[Recording muscle spasm in the musculus erector spinae using in vivo 31P magnetic resonance spectroscopy in patients with chronic lumbalgia and generalized tendomyopathies].

Using 31P nuclear magnetic resonance, the following parameters were determined in the resting musculus erector spinae of five patients suffering from chronic low back pain, five patients with fibromyalgia, and five healthy controls: Inorganic phosphate (Pi), phosphocreatine (PCr), ATP gamma, ATP alpha, ATP beta. The intracellular pH was derived from the chemical shift of Pi referenced to the PCr resonance. In addition, the Pi-Index was calculated according to the formula: Pi/(Pi + PCr). We discovered a tendency towards a shift of the Pi resonance in the alcalic direction, which was the larger, the stronger muscle spasm was found on palpation. The pH showed the most reliable relationship to the clinical status of muscle spasm. The surprising finding that there is no acidification within the spasmed muscle indicates that generalized hypoxia does not exist in this tissue. This has already been shown with PO2 measurements. An intracellular acidification is only recorded during maximal isometric contraction. Thus, ischemia cannot be responsible for pain experienced during muscle spasm.