Proton magnetic resonance spectroscopy of the thalamus in patients with chronic neuropathic pain after spinal cord injury.
OBJECTIVE
Spinal cord injury (SCI) results in a number of consequences; one of the most difficult to manage is chronic neuropathic pain. Thus, defining the potential neural and biochemical changes associated with chronic pain after SCI is important because this may lead to development of new treatment strategies. Prior studies have looked at the thalamus, because it is a major sensory relay station. The purpose of our study was to define alterations in metabolites due to injury-induced functional changes in thalamic nuclei by using single-voxel stimulated echo acquisition mode MR spectroscopy.


METHODS
Twenty-six men were recruited: 16 patients with SCI and paraplegia (seven with pain, nine without pain) and 10 healthy control subjects. Pain was evaluated in an interview, which included the collection of information concerning the location, quality, and intensity of pain, carefully identifing the dysesthetic neuropathic pain often seen in SCI. Localized single-voxel (8-cm(3) volume) proton spectra were acquired from the left and right thalami.


RESULTS
The concentration of N-acetyl (NA) was negatively correlated with pain intensity (r = -0.678), and the t test showed that NA was significantly different between patients with pain and patients without pain (P =.006). Myo-inositol was positively correlated with pain intensity (r = 0.520); difference between patients with pain and those without pain was almost significant (P =.06).


CONCLUSIONS
The observed differences in metabolites in SCI patients with and pain and in those without pain suggest anatomic, functional, and biochemical changes in the thalamic region.
Pattany
Pradip M
PM
Department of Radiology, MRI Center, University of Miami School of Medicine, FL 33136, USA.
Yezierski
Robert P
RP
Widerström-Noga
Eva G
EG
Bowen
Brian C
BC
Martinez-Arizala
Alberto
A
Garcia
Bernardo R
BR
Quencer
Robert M
RM
D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D002908:Chronic Disease; D006801:Humans; D007294:Inositol / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D010146:Pain / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology; D012016:Reference Values; D012720:Severity of Illness Index; D013119:Spinal Cord Injuries / Q000150:complications*; D013787:Thalamic Nuclei / Q000378:metabolism / Q000473:pathology*
D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate