Insult to the midbrain

No-one really knows what causes the prominent “cognitive” problems in ME/CFS, such as memory, concentration and attention deficits. However, vascular insufficiency, metabolic dysregulation or an ongoing infectious process have all been postulated as being involved.

A fascinating case–control study from the University of Adelaide has reported findings from magnetic resonance imaging of the brain using voxel-based morphometric techniques in 25 ME/CFS subjects (who all fulfilled the Fukuda and Canadian criteria for the condition) and 25 normal control subjects. In addition to brain imaging, clinical and biochemical parameters were all measured in the participants, as well as assessments of haemodynamic (blood flow) aspects, including blood pressure monitoring over 24 hours and autonomic function assessment via blood pressure and heart rate responses.

While there were no differences in the volumes of total brain grey matter, white matter or cerebrospinal fluid between patients and controls, the researchers did find abnormalities in various regions of the brain in ME/CFS patients. For example, there was a highly significant relationship been the patients’ duration of fatigue and the reduction in white matter volume at the midbrain. This finding is consistent with midbrain volume loss occurring at a rate of 1% per year of duration of fatigue.

Furthermore, in the brainstem, the caudal basal pons and hypothalamus, relationships were observed between haemodynamic and relative brain volume measurements. In particular, a correlation was observed between grey matter volume at the brainstem and patients’ seated pulse blood pressure – a correlation not seen in the healthy controls – suggesting an impaired regulation of brain blood flow.

The authors say that these results are “consistent with an insult to the midbrain at fatigue onset” that has a range of effects on other bodily systems. And their conclusion will come as no surprise to the many people with ME/CFS who can report clear triggers for the start of their illness, including physical trauma, surgery and infection.

Reference: A brain MRI study of chronic fatigue syndrome: evidence of brainstem dysfunction and altered homeostasis. Barnden LR et al. NMR Biomed 2011 Dec; 24(10): 1302-12.

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