abnormal head posture
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head posture, abnormal
A deviation in position of the head, aimed at mitigating the effects of diplopia. It may be due to a field restriction or shyness, but the most frequent reason is an incomitant strabismus. Patients usually adjust their heads to permit fusion. If the deviation is too large to achieve fusion, patients may adjust their heads so as to increase the separation between the diplopic images and thereby making the diplopia less troublesome. Examples: if the right medial rectus or the left lateral rectus is affected, the face may be turned to the left, and vice versa if the other horizontal muscles are affected; if the left superior oblique is affected, the face may be turned to the right, the chin may be depressed and the head may be tilted to the right. If the cause of abnormal head posture remains untreated it may produce torticollis. See paralysis of the fourth nerve; paralysis of the sixth nerve; paralytic strabismus.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann