Q: "Worst headache of life" or "like being kicked in the head" is the classic presentation in SAH (Subarachnoid hemorrhage) . Many patients report neck stiffness too. What is the usual lag time reported between headache and neck stiffness, and strongly suggests SAH?

Answer: About 6 hours.

In classic SAH presentation, neck stiffness usually presents six hours after initial onset of SAH.

Reference:

Warrell, David A; Timothy M. Cox, et al. (2003). Oxford Textbook of Medicine, Fourth Edition, Volume 3. Oxford. pp. 1032–34