Objective: During dopaminergic agonist treatment for macroprolactinoma, tumour shrinkage can be accompanied by secondary deterioration of the visual field in rare instances. The aim of the present study was to evaluate the incidence of symptomatic or asymptomatic delayed visual loss associated with chiasmal herniation during long-term cabergoline treatment of macroprolactinomas and to report our experience of its management.
Patients: The study included 28 patients (11 women and 17 men) aged 14-85 years treated for macroprolactinoma with cabergoline at our centre from 1997 to 2006.
Results: Chiasmal herniation was observed at MRI in five out of the 28 cases. A systematic visual field evaluation revealed visual field worsening, during cabergoline treatment, in three out of these five patients. In two asymptomatic patients, secondary deterioration of visual field occurred 2.5 years and 4 years, respectively, after cabergoline treatment initiation. In the third case, cabergoline treatment resulted in a paradoxical worsening of an initial visual defect. In all three cases, visual fields improved after cabergoline withdrawal although chiasmal herniation persisted. Visual field remained normal in the two other patients.
Conclusions: Our results suggested that chiasmal herniation associated with delayed visual field defect is not a rare feature during cabergoline treatment of macroprolactinomas. It should be assessed by systematic visual field evaluation and treated by adaptation of medical treatment.