Differentiating Acute and Subacute Vertical Strabismus Using Different Head Positions During the Upright-Supine Test

Area of Science:

• Ophthalmology
• Neuro-ophthalmology

Background:

• Accurate clinical differentiation between skew deviation and fourth nerve palsy (4NP) is crucial for timely and appropriate patient management in acute and subacute settings.
• Distinguishing these conditions can be challenging due to overlapping symptoms of vertical diplopia.

Purpose of the Study:

• To evaluate the sensitivity and specificity of the upright-supine test in detecting changes in vertical misalignment.
• To assess the utility of different head positions during the upright-supine test for diagnosing acute/subacute skew deviation versus 4NP.

Main Methods:

• A multicenter study involving patients with vertical diplopia diagnosed with skew deviation or 4NP.
• Utilized the alternate prism and cover (APC) test and double Maddox rod test to measure vertical misalignment in upright and supine positions with various head tilts.
• Calculated the APC test change index and assessed sensitivity and specificity.

Main Results:

• The upright-supine test with a centered head showed low sensitivity (5%) but high specificity (100%) for skew deviation.
• Significant differences in vertical misalignment changes and cyclotorsion were observed between skew deviation and 4NP groups with head tilting.
• The conversion of incomitant to comitant vertical strabismus in the supine position and absence of neurological signs were noted in 4NP.

Conclusions:

• The upright-supine test with the head centered is not a sensitive diagnostic tool for differentiating skew deviation from 4NP.
• A change from incomitant to comitant vertical strabismus in the supine position, alongside the absence of neurological signs, may be more indicative of 4NP.