Proton Nuclear Magnetic Spectroscopy

Everyone at this site has heard of MRI, and even functional MRI. fMRI measures 3D activity (typically oxygen consumption). A new technique, PNMS looks interesting.

While fMRI looks at 3D spatial imaging, PNMS looks at activity at the cellular level. It has been a traditional tool for chemists. Now it is expanding into medicine and seems highly likely to become of considerable research and clinical use.

Schizophrenics, for example, have been shown to have reduced N-acetyl aspartate in the brain. You will recall that the two excitatory amino acids are glutamate and aspartate.

N acetyl aspartate (NAA) gives off the highest signal in Nuclear Magnetic Resonance Spectroscopy of any substance in the brain. NAA is also decreased in other conditions such as Alzheimer’s and stroke. The reported findings therefore are non specific. In the brain, NAA comes from from aspartate and Acetyl CoA.

Acetyl CoA is involved in energy production and fatty acid reactions; and indeed, we find NAA involved in formation of myelin in glial cells (neuronal).

Pain patients have to worry about N-methyl-D aspartate (NMDA), a pain chemical. An acetyl group and a methyl group are not far apart, Acetyl, a functional group in organic chemistry, refers to a Carbon atom double bonded to an Oxgyen atom, and singly bonded to a methyl group. (R-C=O) Despite the fact that a minor alteration in NAA concentration is linked to the major disorder known as schizophrenia, too many clinicians do not seem to realize that increased NMDA wreaks havoc in the pain system. Few pain experts, if any, would deny this, however. NMDA is very important in sustained neuropathic pain.

Strangely, no one has used PNMS to study central pain, nor any other pain for that matter; but it has now been used to study pain in fibromyalgia. The scientists Bustillo et al in Arthritis Rheum. 2008 Feb 29;58(3):903-907 showed that using PNMS revealed that glutamate levels in the insula are a good indicator of fibromyalgia pain.

Elsewhere at this site, Crick and McHenry reported that the “painfulness of pain” was located in the insula,(a new principle when the authors first collaborated, but an established concept now).

Here is evidence that insular glutamate is a flag that fibromyalgia patients are having pain. Surely investigators will not look past central pain forever. We have long needed a marker, an objective tool, to help establish the reality of central pain.