Similarities Between Tinnitus and Pain

1. Both pain and tinnitus have many different forms. 2. Tinnitus and central neuropathic pain are phantom sensations similar to the phantom limb symptoms that occur without any physical stimulation of sensory receptors. 3. Tinnitus and neuropathic pain are typical examples of “plasticity disorders” where the symptoms are caused by plastic changes that are not beneficial to an individual person. 4. Central neuropathic pain and tinnitus have no physical signs. 5. The severity of pain and tinnitus are difficult to assess quantitatively even under laboratory circumstances. Only the patients’ own perception is a true measure of the severity of central pain and subjective tinnitus. 6. The perception of pain and tinnitus is affected by many factors such as actual circumstances, expectation, stress, and a person’s emotional state. 7. Many forms of pain are best described as suffering; the same is the case for severe subjective tinnitus. 8. Pain and tinnitus can have strong emotional components, it often prevents or disturbs sleep, and it can interfere with or prevent intellectual work. 9. It is difficult to get reliable data on epidemiology of tinnitus and central neuropathic pain because of their subjective nature and large variability. 10. Activation of neural plasticity is involved in causing and maintaining central neuropathic pain and many forms of subjective tinnitus. 11. The nervous system is the site of the anomalies that cause central neuropathic pain and many forms of tinnitus. Both tinnitus and pain involve a cascade of neural structures. 12. The pathology of the nervous system in some forms of central neuropathic pain is stable in the pathologic state. It may be similar for some forms of tinnitus. 13. Pain that is perceived as escapable uses a different part of the periaquaductal gray than pain that is perceived as inescapable. It is not known if tinnitus also has such distinctions. 14. Severe tinnitus is often accompanied by hyperacusis (lowered tolerance to sounds); pain may be accompanied by allodynia (pain from normally innocuous touch of the skin) hyperpathia (exaggerated reaction to acute pain), and hypersensitivity (lowered threshold for painful stimulation). 15. Some forms of tinnitus and pain can be modulated by electrical stimulation of the skin. 16. Electrical stimulation of several cortical structures can modulate both pain and tinnitus. 17. The sympathetic nervous system can modulate pain and some forms of tinnitus.