Clinical and instrumental diagnosis of autonomic neuropathy in insulin-dependent diabetes

Abstract

The author report a study of the relationship between symptomatic autonomic neuropathy and the response to simple cardiovascular autonomic tests (Valsalva maneuver, handgrip-test, detection of postural hypotension), in a large series of insulin-dependent diabetics (IDD). Symptoms of autonomic neuropathy were referred by 28 out of 130 IDD, prevalence and severity showed a clear relationship with the duration of diabetes. Only 4 out of 36 patients examined showed a pathologic response to the handgrip-test, while an abnormal Valsalva maneuver was evident in 24 out of 113 IDD. The data show that while the recognition of symptoms indicating a widespread autonomic derangement is rather easy, the diagnosis of autonomic neuropathy may be more difficult in the presence of mild or unspecific symptoms. The Valsalva maneuver exhibited the higher frequency of abnormal responses suggesting that the parasympathetic cardiovascular regulation may be impaired earlier than the sympathetic one. This early subclinical autonomic neuropathy may be due to metabolic or functional factors. Even if clinical consequences of an autonomic derangement of cardiovascular regulation may be serious, in our opinion subclinical impairment, being detectable in a large proportion of patients within the first year of disease, is unlikely to have a short-term severe prognostic value.

The Relationship between Diabetic Autonomic Neuropathy and Diabetic Risk Factors in a Taiwanese Population

“…In DAN, parasympathetic impairment occurs earlier and is more relevant than sympathetic impairment. 23 In normal subjects, spectral analysis of R-R variability shows two major peaks: one at low frequency (LF), which is mainly an expression of sympathetic control, 24 and one at high frequency (HF), which represents vagal control. The LF component of the spectrum is more frequently abnormal than the HF component in patients with DAN, suggesting that early damage occurs in the sympathetic pathways to the heart in diabetic patients.…”