Headache may be a risk factor for complex regional pain syndrome.

We investigated whether headache and family history of headache are risk factors for complex regional pain syndrome (CRPS) or not. Twenty-three CRPS patients and 69 healthy persons were interviewed whether or not they suffered from headache and had first-degree family history of headache. A headache sufferer was defined as a person who regularly suffered from headache for more than 2 days per month. Headache after an occurrence of CRPS (headache after an injury or operation in case of CRPS after an injury or operation) was excluded and just headache before an occurrence of CRPS was included. If a first-degree family had a regular headache, she or he was regarded as a headache sufferer regardless of the frequency of headache. Of the 23 patients with CRPS, 12 (52.2%) had suffered from headache before an occurrence of CRPS. Of the 69 healthy persons, 18 (26.1%) suffered from headache. Significant differences between patients and healthy persons were found. Of the 23 patients with CRPS, eight (34.8%) had a first-degree family history of headache. Of the 69 healthy persons, ten (14.5%) had a first-degree family history of headache. Significant differences between patients and healthy persons were found in a family history. The results suggest that headache and a first-degree family history of headache are risk factors for CRPS. To determine whether or not headache and first-degree family history of headache are risk factors for CRPS, further prospective studies with larger patient numbers should be carried out.