Pain

Jun 07

Shoulder Injury and Pain After SCI

By Scire Admin | | No Comments

Authors: Jaashing He, Hannah Goodings | Reviewer: Darryl Caves | Published: 7 June 2023 | Updated: ~

Key Points

Shoulder injuries and pain are a common experience for many, with individuals with SCI having a slightly higher rate of occurrence.
Many factors contribute to the risk of shoulder injury or shoulder pain such as age and female sex. Some factors such as strength can be improved.
The best way to prevent shoulder injuries is to actively work to avoid them in the first place. Preventative strength training, practicing good ergonomics and improving your wheelchair handling skills can all help reduce your risk.

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Is shoulder pain common?

Shoulder pain and injury is something that many people experience, SCI or not. In the general population, 26% of people live with shoulder pain compared to 36% for SCI populations. Interestingly, when looking at the wide variation within SCI populations, there is a similar incidence of shoulder pain whether you use a powerchair, manual chair, gait-aid or no gait-aid. It is helpful to have a good understanding of what is involved in shoulder movement to understand what makes the shoulder vulnerable to injury and how best to prepare and maintain your shoulder to avoid injury.

Shoulder anatomy

Posterior view of man's torso with arm raised. Muscles of the rotator cuff (supraspinatus, subscapularis, teres minor, and infraspinatus) are superimposed and labeled. The shoulder is designed for movement and a large range of motion. Bone shape, muscle coordination and connective tissue all work together to form our most flexible joint. With this large range of movement, we sacrifice some stability. Unlike the hip joint with its “ball in cup” design giving great bony stability, the shoulder has a “ball on small plate” design. The surrounding muscles and connective tissue help keep the upper arm bone (the “ball”) in place on the shoulder blade (the “dish”). There are four muscles responsible for keeping the ball in place during movement. This group of muscles is referred to as the rotator cuff muscle group and includes the supraspinatus (above the spine of the scapula), subscapularis (on the front of the scapula), and infraspinatus (below the spine of the scapula) and teres minor (on the back of the scapula). These four small muscles are responsible for “balancing the ball” but they are not the only muscles found in the shoulder. There are larger muscles that surround the joint that are used to perform movements that involve strength such as lifting, pushing or carrying.

Cartoon of front shoulder skeleton with joints (sternoclavicular, acromioclavicular, glenohumeral, scapulothoracic) labeled.

Though we often think of the shoulder as a singular joint, there are actually four joints and articulations within the shoulder system.

The joints/articulations are:

Sternoclavicular joint (sternum and collar bone)
Acromioclavicular (shoulder blade and collar bone)
Glenohumeral joint (shoulder blade and upper arm)
Scapulothoracic (ribcage and shoulder blade)

Shoulders do not work in isolation. The bones, muscles and connective tissue all interact with surrounding regions of the body resulting in the potential for disruptions in movement patterns in the shoulder. For example, the shape of the ribcage can also impact shoulder movement. It is what the shoulder blade slides on to allow for movement of the arm above shoulder height. If the shoulder blade cannot move smoothly over the ribs, reaching above shoulder height may become difficult and painful.

What are the different classifications of pain?

Shoulder pain can be grouped into two categories: neuropathic (nerve) pain and mechanical (muscle, joint and bone) pain and their treatments are different.

Neuropathic pain results from disease or damage to the nervous system (brain, spinal cord and/or nerves). This pain is often described as pins and needles, shooting electrical sensations, stabbing, coldness, burning and increased sensitivity.

Coronal section of the shoulder with bone, joint, and muscle tissue displayed.

Mechanical pain is related to pain from damaged joints (blue), bones (grey) or muscles (pink).⁴

Mechanical pain is pain that occurs when tissues (bone, joint, ligament, tendon, muscle) are pushed beyond the load they can handle, also known as exceeding their tissue capacity. This can be from a sudden event or misuse (overuse, repetitive) of the shoulder and can lead to damage of these tissues resulting in pain or injury. Tissue capacities can become more resilient with increased strength and movement training. They can also become less resilient with disuse, aging, or metabolic conditions such as poorly managed diabetes. A large decrease in activity for the shoulder can lead to decreased tissue capacity and can result in a higher likelihood for injuries and pain.

Mechanical pain can help guide us to understand when a tissue may be near its capacity and our activities should be adjusted to allow for rest and recovery. Sometimes pain will continue despite rest and become an unhelpful signal.

Refer to our article on Pain for more information!

What is involved in a shoulder assessment?

Identifying the type (neuropathic vs. mechanical) and cause of shoulder pain can be complicated. As shoulders can be affected and affect many regions of the body, a thorough examination of the medical history and a physical examination, conducted by a health professional, is needed to best uncover the cause of pain. This thorough examination may involve:

A detailed history, including:

Diagnosis (if this pain is a result of an injury or previous diagnosis)
Pain history
Occupation
Recreational activities
Equipment history and usage

A physical examination of the:

Neck
Spine
Ribcage
Shoulder joints
Arm
Posture
Position of the shoulder blade on the ribcage
Range of movement and strength

What are the risk factors for developing shoulder pain?

There are certain risk factors that increase your likelihood of developing shoulder injury or pain. Many of these risk factors also exist for the general population but there are some risk factors specific to the SCI population. Some of these factors can be changed and some cannot.

Non-modifiable risk factors for all populations

Non-modifiable factors are things that can increase risk of shoulder injuries but cannot inherently be changed. These include:

Higher age
Being female
Prior shoulder injury
Metabolic diseases leading to poor connective tissue capacity (e.g. diabetes, vascular diseases)

Non-modifiable risk factors specific to SCI

Higher level and complete injury
Longer duration of injury
Muscle imbalances due to paralysis of specific muscles
Reduced functional strength around the joint due to SCI-related muscle weakness/paralysis
Relying heavily on upper body movement for everyday life tasks
Postural issues due to SCI-related muscle weakness/paralysis

Risk Factors: Tetraplegia vs Paraplegia

While shoulder pain is more common in persons with tetraplegia and in those with complete injuries (Dyson-Hudson 2004), the cause of that shoulder pain can differ:

In paraplegia, overuse-related shoulder pain is more common and is seen in later years after injury (Mulroy et al., 2020), a result of using the shoulders for mobility over a long period.
In someone with tetraplegia where shoulder muscles are affected by paralysis, an imbalance in the shoulder muscles can result and there may be spasticity that pulls the shoulder capsule. Then, just moving the shoulder can result in pain due to subluxation and impingement.

Modifiable risk factors for all populations

Modifiable factors are things that may be able to be changed with lifestyle adjustment. The risk for shoulder injury can be reduced by:

Improving shoulder flexibility or range of movement deficit.
Increasing shoulder muscle strength and/or balance.
Improving posture, especially of shoulders hunched forward which can increase impingement.
Reducing occupational exposure: percentage of time spent working at or above shoulder height, high loads or force demands, repetitive tasks, exposure to vibration, sustained or awkward postures.

Modifiable risk factors specific to SCI

Reduce spasticity
Reduce body weight if obese
Improve balance or stability of the body for upper extremity tasks
Improve home or workplace set-up to reduce shoulder height movements and weight transfers without equipment support

It is important to note that some of the factors within the modifiable lists may actually be non-modifiable for some individuals.

Refer to our article on Spasticity for more information!

How can shoulder injuries be prevented and treated?

Having had a shoulder injury is one of the main predictors of shoulder pain or subsequent shoulder injury. With this in mind, preventing an initial shoulder injury should be a priority.

If a shoulder injury does occur, the treatment should focus on decreasing pain and beginning initial rehabilitation followed by continued rehabilitation and prevention of future shoulder injuries.

Rehabilitation from an incident of shoulder pain or shoulder injury can seem to follow the same pathway as when one initially undergoes rehabilitation for an SCI. This is because of the need to restore and maintain mobility and strength to enable tissue capacity for function, to do the things you want and need to do. At the same time, we need to continually evaluate and re-evaluate our lifestyle, environment, and equipment choices as we age and change to ensure that these variables remain optimized and if not to change them. The following represent the key variables that need to be addressed in all situations:

Manual wheelchair with a propulsion assist device attached.

Using a propulsion assist device can eliminate the use of the arms for propulsion on a manual wheelchair.⁶

Managing pain

Rest and Activity Modification

Following a shoulder injury or the onset of pain, rest is often recommended as the first step in recovery. However, it can be difficult for manual wheelchair users or mobility aid users to fully rest their shoulders. In this case, you may be advised to pick and choose when to use your arms and when to use assistive technology. For example, for a manual wheelchair user, the use of a power-assisted add-on or adding a powered front-mounted system may reduce the use of the shoulders significantly.

Refer to our article on Propulsion Assist Devices for more information!

Rehabilitation techniques

Physical and occupational therapists can be great resources for injury assessments as well as pain reduction treatments and therapies. The focus of shoulder recovery should revolve around building tissue capacity through strength and flexibility training and increasing variability in movements.

Pharmacological

Medications can be used to relieve pain and allow for more movement. These pharmacological interventions include nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, muscle relaxants, local anesthetic and corticosteroid injections.

Prevention and Rehabilitation

To best prevent subsequent shoulder injuries and to reduce shoulder pain, continued rehabilitation as well as strategies to reduce shoulder strain should be used.

Exercise and Stretching

Exercise programs and stretches, prescribed by a medical professional, to strengthen the shoulders, neck, chest and back muscles are helpful in preventing shoulder injuries.

The following exercises are recommended for shoulder pain after SCI, beginning with shoulder stretches and rotator cuff muscle strengthening and then other shoulder stabilizers as the pain decreases:

Stretching exercises for the front of the shoulder are recommended to counter tightness associated with shoulder pain in SCI.

Man supine in bilateral stretch of anterior shoulder structures with “open book” stretch.

Bilateral stretch of anterior shoulder structures with “open book” stretch.⁷

Man seated in wheelchair stretching front of one shoulder using a doorway.

Seated stretch of anterior shoulder using a doorway.⁸

Shoulder strengthening exercises are effective in reducing pain in most overuse-related shoulder pain. Start with exercises for the rotator cuff muscles.

Man using resistive band to externally rotate the shoulder with elbow tucked against body.

External rotators can be strengthened using resistive bands with the elbow pressed against the body.⁹

Man seated in wheelchair lifting a dumbbell to shoulder height in the scapular plane with thumb up.

The safest and most effective exercise to strengthen the supraspinatus muscle involves lifting the hand to shoulder height (90 degrees) diagonally (between directly in front and to the side- the scapular plane) with the thumb up (glenohumeral external rotation).¹⁰

Exercises for scapular retractors (rhomboids/middle trapezius), scapular protractors (serratus anterior), and thoracohumeral depressors (pectoralis major/latissimus) can be added as pain decreases.

Man in wheelchair performing a one-arm row using a resistive band.

Scapular retractors strengthening using a rowing exercise with the elbow down.¹¹

Man in wheelchair using resistive band to execute a pushing movement.

Strengthening of the scapular protractors with the opposite motion, pushing forward.¹²

Man in wheelchair performing resisted adduction exercise (pull-down and across the body with the elbow starting no higher than the shoulder).

Thoracohumeral depressors strengthening with resisted adduction exercises (pull-down with the elbow no higher than the shoulder).¹³

Ergonomically Sound Environments

Wheelchair users and mobility-aid users are exposed frequently to environments with above-shoulder-height movements because typical environments are not adapted for their mobility needs. This is a common and often distressing issue that many people living with SCI experience. An important component of a preventative injury strategy is to arrange your work, home, and other frequented spaces in an ergonomically sound set-up style to suit your needs. A physical therapist, occupational therapist or care team can evaluate your environment to create a space that reduces effort and pain for you. Modifications may include lowering shelves to avoid raising arms above the head or arranging the storage of items so that the most frequently used objects are easier to access. Having an ergonomically sound set-up that allows you to move and function efficiently and safely is a valuable tool in preventing shoulder pain.

Refer to our article on Housing for more information!

Posture and wheelchair setup

Posture has a major impact on how the body moves and should be considered when addressing a shoulder injury or the onset of shoulder pain.

Sitting

When sitting upright, your head and back should be aligned. Hunched shoulders with a forward head can increase impingement of shoulder structures. Be aware of your sitting posture in your wheelchair by regularly looking at your posture with a camera or in the mirror. People with SCI are at risk for postural issues especially if they have some paralysis of trunk and/or upper limb muscles. This shift in posture can cause issues with the shoulder blade sliding as the arm is raised above shoulder height. If posture problems develop, request a seating review from health professionals.

Sleeping

When sleeping, ensure your shoulders are well supported. If you sleep on your side, do not lay directly on the shoulder. Pull it forward and lie on the shoulder blade. If a comfortable position cannot be found, consult your OT or PT to find an alternate technique.

Wheelchair setup

Two images of a man in a wheelchair with differing axle position. One with the wheels forward and the other with wheels rearward. Changes can be made to your wheelchair to help improve shoulder pain. It is important to make sure your wheelchair is set up in the most efficient way for your propulsion. Adjustment of your position in the chair as well as how the wheel is positioned will alter how you are pushing the chair, and how much energy is required to propel. Some possible adjustments include moving the rear wheel forward to reduce the reaching distance to the wheel, adjusting the wheel axle height to optimize your elbow angle (between 100-120 degrees), and general wheelchair maintenance (e.g, tire pressure, caster functions) to ensure your wheelchair remains easy to propel.

Refer to our articles on Wheelchair Seating and Manual Wheelchairs for more information!

Wheelchair Skills

Increasing wheelchair skills by learning correct propelling and maneuvering techniques will aid in protecting against shoulder injuries. This includes skills such as wheelies, propulsion techniques such as using long, smooth strokes and recognizing signs that your wheelchair may need maintenance.

Refer to our article on Wheelchair Provision for more information!

The bottom line

Shoulder injuries are a common experience for many people. Prevention is the best approach and there are many factors that can be modified to reduce your risk of shoulder pain. These include stretching and strengthening your shoulder muscles, ensuring good posture, ergonomic assessments and bettering your wheelchair handling skills.

If you are experiencing shoulder pain or have injured your shoulder, please seek advice from your health care team. It is best to discuss all treatment options with your health providers to find out which treatments are suitable for you. For a review of how we assess evidence at SCIRE Community and advice on making decisions, please see SCIRE Community Evidence.

Reference list

Parts of this page have been adapted from the SCIRE Professional “Pain Management”, “Upper Limb”, and “Wheeled Mobility and Seating Equipment” Modules:

Mehta S, Teasell RW, Loh E, Short C, Wolfe DL, Hsieh JTC (2014). Pain Following Spinal Cord Injury. In Eng JJ, Teasell RW, Miller WC, Wolfe DL, Townson AF, Hsieh JTC, Connolly SJ, Noonan VK, Loh E, McIntyre A, editors. Spinal Cord Injury Research Evidence. scireproject.com/evidence/pain-management/

Harnett A, Rice D, McIntyre A, Mehta S, Iruthayarajah I, Benton B, Teasell RW, Loh E. (2019). Upper Limb Rehabilitation Following Spinal Cord Injury. In Eng JJ, Teasell RW, Miller WC, Wolfe DL, Townson AF, Hsieh JTC, Connolly SJ, Noonan VK, Loh E, Sproule S, McIntyre A, Querée M, editors. Spinal Cord Injury Research Evidence. scireproject.com/evidence/upper-limb/

Titus L, Moir S, Casalino A, McIntyre A, Connolly S, Mortenson B, Guilbalt L, Miles S, Trenholm K, Benton B, Regan M. (2016). Wheeled Mobility and Seating Equipment Following Spinal Cord Injury. In Eng JJ, Teasell RW, Miller WC, Wolfe DL, Townson AF, Hsieh JTC, Connolly SJ, Loh E, McIntyre A, editors. Spinal Cord Injury Research Evidence. scireproject.com/evidence/wheeled-mobility-and-seating-equipment/

References

Bossuyt, F. M., Arnet, U., Brinkhof, M. W. G., Eriks-Hoogland, I., Lay, V., Müller, R., Sunnåker, M., & Hinrichs, T. (2018). Shoulder pain in the Swiss spinal cord injury community: prevalence and associated factors. Disability and Rehabilitation, 40(7), 798–805. https://doi.org/10.1080/09638288.2016.1276974

Hodgetts, C. J., Leboeuf-Yde, C., Beynon, A., & Walker, B. F. (2021). Shoulder pain prevalence by age and within occupational groups: a systematic review. In Archives of Physiotherapy (Vol. 11, Issue 1). BioMed Central Ltd. https://doi.org/10.1186/s40945-021-00119-w

Jain, N. B., Higgins, L. D., Katz, J. N., & Garshick, E. (2010). Association of shoulder pain with the use of mobility devices in persons with chronic spinal cord injury. PM and R, 2(10), 896–900. https://doi.org/10.1016/j.pmrj.2010.05.004

Dyson-Hudson, T. A., & Kirshblum, S. C. (2016). Shoulder Pain In Chronic Spinal Cord Injury, Part 1: Epidemiology, Etiology, And Pathomechanics. Http://Dx.Doi.Org/10.1080/10790268.2004.11753724, 27(1), 4–17. https://doi.org/10.1080/10790268.2004.11753724

Pannek, J., Pannek-Rademacher, S., & Wöllner, J. (2015). Use of complementary and alternative medicine in persons with spinal cord injury in Switzerland: a survey study. Spinal Cord 2015 53:7, 53(7), 569–572. https://doi.org/10.1038/sc.2015.21

Kim, E., & Kim, K. (2015). Effect of purposeful action observation on upper extremity function in stroke patients. Journal of Physical Therapy Science, 27(9), 2867–2869. https://doi.org/10.1589/JPTS.27.2867

Carlson, M. J., & Krahn, G. (2009). Use of complementary and alternative medicine practitioners by people with physical disabilities: Estimates from a National US Survey. Https://Doi.Org/10.1080/09638280500212062, 28(8), 505–513. https://doi.org/10.1080/09638280500212062

Image credits

Sore shoulder ©Gan Khoon Lay, CC BY 3.0
Modified from: Man view from back. Blades, shoulder and trapezoid illustration. Shutterstock
Humerus Fracture ©Servier Medical Art, CC BY 3.0
Coronal section of the shoulder joint ©Database center for life science, CC BY 4.0
Pulley Row by SCIRE Community
Firefly Electric Attachable Handcycle for Wheelchair © Rio Mobility 2020
– 13. Reprinted with permission from Topics in Spinal Cord Injury Rehabilitation, American Spinal Injury Association. Sara J. Mulroy et al. (2020). A Primary Care Provider’s Guide to Shoulder Pain After Spinal Cord Injury. 26(3): 186–196.

Wheelchair disability injured disabled handicapped ©stevepb, Pixabay License
Axle Position by SCIRE Community

Disclaimer: This document does not provide medical advice. This information is provided for educational purposes only. Consult a qualified health professional for further information or specific medical advice. The SCIRE Project, its partners and collaborators disclaim any liability to any party for any loss or damage by errors or omissions in this publication.

Feb 14

Epidural Stimulation

By Scire Admin | | No Comments

Authors: Dominik Zbogar and Sharon Jang | Reviewer: Susan Harkema | Published: 14 February 2022 | Updated: ~

Key Points

Epidural stimulation is a treatment that sends electrical signals to the spinal cord.
Epidural stimulation requires a surgical procedure to implant electrodes close to the spinal cord.
One of the ways epidural stimulation works is by replacing the signals that would normally be sent from the brain to the spinal cord before spinal cord injury (SCI).
Epidural stimulation affects numerous systems. Stimulation aimed at activating leg muscles may potentially also affect bowel, bladder, sexual, and cardiovascular function.
Studies of epidural stimulation in spinal cord injury (SCI) generally do not include a comparison group without stimulation. The benefits of epidural stimulation that have been reported have been in small numbers of participants. So, while reports thus far are encouraging, more research is necessary.
Because it is in the research and development phase, epidural stimulation for spinal cord injury is not part of standard care nor is it a readily available treatment.

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What is epidural stimulation?

Neuromodulation is a general term for any treatment that changes or improves nerve pathways. Different types of neuromodulation can work at different sites along the nervous system (e.g., brain, nerves, spinal cord) and may or may not be invasive (i.e., involve surgery). Epidural stimulation (also known as epidural spinal cord stimulation or direct spinal cord stimulation) is a type of invasive neuromodulation that stimulates the spinal cord using electrical currents. This is done by placing an electrode on the dura (the protective covering around the spinal cord).

To read more about other types of neuromodulation used in SCI, access these SCIRE Community articles: Functional Electrical Stimulation (FES), Transcutaneous Electrical Nerve Stimulation (TENS), sacral nerve stimulation, and intrathecal Baclofen.

Watch our neuromodulation series videos! Our experts explainexperimental to more commonplace applications, and individuals with SCI describe how neuromodulation has affected their lives.

What is “an Epidural”?

Epi- is a prefix and means “upon”, and the dura (full name: dura mater) is a protective covering of the spinal cord. So epidural means “upon the dura”, and in the context of epidural stimulation, this is where the electrodes that stimulate the spinal cord are placed. Yes, it is also possible to have sub-dural (under the dura) or endo-dural (within the dura) electrode placement. And, there are more layers between the dura and the spinal cord, not to mention the spinal cord itself where electrodes could be placed in what is called intraspinal microstimulation. The benefit of being beneath the dura and closer to the spinal cord is that there is a more direct stimulation. Having the electrode closer to the spinal cord allows more precision with the signal going more directly to the neurons.

The drawback is that more complications can arise with closer placement because the electrodes are in the spinal cord tissue. Such placement is currently rare, experimental, or non-existent but that will change as the technology advances. Intraspinal microstimulation has been tested in animal models and is in the process of being translated to humans.

You are probably familiar with the term “epidural” already, as it is often mentioned in relation to childbirth. If a new mother says she had an epidural, what she usually means is that she had pain medication injected into the epidural space for the purpose of managing pain during birth.

We specifically discuss epidural spinal cord stimulation in this article. Spinal cord stimulation can also be applied transcutaneously. This type of spinal cord stimulation is non-invasive as the stimulating electrodes are placed on the skin. With transcutaneous stimulation, the signal has to travel a greater distance through muscle, fat, and other tissues, which means the ability to be precise with stimulation is hampered. However, it does allow for more flexibility in electrode placement and does not require surgery. There is research published or underway investigating the impact of transcutaneous stimulation in some of the areas discussed above, including hand, leg, and cardiovascular function.

How does epidural stimulation work?

Normally, input from your senses travels in the form of electrical signals through the nerves, up the spinal cord, and reaches the brain. The brain then tells the muscles or organs what to do by sending electrical signals back down the spinal cord. After a spinal cord injury, this pathway is disrupted, preventing electrical signals from traveling below the level of injury to reach where they need to go. However, the nerves, muscles, and organs can still respond below the injury to electrical signals.

Epidural stimulation works by helping the network of nerves in the spinal cord below the injury function better and take advantage of any leftover signals from the spinal cord. To do so, the stimulation must be fine-tuned to make sure the amount of stimulation is optimal for each person and a specific function, such as moving the legs.

Recent studies of the role of epidural stimulation on standing and walking have noted unexpected beneficial changes in some participants’ bowel, bladder, sexual, and temperature regulation function. This highlights both the potential for epidural stimulation to improve quality of life in multiple ways and that much research remains to be done to understand how epidural stimulation affects the body.

There may still be spared connections in the spinal cord with a complete injury.

How can someone with a complete injury regain movement control with epidural stimulation?

Being assessed with a complete injury implies that there is no spared function below the injury. However, scientists are finding that this may not be the case. Studies have found that even with a complete loss of sensory and motor function, there may be some inactive connections that are still intact across the injury site. These remaining pathways may be important for regaining movement or other functions. Another hypothesis is that epidural stimulation in combination with training may encourage stronger connections across the level of injury. Although these pathways may provide some substitution for the injured ones, they are not as effective as non-injured pathways across the injury level.

How are epidural stimulation electrodes implanted?

When it is decided that an individual will receive epidural stimulation, a health professional, such as a neurosurgeon, will perform an assessment of the spinal cord using magnetic resonance imaging (MRI) to determine the best place to implant the electrodes.

In most of the studies mentioned in this article, the electrodes were placed between the T9-L1 levels, though researchers are investigating the impact of epidural stimulation on hand function.

Xray image of wires connecting power and signal to electrodes (red circle) placed on a spinal cord.

There are two possible procedures. One approach is to have two surgeries. During the initial surgery, a hollow needle is inserted through the skin into the epidural space, guided using fluoroscopy, a type of X-ray that allows the surgeon to see where the needle is in real time. Potential spots on the spinal cord are tested using a stimulator. A clinician will look to see if stimulation over those areas of the spinal cord leads to a desired response. Once found, the electrode array is properly positioned over the dura and the surgery is completed. This begins a trial period where the response to epidural stimulation is monitored. During this time the electrode array is attached to an electrical generator and power supply, which is worn on a belt outside of the body. When it is shown that things are working as desired, the generator is implanted underneath the skin in the abdomen or buttocks. The generator can be rechargeable or non-rechargeable. A remote control allows one to turn the generator on or off and control the frequency and intensity of stimulation.

The second method is to only have one surgery and no trial period. This is possible due to increased knowledge in how to stimulate the spinal cord. Soon after surgery, the individual will be taught how and when to use the epidural stimulation system at home. If needed, the frequency (how often) and intensity (how strong) of the stimulation will be adjusted at follow-up appointments with the physician. In other cases, many practice sessions of learning the right way to stimulate may be needed before a person can stimulate at home.

If the epidural stimulation is used for leg control, movement training, standing, and stepping will be required to learn how to coordinate and control movement during stimulation. This is required for the recovery of voluntary movements, standing and/or walking.

Are there restrictions or precautions for using epidural stimulation?

Epidural stimulation can be used in all people with SCI, regardless of the level or completeness of injury. However, certain situations can make it an unsafe treatment in some. It is important to speak to a health professional about your health history before beginning any new treatment.

Epidural stimulation should not be used in the following situations:

By people with implanted medical devices like cardiac pacemakers
By people who are unable to follow instructions or provide accurate feedback
By people with an active infection
By people with psychological or psychiatric conditions (e.g., depression, schizophrenia, substance abuse)
By people who are unable to form clots (anticoagulopathy)
Near areas of spinal stenosis (narrowing of the spinal canal)

Epidural stimulation should be used with caution in the following situations:

By children or pregnant women
By people who require frequent imaging tests like ultrasound or MRI (some epidural stimulation systems are compatible)
By people using anticoagulant medications (blood thinners)

What are the risks and side effects of epidural stimulation?

Epidural stimulation is generally well-tolerated, but there is a risk of experiencing negative effects.

The most common risks and side effects of epidural stimulation include:

Technical difficulties with equipment, such as malfunction or shifting of the electrodes that may require surgery to fix
Unpleasant sensations of jolting, tingling, burning, stinging, etc. (from improper remote settings)

Other less common risks and side effects of epidural stimulation include:

Damage to the nervous system
Leakage of cerebrospinal fluid
Increased pain or discomfort
Broken bones
Masses/lumps growing around the site of the implanted electrode

Risks specific to the surgery which involves the removal of part of the vertebral bone (laminectomy) include:

bleeding and/or infection at the surgical site
spinal deformity and instability

Proper training on how to use the equipment and using the stimulation according to the directions of your health provider can help decrease the risks of experiencing these side effects.

Epidural stimulation and bladder and bowel function

Neuromodulation methods to manage bladder function have usually involved stimulation of the sacral nerves (which are outside of the spinal cord), not with epidural spinal cord stimulation. This is reflected in the fact that almost no research exists regarding the effects of epidural stimulation on bowel and bladder function in the previous century.

New information on epidural stimulation relating to bladder function is coming. In the last several years, several studies (weak evidence) from a very small group of participants of participants (who were AIS A or B) have found consistent improvements in bladder function. Participants in these reports were fitted with epidural stimulators for reactivation of paralyzed leg muscles for walking and reported additional benefits of improvements in bladder and/or bowel function. However, other studies have shown small changes to bladder function and no changes to bowel function. Negative changes, such as decreased control over the bladder, have even been noticed by some participants in another study. These findings suggest that epidural stimulation may improve quality of life by safely increasing the required time between catheterizations. Fewer catheterizations and reduced pressure in the bladder would preserve lower and upper urinary tract health. More research is required, especially with respect to bowel function. It must be noted that walk training alone has been shown to improve bladder and bowel function. Epidural stimulation may provide additional improvement to bladder function in comparison to walk training alone. Neuromodulation methods to manage bladder function have usually involved stimulation of the sacral nerves (which are outside of the spinal cord), not with epidural spinal cord stimulation. This is reflected in the fact that almost no research exists regarding the effects of epidural stimulation on bowel and bladder function in the previous century.

For more information, visit our pages on Bowel and Bladder Changes After SCI!

Why does walk/stand training alone have a beneficial effect on bladder, bowel, and sexual function?

Relationships between the leg movement and nerves in the low back regions have been identified.

Some evidence suggests that walk/step training alone can create improvements in bladder/bowel function. Researchers hypothesize that the sensory information created through walking or standing provides stimulation to the nerves in the low back region, which contains the nerves to stimulate bowel, bladder, and sexual function. Research has shown that bending and straightening the legs can be enhanced by how full the bladder is and the voiding of urine.

Epidural stimulation and body composition

One of the consequences of SCI is the loss of muscle mass below the injury and a tendency to accumulate fat inside the abdomen (abdominal fat or visceral fat) and under the skin (subcutaneous fat). These changes and lower physical activity after SCI increase the risk for several diseases.

A single (weak-evidence) study measured body composition in four young males with complete injuries. Participants underwent 80 sessions of stand and step training without epidural stimulation, followed by another 160 sessions of stand/step training with epidural stimulation. This involved one hour of standing and one hour of stepping five days a week. After all, training was complete, all four participants had a small reduction in their body fat, and all participants but one experienced an increase in their fat free body mass (i.e., the weight of their bones, muscles, organs, and water in the body) in comparison to their initial values prior to stimulation. While all participants experienced a reduction of fat, the amount of fat loss was minimal, ranging from 0.8 to 2.4 kg over a period of a year.

Epidural stimulation and pain

The first use of epidural stimulation was as a treatment for chronic pain in the 1960s. Since then, it has been widely used for chronic pain management in persons without SCI. However, it is important to recognize that the chronic pain experienced by those without SCI is different from the chronic neuropathic pain experienced after SCI. This may explain, to some extent, why epidural stimulation has not been as successful in pain treatment for SCI. The mechanism by which electrical stimulation of the spinal cord can help with pain relief is unclear. Some research suggests that special nerve cells that block pain signals to the brain may be activated by epidural stimulation.

There are a few studies focused on the role of epidural stimulation in managing pain after SCI. A number of other studies included a mix of different people with and without SCI. Because chronic neuropathic pain after SCI may not be the same as the chronic pain others experience, studies that do not separate mixed groups raise questions about the validity of findings. The number of individuals with SCI in these studies is often small, most were published in the 1980s and 1990s and so are quite dated, and the research is classified as weak evidence.

The results of this body of research show that some people may receive some pain reduction. Those who saw the most reduction in pain were individuals with an incomplete SCI. Also, satisfaction with pain reduction drops off over time. One study showed only 18% were satisfied 3 years after implantation. A different study looking at the long-term use of epidural stimulation for pain reduction found seven of nine individuals stopped using this method.

In the only recent study in this area, one woman with complete paraplegia (weak evidence) experienced a reduction in neuropathic pain frequency and intensity, and a reduction in average pain from 7 to 4 out of 10, with 0 being no pain and 10 being the worst imaginable pain. This improvement remained up to three months later after implantation of the epidural stimulation device.

It should be noted that the studies for pain place electrodes in different parts of the spinal cord compared to the more recent studies for voluntary movement, standing and stepping.

Refer to our article on Pain After SCI for more information!

Epidural stimulation and respiratory function

Using epidural stimulation to improve respiratory function is useful because it contracts the diaphragm and other muscles that help with breathing. Also, these muscles are stimulated in a way that imitates a natural pattern of breathing, reducing muscle fatigue. More common methods of improving respiratory function do not use epidural stimulation, but rather, directly stimulate the nerves that innervate the respiratory muscles. While such methods significantly improve quality of life and function in numerous ways, they are not without issues, including muscle fatigue from directly stimulating the nerves.

To date, most research into using epidural stimulation to improve respiratory function has been done in animals. Recently, research has been done in humans and weak evidence suggests that epidural stimulation may:

help produce a cough strong enough to clear secretions independently.
reduce frequency of respiratory tract infections.
reduce the time required caregiver support.
help individuals project their voice better and communicate more effectively.

Long term use of epidural stimulation shows that improvements remain over years and that minimal supervision is needed, making it suitable for use in the community.

Refer to our article on Respiratory Changes After SCI for more information!

Epidural stimulation and sexual function

The impact of epidural stimulation on sexual function has been a secondary focus in research studies looking at standing and walking. Currently, there are reports from one male and two females.

After a training program of walk training with epidural stimulation, one young adult male reported stronger, more frequent erections and the ability to reach full orgasm occasionally, which was not possible before epidural stimulation. However, this study looked at the effects of walk training and epidural stimulation together, which took place after several months of walk training without stimulation. Because the researchers did not describe what the individual’s sexual function was like after walk training, it is difficult to say how much benefit is attributed to epidural stimulation versus walk training.

In another study with two middle-aged females 5-10 years post-injury, one reported no change in sexual function and the other reported the ability to experience orgasms with epidural stimulation, which was not possible since her injury.

Refer to our article on Sexual Health After SCI for more information!

Epidural stimulation and spasticity

Botulinum toxin (Botox) injections and surgically implanted intrathecal Baclofen pumps are the most common ways to manage spasticity. Baclofen pumps are not without issues, however. Many individuals do not qualify for this treatment if they have seizures or blood pressure instability, and pumps require regular refilling.

Research in the 80s and 90s on the use of epidural stimulation for spasticity did not report very positive findings. It was noted that greater benefits were found in those with incomplete injury compared to those who were complete. Another paper concluded that (weak evidence) the beneficial effects of epidural stimulation on spasticity may subside for most users over a short period of time. This, combined with the potential for equipment failure and adverse events, suggested that epidural stimulation was not a feasible approach for ongoing management of spasticity.

More recently, positive results with epidural stimulation have been observed (weak evidence). This is likely due to improvements in technology, electrode placement, and stimulation parameters. Positive findings show that participants:

reported fewer spasms over 2 years
reported a reduction in severe spasms over 2 years
reported a reduction in spasticity
reported an improvement in spasticity over 1 year
were able to stop or reduce the dose of antispastic medication

For more information, visit our page on Botulinum Toxin and Spasticity!

Epidural stimulation and temperature regulation

In a study with a single participant (weak evidence) investigating walking, an individual implanted with an epidural stimulator also reported improvement in body temperature control, however details were not provided. More research is required to understand the role of epidural stimulation for temperature regulation.

Epidural stimulation and cardiovascular function

In severe SCI, individuals may suffer from chronic low blood pressure and orthostatic hypotension (fall in blood pressure when moving to more upright postures). These conditions can have significant effects on health and quality of life. Some recent studies have looked at how epidural stimulation affects cardiovascular function to improve orthostatic hypotension. Overall, they show (weak evidence) that epidural stimulation immediately increases blood pressure in individuals with low blood pressure while not affecting those who have normal blood pressure. They also showed that there is a training effect with repeated stimulation. This means that after consistently using stimulation for a while, normal blood pressure can occur even without stimulation when moving from lying to sitting.

Moreover, researchers are starting to believe that changes in orthostatic hypotension and blood pressure can promote changes in the immune system (Bloom et al., 2020). In the body, the blood helps to circulate immune cells so they are able to fight infections in various areas. One case study found that after 97 sessions of epidural stimulation, the participant had fewer precursors for inflammation and more precursors for immune responses. Although these changes are exciting, researchers are still unsure why this happens, and whether these effects occur with all people who are implanted with an epidural stimulator.

Refer to our article on Orthostatic Hypotension for more information!

Epidural stimulation and hand function

For individuals with tetraplegia, even some recovery of hand function can mean a big improvement in quality of life. Research into using epidural stimulation to improve hand function consists of one case study (weak evidence) involving two young adult males who sustained motor complete cervical spinal cord injury over 18 months prior.

The researchers reported improvements in voluntary movement and hand function with training while using epidural stimulation implanted in the neck. Training involved grasping and moving a handgrip while receiving stimulation. For 2 months, one man engaged in weekly sessions while the other trained daily for seven days. One participant was tested for a longer time as a permanent electrode was implanted, while the other participant only received a temporary implant. Both participants increased hand strength over the course of one session. Additional sessions brought additional gradual improvements in hand strength as well as hand control (i.e., the ability to move the hand precisely). These improvements carried over to everyday activities, such as feeding, bathing, dressing, grooming, transferring in and out of bed and moving in bed. Notably, these improvements were maintained when participants were not using epidural stimulation.

Epidural stimulation and movement: trunk control

Being able to control your trunk (or torso) is important for performing everyday activities such as picking things up or reaching for items. One study found that using epidural stimulation can increase the amount of distance you are able to lean forward. The improvement in forward reach occurred immediately when the stimulation was turned on. The two participants in this study were also able to reach more side to side as well, but the improvement was minor.

Epidural stimulation and movement: voluntary movements

Learning to make voluntary movements

Voluntary movements (i.e., being able to move your body when you want to) of affected limbs can occur with the use of epidural stimulation. Researchers are still unsure of the right training regimen to optimize results. For example, one study found that many sessions of step and stand training with epidural stimulation are required for participants to slowly regain voluntary movement of the leg and foot with epidural stimulation when lying down. However, another study found that participants were able to voluntarily move their legs with stimulation and no stand training though the amount each participant was able to move their legs with epidural stimulation varied greatly. For example, one participant was able to voluntarily move their leg without any stimulation after over 500 hours of stand training with epidural stimulation while another participant from the same study was not able to voluntarily move their leg without stimulation after training. Overall, more than 25 people can move some or all of their leg joints voluntarily from the first time they receive epidural stimulation.

More recently, research shows that some with epidural stimulators can produce voluntary movements without stimulation on and without any intensive training program. In one study, participants did not do a consistent intensive training program, although many of them attended out-patient therapy or did therapy at home. Over the period of a year, 3 of 7 participants were able to voluntarily bend their knee, and bend and straighten their hips. Additionally, of those 3 participants, 2 were able to point their toes up and down. While the number of people able to make voluntary movements without stimulation is small, many more studies are underway.

Epidural stimulation and movement: walking and standing

Recent research indicates that epidural stimulation can influence walking function in individuals with limited or no motor function. While these findings are exciting, researchers are still learning how to use stimulation effectively to produce walking motions. Before being able to walk again, people must be able to make voluntary movements and be able to stand.

Learning to stand

Some studies have also found that with extensive practice (e.g., 80 sessions), independent standing (i.e., standing without the help of another person, but holding onto a bar) may be achieved without epidural stimulation. Gaining the ability to stand may also occur with stand training combined with epidural stimulation. However, the findings with regard to the effect of stand training with epidural stimulation have been mixed. For example, one study showed that stand training for 5 days a week over a 4 month period with epidural stimulation resulted in independent standing for up to 10 minutes in an individual with a complete C7 injury, while another study has suggested that independent standing for 1.5 minutes can be achieved with epidural stimulation and 2 weeks of non-step specific training in an individual with complete T6 injury.

Learning to walk

Earlier research has found that epidural stimulation can help with the development of walking-like movements, but these movements do not resemble “normal” walking. Instead, they resemble slight up and down movements of the leg. Recent studies have shown that with 10 months of practicing activities while lying down on the back and on the side, in addition to standing and stepping training, people are able to take a step without assistance from another person or body weight support. While some individuals in these studies have been able to regain some walking function, they are walking at a very slow pace, ranging from 0.19 meters per second to 0.22 meters per second. This is much slower than the 0.66 meters per second required for community walking. For example, of the 4 participants in one study, two were able to walk on the ground with a walker, one was only able to walk on a treadmill, and one was able to walk on the ground while holding the hands of another person. These differences in walking abilities gained by participants were not expected.

In late 2018, one researcher demonstrated that constant epidural stimulation was interfering with proprioception, or the body’s ability to know where your limbs are in space, which ultimately hinders the walking relearning process. The solution to this problem involves activating the stimulation in a specific sequence, rather than having it continuously on. With this method and a year’s worth of training, participants were able to begin walking with an assistive device (such as a walker or poles) without stimulation. However, these individuals had to intensively practice standing and walking with stimulation for many months to produce these results. In these studies, one case of injury was reported where a participant sustained a hip fracture during walking with a body weight support. Further studies on how to individualize therapy will be necessary as the response to treatment in these studies varied greatly from person to person depending on the frequency and intensity of the stimulation.

Is it the training or the epidural stimulation?

Most of the stand/walk training conducted in the studies is with the use of a body weight support treadmill.

Arm and leg movement and blood pressure have been seen to improve with epidural stimulation, but the role of rehabilitation in these recoveries is unclear. Rehabilitation techniques can have an effect on regaining motor function. For example, step/walk training alone can help improve the ability to make voluntary movements, walking and blood pressure among individuals with incomplete injuries. In much of the current research, epidural stimulation is paired with extensive training (typically around 80 sessions) before and after the epidural stimulator is implanted. Furthermore, these studies do not compare the effects of epidural stimulation to a control group who receives a fake stimulation (a placebo) which would help to see if stimulation truly has an effect. Without this comparison, we are unable to clearly understand the extent of recovery that is attributable to epidural stimulation versus the effects of training. However, evidence now shows that voluntary movement and cardiovascular function can be improved from the first time epidural stimulation is used, if the stimulation parameters are specific for the function and person, which supports the role of epidural stimulation in improving function.

Costs and availability of epidural stimulation

Access to new medical treatment for those requiring it cannot come soon enough. Experimental therapies are typically expensive and not covered by health care. Rigorous and sufficient testing is required before treatments become standard practice and receive health care coverage. Epidural stimulation for improving function in SCI is a unique example because epidural stimulation technology has been used widely to treat intractable back pain in individuals without SCI. The benefit of this is that, if/when epidural stimulation for individuals with SCI is shown to be safe and effective, the move from experimental clinical practice could happen relatively quickly as a number of hurdles from regulatory bodies have already been overcome. That said, current barriers to accessing epidural stimulation noted in a survey study of doctors include a lack of strong evidence research showing benefits, a lack of guidelines for the right stimulation settings, and an inability to determine who will benefit from it.

In Canada, the cost for an institution to install an epidural stimulation system for back pain in those without spinal cord injury, which is a common procedure, was $21,595 CAD. The cost incurred by a Canadian citizen undergoing implantation in Canada is $0 as it is covered by publicly funded health care.

In the United States, the cost for an institution to install an epidural stimulation system for back pain in those without spinal cord injury ranged between $32,882 USD (Medicare) and $57,896 USD (Blue Cross Blue Shield). The cost incurred for American citizens in the US will vary widely depending on their insurance coverage.

In contrast, for individuals with SCI, an epidural stimulation system is reported to cost over $100,000 USD in Thailand, and higher in other countries. Prospective clients should be aware that the epidural stimulation offered by these clinics may not be the same as that in the research reported in this article.

The recommended course for those wishing to try epidural stimulation is to register in a clinical trial. Regardless, persons interested in pursuing surgery at a private clinic or registering for clinical trials will find it useful to refer to the clinical trial guidelines published by ICORD (https://icord.org/research/iccp-clinical-trials-information/) for information on what they should be aware of when considering having an epidural stimulator implanted. Research studies that involve epidural stimulation can be found by searching the clinicaltrials.gov database.