Natural History of Acquired Demyelination in Diabetic Distal Symmetric Polyneuropathy
Roopa Sharma1, Daniel Menkes2, Kazim Jaffry1, Iqra Faiz1, Nizar Souayah1
1Rutgers New Jersey Medical School, 2Oakland University William Beaumont School of Medicine
Objective:
Features of acquired demyelination have been reported in diabetic distal symmetrical polyneuropathy (DDSP).
Background:
To characterize the natural history of demyelination in DDSP.
Design/Methods:
We retrospectively reviewed changes in motor nerve conduction studies in 71 patients with DDSP who underwent at least 2 electrodiagnostic testing sessions and divided into three groups- G1 (patients without any new conduction velocity slowing (CVS), G2 (patients with new CVS) and G3 (patients with new CVS in demyelinating range per AAN criteria). Mean HbA1c, age, body mass index (BMI) and duration between the two studies were compared between the 3 groups.
Results:
30 men and 41 women were included. The mean age and time between the first and subsequent studies was 55.91±10.44 and 32±31 months respectively. 57/71 patients had at least one HbA1c value with an average of 7.87± 2.61. Thirty of 71 patients, (42.2%) showed CVS in at least one nerve including 16.6% (5/30) with CVS into the demyelinating range. Of 30 patients, 40% (12/30) had interval CVS in one nerve, 33% (10/30) in 2 nerves and 27% (8/30) in 3 or more nerves. Interval CVS into the demyelinating range was observed in 7% (5/71) of diabetic DSP patients. When comparing groups G1/G2, G2/G3 and G1/G3, the mean HbA1c values demonstrated statistically significant differences between G2/G3 (8.14±2.48 vs 10.56±5.25; p<0.05) and G1/G3 (7.48±2.21 vs 10.56±5.25; p<0.002). However, there were no statistically significant differences observed with respect to age, BMI, and the time interval between studies among the groups.
Conclusions:
In a subgroup of DDSP patients, an evolving CMAP independent motor nerve CVS, interval prolongation of the distal motor latency, and interval prolongation or absence of F waves may occur, consistent with a superimposed acquired demyelination. These changes were more frequently identified in patients with higher mean HbA1c values.