Validation of a clinical examination to differentiate a cervicogenic source of headache: a diagnostic prediction model using controlled diagnostic blocks

OBJECTIVES: Neck pain commonly accompanies recurrent headaches such as migraine, tension-type and cervicogenic headache. Neck pain may be part of the headache symptom complex or a local source. Patients commonly seek neck treatment to alleviate headache, but this is only indicated when cervical musculoskeletal dysfunction is the source of pain. Clinical presentation of reduced cervical extension, painful cervical joint dysfunction and impaired muscle function collectively has been shown to identify cervicogenic headache among patients with recurrent headaches. The pattern's validity has not been tested against the 'gold standard' of controlled diagnostic blocks. This study assessed the validity of this pattern of cervical musculoskeletal signs to identify a cervical source of headache and neck pain, against controlled diagnostic blocks, in patients with headache and neck pain. DESIGN: Prospective concurrent validity study that employed a diagnostic model building approach to analysis. SETTING: Hospital-based multidisciplinary outpatient clinic in Joliet, Illinois. PARTICIPANTS: A convenience sample of participants who presented to a headache clinic with recurrent headaches associated with neck pain. Sixty participants were enrolled and thirty were included in the analysis. OUTCOME MEASURES: Participants underwent a clinical examination consisting of relevant tests of cervical musculoskeletal dysfunction. Controlled diagnostic blocks of C2/C3-C3/C4 established a cervical source of neck pain. Penalised logistic regression identified clinical signs to be included in a diagnostic model that best predicted participants' responses to diagnostic blocks. RESULTS: Ten of thirty participants responded to diagnostic blocks. The full pattern of cervical musculoskeletal signs best predicted participants' responses (expected prediction error = 0.57) and accounted for 65% of the variance in responses. CONCLUSIONS: This study confirmed the validity of the musculoskeletal pattern to identify a cervical source of headache and neck pain. Adopting this criterion pattern may strengthen cervicogenic headache diagnosis and inform differential diagnosis of neck pain accompanying migraine and tension-type headache.