Trochlear nerve palsy as a false localizing sign.

A 12-year-old boy developed a fourth nerve palsy during the course of pseudotumor cerebri syndrome. False or nonlocalizing signs that occur during the course of intracranial disease are briefly reviewed. The rarity of a fourth nerve palsy as a false localizing sign is pointed out. However, the question is raised whether a number of subtle fourth nerve palsies go unnoticed and that the true incidence of false localizing fourth nerve palsies is higher.