[Parinaud syndrome and Collier signal. Initial neurological manifestation in an HIV-1 positive patient].

We describe the third case in the literature of Parinaud's syndrome as the sole manifestation of brainstem toxoplasmosis, in a positive HIV-1 patient and review the literature concerning the possible etiologies of Parinaud's syndrome, enforcing that it is a rare manifestation of central nervous system toxoplasmosis. We refer to its occurrence without simultaneous obstructive hydrocephalus and increased intracranial pressure, pointing out the Collier signal which is not very well known, but has great semiotic value once it locates the lesion in the brainstem.