RESUMEN
BACKGROUND: Although up to 15% of patients with whiplash injury develop chronic headache, the basis and mechanisms of this posttraumatic headache are not well understood. METHODS: Thirty-two patients with posttraumatic headache following whiplash injury were investigated within 14 days after the accident and again after 3 months using magnetic resonance-based voxel-based morphometry. Twelve patients developed chronic headache lasting longer than 3 months and were studied a third time after 1 year. RESULTS: Patients who developed chronic headache revealed decreases in gray matter in the anterior cingulate and dorsolateral prefrontal cortex after 3 months. These changes resolved after 1 year, in parallel to the cessation of headache. The same patients who developed chronic headache showed an increase of gray matter in antinociceptive brainstem centers, thalamus, and cerebellum 1 year after the accident. CONCLUSION: We demonstrate adaptive gray matter changes of pain processing structures in patients with chronic posttraumatic headache in regard to neuronal plasticity, thus providing a biologically plausible basis for this common, disabling problem.
Asunto(s)
Encéfalo/patología , Trastornos de Cefalalgia/etiología , Trastornos de Cefalalgia/patología , Lesiones por Latigazo Cervical/complicaciones , Adulto , Anciano , Atrofia/etiología , Atrofia/patología , Atrofia/fisiopatología , Encéfalo/fisiopatología , Tronco Encefálico/patología , Tronco Encefálico/fisiopatología , Cerebelo/patología , Cerebelo/fisiopatología , Enfermedad Crónica , Estudios de Cohortes , Estudios Transversales , Femenino , Giro del Cíngulo/patología , Giro del Cíngulo/fisiopatología , Trastornos de Cefalalgia/fisiopatología , Humanos , Hipertrofia/etiología , Hipertrofia/patología , Hipertrofia/fisiopatología , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Vías Nerviosas/patología , Vías Nerviosas/fisiopatología , Plasticidad Neuronal/fisiología , Corteza Prefrontal/patología , Corteza Prefrontal/fisiopatología , Tálamo/patología , Tálamo/fisiopatología , Tiempo , Adulto JovenRESUMEN
The conformational behaviour of host-guest peptides of the type Ac-Ala-Xxx-Ala-Ala-Xxx-Ala-Ala-Xxx-Ala-Ala-NH-PEGM (Xxx = alpha-aminoisobutyric acid (Aib), (S)-2-ethylalanine ((S)-Iva), (S)-2-methylserine ((S)-alpha-MeSer)) has been studied by CD spectroscopy in CF3CH2OH, CH3OH, and water and by i.r. spectroscopy in CHCl3 and in the solid state. In this way the relative helix-inducing potential of the two chiral alpha-methyl-alpha-amino acids (S)-Iva and (S)-alpha-MeSer could be established in comparison to the strong helix-former Aib. The results show that (S)-Iva exerts a comparable helix-inducing effect as Aib, making this amino acid a valuable complementary tool for the stabilization or induction of helices. No significant helix-promoting effect was observed for (S)-alpha-MeSer in polar solvents; however, the i.r.-spectroscopic data in CHCl3 and in the solid state point to a helical conformation under these conditions. Possible reasons for the different behaviour of (S)-Iva and (S)-alpha-MeSer are briefly discussed.