Management of Extra‐sellar Pituitary Tumours With Bromocriptine: Comparison of Prolactin Secreting and Non‐functioning Tumours Using Half‐field Visual Evoked Potentials and Computerised Tomography

To determine whether prolactin secreting and non-functioning pituitary tumours respond differently in terms of shrinkage to bromocriptine, we prospectively studied ten consecutive patients (five with prolactinomas and five with non-functioning tumours) complicated by extra-sellar extensions. No patient had received prior radiotherapy or bromocriptine and the mean dose and duration of bromocriptine treatment were identical in the two groups of patients. Objective evidence of tumour shrinkage was provided by serial half-field visual evoked potentials (VEPs) and computerised tomography (CT). All five prolactinomas were shown to shrink as assessed by improvement in VEP and four of the five as assessed by CT. In contrast, only one of the five patients with non-functioning tumours showed any improvement in VEP or CT. Macroprolactinomas frequently shrink rapidly when treated with bromocriptine, whereas non-functioning tumours seldom show such a dramatic response.