Macroprolactinomas and epilepsy

Objective To assess the prevalence and characteristics of epilepsy in patients with macroprolactinomas. Secondly, to report the response to dopamine agonist (DA) therapy.

Patients A case note analysis of all patients with a diagnosis of macroprolactinoma attending a neuroendocrine clinic between 1996 and 2006. Those with epilepsy at diagnosis of macroprolactinoma were examined in detail.

Results There were 64 patients with macroprolactinoma and 29 of these had tumours with suprasellar extension compressing/invading the optic apparatus and/or surrounding brain structures. Six of these 29 patients (four men), had a history of seizures at the time of diagnosis, five of whom had features suggestive of temporal lobe epilepsy. None of the other 35 patients had epilepsy. All six patients with epilepsy had invasive prolactinomas on cranial imaging and marked hyperprolactinaemia (median prolactin 369 000 mU/l, range 28 000 to > 750 000). Seizures had been present for a median of 2 years (range 1–23 years) before the diagnosis of macroprolactinoma. A rapid reduction in seizure frequency occurred in all patients with initiation of DA therapy. Four have been seizure-free between 18 months to 15 years despite only small reductions in tumour size.

Conclusions Invasive macroprolactinomas can commonly be associated with epilepsy, particularly of temporal lobe origin. It is essential to enquire about epileptic symptoms, as the seizure disorder may have been undiagnosed/untreated for years. DA therapy can reduce ictal frequency and the doses of anti-epileptic drugs. Complete freedom from epilepsy can also occur.