Listening to the Voices of Pain

Figure 2.1 Cervical, thoracic, and lumbar vertebrae

Figure 2.1 Cervical, thoracic, and lumbar vertebrae

To a neurologist, orthopedist, or other pain doctor, the anatomy of pain means understanding what part of the spine has been injured and what the pain tells us. You need to listen to what the pain is telling you because each anatomical structure has its own voice. Symptoms such as tingling, weakness, and urinary problems also contribute to the voice of pain.

Anyone who has had severe acute spine pain will tell you that spine pain is like many voices all screaming at once. How do you distinguish each voice of pain? Spine pain is like a symphony. A trained ear can pick out each instrument—the horns from the strings from the piano—because it is aware of the distinctive sounds of each instrument. In the case of pain, each anatomical part has a distinctive localization, quality, radiation, and associated symptoms such as weakness, numbness, or bowel or bladder incontinence. Each speaks its own language. The anatomy of pain is what your doctor uses to build a case or, in medical terms, a diagnosis of the cause or origin for your pain. An effective treatment plan is built on the proper diagnosis.

The lumbosacral (L-S) and cervical spine (C-S) have the same anatomical parts, except the lumbosacral spine has the cauda equina and the cervical spine has the spinal cord. Figure 2.1 shows the three types of vertebrae: cervical, thoracic, and lumbar. The neck (cervical) and back (thoracic and lumbar) spines are different in that they have different shapes. The neck bones are smaller and rounder so that you can easily bend and turn your neck. The low back bones are larger and squarer so that they can bear all your weight.

Each anatomical part has a particular symptom or pain, its language (see table 2.1). Listen to what your pain is telling you.



table-2-1

table-2-1-continued

Nerve Radicular Pain

Nerves (figure 2.2) have the most intricate anatomy and the most distinctive voices and symptoms. You must appreciate nerve pain because this voice signifies danger that may be permanent and lead to disability or paralysis. A study done of 100 patients with acute severe low back pain of a nerve origin showed that 90 percent were able to describe distinctly that the pain felt was nerve pain—not joint, muscle, or disc—although some of these structures may have also been involved.

Nerve pain has several elements—quality, quantity, location, radiation, and asso- ciated symptoms—which include dermatomal (sensation) and myotomal (muscle) and end organs if the affected nerve supplies the bowel and bladder. Let’s listen to the nerves, one of the most important parts of the spine.

Quality, Quantity, Location, and Radiation

Figure 2.2 Nerves coming out of the spine

Figure 2.2 Nerves coming out of the spine

When irritated or crushed, a nerve produces a stabbing, knifelike pain of horrible proportions. Patients describe it as the worst pain that they ever felt, like a knife in the back or neck, or a toothache. It also may feel like an electric shock. Nerve pain is loud and always severe. On a scale of 1 to 10, with 1 being little pain and 10 being excruciating pain, nerve pain often rates a 5 to 10.

Nerve pain has a distinctive location and radiation. A nerve is like a telephone line with connections. For example, pain in the hand may originate 3 feet (90 cm) away in the neck. Therefore, the pain can begin in the neck and radiate down the arm all the way to the hand. Neck pain that radiates below the shoulder to the hand or low back pain that radiates below the knee to the foot often is from a nerve root, where the nerve exits the foramen, or window.

A characteristic of nerve pain is that it more often is in the extremity, the arm or leg, than in the neck or low back. In several studies in which patients were asked to distribute their pain, extremity verses spine, patients with definite nerve pain localized the pain to be greater in the extremity than in the spine; for example, they attributed 70 percent of the pain to the extremity versus 30 percent to the back. A distinct difference is found between nerve pain and pain from other structures such as the bone, muscle, or disk, in which pain is usually localized completely in the spine or radiates only in the neck to the shoulder or in the low back to the buttocks.

Modifiers of Nerve Pain

An important sign of nerve pain is what makes symptoms worse and what improves them. Identifying what provokes the pain is important. Nerve pain may be provoked if you do a straight leg raise. Nerve pain is worsened by movement, especially bending, twisting, and lifting. Typically, pain improves with rest, especially when you lie on your back or on your side with your legs flexed. Pain that originates from other structures such as the facette joint may be made worse with rest and improve with movement.

Nerve Pain’s Unique Voice

The dermatome and myotome of nerve pain resemble the names of musical instru- ments. (Dermatome refers to the sensory distribution of a nerve. Myotome refers to the motor or strength distribution of a nerve.) On a string instrument, each string gives a distinctive resonance that tells a trained musician what note it is. The myo- tome and dermatome of nerve pain tells a well-trained doctor exactly what nerve is causing the problem.

When injured, the sensory fibers (figure 2.3) produce a tingling sensation like pins and needles or sometimes a burning sensation. These are the most common sensory symptoms and must not be confused with pain. Pain is an unpleasant feeling that is sharp, aching, or throbbing. Pain can arise from most of the spinal structures, so pain in itself does not mean that a nerve is injured. Pain with tingling, however, does. If the nerve is completely severed, you will have no feeling.

Figure 2.3 Nerve Root

Figure 2.3 Nerve Root

A trained musician listening to a symphony can distinguish the strings from the horns and the piano forte from the percussion instruments. When evaluating nerve pain, trained physicians distinguish the quality of the pain, its radiation, the things that provoke or improve it, and the things that worsen or aggravate the pain. The distinctive elements associated only with nerve injury are specific sensory, motor, and bowel and bladder signs.

For example, an injured S1 nerve (S for sciatic, 1 for the first level) causes pain down the back of the leg to the lateral part of the knee and then to the ankle and the foot, especially the lateral part of the foot near the fifth toe. An injury to the L5 nerve root causes tingling and sensory changes to the large toe. Each nerve has its own voice. Luckily, this voice is the same in every person, making the diagnostic process easier. Your doctor should be able to tell you what nerve is involved based on his or her evaluation of your pain. The correct diagnostic test (EMG or MRI scan) and physical exam will confirm the diagnosis.

The myotome refers to the muscles to which a particular nerve goes. The myotome distribution for the S1 nerve is the gastrocnemius, or calf, muscle that allows you to stand on your toes and is important for running. An L3 or L4 myotome goes to the quadriceps, or thigh, muscle. Just as a pianist can tell the key played by its tone, a trained physician can tell the exact nerve involved by its distinctive myotomal and dermatomal voices.

If the entire bundle of spinal nerve roots (cauda equina) is injured, the nerves to the bowel and bladder are impaired. You will have difficulty controlling urination or bowel function. You may also experience numbness to the saddle area around your rectum and genitals. This important voice should never be ignored. Beware. When a nerve is involved, it is a medical emergency. If your doctor cannot see you, consider going to the emergency room, especially if you have bowel and bladder symptoms or progressive weakness. Don’t wait!

Joint or Facette Pain

The facette is a joint. A facette is round and looks like a face, hence the word facette, which is from face and ette, or little. The facette joint has a superior (above) part and an inferior (below) part that include facettes from adjacent vertebrae (figure 2.4). It has a covering, or membrane, that has many small blood vessels and fluid in between so that the joint flows smoothly and allows the bending, twisting, and extending movements that are vital to swinging a golf club, bending forward to brush your teeth, or extending to put that light bulb in the ceiling fixture.

The facette is also well innervated, meaning that it has sensation nerves going to it that connect it to other parts of the spine, usually one level above the affected area and two levels below it. The facettes have input for multiple spinal levels.

Figure 2.4 Structure of the vertebrae

Figure 2.4 Structure of the vertebrae

The pain can be acute or stabbing, but more often it is described as a dull ache or stiffness. Facette pain radiates differently than nerve pain. Facette back pain never goes below the knee and rarely goes below the buttocks. Facette neck pain never goes below the trapezius or shoulder. Facette pain usually is given a 2 to 4 on a scale of 1 to 10, but in acute cases it can get an 8.

Aggravating factors for facette pain in the low back and neck are activities such as lying down or sitting for 15 minutes or more. Often facette pain is worse in the morning. Usually this is a stiff, aching pain that improves with moving and stretching, which is different from nerve pain. Back extension, or bending backward, may worsen pain. Bending backward pushes the facettes together, irritating the joint.

The facette is often injured while playing golf or participating in other twisting activities. The pain is not necessarily noted when the golfer is swinging, but minutes or even hours later. The same is true if the injury occurs while you are working at your desk, gardening, or housecleaning. You may feel fine while doing it, but your back aches a half hour later. The pain can come on suddenly, such as when brushing your teeth.

Often facette pain is called the pain of long-earned wear and tear. For the secretary, it is the constant bending over to pull files; for the electrician or dentist, it is the twisting of the neck to fix what the job requires. This is the pain of the shortening adaptive syndrome.

Facette Degeneration

Over time, normal wear and tear and bleeding into the facette joint cause inflammation or the formation of bone spurs that jut out into the foramen where the nerve lives. This is part of a derangement syndrome. In time, these bone spurs can stab into the nerve, causing tingling and loss of strength. This bony arthritis is an inflammation in the joint. (Arthro means “joint.”) This inflammation also can narrow the central canal of the lumbosacral or cervical spine. When this occurs, you are in big trouble. (See the section on spinal stenosis on page \bb\, later in this chapter.) In a way, this inflammation is the body attacking itself with substances such as tumor necrosis factor (TNF). The effect of these substances can be stopped by the use of anti-inflammatory drugs such as aspirin, ibuprofen, and others. Anti- inflammatory drugs relieve facette pain. Facette degeneration often precedes nerve pain, but not always.

Take an anti-inflammatory drug before any activity that will aggravate the joint. For example, take an ibuprofen one hour before you play golf. Taking the medication after performing the activity is not as effective.

Muscle, Ligament, and Tendon Pain

Injuries to the muscles, ligaments, or tendons are categorized as soft-tissue injuries. A muscle injury might be the most painful, but injuries to the ligaments and tendons are the most enduring and limiting. Fortunately, ligament and tendon injuries are rare. Muscle injury is more common and is frequently seen in weekend warriors who play softball, tennis, golf, basketball, or other recreational sports.

Muscles have many blood vessels. Muscles are innervated by nerves from the spine in a distinct myotome fingerprint. Because the muscles of the upper chest, upper back, shoulder, and pelvis, including the buttocks and thighs, are of great size and strength, they provide stability and ease of movement to the neck and low back. When injured, these muscles spasm, limiting motion to prevent further pain. In any injury—bone, nerve, facette, or tendon—the nervous system causes the muscle to spasm to protect the whole spinal circuitry, sort of like a short circuit switch. The muscle spasm inactivates the spine and shuts it down. When a muscle goes into spasm, the blood supply to that muscle is cut off, further injuring the muscle.

A violent action can cause the muscle to tear. But even when the muscle is not torn, a reflex spasm to protect the joint will cause it to shut down. The muscle spasm contracts the muscle, making it reduce its size by half at times, and squeezes on the blood supply. The muscle is unable to get proper nutrition and oxygen, which injures the muscle and inhibits the removal of toxins. The muscle breaks down and becomes inflamed, creating additional problems. This is collateral damage. The muscle is involuntarily in spasm, and the body will begin to attack itself with cytokines. Cytokines are the artilleries that the body uses to defend itself. They destroy any tissue that they are released on, even normal muscle. In most injuries to the nerves, facettes, or bones of the spine, collateral damage to the muscle will occur.

The quality of muscle pain may be sharp at first and then become a deep sore- ness localized over the area of injury. If you try to use that muscle, you will feel the tenderness and pain. When a doctor palpates the muscle, he or she can feel the knot. That knot is the swelling caused by the inflammation and sometimes by blood or other fluid seeping into the injured area.

In the acute stage of injury or spasm, ice helps and heat makes it worse. Heat draws more blood and causes collateral damage to the area. Ice slows down the whole inflammatory process. Remember, facettes and soft tissues do not have the same fingerprint as nerves do. Injuries to facettes and soft tissues do not create sensory loss or weakness in a distinctive dermatomal or myotomal pattern. Here the weak- ness from soft-tissue injury is limited to the muscle or tendon involved.

A health care professional must be knowledgeable in neuroanatomy. Unfortunately, many are not so trained. Each nerve goes to a particular muscle. The well-trained spine specialist can identify the origin of the injury.

Movement makes muscle pain worse, but the pain is localized over the injured muscle. (Remember that movement causes nerve pain to radiate down the arm or leg and is often associated with sensory or motor changes.) Rest helps a torn muscle, as does ice at first and anti-inflammatory drugs.

Disc Pain

Figure 2.5 Vertebral disc

Figure 2.5 Vertebral disc

The vertebral disc (figure 2.5) consists of two parts. The annulus fibrocartilaginous, which is made of dense fibers and cartilage, surrounds a soft yet dense liquidlike mass called the nucleus pulposus (NP). The NP acts as a cushion or shock absorber to the spine so that when you land on your rear end you don’t fracture your spine. The NP takes the thrust and torque and changes shape, giving elasticity to the spinal column.

Think of the annulus fibrosa (AF) and the nucleus pulposa as a hard rubber tire (AF) and an inner tube (NP). Sometimes the tire splits and the inner tube pushes out. This occurrence is called a herniated disc (figure 2.6). The nerve fibers of the annulus fibrosa create a dull ache localized to the injured disc. A discogram, a procedure in which the disc is injected with liquid, uses the nerve fibers of the annulus fibrosa to indentify which disc is abnormal. If the injection of the liquid causes pain, that disc is abnormal. When the nucleus pulposus extrudes in a herniated disc, pressure can be put on the nerve root. This creates radicular pain, or radiculopathy (from radice, meaning “root,” and pathy, meaning “suffering”). Therefore, radiculopathy means “suffering nerve root.”

Ligament Pain

The spine has several ligaments (figure 2.7). The anterior and posterior longitudinal ligaments are mainly for support. These ligaments are poorly innervated, which means that they give little pain but are anatomically important. When the disc space is normal size, these ligaments are stretched out. But as the disc dehydrates, which starts to occur after age 25, the disc begins to shrink, reducing the tautness of the ligaments and causing the ligaments to buckle, decreasing the size of the canal.

Figure 2.6 Herniated disc

Figure 2.6 Herniated disc

As we age, we lose height due to de-hydration of the nucleus pulposus and the collapse of a disc space. The buckling ligament goes into the central canal and can create narrowing, causing spinal stenosis (stenosis means “narrowing”; figure 2.8). In the neck, spinal stenosis puts pressure on the spinal cord and can result in paralysis or weakness from the neck down, a real medical emergency. If the narrowing occurs in the lumbosacral spine, you might lose strength in both legs.

Spinal Cord Injury

The spinal cord carries all the pain, motor, and coordination fibers of the body but does not have any pain receptors itself to speak of. What it does not say in pain, it says in actions and sensations. Sensation and strength, together with bowel and bladder function, are turned off or severely impaired. An injury at the cervical level results in quadriplegia, weakness or paralysis of all four extremities. Spinal cord impairment is a medical emergency.

Spinal cord impairment may occur slowly over months or years. At first, only segmental sensory loss or motor loss occurs. This means loss of sensation below the level of the injury. A patient once reported that when she took a shower she couldn’t feel the water below her waist. Soon afterward both legs weakened and she lost control of her ability to urinate. Symptoms such as this constitute a medical emergency. If you experience any of these symptoms, immediately go to the emergency room.

Figure 2.7 Ligaments of the spine

Figure 2.7 Ligaments of the spine

Bone Pain

The vertebral bone has an outer shell called the periosteum, which has many pain nerve fibers. The inner part, the cancellous, is a network of dense calcium bridges that reinforce the outer bone covering. Inside the cancellous is the nutrition network that keeps the bone healthy. The inner cancellous has no nerves, so when injured it does not give the sensation of pain.

The quality of bone pain is severe, sharp, and localized over the injured bone. The onset of symptoms is usually sudden. The quantity is usually a 7 to 10 on a scale of 1 to 10. Lying down, bending, and twisting make the pain worse. Radiation is local and does not extend down the arm or leg unless the fracture compresses a nerve.

Bone pain is an acute, piercing pain localized to the area of the fracture; 60 percent of fractures occur to the thoracic 12 (T12) or L1 bones. Localization of pain often is over the spinous process, the steeple of the spine. Lying down makes pain worse, whereas sitting up makes it somewhat better. Bending, lifting, or twisting causes acute pain. Injury to the bone often is associated with secondary muscle spasm in the area. Bone pain is always a danger sign for possible severe spinal disease, such as severe osteoporosis or, rarely, a spinal tumor.

An immediate X-ray and medical evaluation is of utmost importance. Bone pain does not have sensory loss or motor loss or loss of bowel or bladder function, unless it causes narrowing and puts pressure on the spinal canal. In those with osteopo- rosis, fractures can occur without any acute trauma, such as a fall or an accident.

Osteoporosis and Osteopenia

Figure 2.8 Spinal stenosis

Figure 2.8 Spinal stenosis

The word osteo means “bone.” Osteopenia (penia means “too little”) is a con- dition in which there is too little bone. Osteoporosis (porosis means “porous”) is a condition in which the bone has holes. Most spine injuries are result from accidents or osteoporosis, which weakens the bone and predisposes it to com- pression fractures. About 750,000 spine fractures occur each year, 80 percent in postmenopausal women, and 250,000 hip fractures occur each year as well.

Psychological Pain

Often the brain is not included as part of the anatomy of the spine, but it is a major contributor to all pain, especially chronic pain that lasts more than six weeks. Extensions from the brain, called axons, reach into the spine. All doctors know that without the brain, there is no pain. For that reason, doctors anesthetize people before any surgical procedure. Putting the brain to sleep puts pain to sleep. But the brain’s appreciation of pain is great.

Any health care professional will tell you that the brain has volume control when it comes to pain. Having a dull ache and stiffness in your back from a joint is one thing, but if your brain interprets it as a malignant tumor that will soon paralyze you, that dull ache takes on a new severity including dread, anxiety, and even panic. Most doctors and nurses can attest to this based on their own experiences during training. The psyche works overtime.

The psyche often is controlled by neurotransmitters such as dopamine, serotonin, neuradenaline, glutamine, gabamine, cytokinins, and many others. Cytokinis are not kind; these hormones are extremely painful. Kinins, postaglandins, leukotrenes, and other factors such as substance P can stimulate pain receptors in the skin and elsewhere, markedly increasing pain. The immediate injury is like a bomb blast; the release of the kinins is the radiation or fire damage afterward. Pain control must take both into account, as well as the psychological component.

When we note that the pain is in the brain, this is not to say that it is imagined, faked, or made up. The brain, especially the brain stem and spinal cord pathways, can modulate the perception of pain. Remember, pain is a conscious perception. Someone who is comatose, despite severe injury, does not feel it. Someone who is unconscious feels no pain. Again, this is the reason that patients are put to sleep before surgery. People who have been hypnotized or who use acupuncture may per- ceive no pain despite being operated on because neurotransmitters and hormones have been activated and deactivated.

Psychological Pain Test

  1. Do you experience pain 24 hours a day, 7 days a week?
  2. Does your pain awaken you most nights?
  3. Is pain ruining your life?
  4. Have you lost a significant amount of time from work?
  5. Do you think that no one can help?
  6. Do you believe that your family does not appreciate how much you hurt?
  7. Have doctors suggested to you that your pain is imagined?

If you answered yes to four or more questions, you have chronic pain or depression. See a competent pain specialist.

Sleeplessness and Pain Perception

Any person with pain will tell you that after a good night’s sleep, pain is less, but after a bad night’s sleep, pain is worse. Why?

Serotonin, a neurotransmitter, and other neurotransmitters block pain perception in the thalamus, the middle part of the brain, and ascending pathways in the spinal cord. Serotonin is not like morphine. Serotonin actually reduces the pain messages received by the conscious brain, just as the valves of a shower increase or decrease the flow of water. Morphine dulls consciousness, whereas serotonin increases consciousness and the feeling of well-being. Norepinephrine, another neurotransmitter, has also been shown to decrease pain perception.

Research shows that pain perception can be reduced or increased 10-fold depending in part on the increase or decrease in serotonin. Students who received ethyl- amine, which depletes serotonin, complained of severe pain from walking to class. The effectiveness of a pharmacological agent depends on its actions on the body’s complex system of neurotransmitters and hormones. Serotonin and noradrenaline either decrease or increase pain perception. They act like a thermostat, cooling or heating pain perception, turning it up or down.

At night especially, you want your pain turned down. Unfortunately, this is when pain is naturally turned up. Antidepressants and selective serotonin reuptake inhibitors (SSRIs) were initially designed to treat depression, but because of their effect on increasing serotonin and norepinephrine they were found to decrease pain perception and are now a first- line defense in the fight against chronic pain. The advantage of these drugs is that they don’t cause dependency. (See chapter 10 for more on using medication to treat spinal pain.)

Sleeplessness is rampant in the United States. Often sleeplessness is self-induced, although many suffer from sleep disorders such as sleep apnea. Sleep apnea interferes with the stages of sleep that replenish the stores of serotonin, norepinephrine, and other neurotransmitters. Obstructive sleep apnea is a major cause of chronic pain and fibromyalgia. If you snore, feel tired or have headaches when you awaken in the morning, fall asleep easily during the day, have high blood pressure, or are overweight, check with your medical professional to discuss if you might have sleep apnea.

Proper sleep of seven to eight hours is essential for pain control and neurotransmitter levels. Those neurotransmitters determine pain threshold. We can tell whether a patient will overreact to a needle puncture just by holding her or his hand. If it is cold and sweaty, it means that the alarm neurotransmitter, adrenaline, is high, which increases pain awareness. Adrenaline, a fight or flight neurotransmitter, increases the perception of any stimulus. When adrenaline is high, the pain threshold is low.

Those who have slept well and have high serotonin levels can tolerate a lot of pain. In fact, the brain is not receiving the pain message because serotonin and other neurotransmitters are blocking it. People with chronic pain often sleep poorly and consequently have low levels of serotonin. A low level of serotonin is associated with depression and low levels of adrenaline. This makes the pain threshold low and pain perception high. This condition is particularly true for those who have chronic pain that lasts six weeks or more.

The average person needs seven hours of sleep, not just seven hours in bed, but seven hours of sleep. Because pain is often worse at night, many pain sufferers begin to dread bedtime. This condition can be treated with cognitive therapy and a doctor who specializes in sleep disturbance.