Sciatica – Causes
Sciatica or lumbar radiculopathy is the condition caused by compression of the nerve roots in the lower back. The symptoms of Sciatica include pain in the lower back or buttocks that may radiate down the thighs, legs or ankles. The pain may be associated with feelings of numbness and tingling, or motor and sensory weakness in the lower extremities.
The Sciatic nerve is formed by the collection of nerve roots L4, L5, S1, S2, and S3. The nerve roots arise from the distal part of the spinal cord. The roots exit the vertebral column through neural foramen.
MRI showing the axial section of the lumbar spine with neural foramen narrowing.
The dural sac containing all the nerve roots from cauda equina lie inside the central canal. The central canal is bound by the vertebral body and the intervening intervertebral disc in the front and the lamina in the back. The facet joints are present near the neural foramen on the sides of the vertebral canal.
Any pathology leading to compression or irritation of the nerve roots L4 to S3 may cause symptoms of Sciatica. The symptoms may be acute and may last for a few days to weeks or may progressively worsen.
Herniated Intervertebral Disc
The herniation of intervertebral discs is the most common cause of sciatica symptoms. A bulging or herniated disc may press the nerve roots forming the Sciatic nerve.
The herniated disc may protrude and cause compression. The protrusion happens when the inner soft gel material is contained within the outer covering. In some cases there may be disc extrusion or sequestration. In disc extrusion, the inner nucleus pulposus herniates through the outer annulus but is still contained inside the disc space. In disc sequestration, the herniated disc material loses contact with the parent disc.
Furthermore, the symptoms depend upon the location of the herniated disc. In central disc herniation, the entire dural sac containing the nerve roots may be compressed. In cases where the herniation is paracentral or foraminal the disc material presses upon the traversing and the exiting nerve roots respectively.
Disc herniations may either be caused by age-related wear and tear of the spine known as degenerative disc disease. In the younger age group, the herniation may be a result of sudden trauma which may be sustained in a fall from height or in a motor vehicle accident. Disc herniations may also occur in patients involved in repetitive motion in the lower back.
The degenerative disc disease is caused due to loss of water content of the disc with growing age. The loss of water makes the disc less flexible and more prone to tears with day to day activities. Patients who are overweight, obese, smokers, and those participating in track and field sports are especially vulnerable.
Lumbar canal stenosis
The degenerative disc disease may lead to accelerated degeneration of the facet joints. There may be development of bone spurs and ossification of the ligaments in the vertebral column. The overgrowth of bone and calcification of ligaments lead to decreased space in the already precarious space available for nerves causing lumbar canal stenosis.
The symptoms get worse on bending backward or walking downhill as the ligament being the dural sac buckles to press on the sac. The neural foramen may also be stenosed causing nerve root compression as they exit the foramen.
Trauma and Tumors
Direct trauma to the nerve roots from accidental falls and motor vehicle accidents may cause Sciatica. There may be injury to the nerve roots from traumatic hip dislocations or inadvertently during surgery.
Rarely, tumors of the vertebral column and the spine in the lumbar region may encroach upon the nerve roots forming the Sciatic nerve. The compression of nerve roots by the tumor growth causes symptoms of Sciatica.
Malignant tumors of organs such as the prostate or breast may metastasize to the lumbar vertebrae and cause compression of the nerve roots. Primary spine tumors in the lumbar region such as bone cysts and osteoid osteoma may rarely cause Sciatica.
Spondylolisthesis
Spondylolysis is the break in the pars interarticularis that may cause the vertebrae to displace. The malpositioned vertebrae may narrow the space available for the dural sac and the nerve roots and cause symptoms of Sciatica.
Spondylolisthesis may result from degenerative changes in the spine, a traumatic or repetitive activity causing break of pars, or rarely a patient may be born with spondylolisthesis.
Other causes
A number of different conditions may cause Sciatica. The nerve may get entrapped in there piriform muscle as it exits the pelvic region. The nerve roots may also be irritated by infection of any structures close to them. Additionally pregnant females may experience Sciatica as the fetus grows or shifts. Inadvertent gluteal injections related to Sciatic nerve injury may also result in the symptoms of Sciatica.
Do you have more questions?
What causes sciatica?
Sciatica is caused by irritation and inflammation of the nerve root. This nerve root can be inflamed due to compression possibly due to disk herniation or a synovial cyst or an osteophyte. The injury is essentially a chemical injury due to decreased blood supply to the nerve root leading to inflammation.
Where is the sciatic nerve?
Sciatic nerve is formed by the fusion of multiple nerve roots in the lower back. These nerve roots come out at different levels and immediately after coming out merged to make a big nerve, which is called the sciatic nerve. This sciatic nerve travels along the back of the hip and the thigh up to the knee where it is divided into two main nerves, the common peroneal nerve and the tibial nerve. The sciatic nerve essentially supplies the muscles below the knee and controls the movement of the foot and toes.
How to sleep with sciatica?
Patients with sciatica may have difficulty sleeping, especially lying supine. They can put pillows under the knee to bend the knee and the hip and therefore, relax the sciatic nerve. Sleeping by the side with the knee and hip bent can also help.
What do you do for sciatica pain?
Sciatica pain is usually treated with the short-term rest, antiinflammatory medications in the form of Aleve or Advil, corticosteroid medications like Medrol Dosepak and physical therapy or chiropractic care. Patients who do not get relief may also need cortisone injection in the form of epidural or selective nerve root block.
Patients who do not get relief with all the above-mentioned treatments may need surgical intervention. Patients who also have worsening pain or neurological deficit in the form of weakness or involvement of bowel or bladder imbalance may also need surgical treatment as an emergency to stop the progression and optimized recovery.
How to cure sciatica permanently?
It is difficult to say that the sciatica can be cured permanently because it can happen at multiple levels and can have recurrence at the same level and on either side. Sciatica is essentially treated symptomatically initially, but may need surgical treatment to remove the compression on the nerve root. Even after the surgery, there are chances of recurrence at the same level as well as on the other side or at other levels, which may or may not be related to the initial sciatica.
Can sciatica cause hip pain?
Sciatic pain can radiate along the back or the outer aspect of the hip and can sometimes be confused with a hip pain and itself. Thorough history and examination by the physician as well as radiological examination in the form of x-rays and MRI may be needed to differentiate the two pains.
How to sit with sciatica?
Patients with sciatica may have difficulty sitting. Such patients should sit such that their knees are bent 90 degrees while they are resting on the floor. They should sit on a soft comfortable seat with the lumbar back support to support their back. These patients may need to bend forward a little bit to relieve the pressure over the nerve root.
Can sciatica cause foot pain?
Sciatic nerve presents with pain along the outer aspect of the back of the thigh, knee, leg and foot. Pain in the sole of the foot or on the dorsum of the foot involving either the outer toes or the inner toes may be related to sciatica on examination by the physician along with radiological examination may help find the cause of the pain.
Can sciatica cause groin pain?
Though the sciatic nerve runs along the back of the hip and can present with pain along the back of the hip and over the outer aspect of the hip, it is highly unlikely for it to cause groin pain. The groin pain can usually be caused by hip joint problems or issues like inguinal hernia. Occasionally compression of higher nerve roots, which suffered a femoral nerve can present with groin pain.
How do you know when sciatica is getting better?
When sciatica is improving, the pain that radiates from the back into the leg decreases in intensity as well as frequency. The tingling and numbness will also improve. The patient will have more relief and longer durations of pain free period. This is a good sign and indicates a path towards complete resolution of sciatica.
How to massage sciatica trigger points?
Occasionally, sciatica may be associated with the trigger points in the muscles on the side of the back or even into the hip area. Deep massage of these trigger points can help decrease the pain and relieve the spasm. The deep massage is usually done by another person with the use of the elbow or palm or the thumb. Knuckle of the fingers can also be used. There are many mechanical devices that are available in the market, which can also be used for deep massage.
Can sciatica cause calf pain?
There are multiple reasons for calf pain, one of the dreaded one is blood clots and should always be checked for sciatica. Especially the involvement of S1 nerve root can also cause pain along the calf. This pain is usually felt around the back of the thigh as well as the calf into the foot. If it is caused by sciatica, it may be associated with tingling and numbness and occasionally weakness.
Is sciatica permanent?
Sciatica is not permanent, though it can be a recurrent. Patients who have had one episode of sciatica are at a higher risk of getting recurrence over the period of months and years. If the patient gets relieved with recurrent episodes of sciatica in shorter duration of time then it can be still treated nonoperatively.
Patient who have recurrent or prolonged episodes of sciatica, not relieved medications and physical therapy or patients who have neurological deficit or worsening pain, may need surgical treatment.
Can the sciatica cause ankle pain?
Sciatica or lumbar radiculopathy causes pain radiating from the back or the hip into the lower extremities down the leg. The pain radiates along the back or the side of the thigh and leg and radiates down foot. An isolated ankle pain may not be caused by radiculopathy. If the pain is on outer or inner side of the ankle and is radiating down or coming from the top then it may be associated with sciatica or lumbar radiculopathy.
Can sciatica cause pelvic pain?
Occasionally, sciatica can present with pain in the back muscles only or the muscles of the hip. Such pain causes soreness or pain in one or both hips on the back or the outer aspect. Such pain can be confused with the pelvic pain. True pelvic pain will usually be on the front of the belly or on the side of the belly. These pains can also be confused with a hip pathology. A thorough history as well as examination with or without further imaging may be helpful to rule out pelvic cause, sciatica.
My name is Dr. Suhirad Khokhar, and am an orthopaedic surgeon. I completed my MBBS (Bachelor of Medicine & Bachelor of Surgery) at Govt. Medical College, Patiala, India.
I specialize in musculoskeletal disorders and their management, and have personally approved of and written this content.
My profile page has all of my educational information, work experience, and all the pages on this site that I've contributed to.
