CCI Radiologic Measurements – Morphometrics

Clivo-Axial Angle Range

  • Neutral:  150-170 Degrees

Borderline 149-136 Degrees is noted : It’s tough to agree this is significant as I found in many routine MRIs for Thyroid some as low as 145 in lives without CCI related symptoms

Below 135 is considered pathological

Related pathologies to check:

  • Medulla Compression

Basilar Invagination (detected with)

Chiari I malformation (detected with)

References:

 

Grabb-Oakes (pBC2) or GOL Range

Normal Ranges

  • <= 9 mm is considered normal
  • > 9 mm is abnormal where 11 is pathological.

Related pathologies to check:

  • Normally seen with a Powers Ratio > 1, Retroflexed Odontoid, Pannus of C2
  • This appears to be an “additional” measurement to supplement spinal compression
  • Although in cases where a Pannus is noted (inflammation of the C2 Odontoid / Transverse & Cruciform Ligaments) can cause a positive test alone.

References:

Atlanto-Dental Interval (ADI) Range

Normal Ranges

  • Men: < 3 mm
  • Women: < 2.5 mm
  • CT: < 2 mm
  • < 4.5 mm for children

Related pathologies to check:

  • Head Trauma
  • Pannus / RA

References:

Basion-Dens Interval (BDI) Range

    Normal Ranges

    • The BDI is abnormal in the presence of a displacement between the basion and the dens of more than 10 mm in adults or more than 12 mm in pediatric patients
    • A low BDI is not discussed in literature but this indicates the degree of upward odontoid migration or Platybasia.

    Related pathologies to check:

    • Trauma to the Craniocervical Joint

    Cruciate Ligament

    Longitudinal (Posterior) Ligament

    Apical ligament

    • Abnormal Power’s Ratio
    • Cranial settling: vertical subluxation of the dens caused by loss of ligamentous support structures
    • Brain stem compression 

    References:

    Basion-Axial Interval (BAI) Range

    Normal Ranges : < 12 mm

    Dynamic (Translation) see following page:  Studies reveal that patients with 3mm + BAI translation from Flexion to Extension are deemed pathological.

    Related pathologies to check:

    • BDI 
    • Grabb Oakes
    • Power’s Ratio
    • Increased space between Occipital Condyles & C1 Lateral Mass

    Reference:

    Translational BAI

    Normal ranges

    • Normal: < 1
    • Borderline: between ≥ 1 and ≤ 2
    • Pathological: > 2
    • Surgical: > 4

    Symptoms : Occipital tightness, pressure stuck sensation dead center in base of skull,  Crunching, Grinding, Sliding sensation, Neuralgia

    References:

    Power’s Ratio Range

      Normal Ranges

      • < 1

      Related pathologies to check:

      • BDI > 10
      • BAI > 12

      References:

      Atlanto-Occipital Interval (AOI/OC1) Range

      Normal Ranges

      < 2 mm

      Related pathologies to check:

      • BDI > 10
      • BAI > 12
      • Power’s Ratio > 1

      Reference:

      Chamberlain Line Range

      Normal Range:

      • < 4.5 mm, whereas the Tip of the Odontoid is normally around 5 mm below this line. 

      Below 4.5 mm it’s been called upward odontoid migration

      References: