Disc bulge, disc herniation, disc degeneration, sciatic pain, sciatic symptoms, upper limb pain, upper limb radiation, neck pain, back pain, radiating pain, lower limb pain, leg pain, muscle weakness, numbness, tingling, disc prolapse, disc protrusion
In a disc protrusion, also known as disc herniation or prolapse, the inner mass of the intervertebral disc, the nucleus pulposus, shifts towards the outer wall of the disc, causing it to bulge outward. Typically, the protrusion creates increased pressure and irritation on nerve roots, resulting in irritation and symptoms.
In addition to the increased pressure and irritation, the nucleus pulposus chemically irritates the nerve root. The intensity, location, and spread of pain and dysfunction caused by disc herniation depend on the location and size of the herniation, as well as other factors affecting the condition and inflammation of the nerve root.
Pain caused by disc protrusion differs in many ways from mechanical or nonspecific back or neck pain. Firstly, the pain is usually more intense in the limb than in the back or neck, surpassing the intensity of mechanical back or neck pain. Furthermore, the nature of the pain is neuropathic, accompanied by neurological or neurodynamic components.
Read more about neuropathic pain and pain mechanisms here.
Anatomy of the Intervertebral Disc
The intervertebral disc consists of a outer fibrous tissue (annulus fibrosus), a central core (nucleus pulposus), and two cartilaginous endplates. The discs play a crucial role in enabling movement between two vertebral bodies, providing support to the spine, absorbing spinal stress, and acting as shock absorbers during spinal loading.
The annulus fibrosus is composed of multiple layers of type I and II collagen, working together to reinforce the disc's wall and connect the vertebrae to each other.
The nucleus pulposus, in contrast, is a substantially gel-like structure compared to the annulus fibrosus. It allows for pressure to distribute evenly across the entire disc, preventing the development of load peaks and safeguarding the vertebrae from excessive stress. It also acts as a shock absorber, absorbing impact from bodily movements and maintaining separation between the vertebrae.
Over time, the water content of the nucleus pulposus decreases, causing it to become harder and structurally similar to the outer layer of the intervertebral disc. This is why disc protrusions and herniations are rare in individuals over 70 years old.
The cartilaginous endplates of the intervertebral disc separate the vertebral body from the disc itself and prevent the gel-like core of the disc from protruding into the vertebrae. These endplates also absorb the intense hydrostatic pressure exerted on the intervertebral discs due to mechanical loading of the spine.
Etiology
A disc protrusion occurs when a part or the entire core of the intervertebral disc bulges through its outer wall. The herniation process begins with the failure of the inner portions of the outer wall and progresses gradually outward. In the pre-herniation stage, known as disc protrusion, the nucleus pulposus has not yet advanced through all layers of the outer wall, resulting in a bulge that is flatter than a prolapse. The development of disc protrusion can occur suddenly or gradually over weeks or months.
The different stages of disc herniation as presented in the image are as follows: A: Protrusion, B: Prolapse, C: Extrusion, D: Sequestration.
Causes of Disc Herniation
The most common cause of disc herniation is the degenerative process as the nucleus pulposus loses moisture and weakens with age, leading to progressive disc herniation. The second most common cause is trauma.
Other causes include connective tissue disorders and congenital conditions, such as short vertebral pedicles. Biomechanical challenges and impaired pelvic and core control also appear to increase the prevalence of disc herniation in the lumbar spine.
In the case of cervical disc herniation, there is also a weak correlation with decreased upper thoracic mobility and impaired cervical spine control.
Disc herniation is:
Most common in the lumbar spine.
The second most common in the cervical spine. The increased prevalence of disc herniation in the lumbar and cervical spine can be partially explained by repeated biomechanical forces acting on these areas.
Disc herniations are less common in the thoracic spine. This is likely due, at least in part, to the relative stiffness of the thoracic spine and the additional support provided by rib joints and the ribcage.
Repetitive mechanical loading, such as twisting and bending of the spine, especially with impaired control, can lead to disc damage. Poor sitting posture, improper lifting techniques, biomechanical challenges, weak core control, restrictions in movement in the pelvic, hip, or thoracic regions, being overweight and smoking also appear to increase the prevalence of disc herniation.
The pathological process in a disc herniation
Compression of the nerve root or dorsal root ganglion typically causes dysesthesia in a healthy nerve, which is a reduction or alteration of sensation in the area innervated by that nerve. Nevertheless, in addition to these symptoms, disc herniation can also cause radiating nerve pain in the limb. Why is this?
The answer seems to be found in the inner mass of the intervertebral disc, the nucleus pulposus, which, when protruding, irritates the nerve root not only mechanically but also chemically. The nucleus pulposus appears to irritate nerve roots and dorsal root ganglia through inflammatory factors. In the epidural space, the nucleus pulposus also seems to be able to alter nerve conduction speed, even without mechanical compression against the nerve root. This chemical irritation seems to simultaneously accelerate the degeneration of nerve fibers and possibly alter the function and structure of the nerve root.
Increased pressure and compression on the nerve root seem to explain the numbness and decreased tactile sensation caused by a disc herniation, while chemical irritation and inflammatory factors directed towards the nerve root may account for the pain associated with disc herniation.
The interplay between mechanical compression and the inflammatory process is complex, but the released chemical factors during intervertebral disc damage appear to be crucial. Therefore, reducing or eliminating mechanical compression does not typically immediately alleviate symptoms, but addressing inflammation is also necessary for that to happen.
It's also worth noting that effective treatment of inflammation alone may be sufficient to reduce pain, even if nerve compression persists. However, prolonged increased pressure on the nerve or nerve root can damage the nerve, so addressing compression is necessary even if adequate treatment of inflammation is enough to eliminate radiating nerve pain caused by disc herniation.
You can read more about Sciatica and Sciatic pain here.
Epidemiology
The prevalence of a disc herniation is approximately 5-20 cases per 1000 adults annually, with the highest occurrence in individuals aged 30-50 years. In males, herniations seem to be more common than in females. Disc herniations in the lumbar spine are the most prevalent, with the two lowest discs, L4 and L5, protruding more frequently than other segments.
For cervical disc herniation, the most typical occurrences are in the lower part of the cervical spine, specifically in the C5-C7 segments. The majority of radiologically detected disc changes are asymptomatic. In other words, the mere observation of a protrusion in imaging is not a cause for immediate concern.
Symptoms
The symptoms caused by a disc herniation varies based on the location, size and other factors influencing the condition of the nerve root. Broadly, we can observe that a disc herniation in the cervical spine primarily causes symptoms in the upper extremities, while a lumbar disc herniation primarily causes symptoms in the lower extremities.
The symptom profile induced by herniations in the thoracic spine is often more diverse, occasionally leading to changes in the functioning of the autonomic nervous system. However, these are relatively rare compared to cervical and lumbar spine herniations, so I won't delve into this further in this text.
Regardless of the location of the disc herniation, nerve root irritation typically involves neurological symptoms such as:
Sensory disturbances within the dermatomal area innervated by the affected nerve. These disturbances can manifest as sensations of heat or cold on the skin, tingling or burning pain or a sense of numbness in the limbs.
Muscle-related symptoms may involve characteristic muscle weakness associated with nerve damage.
Changes in reflex activity, such as diminished or exaggerated reflex responses, may also be observed.
Here are typical symptoms and findings in disc herniations at different levels of the spine:
C5 Nerve Root:
Pain in the neck, shoulder, and scapular region.
Numbness on the outer side of the upper arm.
Weakness in shoulder abduction and external rotation, elbow flexion and forearm supination.
Diminished reflex response in the biceps and/or brachioradialis muscles.
C6 Nerve Root:
Pain in the neck, shoulder, scapula and the outer side of the upper limb down to the palm.
Numbness and possible tingling in the outer part of the forearm, thumb and index finger.
Weakness in shoulder abduction, external rotation, elbow flexion and wrist extension.
Diminished reflex response in the biceps and/or brachioradialis muscles.
C7 Nerve Root:
Pain in the neck, shoulder and middle finger.
Numbness in the index, middle and little fingers.
Weakness in elbow extension and wrist flexion.
Diminished reflex response in the triceps muscle.
C8 Nerve Root:
Pain in the neck, shoulder and the middle part of the forearm.
Numbness in the middle of the forearm and hand.
Weakness in thumb extension and ulnar deviation of the wrist.
There are no reflex changes associated with C8 nerve root irritation.
T1 Nerve Root:
Pain in the neck and forearm.
Numbness in the front of the upper arm and forearm.
Weakness in finger abduction and adduction.
There are no reflex changes associated with T1 nerve root irritation.
L1 Nerve Root:
Pain and sensory disturbances are common in the groin area.
Weakness in hip flexion may occur, but no reflex changes are observed.
L2-L3-L4 Nerve Roots:
Pain, tingling and sensory changes in the front of the thighs or shin area.
Possible weakness in the quadriceps and alterations in the patellar reflex.
L5 Nerve Root:
Pain, tingling and numbness in the leg or the area of the big toe.
Weakness in ankle dorsiflexion or big toe extension may occur.
Walking on heels may become difficult.
S1 Nerve Root:
Pain, tingling and numbness on the outer edge of the foot.
Difficulty in rising on tiptoes due to weakened calf muscles.
The Achilles reflex may not respond as expected.
S2-S4 Nerve Roots:
Deep-seated pain in the buttocks radiating to the back of the leg or perianal area.
Sensory disturbances in the buttocks, genitals, and perianal area.
Absence of anal sphincter reflex.
Treatment
The primary treatment for disc herniation is conservative in nature. Treatment involves a combination of pharmacological and non-pharmacological pain management methods, as well as physiotherapy. The majority of disc herniations heal on their own over time without surgery.
The goal of conservative treatment is to alleviate pain and promote functional and work capacity. This is achieved through guidance and counseling, a precise and progressive exercise program and a combination of manual therapy. Pain and anti-inflammatory medication should also be considered for the best possible treatment outcome. Exerting oneself against severe pain often complicates recovery and can, in the worst case, lead to chronic pain symptoms.
In medication, a combination of pain relievers and anti-inflammatory drugs is commonly used and potential inflammation can also be treated with cold therapy that is repeated several times a day. For more severe pain, the use of opioids or medications that raise the pain threshold are often considered.
Surgical treatment should be considered if desired results are not achieved with conservative treatment within a 3-6 months or if symptoms worsen.
Emergency surgery may be considered if a patient experiences rapidly progressing neurological changes, intense pain or symptoms of progressive paralysis in a limb. However, these cases are rare, and typically conservative treatment is continued for 3-6 months before potentially moving on to surgical interventions.
Physiotherapy
The content of physiotherapy varies based on symptoms, the area of pain and any clinically observed findings. Physiotherapy always begins with a thorough assessment of background factors, allowing for the development of an individualized rehabilitation program.
Physiotherapy content is designed on an individual basis, often including a combination of the following methods:
Manual Therapy: Soft tissue treatments and joint mobilizations to reduce muscle tension, promote fluid and blood circulation, and improve fascial function.
Movement and Posture Treatments: Aimed at promoting the mobility of nerve structures and reducing increased pressure or pinching on the nerve or nerve root.
Activating Exercises: Intended to promote fluid circulation and maintain muscle function.
Pain Management Techniques: Use of heat or cold therapy, manual therapy, acupuncture, or self-directed exercises.
Biomechanical Assessment and Treatment: Identifying and addressing biomechanical challenges to reduce peak loads and enable decreased strain on irritated tissues.
The combination of manual therapy, home exercise programs, and time has been shown to produce positive results in the treatment of disc herniation. However, the effectiveness may depend on the size, location, and other general health-related factors of the herniation.
Here are a few additional physiotherapy treatment methods and their primary goals in the management of disc herniation:
Progressive training and load modification aim to:
Manage the overall load on the body.
Alleviate pressure and stretching on sensitive nerve tissues.
Increase fluid and blood circulation to enhance nutrient and oxygen supply to irritated tissues.
Provide relief from discomfort.
Improve sliding properties of irritated nerves by neural tissue mobilization with specific exercises.
Manual therapy aims to:
Provide relief from pain and activate pain-modulating pathways.
Reduce friction and compression on the irritated nerve
Decrease muscle tension by relaxing tense muscles.
Improve muscle and joint performance by enhancing the function of muscles and joints.
Decrease cortisol release in treated tissues.
Enhance blood flow in the targeted areas.
Enhance range of motion.
Reduce the disruptive nature of pain by lessening the impact of pain.
Education and guidance aim to:
Offer information about the nature of the issue, its underlying factors, and the rehabilitation process to ease patient concerns and improve self-efficacy.
Share knowledge about the healing process and prognosis, motivating patients for self-guided rehabilitation.
Address factors influencing prognosis and discuss factors that positively or negatively affect the treatment prognosis and timeline, reducing patient uncertainty and concerns.
Improve coping mechanisms for living with pain.
Read more about the effectiveness of manual therapy and the methods used here.
Self care
If you suspect you have a herniated disc, I recommend contacting a healthcare professional before taking on any vigorous self-care measures. However, you can still initiate self-treatment with the following self-care tips, as long as they do not exacerbate your symptoms.
Avoid provoking activities: Identify activities that worsen your symptoms and try to avoid them. Typical aggravating factors include prolonged sitting, excessive physical exertion, heavy lifting or prolonged immobility.
Change positions regularly: Avoid sitting or standing in the same position for too long. Change your position regularly to prevent additional compression or tension on nerves and nerve roots.
Use proper lifting techniques: Lift objects by kneeling and using your leg muscles instead of your back. Avoid lifting heavy objects if possible.
Activate core muscles: Perform exercises that promote core control and muscle work. A well-activated core provides better support for your spine and may help alleviate symptoms caused by lumbar disc herniation.
Relax muscles: Pain often causes increased muscle tension as a protective mechanism. Practice relaxation exercises regularly.
Gentle stretching: Engage in gentle stretching exercises, but be cautious if they cause pain or worsen symptoms—skip them in such cases, as muscle stretching can sometimes exacerbate nerve pain.
Low-impact exercise: Include low-impact exercises in your daily routine. Good options include walking, swimming or water aerobics, using a cross-trainer, or light bodyweight exercises.
Rest: Ensure you get enough rest and sleep. Adequate sleep and rest improves recovery and accelerates tissue healing.
Reduce stress: Consider stress-reducing techniques such as deep breathing, meditation or yoga. Stress management can positively impact overall well-being and may often alleviate nerve-related symptoms.
Remember, it's crucial to consult a healthcare professional for an accurate diagnosis and discuss suitable self-care strategies based on your individual situation. If symptoms persist or worsen, seek medical attention from a doctor or physiotherapist.
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