Open Access

Dementia is a clinical diagnosis reflecting many possible underlying pathologies, for example, vascular dementia and neurodegenerative disorders such as frontotemporal dementia, Lewy body-type disorder or Alzheimer’s disease (AD). The breakthrough of 99mtechnetium-labelled perfusion tracers in the 1990s resulted in many SPECT studies of flow changes in AD. In the first decade of 2000, the role of perfusion SPECT was shifted from diagnosis towards differential diagnosis, parallel to the growing attention for diagnosing early stages of dementia. Previously a diagnosis based largely on a process of exclusion, new guidelines have emerged increasingly employing positive criteria to establish the diagnosis, including neuroimaging biomarkers. Nowadays, FDG PET has largely limited the role of perfusion SPECT, although it is still considered a valuable and cost-effective alternative when PET is not available.

There is increasing evidence of central hyperexcitability in chronic whiplash-associated disorders (cWAD). However, little is known about how an apparently simple cervical spine injury can induce changes in cerebral processes. The present study was designed (1) to validate previous results showing alterations of regional cerebral blood flow (rCBF) in cWAD, (2) to test if central hyperexcitability reflects changes in rCBF upon non-painful stimulation of the neck, and (3) to verify our hypothesis that the missing link in understanding the underlying pathophysiology could be the close interaction between the neck and midbrain structures. For this purpose, alterations of rCBF were explored in a case-control study using H215O positron emission tomography, where each group was exposed to four different conditions, including rest and different levels of non-painful electrical stimulation of the neck. rCBF was found to be elevated in patients with cWAD in the posterior cingulate and precuneus, and decreased in the superior temporal, parahippocampal, and inferior frontal gyri, the thalamus and the insular cortex when compared with rCBF in healthy controls. No differences in rCBF were observed between different levels of electrical stimulation. The alterations in regions directly involved with pain perception and interoceptive processing indicate that cWAD symptoms might be the consequence of a mismatch during the integration of information in brain regions involved in pain processing.