[Alteration of the antinociceptive systems in chronic daily headaches].
BACKGROUND
Chronic daily headache (CDH) is a chronic painful clinical condition that is frequently found in neurological practice. Diagnosis is clinical and the therapeutic approach is complex. Its mechanism of production is still not altogether clear, but a genetic component is acknowledged as a predisposing factor. Numerous areas are involved in the generation of primary headaches, including the periaqueductal grey matter (PAGM), which plays a role as a neuromodulator both in headaches and in other chronic painful conditions.


OBJECTIVE
In order to evaluate possible biochemical changes in patients with CDH, magnetic resonance imaging was used to study the spectra produced in the PAGM.


METHODS
The spectra in the PAGM were studied in 17 patients with CDH. These were compared with the average spectra in 17 healthy subjects by means of differential spectroscopy.


RESULTS
Subjects with CDH show a reduction of over 70% in the level of the metabolite N-acetyl-aspartyl-glutamate (NAAG) in the PAGM. NAAG is a peptide involved in antinociceptive activity.


CONCLUSIONS
The reduction of NAAG in the PAGM suggests altered neuromodulation of the antinociceptive systems in subjects with CDH. Whether CDH is the cause or the consequence has still to be determined.
Buonanotte
F
F
Facultad de Ciencias Médicas, Universidad Nacional de Cordoba, Cordoba, Argentina. buonanottefederico@arnet.com.ar
Schurrer
C
C
Carpinella
M
M
Surur
A
A
Marangoni
A
A
Palacio
S
S
Forteza
M
M
Fernandez
R
R
Enders
J
J
D000328:Adult; D004151:Dipeptides / Q000378:metabolism; D005260:Female; D020773:Headache Disorders / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D018696:Neuroprotective Agents / Q000378:metabolism; D010146:Pain / Q000503:physiopathology*; D010487:Periaqueductal Gray / Q000033:anatomy & histology / Q000378:metabolism* / Q000473:pathology
D004151:Dipeptides; D018696:Neuroprotective Agents; C027172:isospaglumic acid