Cognitive effects of pituitary tumours and their treatments: two case studies and an investigation of 90 patients

Objectives-Two case studies are reported of patients with pituitary adenoma s who had been treated with trans-sphenoidal surgery, one with and one with out adjunctive radiotherapy, in whom memory impairment was found. Further t o this, neuropsychological investigations of 90 patients were carried out ( 1) to establish the prevalence of such deficits, and (2) to try to determin e their cause. Methods-Two case studies are described. For the expanded study, patients we re recruited from the data base of the endocrinology department of St Thoma s's Hospital, London, if they had previously been treated for a pituitary a denoma in the past 30 years. Ninety patients were contacted and assessed wi th a wide range of neuropsychological tests. They were divided into five tr eatment groups: those who had received transfrontal surgery with radiothera py, trans-sphenoidal surgery with or without radiotherapy, radiotherapy onl y, and a bromocriptine therapy group, as well as a group of 19 healthy cont rol subjects matched for age and sex. Results-In the two patients presented, both showed severe memory impairment s compared with their intact intellectual ability. The more severely affect ed patient had received adjunctive radiotherapy and superimposition of the 90% isodose fields on a postoperative MRI examination suggested involvement of the diencephalic structures. In the group study, significant deficits i n anterograde memory were also obtained on two measures (WMS-R, RMT) for al l patient groups when compared with the healthy controls, although these im pairments varied in degree and were less in the bromocriptine group. Howeve r, the individual surgical and radiotherapy treatment groups did not differ significantly from one another. By contrast, general intellectual function (IQ) remained intact for all groups, as did performance on supplementary c ognitive tests, including measures of frontal lobe Or "executive" function, language comprehension, and speed of mental processing. Psychiatric morbid ity and tumour aetiology did not seem to relate to the presence of memory d eficits. Conclusions-Anterograde memory deficits were seen in the two case studies a nd in all our treatment groups when compared with the healthy controls, and these occurred in the context of preserved intellectual function. The pres ent findings suggest that these memory deficits result from treatment rathe r than from the underlying tumour, but there was no difference between the effects of surgery and radiotherapy. It is suggested that they result from damage to diencephalic structures implicated in memory.