A child has right superior oblique palsy (CN IV) confirmed by 3-step test. The head tilt is to the LEFT (away from affected eye). Which of the following best explains the pathophysiology of the head tilt in CN IV palsy?

• A Head tilts toward the side that increases superior oblique action to clear diplopia
• B Head tilts AWAY from the palsied side to neutralize the hyperdeviation by using intact intorsion of the opposite eye ✓
• C Head tilts toward the opposite side to use the intact inferior oblique for vertical fusion
• D Head tilt is a reflex response to unilateral trochlear nucleus damage in the midbrain

Explanation

In right superior oblique palsy the right eye is hyperdeviated and excyclotorted, since the SO is the main intorter and depressor. Tilting the head toward the palsied (right) side forces the right eye to intort; with the SO weak, the superior rectus acts unopposed and its elevating action drives the eye further up, worsening the hyperdeviation — this is the positive Bielschowsky head-tilt test. The patient therefore adopts a compensatory tilt AWAY from the palsied side (to the left), where ocular counter-rolling is achieved by the intact intorsion of the opposite (left) eye, neutralizing the vertical deviation and relieving diplopia. Options A and C state the wrong direction/muscle, and D is incorrect because the tilt is an adaptive anti-diplopia posture, not a reflex from nuclear damage.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.