Sciatica: definition, main causes and forms of natural therapy treatments.
The spinal cord occupies the vertebral canal within the vertebral column, which provides support and protection. The cord is approximately cylindrical in shape and bears two enlargements, cervical and lumbar. The cervical enlargement extends from C4-T1 and innervates the upper limb via the brachial plexus. The lumbar enlargement extends from T9-T12 and is associated with innervation of the lower limb via the lumbar plexus (L1-L4) and the sacral plexus (L4/L5 & S1/S3). Caudal to the lumbar enlargement, the cord tapers to form a conical termination, (conus medullaris). From the tip of the conus a strand of connective tissue, (filum terminate), extends caudally and attaches to the dorsal surface of the 1st coccygeal vertebra.
Nerves to the Lower Limbs
These are derived from two plexuses, the lumbar and the sacral (lumbosacral plexus). The lumbar plexus arises primarily from the ventral rami of L1-L4. Its two chief branches to the lower limb are the femoral and obturator nerves, which pass to the anterior and anteromedial sides of the thigh, respectively, to supply the muscles there. The sacral plexus is formed by the union of the ventral rami from L5 and S1-S3, joined by branches of L4 and S4. Most branches of the sacral plexus pass posteriorly between the sacrum and the coxal bone. Branches from the lumbosacral plexuses supply the gluteals, pelvic muscles, the muscles about the hip joint, the muscles of the posterior thigh, and all the musculature of the leg and foot. They also supply selected cutaneous areas of the posterior thigh, the gluteals, the leg and foot. The largest portion of the plexus is continued down the posterior aspect of the thigh as the sciatic nerve (L4, 5; S1, 2,3).
The sciatic nerve is about 2 cm in diameter at its commencement (being the largest nerve in the body). It leaves the pelvis through the inferior part of the greater sciatic foramen and enters the gluteal region below the piriformis muscle. It runs inferiolaterally under cover of gluteus maximus, midway between the greater trochanter of the femur and the ischial tuberosity. The sciatic nerve rests on the ischium and then passes posterior to the obturator internus, quadratus femoris, and adductor magnus muscles. It emerges from the cover of gluteus maximus and for a short distance it is surrounded by only deep fascia, before it passes deep to the two heads of biceps femoris. In the thigh, the sciatic nerve provides branches to both heads of biceps femoris, semimembranosus, semitendinosus, and part of adductor magnus as well as articular branches to the hip joint. Then it travels vertically down the thigh to the apex of the popliteal fossa deep to the hamstrings. The nerve ends by dividing into the tibial and common peroneal nerves, usually in the lower third at the back of the thigh. The larger tibial nerve descends through the middle of the popliteal fossa and passes deep between the heads of gastrocnemius and soleus muscles. It lies on the posterior surface of tibialis posterior, and lower down the leg, on the posterior surface of the tibia. The nerve then passes behind the medial malleolus, between the tendons of flexor digitorum longus and flexor hallucis longus. It is covered here by the flexor retinaculum and divides into the medial and lateral plantar nerves in the foot. The smaller common peroneal (fibular) nerve arises in the lower third of the thigh and runs downward through the popliteal fossa, following the medial border of biceps femoris. It leaves the fossa passing behind the head of the fibula, winds laterally around the neck of the bone, and passes deep to peroneus longus, dividing into its two terminal branches: superficial peroneal and deep peroneal nerves.
Sciatica is a form of neuritis (nerve inflammation) characterised by severe pain along the sensory distribution of the sciatic nerve and its branches. It creates a stabbing-type pain generally in the gluteal region, particularly in the area of the greater sciatic notch, that extends mainly down the posterior aspects of the thigh, the posterolateral aspects of the leg and into the foot. The site for sciatica to occur is a disc lesion between L4 - L5 and L5 - S1.
Significant Causes of Sciatica 1) An intervertebral (IV) disc injury in the lumbar spine
An IV disc has an outer wrapping of tough, fibrocartilage (annulus fibrosis), which envelopes a soft, gelatinous centre (nucleus pulposis). This allows flexibility, resilence and shock absorption to the vertebral column. Disc lesions can be variable such as a protruded disc, which refers to eccentric accumulation of the nucleus pulposis with slight deformity of the annulus. If it protrudes postero-laterally, it will tend to put pressure on nerve roots. Another example is a sequestrated (ruptured) disc, where the nucleus pulposis has burst and leaked its contents into the surrounding area again running the risk of nerve root impingement.
Some Principal Causes of IV Disc Lesions
* Major trauma such as a lower back accident
*Weak, loose intervertebral ligaments (anterior and posterior longitudinal) whereby the spine is less stable and the risk of disc damage from everyday activity is higher
* Simultaneous lifting and twisting causing disc compression and torsion
* Age related disc degeneration where the nuclei of the discs are no longer as gelatinous because they have hardened and thinned
* Gross obesity causing excessive compressional forces on the discs
Signs And Symptoms of IV Disc Lesions
The IV discs are not innervated, so damage to the disc does not, in itself, result in the sensation of pain. The symptoms elicited are from the pressure exerted on surrounding ligaments and nerve fibres.
* Local and referred pain: There could be pain at the disc from the local inflammation and ligament irritation, as well as pain felt along the dermatome for the affected nerve roots (e.g. shooting, burning pains through the gluteal region and down the back of a leg). It should be noted that the sensory component of each spinal nerve is distributed to a dermatome, which is a well-defined segmental portion of the skin. The pattern of cutaneous innervation generally follows the segmental distribution of underlying muscle innervation. The dermatomes of the lower extremity are related to the development of the limb, as their spiral course in the lower extremity is an expression of the rotation of the limb as an adaptation to the erect position.
* Specific weakness in the muscles (myotome pattern) supplied by the affected nerve
* Paresthesia: Pins and needles' along the affected dermatomes
* Numblessness: which is a feeling of reduced sensation, but not completely absent sensation. It can a common symptom of ligament damage (which may accompany disc damage).
* Diminished reflexes in the lower extremity served by that particular nerve root. (e.g. absence of the Achilles tendon reflex (testing L5 and S1))
* Aggravation of pain by coughing, sneezing, straining and bending backward which are movements that increase abdominal pressure
* Spasms of the paravertebral muscles especially on the side of the herniation due to pressure on the spinal nerve root. Muscle guarding is an indication of the body attempting to restrict movement in order to allow time for healing to occur.
If related to a herniated disc, radiating leg pain is greater than back pain, and increases with sitting and leaning forward, coughing, sneezing, and straining. With annular tears, back pain is more prevalent and exacerbated with straight leg raising. A disc need not be completely herniated to provide symptoms. The fascial sheaths (epineurium) of the sciatic nerve are continuous with the dura mater. If the epineurium is pulled upon during a straight-leg-raising test, some degree of tension could be transmitted to the dura mater and thus to the nerve roots.
Some Natural Therapy Treatments
These depend on the severity of symptoms, type of exercise, occupation, and normal daily activities. In mild cases, treatment consists of minimizing the load on the spine.
* An educational component on postural and back mechanics
* Physical therapy to restore or improve spine and hamstring flexibility. In addition, abdominal and trunk extensor strengthening can be addressed following the resolution of a spasm and acute pain. Lifting, bending, twisting, prolonged sitting and standing aggravate the condition by increasing intra-discal pressure and thus should be avoided.
* Massage of the regions of referred pain and muscle spasms, which accompany this condition.
Compensation patterns that develop with chronic back pain can benefit from massage. Massage the lower back, gluteals, especially piriformis and the posterior surface of the legs.
* Ice/heat and transcutaneous electrical nerve stimulation (TENS)
* Gentle traction to the lower back and legs
This is osteoarthritis occurring in the vertebral column (especially cervical and lumbar) caused by degenerative changes in the joints of the spinal column compressing spinal nerve roots. Bony remodeling of the vertebral bodies and joints could lead to inflammation and restricted range of motion. Sciatica can occur by osteophyte (bony) growth in the exit area of the lumbosacral plexus.
Some Causative Factors
* Thinned IV discs, which are no longer elastic or resilient. The nucleus pulposis of the disc can calcify with the aging process.
* A complication of herniated discs
* Chronic misalignment of the vertebral column
Symptoms and Complications
Sometimes spondylosis is asymptommatic. Contacting bones respond by thickening resulting in osteophytes. These can grow inside joint capsules or in the intervertebral foramen, placing pressure on the existing nerve roots and emerging spinal nerves which could manifest as shooting pain, tingling, pins and needles, numbness, and specific muscle weakness.
* Spreading problems in the spine creating vertebral fusion through bony remodeling leading to instability and arthritic developments
* Secondary muscle spasms could accompany the nerve pain and may be confined to the paraspinals, where it may exacerbate the problem by compressing the affected joints, or it may follow the path of referred pain. Muscles may also go into spasm to guard vertebral column movement
* Blood vessel pressure due to osteophyte development leading to impaired blood flow
* Spinal cord pressure due to osteophyte growth. This could be felt as progressive weakening down the body, possible loss of bladder and bowel control, and even paralysis.
Treatment will depend on which (if any) complications are present and in severe cases may include surgical intervention such as spinal fusions and laminectomies to create more space for nerve roots or the spinal cord. If suitable for massage therapy, treatments could include, exercise and releasing restricting muscle spasms with massage.
3) Muscular Compression such as Piriformis Syndrome
The piriformis muscle originates on the ventral side of the sacrum, exits via the sciatic foramen deep to the iliopsoas muscle, and tracks deep to gluteus medius to insert on the superior aspect of the greater trochanter. The muscle serves as an accessory hip abductor and external rotator. Normally, the sciatic nerve passes through the sciatic notch beneath the piriformis muscle to travel into the posterior thigh. In some people, the nerve passes through or above the muscle, subjecting the nerve to compression from trauma or spasm of this muscle.
A history of prolonged sitting, overuse, a recent increase in activity, or gluteal trauma.
Resulting symptoms may mimic a herniated lumbar disc problem with nerve root impingement. The individual may complain of a dull ache in the mid-gluteal region, pain that worsens at night, difficulty walking up stairs or on an incline, and weakness or numbness along the back of the leg.
Low back pain is not usual. Muscular stiffness that worsens if chilled or when the weather changes, or increases when subjected to prolonged use is characteristic of muscle related disease.
Assessment reveals point tenderness in the mid-gluteal region and weakness on hip abduction and external rotation. The individual may stand with the leg in slight external rotation. Pain typically radiates into the gluteal and thigh region. A measurement of differential leg lengths could be made. Palpation in the sciatic notch may produce pain and/or discomfort, and may cause symptoms down the leg.
Some Natural Therapy Treatments
Treatment for piriformis strains could involve immediate ice, compression, elevation, and protected rest (RICE). After the acute phase, active stretching (e.g. PNF to piriformis, obturators (internus and externus) and gemelli (superior and inferior) which all abduct and rotate the thigh laterally, progressive resistance exercises, friction massage, and soft tissue mobilization.
4) Restrictions in the Fascial Sheaths Compressing the Sciatic Nerve Complex
Fascia is defined as a sheet or a broad band of fibrous connective tissue (CT) deep to the skin or around muscles and other organs of the body.
A) Superficial (subcutaneous) immediately deep to the skin is composed of loose CT and adipose and functions to store water, mechanical protection, and a framework for nerves and blood vessels to enter and exit muscles.
B) Deep fascia is dense, irregular CT that lines the body wall and limbs and holds and separates muscles into functional groups. It allows free muscle movement, supports nerves, blood and lymphatic vessels and fills spaces between muscles.
Regions of Fascia in the Lower Limb
The lower limb fascia consists of superficial fascia, which lies deep to the skin and contains loose CT that contains fat, cutaneous nerves, superficial veins (greater and lesser saphenous veins), lymphatic vessels, and lymph nodes. The superficial fascia of the hip and thigh is continuous with that of the inferior part of the anterolateral abdominal wall and the gluteals. At the knee, the superficial fascia blends with the deep fascia. The deep fascia is a dense layer of CT between the superficial fascia and the muscles. The deep fascia invests the lower limb like an elastic stocking and is called fascia lata in the thigh and called crural fascia in the leg. From the surface of the crural fascia, anterior and posterior intermuscular fascial septa pass deeply to attach to the corresponding margins of the fibula. These septa along with the interosseous membrane divide the leg into compartments.
At the ankle joint, the fascia blends with both the flexor and extensor retinacula. This is of great mechanical importance as the retinacula closely bind the assorted tendons, which pass across the ankle joint, to the underlying bony tissues of the joint and keep the tendons from bowstringing during dorsiflexion and plantar flexion. The deep fascia of the foot is thin on the dorsum of the foot where it is continuous with the inferior extensor retinaculum. Over the lateral and posterior aspects of the foot, the deep fascia is continuous with the plantar fascia (deep fascia of the sole). The central part forms the strong plantar aponeurosis.
Fascial Wrappings of Spinal Nerves
A sleeve of meninges (dura, arachnoid and pia mater) occurs at the point of exit from the spinal column through the intervertebral foramina. The dura mater fuses with the superficial CT covering of the entire nerve (epineurium).
Restrictions in the fascial sheaths can cause compression on the nerves (e.g. sciatic nerve complex) and could disturb the motor and sensory pathways in the lower limbs. Importantly, kinematic-skeletal distortions such as different leg lengths, vertebral column displacements (e.g. lordosis) or foot disorders (e.g. pes planus, pes cavus) reverberate up into the hips and can cause compressional and torsional forces on the sciatic nerve and its branches.
5) Pressure in the Sacral Plexus by a Tumour or Tumours in the Pelvic Area
6) Facet Joint Athropathy and Spinal Stenosis
Facet joints are joints between articular processes of vertebrae and spinal stenosis can occur due to a posterior displaced IV disc. Facet joint arthropathy could produce localized pain over the joint on spinal extension, and can be exacerbated with ipsilateral lateral flexion. If lumbar spinal stenosis is present, back and leg pain can develop after the individual walks a limited distance and concomitantly increases as the distance increases.
7) A Dislocated Hip Joint and Vertebral Subluxations in the Lower Lumbar Area
8) Intra-Uterine Pressure During Pregnancy
This could be due to intermittent intrauterine pressure resulting from the movement of the developing fetus inside the uterus moving across the sciaticnerve.
9) Vertebral Disc Degeneration
This can occur as the fluid content of the disc decreases, the disc becomes narrower so the space between vertebrae declines. Because spinal nerves exit and enter in the spaces between the vertebrae, this increases the likelihood of nerve root compression. These areas are where the spine moves the most: C6-C7, L3-L4, and L5-S1. The result is radiating nerve pain, often associated with protective and stabilizing muscle spasm or weakness, or both.
10) Sacroiliac Joint Disease
This can cause low back pain. It is a very strong joint responsible for the transfer of weight from the vertebral column to the hipbones. This joint is innervated by lower lumbar and sacral nerves so disease in the joint may produce low back pain and sciatica. In sacroiliac disease, pain is extreme on rotation of the vertebral column and is worst at the end of forward flexion. The latter movement causes pain, since the hamstring muscles hold the hipbones in position while the sacrum is rotating anteriorly as the vertebral column is flexed.
11) Trauma to the Main Branches of the Sciatic Nerve
* The common peroneal (fibular) nerve is a commonly injured nerve in the lower limb, mainly because it winds superficially around the neck of the fibula. This nerve may be severely stretched when the knee joint is injured. In addition, the sural anastomotic nerve from the common peroneal nerve joins the sural nerve so that there can be variable loss of sensation on the anterolateral aspect of the leg and the dorsum of the foot.
* The tibial nerve lies superficial to the popliteal vessels, so that an enlarging popliteal aneurysm may stretch the nerve. Pain is usually referred down the dorsal surface of the calf of the leg with possible loss of sensation on the sole of the foot.
12) Some Injuries That Could Cause Gluteal and Leg Pain
These can impact on the sciatic nerve and include sacro-iliac, sacrotuberous, and sacrospinous ligament tears and spasms of deep lateral rotator muscles (e.g. obturators, gemelli).
Patrick de Permentier | BSc (Hons), UNSW, MSc (Research), UNSW, Grad Cert H Ed (UNSW), Diploma Remedial | Massage (NSW School of Therapeutic Massage)
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|Author:||de Permentier, Patrick|
|Publication:||Journal of the Australian Traditional-Medicine Society|
|Article Type:||Disease/Disorder overview|
|Date:||Jun 22, 2018|
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