbs lie, and if he