Headache subsequent to whiplash.

Methodology varies greatly in whiplash studies; therefore, results are not directly comparable. Headache seems to be present in 50% to more than 75% of cases in the acute stage, and in 20% to 30% of cases in the early chronic stage. Headache naturally occurs frequently (> 75% of the cases ) in patients who consult headache specialists due to protracted symptoms. Malingering may explain some cases, and continuation/activation of prewhiplash headache may explain other cases. De novo headache also seems to occur. This headache may partly have cervicogenic headache characteristics: side-locked unilaterality and occipital onset. In one study, this type of headache was present in 8% at 6 weeks and 1% at 6 years. It was more rare than postwhiplash, unspecified headache. De novo postwhiplash headache may consist of cervicogenic headache and of noncervicogenic headache (probably in the acute phase).