Regional differences in temporal dura mater innervation and vascularization; A substrate for post-craniotomy headache?

Background Post-craniotomy headache is a common adverse effect of anterior temporal lobectomy. It is hypothesized that increased pain sensation may be associated with manipulation of the dura intraoperatively. To explore a potential origin, we analyzed the blood vessel and nerve bundle distribution in the mesial and lateral temporal dura of the middle cranial fossa. Method Human temporal dura sections were immunohistochemically stained for α-smooth muscle actin to visualize blood vessels and/or neurofilament protein to detect nerve bundles. Immunoreactive blood vessels and nerve bundles were counted by a blinded observer in a random order. Statistical analysis was conducted using a linear mixed model. An intraclass correlation coefficient (ICC) was calculated to assess inter-observer reliability. Result The number of blood vessels/cm in the temporo-mesial dura was about 57% higher than that in the temporo-lateral dura (n= 4; 29.9 (95% confidence interval (CI) [23.3; 36.5]) vs 18.9 (95% CI [17.4; 20.3]), p<0.001). Similarly, the number of nerve bundles/cm in the temporo-mesial dura was almost 4 times higher than that in the temporo-lateral (n= 4; 7.5 (95% CI [5.3; 9.6]) vs 2.0 (95% CI [1.5; 2.5]), p<0.001). Double-stained sections (n= 6) revealed that neurovascular structures were frequently in close proximity. ICC was 0.9 and 1.0 for α-SMA and NFP, respectively. Conclusion The densities of blood vessels and nerve bundles are significantly higher in the temporo-mesial dura than in the temporo-lateral dura. Although the functional relevance remains unknown, these findings provide an anatomical basis for future studies investigating nociceptive innervation and the role of neurovascular structures in post-craniotomy headache.