| Abnormal Head Postures |
What are the causes of abnormal head posture?
Constant abnormal head posture can arise from ophthalmic or non-ophthalmic
causes. Non-ophthalmic causes could be from abnormality of neck muscles,
vertebral bones, cerebral palsy, unilateral hearing loss or sometimes out of
faulty habits.
Ophthalmic causes are
usually related to squint or nystagmus (involuntary purposeless jerky movement
of eye ball).
Squint:
It is generally seen in cases of paralytic type of squint or in any restrictive eye
movement disorder. The eyeball can not be rotated in the direction of action of
muscle once it is paralysed or has restricted mobility, so the face is turned in
the same direction to compensate for the underaction. Sometimes because of
misalignment of eyes, images are formed in the central retina of one eye and in
the peripheral retina of the other eye. Because of this, two dissimilar images
are formed in two eyes and as they are not similar, cannot be fused into one
single image in the brain and patient experiences diplopia or double vision. In
order to avoid diplopia patient assumes a head posture in which there is minimal
diplopia or there is a possibility of fusion. This is achieved by face turn,
head tilt or chin up and down position.
Nystagmus:
In nystagmus many a time there is a certain position of gaze where nystagmus is
lessened; improving vision in that position of the eye which is called null point. By
acquiring that position by head tilt or turn, patient achieves better vision.
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