Isolated trochlear nerve palsies in herpes zoster ophthalmicus.

The clinical course of six patients with isolated trochlear nerve palsy as the only ocular motor manifestation of herpes zoster ophthalmicus has been analyzed. Spontaneous recovery occurred in only three. Review of the literature does not clarify the mechanism of such palsies, which potentially may result from the following conditions: local orbital muscle inflammation and ischemia; contiguous intracavernous spread of inflammation from the trigeminal nerve; and a concurrent but independent motor neuropathy or ganglionitis.