Muscle contraction headache and posture--with special reference to ischemic contraction of the posterior neck muscles
Sakuta, M.
Rinsho Shinkeigaku 30(11): 1197-1201
1990
ISSN/ISBN: 0009-918X PMID: 2085924 Document Number: 361531
Cause of muscle contraction headache (MCH) results from sustained contraction of scalp and posterior neck muscles. Recently, we published an effect of posture on the etiology of MCH. According to our data, head bending posture seems to be one of the main causes of sustained contraction of the posterior neck muscles. Wolff presented a hypothesis of ischemic contraction of these muscles as a cause of pain. However, about the blood flow of scalp or posterior neck muscles, only two reports were published so far. These two papers failed to demonstrate a reduction of blood flow in MCH patients, and neglected the effect of posture. The purpose of this report is to examine a change of blood flow of posterior neck muscles with the change of posture. A total of 40 patients with MCH were studied using laser doppler blood flow meter. Needle shaped probe with a diameter of 0.55 mm was inserted 15 mm into the posterior neck muscle. The angle between orbito-meatal line and horizontal plane were measured using a light helmet with goniometer. Surface EMG of the posterior neck muscles was recorded at the same time. In the case of controls who do not experience headache, the amplitude of EMG increases slightly with the bending posture (40 microV with OM line 20 degrees upward from the horizontal plane, 46 microV with OM line horizontal, and 52 microV when 30 degrees downward). In reverse to the increase of the EMG activity, blood flow of the neck muscles decreases (12 ml/100 g/min with OM line 20 degrees upward, 10.8 with OM line horizontal, 7.6 at 10 degrees down, 4.6 at 20 degrees down, and 4.1 at 30 degrees down).