When Survivors Are Hurting: Understanding Post-Stroke Pain
The stroke recovery journey is often filled with challenges. The physical, emotional, behavioral and communication changes caused by stroke change the lives of not only the survivor, but those who care for them as well. Post-stroke pain can further complicate the situation.
Up to half of stroke survivors may experience some type of pain after their stroke. Neuro-scientists and therapists distinguish four types of post-stroke pain: central pain syndrome (CPS); complex regional pain syndrome (CRPS); spasticity; and shoulder pain.
Pain Terminology — Central & Neuropathic Pain
Dr. Richard Harvey
Let’s start with some basic definitions. Central pain is due to an injury in the central nervous system (brain or spinal cord). Any pain that occurs in the peripheral nervous system (anywhere along the nerves) is peripheral pain. “If you crush your arm in an accident, you are at risk of developing severe peripheral neuropathic or nerve pain,” said Richard Harvey, medical director of the Center for Stroke Rehabilitation at the Shirley Ryan AbilityLab (formerly Rehabilitation Institute of Chicago). “If you have a stroke or a spinal cord injury, you may develop central pain.”
Another pertinent distinction is between nociceptive pain and neuropathic pain. Nociceptive occurs because of tissue damage; neuropathic is the result of nerve damage, regardless of whether tissue is damaged. “Some people with diabetes have peripheral neuropathy caused by the small nerve endings in their feet being damaged because of poor blood flow,” Harvey said. That foot pain is called diabetic neuropathy. “That is a form of neuropathic pain because it’s due to damage to small nerve endings, not to tissue — skin, muscle or bone — damage. It’s the nerve being dysfunctional.”
Central Pain Syndrome
Central pain syndrome occurs when there is damage to an area of the brain that carries lots of sensory pathways. It affects 8 percent to 10 percent of survivors. No particular type of stroke causes CPS, rather strokes in particular areas of the brain do. For instance, the brainstem is full of such sensory pathways, so a stroke involving those pathways puts a survivor at risk of CPS. The same is true of a stroke in the thalamus, which is also rich in nerves. (For many years, CPS was called thalamic pain syndrome because that was where it was often identified. It was also known as Dejerine-Roussy syndrome after the two neuroscientists that first identified it in the early 20th century.) “Starting in the 1960s, scientists determined that essentially any injury along the sensory pathway from anywhere in the spinal cord up through the brain to the cortex can cause CPS,” Harvey said. “But it has to injure the sensory pathway, basically, the nerves that carry pain and temperature sensation. So, if you injure that pathway — anywhere in the brainstem, the thalamus or between the thalamus and the cortex — you can get CPS.”
Typically, CPS doesn’t start right away, but usually shows up in the first 60 days after the stroke. Neuroplasticity during that time results in inappropriate signaling within the pain pathways that results in a perception of pain that isn’t due to any peripheral cause. Harvey referred to this as “aberrant neuroplasticity,” changes to the brain that do not produce a beneficial outcome. “One of the things that people can misconstrue about neuroplasticity is that it’s always good, but it’s not always good,” Harvey said.
And once CPS shows up, in all likelihood it will continue to be there and will require medical management, which is typically medications. “Of all the medications we have available to treat CPS, only about half the patients treated with medications will have any significant pain reduction,” Harvey said. “Of those patients who have significant pain reduction, that pain reduction at best will be only 50 percent. Once CPS starts, it can be very, very difficult to treat.”
Pain and Depression
“There is a relationship between pain and depressed mood,” Harvey said. “People who have CPS are more likely to have depressed mood, and some antidepressants have been shown to help reduce pain. Some say you’re treating the depression which helps reduce the effect of the pain; others say that you’re reducing the pain and therefore, they’re not as depressed.”
Depression may affect how a person perceives the severity of their pain. “Depression can certainly lead to a catastrophizing of the pain,” he said. “‘Oh my God, this is the worst thing in the world. I can’t do anything. I might as well just die.’ A person’s personality, their mood, all of that can have an impact on how they perceive pain,” Harvey said.
Treating depression is generally a part of pain management.
Complex Regional Pain Syndrome
Complex regional pain syndrome (CRPS) is a phenomenon that happens not only in stroke but can also happen in peripheral nerve damage. Its symptoms are extreme neuropathic pain, swelling or inflammation of the joints and skin, loss of range of motion, eventual atrophy of the muscle and loss of the hair in the areas involved. “In stroke patients, it has a tendency to affect the shoulder and the hand,” Harvey said. “In fact, CPRS for stroke has also been called shoulder-hand syndrome because it seems to affect the shoulder and the hand more often than other regions of the body.”
At this time, its cause is unknown, but the treatment is no mystery — early mobilization of the affected limb. “In reality, we don’t see it that often in modern rehabilitation care because we tend to mobilize patients fairly early even in acute hospitals and in doing so, it seems to prevent it,” Harvey said.
Patients who do get CRPS are those who tend to be immobilized for an extended period, perhaps because they’re comatose or they’re on a ventilator for a long time.
Getting survivors to put weight on the affected limb can be difficult. Harvey says he sometimes helps the process by giving high-dose steroids to help reduce the inflammation and allow the survivor to be mobilized and then as they get mobilized, the CRPS begins to resolve over time.
“The key thing is when you discover it, to hit it hard and early. We want to prevent patients from losing range of motion because as the tissue swells up with all the inflammation, affected patients will begin to lose range of motion in their joints. If you don’t treat that early on, eventually the CRPS sort of burns out and you have this atrophic limb with loss of range of motion. At that point, it’s almost impossible to ever get that range of motion back. But you don’t let that happen. You prevent it from the get-go. Prevention is the treatment,” Harvey said.
Spasticity, an abnormal activation pattern of muscles, occurs to some degree within a week in about a quarter of survivors. While it may look painful, spasticity itself is not typically painful, though it often foretells pain syndromes — nearly three-quarters of survivors with spasticity developed pain.
Spasticity may cause nociceptive pain because of injury to tissue. “Depending on how severe their spasticity is and where it’s located, in some people, it may cause stress on the joints and tendons,” said Harvey. Although the mechanism is not clearly understood, spasticity may cause inflammation of those joints and tendons, which is painful. “The treatment is to treat the spasticity with medications and Botox® injections. We also use medications like Tylenol® or anti-inflammatory drugs as appropriate and that generally will take care of the spasticity-associated pain. That one is pretty straightforward: Treat the spasticity.”
Non-pharmacological treatment for spasticity is stretching, maintaining good range of motion, staying active and moving a lot. “Some would recommend splinting but it’s not yet clear whether splinting really helps prevent spasticity,” Harvey said.
The shoulder is the most complex joint in our bodies, perhaps because it has the greatest range of motion. It is a ball-and-socket joint like the hip, but the socket is shallow and the ball at the end of the arm is held in place by rotator cuff muscles. “When a survivor has paralysis of the muscles including the rotator cuff, they will tend to have instability of the shoulder,” Harvey said. The shoulder pain usually develops as the survivor starts getting muscle tone back, perhaps because of poor mechanics around the shoulder or because of spasticity, which also leads to poor mechanics around the shoulder that can lead to shoulder pain. “But that shoulder pain is due to inflammation of the joints, or the biceps and tendons — nociceptive pain, not neuropathic,” Harvey said.
But this is not a subluxation, where the ball and socket dislocate. “The only way that subluxation can cause shoulder pain is if you don’t properly support the arm early on and the rotator cuff gets torn because you just let the arm hang and the tissue gets torn,” Harvey said. That, of course, is a tissue injury (nociceptive pain) and inflammation, but the subluxation itself is not the cause of pain.
Another cause of shoulder pain is when hypertonia (abnormally intense muscle tension that makes it more difficult for a muscle to stretch) develops as a result of some abnormal pulse around the shoulder that can cause a lot of inflammation and pain. If you do not treat this tissue inflammation and pain early on, “the patient can develop a chronic inflammatory problem around the shoulder and all chronic inflammatory problems end up becoming central pain if not properly managed,” Harvey said. “If I let an inflamed shoulder go and it remains inflamed over three to six months, it’s going to become a chronic neuropathic pain problem. So, the treatment of hemiplegic shoulder pain is to nip it in the bud.”
This may involve x-rays and ultrasounds to determine the source of the pain — a fracture, tissue damage or inflammation. Harvey treats inflammation with a steroid injection. “After the injection, the patient can then work in therapy, develop proper mechanics and get their range of motion back and often the pain will suppress and go away,” he said.
In those cases where it doesn’t go away and doesn’t respond to anti-inflammatory medications, the hemiplegic shoulder pain may become chronic neuropathic pain, localized in the shoulder. “At that point, I tend to use the usual medications that we use for central pain to see if that helps, and again, the success rate is about 50 percent,” Harvey said.
For those who don’t respond, there is a new non-drug treatment for shoulder pain — intramuscular nerve stimulators. With these devices, a single wire electrode is inserted in the deltoid muscle, and then the muscle is stimulated at a low level for about six hours a day for 30 days. “You don’t stimulate the skin so the patient doesn’t feel much,” Harvey said. “They may feel something but it’s not like you get this big old stimulator on your skin. It’s in the muscle, and we believe it has a neuromodulation effect and sort of resets the central hypersensitivity back towards normal so that the pain is reduced, at least during treatment. And for some, there seems to be pain reduction for some time after the four-week treatment.”
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