Klinische Neurophysiologie 2013; 44 - P105
DOI: 10.1055/s-0033-1337246

Spatial orientation deficits in mild cognitive impairment

A Zwergal 1, 2, F Schöberl 1, G Kugler 2, S Kohlbecher 2, J Engler 1, G Xiong 2, T Brandt 2, 3, M Dieterich 1, 2, M Dichgans 4, K Bürger 4, E Schneider 2, C la Fougere 2, 5, K Jahn 1, 2
  • 1Universität München, Neurologie, München, Deutschland
  • 2Universität München, Deutsches Schwindelzentrum, IFB, München, Deutschland
  • 3Universität München, Institut für Klinische Neurowissenschaften, München, Deutschland
  • 4Universität München, Institut für Schlaganfall- und Demenzforschung, Müncheln, Deutschland
  • 5Universität München, Nuklearmedizin, München, Deutschland

Aim: Deficits in spatial orientation and navigation appear early in the course of Alzheimer's dementia. In the present study spatial orientation strategy and brain activation during real navigation were compared in patients with amnestic mild cognitive impairment (MCI) and age-matched healthy controls.

Methods: 16 normal persons and twelve patients with MCI were included in the study. The neurocognitive status was tested by the CERAD-plus test. To investigate spatial orientation ability subjects had to perform a navigation paradigm in a complex unknown spatial environment of an outpatient clinic. The area, in which five items had been placed as target points for navigation, was shown to the subjects first. Afterwards FDG was injected and subjects had to find the items in a pseudo-randomized order over the next 10 min. Subjects carried a gaze-controlled head-camera throughout the experiment to document their visual exploration behaviour. PET-scans were done 30 min after FDG-injection. Brain activation patterns were compared between groups and correlated with the recorded visual exploration behaviour during navigation.

Results: During navigation in normal persons an increase of regional cerebral glucose metabolism (rCGM) was found in the pontine brainstem tegmentum and the right anterior hippocampus. In comparison MCI patients had less navigation-induced rCGM increase in the right anterior hippocampus. Severity of cognitive impairment correlated with reduced activation of the right anterior hippocampus during navigation. Analysis of visual exploration behaviour indicated a severely impaired navigation performance in all MCI patients. Confusion of targets and ineffective path trajectories were most common. Patients showed significantly more visual fixations to items along the path, which however were distributed more randomly thus indicating failure to encode specific landmarks.

Conclusions: Deficits in spatial orientation and navigation occur already in MCI and correlate with dysfunction of the right anterior hippocampal. Therefore testing of navigation performance may be a reliable diagnostic tool to identify and differentiate early cognitive impairment.