Evaluation of selected cognitive functions before and after surgery for primary hyperparathyroidism

Cognitive functions have been reported to be impaired in patient with primary hyperparathyroidism (pHPT). The aim of this psychological study was to evaluate cognitive disturbances in pHPT in relation to serum calcium levels before and after surgery.

A prospective, case-control study with 1-year follow-up of 35 pHPT patients versus 35 matched controls was undertaken. All patients were tested before surgery and at 12-18 months following surgery with a battery of selected cognitive function psychological tools: Benton Visual Retention Test (BVRT), Wisconsin Card Sorting Test (WCST), Memory Verbal Learning Test (DCS), The Rey's Auditory Verbal Learning Test (RAVLT), Trail Making Test A & B, Verbal Fluency Test, and Beck Depression Inventory. In addition to psychological testing, serum calcium, parathyroid hormone and phosphate levels were evaluated.

The following cognitive functions of pHPT patients versus controls were deteriorated before surgery: impaired concentration, decreased nonverbal learning process, difficulties in using direct memory, verbal fluency and visual constructive abilities. However, no correlation was found between serum calcium levels and the results of neuropsychological tests. In longitudinal comparison of pHPT patients before and 1 year after surgery, there was a significant improvement in visual memory, visual-constructive abilities and direct memory.

pHPT patients have significantly decreased concentration level, nonverbal learning process, access to verbal resources and constructional and visual memory ability. Thus, neuropsychological testing may be useful in the decision making for early surgery in patients with mild asymptomatic disease in order to avoid further deterioration of cognitive functions.