Reversible dyscognition in patients with a unilateral, middle fossa arachnoid cyst revealed by using a laptop based neuropsychological test battery (CANTAB)

The aim of this study was to evaluate and validate the Cambridge Neuropsychological Test Automated Battery (CANTAB) in a Norwegian group of patients undergoing surgery for middle fossa arachnoid cysts (AC). We also wanted to assess health related quality of life (HRQOL) in these patients to see if it could be improved by decompression of the AC. Adult patients (>18 years) with unilateral middle fossa AC and no previous history of neurological disease, head injury, or a psychiatric disorder were eligible for inclusion. We used four tests from CANTAB to assess the level of neuropsychological performance: paired associate learning (PAL) and delayed matching to sample (DMS) assessed temporal lobe functions, while Stockings of Cambridge (SOC) and intra-extra dimensional (IED) shift focused on frontal lobe functions. Patients with postoperative cerebral complications were reported, but excluded from neuropsychological follow-up. In addition to the CANTAB data, pre- and postoperative clinical and radiological data were collected. HRQOL was assessed using Short Form 36 (SF-36) pre- and postoperatively. We found significant improvement in the two temporal tests assessing memory, but no improvement in the two frontal tests assessing executive function. HRQOL was significantly reduced preoperatively in two of eight SF-36 domains and improved significantly in four domains postoperatively. CANTAB facilitates detection of cognitive improvements after decompression of the cyst in patients with AC in the middle fossa. The improvements were detected on the tests sensitive to temporal lobe problems only, not on the tests more sensitive to frontal lobe affection. This establishes construct validity for CANTAB for the first time in this population.