Journal of IiME Volume 1 Issue 1 ME/CFS: a research and clinical conundrum (continued) patients on the basis of severity of illness or level of functional disability. Indeed, there is a growing realisation that the current CDC-1994-defined “CFS” term is an impossibly inclusive diagnostic construct, begging Simon Loblay (1995) to ask the ontological question: “Is CFS a recognisable disease entity with a unique pathophysiology, or is it a ragbag of common non-specific symptoms with many causes, mistakenly labelled as a syndrome?” As an example, our work in Dundee has compared three groups of patients each fulfilling the CDC-1994 criteria: Syndrome and patients with a definite history of exposure to rganophosphate pesticides. We showed clear differences between the groups in terms of measured parameters, including muscle pain, and physical and mental status (Kennedy et al., 2004). Importantly, a high proportion of people in each group had measurable signs of muscle weakness in arms or legs, indicating that clinical signs can, in fact, be found in these patients if physicians take care to do a full physical examination. explore such important findings. Future work will There have been other definitions apart from the CDC-1994 Fukuda one (see Figure 1). The most recent attempt to revise the definition (Carruthers et al., 2003) is based on clinical experiences with very large numbers of patients. It will, however, be some time before this new “Canadian” description of ME/CFS replaces the CDC1994 definition in clinical and research practice. When comparing scientific studies, it is important to patients with ME, those with Gulf War bear in mind that different definitions of ME/CFS may have been used, and this complicates interpretation and comparison of data. It can also be seen from the Figure below that there have been several attempts in the past decade to define diagnostic criteria for the illness. Each definition has been problematic, reflecting in part the special interest of the author, and taking little account of the extensive literature prior to 1988 (see Figure) that made the case for myalgic encephalomyelitis as a distinct clinical entity based on reports of epidemic and endemic cases. What was this condition “Myalgic Encephalomyelitis” that existed before 1988, when it was subsumed within the “CFS” construct, and which is still referred to by patients in the lay literature as “ME”? Myalgic encephalomyelitis was first defined by Acheson (1959). It had been found to occur in epidemic and sporadic forms, and was believed to result from a continuing or persisting viral systemic illness, infection. It has been defined as a characterised by marked muscle fatigability (not just weakness); muscle (continued on page 18) Figure 2 Orthostatic Hypotension (Streeten et al., 2000; Stewart, 2003) Brain perfusion (Schwartz et al, 1994; Costa et al, 1995) Endothelial dysregulation (Spence et al., 2000; Khan et al., 2003; Khan et al., 2004) Vascular 2002; Tiev et al., 2003) Anti-viral dysregulation (Suhadolnik et al., 1994; De Meirleir et al., 2000; Shetzline SE et al., et al., 2003; Vecchiet et al., 2003) Oxidative stress (e.g., Richards et al., 2000; Manuel et al., 2001; Pall & Scatterle, 2001; Kennedy Biochemical Physiological and biochemical abnormalities found in “CFS” cohorts Enteroviral sequences in muscle (Lane et al., 2003) Abnormal recovery after exercise (e.g., Paul et al., 1999; McCully & Natelson, 1999) Metabolism (e.g., Fulle et al., 2000; Vecchiet et al., 2003) Muscle Metabolic abnormalities (Tomoda et al., 2000; Puri et al., 2002; Chaudhuri et al., 2003) Brain Invest in ME Charity Nr 1114035 www.investinme.org 17
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