The physical examination as a window into autonomic disorders

Abstract

Signs of autonomic dysfunction, although at times seemingly mysterious, can contribute to diagnostic clarification and clinical investigation. Even when sophisticated autonomic testing equipment is not readily available, the experienced clinician, through educated observation and inductive reasoning-in conjunction with an intelligently obtained autonomic medical history-can discern much by a careful physical examination. Elements of the autonomic examination include variations in the pulse, postural measurements of blood pressure and heart rate, pupillary light reactions, skin coloration and temperature, patterns of sweating, and other organ-specific physical findings relevant to the individual patient's presentation. Especially important is the often neglected practice of measuring the blood pressure standing up, for orthostatic hypotension cannot be diagnosed by symptoms alone and is a common source of potential morbidity. The examination should be carried out in the context of understanding the syndromic nature of abnormalities of components of the autonomic nervous system.

Keywords: Autonomic nervous system diseases; Autonomic pathways; Blood pressure determination; Physical examination; Vital signs.

Figure 1.. Cutaneous flushing in erythromelalgia.

These patients cannot tolerate heat and may choose to live in a cool environment.

Figure 2.. Typical hair coloring in a neonate with Menkes disease.

This abnormality reflects decreased activity of tyrosinase, which like dopamine-beta-hydroxylase is a copper enzyme.

Figure 3.. Cutaneous angiokeratomas in Fabry disease.

This disease, which can cause stroke, is characterized also by severe anhidrosis.

Figure 4.. Anatomic location of the mediate arcuate ligament with respect to the celiac artery.

In a patient with POTS and prominent abdominal pain and vomiting, one should consider median arcuate ligament syndrome.

Figure 5.. Examples of Horner’s syndrome.

Note ptosis and miosis of the affected right eye (A) and left eye (B).

Figure 6.. Tracings by Walter B. Cannon showing in vitro intestinal relaxation upon exposure to blood from a cat exposed to a barking dog.

This was the first demonstration of distress-induced release of a hormone (epinephrine). Following baseline (A), alternate application of excited blood (at B and D) and quiet blood (at C), from the same animal, to an intestinal strip initially beating in Ringer’s solution.

Figure 7.. Diagram illustrating reflex micturition pathways and Onuf’s nucleus.

Degeneration of Onuf’s nucleus is a preganglionic lesion seen in MSA.

Figure 8.. Heart rate variability (power spectral analysis in the time domain) in a control subject and a patient with MSA.

Patients with diseases involving baroreflex-cardiovagal failure have an invariable heart rate.