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 adenomas who had been treated with trans-sphenoidal surgery, one with and one without adjunctive radiotherapy, in whom memory impairment was found. Further to this, neuropsychological investigations of 90 patients were carried out (1) to establish the prevalence of such deficits, and (2) to try to determine their cause.

METHODS

Two case studies are described. For the expanded study, patients were recruited from the data base of the endocrinology department of St Thomas's Hospital, London, if they had previously been treated for a pituitary adenoma in the past 30 years. Ninety patients were contacted and assessed with a wide range of neuropsychological tests. They were divided into five treatment groups: those who had received transfrontal surgery with radiotherapy, trans-sphenoidal surgery with or without radiotherapy, radiotherapy only, and a bromocriptine therapy group, as well as a group of 19 healthy control subjects matched for age and sex.

RESULTS

In the two patients presented, both showed severe memory impairments compared with their intact intellectual ability. The more severely affected 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 in anterograde memory were also obtained on two measures (WMS-R, RMT) for all patient groups when compared with the healthy controls, although these impairments varied in degree and were less in the bromocriptine group. However, 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 cognitive tests, including measures of frontal lobe or "executive" function, language comprehension, and speed of mental processing. Psychiatric morbidity and tumour aetiology did not seem to relate to the presence of memory deficits.

CONCLUSIONS

Anterograde memory deficits were seen in the two case studies and in all our treatment groups when compared with the healthy controls, and these occurred in the context of preserved intellectual function. The present findings suggest that these memory deficits result from treatment rather 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.