Diagnosing pain

There is no test or imaging device that can measure the intensity of a person's pain. People perceive and respond to pain differently. Reactions to pain are learned and can be impacted by our thinking processes, social environment, stress levels and quality of sleep. A thorough medical history in addition to examination and appropriate testing are important in the diagnosis and treatment of pain. Before visiting your doctor you should write down any questions you want to ask. You should also be ready to answer a number of questions your physician might ask. Questions your doctor may ask include:

• Do you know the cause of the pain?
• How long have you had the pain?
• What makes it better?
• What makes it worse?
• On a scale of 1-10 (10 being severe) how would you rate the intensity of the pain?
• Describe the pain. (sharp, dull, stinging, burning) (intermittent or ongoing)
• Does it affect your sleep?
• How has it impacted your quality of life? (i.e. unable to work, concentrate, walk, etc.)
• What non- medication treatments have your tried?
• How effective has each treatment been?
• How long have you tried each treatment?
• What medications have you tried? At what dosage? How often did you take each medication? How effective was each medication?

Tools for diagnosing pain

In addition to your medical history other tools your physician may use to determine the cause of pain include:

• Physical examination
• Neurological examination in which the physician tests movement, reflexes, sensation, balance, and coordination.
• Electromyography (EMG) - this test tells precisely which muscles or nerves are affected by pain. Thin needles are inserted into muscles and the physician can see and listen to electrical signals that are displayed on an EMG machine.
• Nerve conduction studies - are used to determine if nerves are damaged. The doctor places two sets of electrodes (similar to those used during an electrocardiogram) on the skin over the muscles. The first set gives the patient a mild shock that stimulates the nerve that runs to that muscle. The second set of electrodes is used to make a recording of the nerve's electrical signals. From this information the doctor can determine if there is any nerve damage.
• Evoked potential (EP) studies - are used to determine the speed at which pain signals are transmitted to the brain. For an EP test the physician places one set of electrodes on the skin of a limb (which will be stimulated) and the second set on the scalp (which will record the speed of transmission).
• Magnetic resonance imaging (MRI) - the use of magnetic fields and radio waves to provide pictures of the body's structures and tissues.
• X-rays - which provide pictures of the body's structures, such as bones and joints

Sites for interrupting pain signals

To feel pain, signals are sent from the affected area along nerve pathways to the spinal cord and from the spinal cord to the brain. Researchers try to find treatments that will interrupt these signals at different sites along the way. For example treatments can target the injured site, the nerves running from the injured site to the spinal cord, the spinal cord itself, nerves running from the spinal cord to the brain and/or the area in the brain that receives and interprets the pain message.

Nociceptors - Nociceptors are specialized areas located on the skin, muscles, ligaments, bones and organs that give rise to the sensation of pain when stimulated through injury, disease or oxygen starvation. Stimulation of nociceptors in the skin, muscles, ligaments and bones often result in sharp, acute, well-localized pain, while stimulation of the nociceptors in organs tends to produce dull, aching, and poorly localized pain. To block pain at the source treatments that block nociceptors may be selected.

Electrical impulses - Messages are sent along nerves via electrical impulses. Some treatments are directed at the nerves in an attempt to slow or block these electrical impulses. These treatments may be directed toward the nerves at the site of the pain, between the site and the spinal cord, in the spinal cord and/or between the spinal cord and the brain.

Neurotransmitters - Neurotransmitters are chemicals in the body that play a role in sending messages along nerve pathways. Nerves respond to neurotransmitters with an increase or decrease in electrical impulses. Two neurotransmitters involved in moderating pain levels are serotonin and norepinephrine. Treatments that affect serotonin and norepinephrine levels can help moderate pain levels.

Serotonin and norepinephrine levels also play a role in moderating mood. As a result medications that are used to treat mood disorders, such as depression are also effective for treating some types of pain, particularly nerve pain (neurological pain). When a physician prescribes an antidepressant for pain, he/she is not implying the pain is 'all in your head.'

Opiate receptors - Opiate receptors are special sites in the body that can be stimulated to provide pain relief. A high concentration of opiate receptors can be found in the areas of the brain that are involved in moderating pain levels. Morphine and other opiates bind to these sites. Opiates are often called narcotics, from the Greek narke? meaning numbness, stupor or insensibility. Aside from providing pain relief (analgesia), other effects experienced when opiate receptors are stimulated with morphine and morphine-like substances include:

• Respiratory depression
• Miosis (decreasing size of pupils-'pinpoint pupils')
• Reduced gastric motility (resulting in constipation)
• Sedation (drowsiness)
• Euphoria (exaggerated feeling of physical and mental well-being)
• Dysphoria - opposite of euphoria (restless, uneasy, dissatisfied, tired, unwell)
• Psychotomimetic effects- (effects similar to those found in psychosis-hallucinations, distortion of perception, schizophrenia-type behavior)

Endorphins are natural opiates produced by the body that decrease pain and improve mood. They attach to the opiate receptors and reduce pain and improve mood. Endorphins also moderate appetite, enhance the immune system and increase the release of sexual hormones. Endorphins are released in response to exercise, laughter, chocolate, sexual activity, massage, acupuncture and meditation.