Skull base angle

Dr Henry Knipe and Dr Jeremy Jones et al.

The skull base angle allows the diagnosis of platybasia and basilar kyphosis. There are several different techniques that may be used on sagittal images from MRI or CT.

Traditionally, basal angle measurements were based on plain skull images. With the advent and generalization of MR imaging it has been supplanted and is rarely used.

MRI techniques produce lower basal angles than those reported by using traditional radiography. For this reason, Koenigsbert et al. described a new measurement method for MRI usage, which provides consistent and reproducible measurements.

For hystorical and utility purposes, both plain skull films and MRI measurement techniques are described.

Standard technique

Angle formed by:

  1. line joining the nasion with the center of the pituitary fossa
  2. line joining the anterior border of the foramen magnum with the center of the pituitary fossa
  • normal: 125°-143°
  • platybasia: >143°
  • basilar kyphosis: <125°
Modified MRI technique

Angle formed by:

  1. line extending across the anterior cranial fossa to the tip to the dorsum sellae
  2. line drawn along the posterior margin of the clivus
  • children: 114° +/- 5°
  • adults:  117° +/- 6°
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Article information

rID: 5241
Section: Gamuts
Synonyms or Alternate Spellings:
  • Basal angle
  • Measuring the skull base angle

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Cases and figures

  • Figure 1: standard measurement
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  • Figure 2: modified measurement
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