Neurological Screening Practice Test

Vertical diplopia that worsens when looking down and toward the affected side is the hallmark of trochlear nerve palsy. This happens because the superior oblique, which this nerve supplies, normally depresses and intorts the eye when it is adducted. When the muscle is weak, the eye drifts upward (hypertropia) and tilts outward, so double vision becomes most noticeable in downward gaze toward the side of the palsy. Patients often compensate by tilting their head away from the affected side.

Other signs point to different nerves: impaired abduction suggests a sixth nerve palsy; reduced sensation in the V1–V3 territories points to trigeminal involvement; ptosis is common with oculomotor (CN III) palsy.