Quantitative sensory and autonomic testing in male diabetic patients with erectile dysfunction

Objective To correlate abnormalities of nerve fibres in the lower limbs wit h erectile dysfunction in male diabetic patients, using a range of quantita tive sensory and autonomic function tests, Patients and methods The study included 68 male diabetic patients with symp tomatic erectile dysfunction and II matched diabetics without erectile dysf unction; none had clinical evidence of peripheral vascular disease or psych ological disorder. Patients were evaluated with a symptom questionnaire bas ed on the Michigan Neuropathy Screening Instrument questionnaire and examin ed clinically. Sural and peroneal nerve-conduction studies, and quantitativ e sensory and autonomic tests (vibration, thermal, light-touch thresholds, sensory and autonomic cutaneous axon-reflexes) were used to detect nerve ab normalities in the lon er limbs, which were correlated with erectile dysfun ction. Results Symptoms of neuropathy were more common in the group with male erec tile dysfunction (MED). but statistically significant only for neuropathic pain (53% MED. 18% nonMED. P < 0.05, chi-square test) and gastroparesis (44 % MED, 0% nonMED, P < 0.05), Tests of unmyelinated afferents (warming perce ption and capsaicin-induced sensory axon-reflex vasodilatation) were most o ften abnormal. sometimes with no other abnormalities on tests or neurologic al examination. However, abnormality of warm perception Mras not significan tly different between groups (81% MED, 70% nonMED), suggesting that it is a poorer discriminant than abnormal sensory axon-reflex vasodilatation (89% MED. 22% nonMED, P < 0.001). The only other significant test difference was decreased sural nerve action potential (70% MED, 22% non-MED, P < 0.01), Conclusions There appeared to be preferential involvement of unmyelinated s ensory fibres that mediate axon-reflex vasodilatation in the limbs of diabe tic patients with erectile dysfunction. This test appears to be a helpful i ndicator of neurological involvement in erectile dysfunction, and may tie u sed to monitor the effect of new treatments.