Anatomic and physiologic measurements in S-CMI and NS-CMI

S-CMI (n = 8)NS-CMI (n = 5)
Anatomic measurements (mean)
    Tonsillar herniation (mm)17.5 ± 7.412.2 ± 6.2
    Clivus length (mm)34.3 ± 5.432.8 ± 2.5
    Supraocciput length (mm)42.4 ± 7.740.4 ± 2.5
    Twining line (mm)81.4 ± 4.881.8 ± 1.3
    McRae line (mm)36.6 ± 4.239 ± 3.4
    Skull base angle131.1° ± 6.9°125.6° ± 4.8°
    Odontoid retroversion angle69.8° ± 9.3°70.4° ± 8.7°
    Clivus-canal angle145.5° ± 10.4°150.6° ± 6.9°
    pB-C2 Line (mm)6.1 ± 27.2 ± 1.5
Physiologic measurements (mean)
    SVCSF resting (mL)0.37 ± 0.270.48 ± 0.20
    SVCSF postcough (mL)0.14 ± 0.130.29 ± 0.13
    SVCSF relaxation (mL)0.36 ± 0.310.51 ± 0.20
    ΔSVCSF resting to postcough (%)−64.9 ± 17.3a−35.1 ± 29.6a
    ΔSVCSF postcough to relaxation (%)190 ± 15898.1 ± 115.7
    ΔSVCSF resting to relaxation (%)−9.6 ± 37.69.3 ± 27.3
  • Note:—ΔSVCSF resting to postcough indicates change in SVCSF from resting to postcough in %; ΔSVCSF postcough to relaxation, change in SVCSF from postcough to relaxation in %; ΔSVCSF resting to relaxation, change in SVCSF from resting to relaxation in %.

  • a P < .05, Mann-Whitney U test.