Testing of Sensory Function in Microsoft Office

Drawing QR in Microsoft Office Testing of Sensory Function

The detail with which sensation is tested is determined by the clinical situation If the patient has no sensory complaints, it is suf cient to test vibration and position sense in the ngers and toes and the perception of pinprick over the face, trunk, and extremities as well as to determine whether the ndings are the same in symmetrical parts of the body A rough survey of this sort occasionally detects sensory defects of which the patient was unaware On the other hand, more thorough testing is in order if the patient has complaints referable to the sensory system or if one nds localized atrophy or weakness, ataxia, trophic changes of joints, or painless ulcers A few other general rules should be mentioned It is generally easier for a patient to perceive the boundary of an abnormal area of sensation if the examiner proceeds from an area of reduced sensation toward the normal area One should not press the sensory examination in the presence of fatigue, for an inattentive patient is a poor witness Also, the examiner must avoid suggesting symptoms to the patient After explaining in the simplest terms what is required, the examiner interposes as few questions and remarks as possible Consequently patients should not be asked, Do you feel that each time they are touched; they are simply told to say yes or sharp every time they are touched or feel pain Repetitive pinpricks within a small area of skin should be avoided, since this will make inapparent a subtle hypalgesia In patients who may be overinterpreting subtle changes in pinprick, differentiating between warm and cold is often more informative than differentiating be-

If an area of diminished or absent touch or pain sensation is encountered, its boundaries should be demarcated to determine whether it has a segmental or peripheral nerve distribution or is lost below a certain level on the trunk As mentioned, such areas are best delineated by proceeding from the region of impaired sensation toward the normal The changes may be con rmed by dragging a pin lightly over the parts in question Testing of Deep Pressure-Pain One can estimate the perception of this modality simply by lightly pinching or pressing deeply on the tendons, muscles, or bony prominences Pain can often be elicited by heavy pressure even when super cial sensation is diminished; conversely, in some diseases, such as tabetic neurosyphilis, loss of deep pressure-pain may be more striking than loss of super cial pain Testing of Thermal Sense A quick but rough way to assess thermal loss (or to corroborate a previously found zone of hypalgesia) is to warm one side of a tuning fork by rubbing it briskly against the palm and apply its alternate sides to the patient s skin This suf ces for most bedside examinations If more careful examination is required, the skin should rst be exposed to room air for a brief time before the examination The test objects should be large, ideally, two stoppered test tubes containing hot (45 C) and cold (20 C) tap water with thermometers that extend into the water through the ask stoppers Extreme degrees of heat and cold (eg, 10 and 45 C) are employed rst to delineate roughly an area of thermal sensory impairment The side of each tube is applied successively to the skin for a few seconds and the patient is asked to report whether the ask feels less hot or less cold in comparison to a normal part The qualitative change should then be quantitated as far as possible by recording the differences in temperature that the patient is able to recognize as the difference in temperature between the two tubes is gradually reduced A normal person can detect a difference of 1 C or even less in the range of 28 to 32 C; in the warm range, differences between 35 and 40 C can be recognized, and in the cold range, between 10 and 20 C If the temperature of the test object is below 10 C or above 50 C, sensations of cold or heat become confused with pain This technique has been largely supplanted by commercially manufactured electronic devices that can present a series of slightly differing thermal stimuli in sequence to a probe placed on the nger or toe Special algorithms are used for the order and magnitude of temperature change and to determine whether the patient s reports are consistent and valid The results are reported in the form of a just noticeable difference (JND) between temperatures or intensities of pain Testing of Proprioceptive Sense Awareness of the position and movements of our limbs, ngers, and toes is derived from receptors in the muscles, tendons (Golgi tendon organs, according to Roland et al), and joints and is probably facilitated by the activation of skin receptors (Moberg) The two modalities comprised by proprioception, ie, sense of movement and of position, are usually lost together, although clinical situations do arise in which perception of the position of a limb or digits is lost while that of passive and active movement (kinesthesia) of these parts is retained The opposite occurs but is infrequent Abnormalities of position sense may be disclosed in several ways When the patient has his arms outstretched and eyes closed, the affected arm will wander from its original position; if the pa-

tient s ngers are spread apart, they may undergo a series of changing postures ( piano-playing movements, or pseudoathetosis); in attempting to touch the tip of his nose with his index nger, the patient may miss the target repeatedly, but he corrects his performance with his eyes open The lack of position sense in the legs is demonstrated by displacing the limb from its original position and having the patient, with eyes closed, place the other leg in the same position or point to the great toe If position sense is defective in both legs, the patient will be unable to maintain his balance with feet together and eyes closed (Romberg sign) This test is often interpreted imprecisely In the Romberg position, even a normal person whose eyes are closed will sway slightly, and the patient who lacks balance due to cerebellar ataxia or vestibulopathy or to some other motor disorder will sway considerably more if his visual cues are removed Only a marked discrepancy in balance with eyes open and with eyes closed quali es as a Romberg sign The most certain indication of abnormality is the need to step to the side or backward in order to avoid falling Mild degrees of unsteadiness in a nervous or suggestible patient may be overcome by diverting his attention, eg, by having him touch the index nger of each hand alternately to his nose while standing with eyes closed or by following the examiner s nger with his eyes Perception of passive movement is rst tested in the ngers and toes, since the defect, when present, is re ected maximally in these parts It is important to grasp the digit rmly at the sides, perpendicular to the plane of movement; otherwise the pressure applied by the examiner may allow the patient to identify the direction of movement This applies as well to testing of the more proximal segments of the limb The patient should be instructed to report each movement as being up or down from the previous position (directional kinesthesia) It is useful to demonstrate the test with a large and easily identi ed movement, but once the idea is clear to the patient, the smallest detectable changes should be determined The sensitivity of testing is enhanced by using the third and fourth ngers and toes The part being tested should be moved rapidly Normally, a very slight degree of movement is appreciated in the digits (as little as 1 degree of an arc) The test should be repeated enough times to eliminate chance (50 percent of responses) Defective perception of passive movement is judged by comparison with a normal limb or, if perception is bilaterally defective, on the basis of what the examiner has learned through experience to be normal Rapid movements are more easily detected than are slow ones Slight impairment may be disclosed by a slowness of response or, if the digit is displaced very slowly, by an unawareness or uncertainty that movement has occurred; or, after the digit has been displaced in the same direction several times, the patient may misjudge the rst movement in the opposite direction; or, after the examiner has moved the toe, the patient may make a number of small voluntary movements of the toe in an apparent attempt to determine its position or the direction of the movement Inattentiveness will also cause some of these errors Testing of Vibratory Sense This is a composite sensation comprising touch and rapid alterations of deep-pressure sense The only cutaneous structure capable of registering such stimuli of this frequency is the rapidly adapting pacinian corpuscle The conduction of vibratory sense depends on both cutaneous and deep afferent bers that ascend mainly in the dorsal columns of the cord It is therefore rarely affected by lesions of single nerves but will be disturbed in patients with disease of multiple peripheral nerves,