Monday 23 January 2012

Platybasia with Basilar invagination

MRI Mid sagittal section of CV junction shows:
  • Platybasia (abnormal flattening of the skull base) evident by wide NTB (Nasion – Tuberculum – Basion) angle,
  • Forward folding of the Clivus – Axis Angle (Angle of Wackenheim) causing lordotic tilt at CV junction, Elevated plane of the foramen magnum with retroflexed dens. 
  • Basilar invagination evident by violation of Chamberlain’s (Hard palate - Ophisthion) line by the Dens. 
  • Among two types of basilar invaginnation (Ventral and Paramesial), this is a Ventral variety of Basilar Invagination characterized by shortening of basiocciput due to short and horizontally placed clivus leading to forward facing plane of foramen magnum. 
  • Abnormal sharp Clivus – Odontoid Angle causing exteme indentation over cervico medullary junction. However signal abnormality not very obvious in compressed medulla or cervico medullary junction.
  • Normal Atlanto- Odontoid Distance. No obvious Atlanto Dental subluxation or dislocation. 
Imaging diagnosis : Platybasia with Basilar invagination.
Basal angle or NTB (Nasion – Tuberculum – Basion) angle. 

Chamberlain's line (Hard plate to Ophisthion)

Clivus – Axis Angle or ‘ Angle of Wackenheim’

Similar Post : Basilar-impression

1 comment:

o kilickesmez said...

I think that also incomplete atlantooccipital assimilation is contributing to this brainstem anomaly complex.