Relationship Between Headaches and Neck Pain Characteristics With Neck Muscle Strength.

OBJECTIVE: The purpose of this study was to assess the correlations between neck muscle strength and pain features, such as neck-related disability, neck pain frequency and intensity, and headache frequency in women with headache. METHODS: Seventy women with migraine between 18 and 55 years of age diagnosed according to International Headache Society criteria were assessed. Participants provided clinical information regarding neck pain and headache. The Neck Disability Index was used to assess neck-related disability, and neck muscle strength was assessed via maximum voluntary contraction during flexion, extension, and lateral flexion with a handheld dynamometer. The correlation was verified with Spearman's correlation coefficient (ρ). Multiple linear regression was performed to verify whether the clinical variables could predict the strength of neck muscles. All calculations were performed adopting a level of significance of 0.05. RESULTS: Neck extensor strength was negatively correlated with all clinical variables (ρrange = -.24 to -.32, p < .05); lateral flexor strength was negatively correlated with headache frequency, neck pain intensity, and neck-related disability (ρrange = -.27 to -.39, p < .05); and flexor strength also correlated negatively with neck pain intensity and related disability (ρr = -.26 to -.29, p < .05). Headache frequency and neck pain intensity were identified as significant predictors of the strength variability in extension (R2 = 0.16, p < .05) and in lateral flexion (R2 = 0.18, p < .05). CONCLUSIONS: For the women with migraine in this study, correlations of headache and neck pain with neck muscle strength features were weakly to moderately negative. Headache frequency and neck pain intensity may influence a small proportion of the strength variability in extension and lateral flexion.

Intrarater and Inter-rater Reliability of Maximal Voluntary Neck Muscle Strength Assessment Using a Handheld Dynamometer in Women With Headache and Healthy Women.

OBJECTIVE: This study aimed to determine the inter-rater and intrarater reliability, agreement, and minimal detectable change (MDC) of the neck muscle strength test using a handheld dynamometer in healthy women and women with headaches. METHODS: Neck muscle strength in maximal voluntary contraction was measured using the Lafayette Manual Muscle Testing attached to a nonelastic belt in 25 women with migraines and in 25 healthy women. Three repetitions of flexion, extension, and lateral flexion were performed. The tests were performed by 2 examiners on the same day, with a 10-minute interval, and by 1 examiner, with a 1-week interval. The reliability was verified by the intraclass correlation coefficient, the agreement determined by standard error measurement, and the MDC calculated. RESULTS: The protocol exhibited moderate to excellent intrarater and inter-rater reliabilities in both groups (intraclass correlation coefficientrange, 0.53-0.90). The standard error measurement ranged from 0.43 to 1.81 and the MDC from 1.49 up to 4.61. CONCLUSION: Quantification of neck muscle strength using the handheld dynamometer with an attached nonelastic belt exhibited moderate to excellent intra- and inter-rater reliability in women with and without migraines. Moreover, the standard error measurement and MDC were proven to be useful in the interpretation of data and in guiding clinical decisions.