Table 2

Nerve conduction data for POEMS syndrome and CIDP patients

ABCp Value
Normal (n=73)POEMS (n=51)CIDP (n=46)B vs C
Motor conduction study
 Median nerve
  Distal latency (ms)3.6 (0.4)5.6 (1.4)8.1 (3.2)<0.0001
  CMAP amplitude (mV)10.4 (2.9)5.2 (3.8)4.7 (3.3)0.5
  CMAP duration (ms)4.8 (0.59)6.6 (2.5)8.5 (0.13)0.13
  Conduction velocity (m/s)57.6 (3.7)33.2 (10.0)32.6 (11.2)0.8
  F wave latency (ms)24.7 (1.8)46.1 (13.6)52.6 (13.9)0.06
  Terminal latency index0.34 (0.03)0.42 (0.11)0.34 (0.16)0.006
  Conduction block10% (5/50)26% (11/43)0.04
  Not response0% (0/73)8% (4/50)0% (0/43)0.08
 Tibial nerve
  Distal latency (ms)4.3 (0.7)7.2 (2.6)8.3 (2.7)0.1
  CMAP amplitude (mV)14.2 (4.7)1.0 (2.3)3.6 (3.5)0.0001
  Conduction velocity (m/s)46.5 (3.8)27.2 (6.6)32.2 (7.5)0.02
  F wave latency (ms)46.1 (3.8)78.9 (15.4)80.3 (19.6)0.8
  Not response0% (0/73)56% (27/48)7% (3/42)<0.0001
Tibial/median CMAP amplitude ratio1.4 (0.5)0.5 (0.8)0.8 (0.6)0.09
Sensory conduction study
 Median nerve
  SNAP amplitude (μV)34.5 (14.8)9.3 (9.7)3.3 (6.0)0.0005
  Conduction velocity (m/s)52.7 (8.3)38.9 (7.0)41.8 (9.1)0.3
  No response0% (0/73)22% (11/50)63% (27/43)<0.0001
 Sural nerve
  SNAP amplitude (μV)15.5 (7.8)1.4 (2.4)7.8 (8.8)<0.0001
  Conduction velocity (m/s)51.4 (5.4)37.4 (6.1)43.6 (6.8)0.004
  No response0% (0/73)68% (32/47)36% (15/42)0.002
  Sural/median SNAP amplitude ratio0.5 (0.2)0.3 (0.2)3.2 (4.2)0.02
  • Data are expressed as mean (SD) or per cent (number).

  • CIDP, chronic inflammatory demyelinating polyneuropathy; CMAP, compound muscle action potential; POEMS syndrome, polyneuropathy, organomegaly, endocrinopathy, M protein and skin changes syndrome; SNAP, sensory nerve action potential.