Dissociated sensory loss in diabetic autonomic neuropathy

Clinical observation has led to the idea that there might be a distinctive form of selective sensory and autonomic neuropathy affecting patients with Type 1 diabetic mellitus with severe symptomatic autonomic neuropathy (Type 1-DAN) and this study was conducted to evaluate the presence of such a neuropathy in Type 1-DAN.

Nineteen Type 1 diabetic patients presenting for treatment of severe symptomatic autonomic neuropathy were examined (all had > or = 2 autonomic symptoms; age 39.3 +/- 10.2 years; duration of disease 25.6 +/- 10.5 years). For comparison, 19 Type 1 diabetic patients with neuropathic foot ulcers (age 44.5 +/- 6.6 years; duration of disease 26.7 +/- 9.2 years), 14 clinically uncomplicated Type 1 diabetic patients (age 39.9 +/- 5.6 years; duration of disease 22.9 +/- 9.3 years) and 16 non-diabetic healthy people as controls (age 39.3 +/- 10.7 years) were also examined. Results The large fibre modalities (light touch and vibration perception) were better preserved in the Type 1-DAN group than in the foot ulcer group. Thus, light touch sensation was normal in 11 out of 19 Type 1-DAN patients compared to only three out of 19 foot ulcer patients (P < 0.01), and vibration perception was 24.9 +/- 15.0 V and 40.5 +/- 7.9 V, respectively (P < 0.002) with some of the Type 1-DAN patients in the normal range. In contrast, the small fibre modalities, thermal perception and autonomic function, were grossly abnormal in both groups (hot thermal perception 14.1 +/- 2.5 degrees C and 12.6 +/- 3.7 degrees C; cold thermal perception 13.8 +/- 2.7 degrees C and 10.9 +/- 4. 7 degrees C; heart rate variation 2.9 +/- 1.5 beats/min and 4.8 +/- 4.0 beats/min, respectively).

There is indeed a subgroup of Type 1 diabetic neuropathy patients who suffer from severe autonomic symptoms associated with a selective small fibre sensory and autonomic loss with relatively preserved large fibre sensory modalities.