DTI of great occipital nerve neuropathy: an initial study in patients with cervicogenic headache

To assess differences in bilateral great occipital nerves (GONs) in patients with unilateral cervicogenic headache (CEH) using diffusion tensor imaging (DTI).

Twenty-three patients with unilateral CEH underwent GON magnetic resonance imaging (MRI). The clinical characteristics and fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) values in bilateral GONs were determined by two observers with 7 and 3 years of experience in MRI. Three segments of GON were defined based on anatomy. The correlation of DTI measurements to the clinical characteristics and inter-/intra-observer performance were also evaluated.

The mean GON FA for the symptomatic side was significantly lower (0.198±0.056) than that on the other side (0.311±0.04; p=0.000). The mean GON ADC for the symptomatic side was significantly higher (0.682±0.174) than that on the other side (0.465±0.138; p=0.000). Among the three defined segments of GON, statistically significant differences of ADC values were not found at segment S3 (0.692±0.257 versus 0.557±0.230; p=0.068). There were statistically significant differences of FA and ADC values in bilateral GON of segments S1 and S2. The intraclass correlation coefficient (ICC) of intra-/interobserver statistical analysis showed excellent inter/intra-observer agreement for FA and ADC. Significant correlation was only found between the duration and ADC.

In patients with unilateral CEH, quantitative evaluation of the GON using DTI demonstrated FA decreases and ADC increases of the symptomatic side. Larger population and other occipital nerve neuropathy can be included in future research.