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Examination of Patients History
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Examination of Patients History

Symptoms suggesting autonomic dysfunction include orthostatic hypotension, heat intolerance, and loss of bladder and bowel control. Erectile dysfunction is an early symptom. Other possible symptoms include dry eyes and dry mouth, but they are nonspecific.

Physical examination.

Valuable information about the functional state of the autonomic nervous system may be obtained from the general observation of the patient. The habitus, body build, state of nutrition, deformities, and abnormalities of configuration are important criteria. Note should be taken to the following aspects of the physical examination: endocrine status, the regulation of vital processes (body temperature, blood pressure pulse, respiratory rate and rhythm, etc.), the skin and mucous membranes, perspiration, hair and nails, salivation, lacrimation and other secretory responses, fat metabolism, bones and joints, presence of specific and focal changes, such as Horner's syndrome.

The examination of the autonomic nervous system provides valuable information in neurologic diseases, and the examiner should be familiar with the important methods of evaluation.

Autonomic nervous system reflexes

Among the autonomic nervous system reflexes are the pupillary, lacrimal, salivary, sneeze, sucking, cough, vomiting, carotid sinus, and oculocardiac reflexes.

Sweat Tests. These are important objective tests of autonomic function. The production of sweat, or perspiration, is a function of the sympathetic division of the autonomic nervous system. Sweating is produced by drugs such as acetylcholine and pilocarpine, which are classed as parasympathomimetic, and is decreased by atropine, scopolamine, and other drugs that inhibit structures innervated by postganglionic cholinergic nerves.

The Pilomotor Response. Piloerection is also a function of the sympathetic division of the autonomic nervous system. Stimulation of the sympathetic nerves causes contraction of the erectors pilorum muscles and erection of the cutaneous hairs, known as cutis anserina or "goose flesh." The response may be elicited with ease, but it is inconstant and transient and cannot be demonstrated adequately on the hands or feet. Piloerection may be provoked by gentle stroking of the skin, tickling, scratching with a sharp object, or the application of cold. Ice, cotton soaked in alcohol or ether, or a methyl chloride spray may be used. Piloerection is elicited best at the nape of the neck, in the axillas, on the abdominal wall, and at the upper border of the trapezius. Piloerection is absent in lesions that involve the descending autonomic pathways in the brain stem and spinal cord, sympathetic trunk, preganglionic and postganglionic fibers, and peripheral nerves. It is abolished below transverse spinal lesions, and the descending reaction to a massive stimulus stops at this level.

Reflex Erythema. Stimulation of the skin by stroking it with a blunt point is followed by focal vasodilation. There is first a local reaction, seen as a red line along the site of stimulation, which is followed in about ?min by a spreading flush, or flare, on each side of the scratch. Depending upon the intensity of the stimulus and individual susceptibility, the site of stimulation becomes elevated, with the development of a welt, or wheal, sometimes with a white line in its center. Exaggeration of reflex erythema is called dermatographia. This phenomenon is present whenever the sympathetic influence is diminished. It is marked in individuals with overactivity of the parasympathetic division and in those with labile autonomic nervous systems or with evidence of sympathetic and parasympathetic imbalance. It may also occur on an allergic basis and as a reaction to chemical and thermal stimuli.

Skin Temperature Studies. The determination of the skin temperature is an important part of the examination of the autonomic nervous system. The vasomotor tonus is reflected in the surface temperature of the body, and interruption of the sympathetic division with resulting vasodilation is followed by a rise in temperature. Conversely, stimulation of the sympathetic with consequent vasoconstriction is accompanied by a fall in surface temperature. Skin temperature studies can be useful in the diagnosis of lesions of the sympathetic division, in determining the level of a transverse spinal lesion, in delineating the extent of a peripheral nerve lesion, in the preoperative appraisal of the continuity of sympathetic pathways, and in the differential diagnosis of Raynaud's and Buerger's diseases, peripheral atherosclerosis, and other vascular diseases of the extremities.

The Cold Pressor Test. Stimulation of the vasomotor center by cold with resultant rise in blood pressure may be used in the diagnosis of hypertension. The sphygmomanometer cuff is applied to one arm while the other hand and arm are immersed in water of about 4°C. Blood pressure readings are taken every 30-60 sec until the highest reading is reached. This is termed the index of response. The arm and hand are then removed from the cold water and readings are taken every 2 min until the basal level is reached. In the normal individual there is a slight rise in both systolic and diastolic blood pressure, with a fall to normal within 3 min after the stimulus is removed. A response of more than 20 mm Hg systolic, and more than 15 mm Hg diastolic, is considered significant. In hypertension there is a greater and more prolonged rise, with a delayed fall; this effect disappears after the administration of tetraethyl-ammonium chloride. There is also increased vasopressor reactivity in patients with cerebral atherosclerosis.

Other Tests of Circulation. Postural effects on blood pressure may be tested by recording with the patient recumbent and erect. More precise evaluation is possible with the use of a tilt table. With orthostatic hypotension due to sympathetic failure the systolic and diastolic blood pressure values fall on assumption of the vertical position. The blood pressure and pulse responses to Valsalva's maneuver may be studied, but this procedure requires an indwelling arterial catheter for recording the pressure. Changes in heart rate with respiration, alteration of body posture, exercise, or drugs can also be noted and recorded as part of autonomic assessment. The parasympathetic innervation of the heart may be tested by the so-called diving reflex in response to immersion of the face in water.



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