Sciatica

Overview of sciatica

The World Health Organisation (WHO) records have shown that nearly 50% of the global population suffers from musculoskeletal disorders or pains. Many of these disorders are associated with spinal cord injuries that may or may not arise from problems of the central and the peripheral nervous systems. Sciatica is one such disorder that causes lower back pain and pain in the extremities. It is one of the primary spinal defects and around 90% of the time, the disease occurs due to dislocated discs. It may also manifest as a birth defect in many cases. At present sciatica is one of the primary contributors to the increasing global burden of spinal cord diseases and back pain.

What is sciatica?

Sciatica is a type of pain that affects the sciatic nerve and affects the lower back and the legs. It begins as a sharp shooting pain near the lower back and slowly radiates to the lower extremities.

The pain mostly arises from an excess pressure on the sciatic nerve due to muscle strain, bone spur, and herniated discs.Typically, the pain is unilateral that is, only one side of the lower body is affected.

Further investigations have also revealed that this pain arises from sciatica in most cases.

What causes sciatica?

Sciatica is caused by a number of physical and environmental factors. The commonly studied causes are given below-

• Spinal disc herniation: Sometimes the gel-like centre of any spinal disc can rupture through any weak spot in the disc wall and exert pressure on the nerves. This causes disc tear and a swelling of the surrounding tissues. The maximum pressure is felt on the sacral and the lumbar nerve roots, that manifests as lower back pain.
• Stenosis: Compression of the spinal cord and the associated nerves may occur in many cases due to constriction of the bony canals in the spine. This condition may arise mainly due to lumbar spinal stenosis where the cauda equina, spinal cord and the sciatic nerve roots get compressed. There is another condition which may give rise to sciatica pain. It is known as spondylolisthesis that causes inflammation of the spinal cord and reduces available space for it. Pinching and irritation of the nerves occur in this case.
• Piriformis syndrome: People having this syndrome have spasms or tightening of the piriformis muscle, which arises from overuse or trauma. In 17% of these cases, the sciatic nerve runs through the piriformis muscles and not below it. This gives rise to compression and muscle spasms. Two situations may occur in this case. One is when the nerve root itself remains in normal condition with no herniation of discs. The other one is known as “wallet sciatica” as the wallet presses on the buttock muscles and the sciatic nerves when the person sits down.
• Osteoarthritis: Osteoarthritis is the erosive degeneration of the joints, cartilages, soft tissues and bony outgrowths of the knee, ankle and other joints of the body due to age. In many patients, the discs may get dried out and may shrink. Mild to severe tears may take place in the disc wall which manifests as pain at the base of the spinal cord. An abnormal thickening of the ligaments, enlargement of the joints and formation of bone spurs may take place in due course of time that may aggravate the existing conditions.
• Spondylolisthesis: In this condition, the patients may experience a weakness or stress fracture in the facet joints. This may cause a vertebra to slip out of position and pinch the neighboring nerves.
• Pregnancy: During pregnancy, the weight of the fetus on the spinal cord causes pinching of the sciatic nerves and the other nerve roots. This may give rise to cauda equina syndrome which is accompanied by pain in the hips and the feet, loss of bladder and bowel control and muscle weakness.

Other risk factors for sciatica include but are not limited to –

• Aging
• Obesity
• Occupational hazards
• Long periods of sitting or standing
• Diabetes
• Presence of tumors (exerts stress on the nerve roots and the spinal cord)
• Problems in the sacroiliac joint

What are the main signs and symptoms of sciatica?

Sciatica is characterized by a number of signs and symptoms which may often mimic the symptoms of other diseases. Hence a clear identification of the following warning signs is necessary in order to detect the disease at an early stage–

• Pain and pinprick sensation on the exterior portion of the calf
• The pain may extend till the space between the little and fourth toes
• Difficulty walking on the heels or toes
• Burning sensation that starts at the back of the thigh and the calf down to the heels
• Stiffness in the legs
• Pain in the buttock after long periods of standing or sitting

What are the different types of sciatica?

Sciatic pain is classified into the following types-

• Acute sciatic pain: It has a sudden onset and heals within a very short time. It results from injuries to the tissues, muscles, ligaments, discs and the nerves.
• Chronic sciatic pain: It persists for more than 3-4 months and is of idiopathic nature. Chronic pain generally worsens with activities.

What are the different diagnostic tests for sciatica?

The most popular test for sciatica is the Lasegue’s sign which is done by asking the patient to raise the leg between 30 and 70 degrees. Other imaging tests such as CT scan and MRI scan may also prove to be effective. 

What treatments are available for sciatica?

Treatment of sciatica involves administering pain relieving drugs such as NSAIDs (no-steroidal anti-inflammatory drugs) or muscle-relaxants.

Physiotherapy is has been shown to be effective in case of sciatica.

Alternating between hot and cold compressions can also be helpful.  Additionally, the patient can also refer to acupuncture, osteopathy, chiropractors, and special massages to get rid of the symptoms.  In extreme cases, where the pain is unbearable and prolongs for longer period of time, then surgical intervention might be required. The surgery is aimed at decreasing the pressure on the sciatic nerve.

Sciatic pain can be prevented by following basic steps such as maintaining the right kind of posture during sitting, standing, and sleeping, not sitting for too long, having a physically active lifestyle. Always practice safe lifting techniques. Use ergonomically designed chairs which provide proper support to the spine. Maintain a healthy body weight and refrain from engaging in smoking and drinking.

References