Volumetric abnormalities of thalamic subnuclei in medication-overuse headache

The thalamus exerts a pivotal role in pain processing and cortical excitability control and a previous voxel-based morphometry study confirmed increased volume in bilateral thalamus in medication-overuse headache (MOH). The aim of this study is to investigate altered thalamic subnuclei volume in MOH compared with normal controls, and to evaluate the relationship of each thalamic subnuclei volume with the clinical variables.

High resolution three-dimensional T1-weighted fast spoiled gradient recalled echo MR images were obtained from 27 patients with MOH and 27 normal controls (NC). Thalamic subnuclei templates were created based on Talairach template with MNI space transformation, and the individual thalamic subnuclei templates were generated by applying the deformation field from structural image segment to the thalamic subnuclei templates, and then individual thalamci subnuclei volume were calculated.

The whole thalamus and each thalamic subnuclei presented increased volume compared with NC (P < 0.05). The correlation analysis demonstrated that the whole thalamus volume and each thalamic subnuclei volume showed a negative relationship with HAMD scores(P < 0.05), and no any correlation with HAMA, VAS score and disease duration (P > 0.05).

Increased gray matter volume in the whole thalamus and all the thalamus subnuclei may reflect central sensitization and higher-order of pain alteration in MOH. These structural changes in the thalamus may also be influenced by mood disturbances related to the MOH.