Chapter 2 How headaches and neck pain occur, and when is pain a sign of a serious condition?
INTRODUCTION
In Chapter 1 headache and neck pain types were described. This chapter provides information on the causes of headache and neck pain. As presented in Chapter 1:
• Vascular headaches are thought to involve abnormal function of the brain’s blood vessels or vascular system.
• Muscle-contraction headaches appear to involve the tightening or tensing of facial and neck muscles and soft tissue structures. This headache type can occur occasionally (episodic) or become chronic. Tension headache is named not only for the role of stress in triggering the pain, but also for the contraction of neck, face, and scalp muscles brought on by stressful events.
Some people have more than one type of headache (Leistad et al 2006).
HEADACHE CAUSAL FACTORS
Breathing pattern disorder
Breathing pattern disorder (BPD) can be simply defined as breathing in excess of need based on activity. The extreme of a BPD is hyperventilation syndrome (HVS), which is defined as breathing in excess of metabolic requirements. The effects of BPDs are bodywide, affecting all systems, having profound neurologic, psychological, digestive, and circulatory influences. BPDs commonly are habitual, and with a cooperative patient, usually are capable of significant improvement over a 3- to 6-month timeframe. Breathing pattern disorders can be both causal and perpetuating factors of headache (tension and vascular) and neck pain. Therapeutic massage intervention coupled with breathing retraining is effective in breaking the cycle of headache pain and neck stiffness and aching. About 10% of all patients attending general internal medicine practice in the US are estimated to be suffering from chronic hyperventilation (Lum 1987). The author’s clinical experience with this sort of problem suggests that a large patient population exists with BPDs who do not meet the criteria for hyperventilation but whose breathing patterns contribute greatly to their symptom picture.
HVS/BPD is female dominated, ranging from a ratio of 2:1 to 7:1 (peak ages 15–55 years). Women are more at risk, possibly because progesterone is a respiratory accelerator. This can also have implications for women on hormone replacement therapy. During the postovulation phase, carbon dioxide levels drop about 25% and additional stress then ‘increases ventilation at a time when CO2 levels are already low’ (Damas-Mora et al 1980). The vast majority of people who chronically overbreathe experience symptoms such as fatigue, widespread pain (e.g., fibromyalgia), irritable bowel symptoms, chronic bladder problems, anxiety, allergies, chemical sensitivities, headaches, premenstrual syndromes, photophobia, and increased sensitivity to noise. In many such conditions, BPDs rarely are causal (except perhaps if anxiety is a major feature), but they almost always are contributory, and sometimes become a major obstacle to recovery.
Excessive carbon dioxide loss during overbreathing causes blood pH to rise, creating respiratory alkalosis causing sympathetic arousal and altering nerve function (including motor control). Calcium and magnesium ions are lost as the kidneys attempt to restore pH balance by excreting bicarbonate. This enhances neural sensitization, encouraging spasm and reducing pain threshold. Smooth muscle cells constrict, leading to vasoconstriction and possibly altering fascial tone, causing connective tissue to shorten. Smooth muscle constriction can lead to colon spasm and pseudo-angina. Breathing pattern disorders automatically increase levels of anxiety and apprehension (Ford et al 1995, Ramachandrun et al 2006).
Overbreathing creates biomechanical overuse stresses, particularly on the accessory breathing muscles (scalenes, sternomastoid, upper trapezius, etc.). There is evidence that the effects of BPDs interfere with motor control, a key component in spinal (and all joint) injury prevention. Loss of motor control involves failure to control joints, commonly because of poor coordination of agonist–antagonist muscle coactivation and trigger point development (Wheeler 2004).
Blood sugar and BPD
• During overbreathing, both EEG and cortical function deteriorate when glucose values are below 100 mg.
• Three minutes of hyperventilation presents mild effects when blood sugar is in the 85–90 mg range, but with blood sugar at 70–75 mg (still within normal range), gross EEG disturbances are noted.
Theories on the causes of vascular headache
People who get vascular headaches appear to have blood vessels that overreact to various triggers. Although many sufferers have a family history of migraine, the exact hereditary link is unknown. People who get migraines are thought to have an inherited abnormality in the neuron regulation of blood vessels. Some individuals who have migraine may have low magnesium levels in the brain and lactic acidosis, which lead to membrane instability. Some researchers have proposed that the neurotransmitters dopamine and serotonin play a role (Datta & Kumar 2006, Di Piero et al 2001, Sahai et al 2005, Sicuteri 1977, Szilagyi et al 2006).
• Something triggers the nervous system to respond by causing a spasm of the arteries supplying blood to the brain, including the scalp artery and the carotid or neck arteries – vasoconstriction.
• Blood flow to the brain is reduced.
• Serotonin levels increase and since serotonin is a powerful vasoconstrictor, the blood supply to the brain is further reduced, thus decreasing the brain’s supply of oxygen.
• Symptoms signaling a headache, such as distorted vision or speech, may develop as a result of the decrease in oxygen supply.
• The reduced oxygen supply stimulates the arteries within the brain to dilate to meet the brain’s energy needs – vasodilation.
• The dilation of the arteries triggers the release of pain-producing substances called prostaglandins and chemicals which cause inflammation and swelling, and substances which increase sensitivity to pain.
Vascular headache triggers
Triggers include stress and other normal emotions, as well as biological and environmental conditions. Fatigue, glaring or flickering lights, changes in the weather, and certain foods can set off migraine (Zivadinov et al 2003) (Box 2.1).
Box 2.1 Triggers for vascular headache
Additives
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