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Table 4 Correlation between the flattening ratio and electro-diagnostic study parameters

From: The correlation between pre-operative ultrasonographic median nerve evaluation and the operative procedure in CTS

  Factors (range) mean ± SD N = 24
r p
Flattening ratio Motor distal latency(ms) (3.6-8) 5.021 ± 1.351 0.63 0.0005
Motor amplitude(mv) (2–7) 4.346 ± 1.526 −0.69 < 0.0001
Motor nerve conduction velocity(m/s) (15-55) 38.33 ± 12.13 −0.59 0.0013
Sensory peak latency(ms) (3.3-6) 4.258 ± 0.756 0.36 0.042
Sensory amplitude(mv) (10–18) 14.42 ± 2.32 −0.24 0.1314
Sensory nerve conduction velocity(m/s) (15-40) 26.46 ± 7.29 −0.26 0.1099
  1. ms millisecond, mv millivolt, m/s meter/second
  2. Spearman Correlation P probability, r correlation coefficient
  3. r = 0–0.2, very low and probably meaningless; r = 0.2–0.4, a low correlation
  4. r = 0.4–0.6, a reasonable correlation; r = 0.6–0.8, a high correlation
  5. r = 0.8–1.0, a very high correlation; P < 0.05 = significant