Heat-sensitive conduction block in ulnar neuropathy at the elbow.
OBJECTIVE
To study the effects of elbow heating on conduction block (CB) and across-elbow conduction velocity (CV) in patients with ulnar neuropathy at the elbow (UNE).


METHODS
We studied 15 patients with UNE, performing motor nerve conduction studies at 32 degrees C and after heating the elbow to 42 degrees C.


RESULTS
At 32 degrees C, mean response amplitude and area with above-elbow (AE) stimulation were 20.4 and 16.0% lower than with below-elbow (BE) stimulation, respectively. With heating the elbow to 42 degrees C, these differences increased significantly to 28.9 and 26.9% (P=0.019 and 0.029), respectively. The mean CV reduction in the across-elbow segment relative to the forearm segment also increased from 20.5 m/s at 32 degrees C to 25.6 m/s at 42 degrees C (P=0.0010). Across-elbow CV at 32 degrees C correlated with increased CB (as measured by amplitude) with heating (r=0.53, P=0.048) and approached significance for area (r=0.48, P=0.068) Likewise, baseline CB at 32 degrees C correlated with the likelihood of increased CB for amplitude (r=0.77, P<0.001), and approached significance for area (r=0.47, P=0.079).


CONCLUSIONS
Elbow heating in UNE increases the relative drop in across-elbow CV and the degree of across-elbow CB; absolute across-elbow CV and the presence of baseline CB at 32 degrees C are good predictors of this latter effect.
Rutkove
S B
SB
Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, TCC-810, MA, Boston 02215, USA. srutkove@caregroup.harvard.edu
Geffroy
M A
MA
Lichtenstein
S H
SH
D000328:Adult; D000368:Aged; D004550:Elbow / Q000294:innervation*; D005260:Female; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction; D011930:Reaction Time; D014459:Ulnar Nerve / Q000503:physiopathology*; D020424:Ulnar Neuropathies / Q000503:physiopathology*