Sciatica Introduction, Causes, Symptoms, Diagnosis

Conditions & Diseases: Brain & Nervous System

Sciatica

Introduction & Overview

Sciatica is a persistent, low back neuralgic pain experienced anywhere along the sciatic nerve due to its irritation by inflammation, pressure caused by arthritis growths or displaced/herniated disk in the lower spine. The sciatic nerve is the longest nerve originating from the lumbosacral plexus, exiting the pelvis below the priformis muscle, entering the posterior compartment of the thigh between ischial tuberosity and the greater trochanter. The nerve descends through the posterior aspect of the thigh and divides into two components namely tibial and common peroneal divisions in the lower thigh innervating the hamstring muscles and all the muscles below the knee. Both the terminal branches contribute to the formation of the sural nerve (1) & (2).

Sciatica is also known as radiculopathy. Radiculopathy is a term used to describe pain, numbness, tingling and weakness in the legs. The nerve problem affecting the low back (lumbar region) is called lumbar radiculopathy (3).

Sciatica is a common problem in the US with incidences ranging from 1 to 10% (2).

Causes & Risk Factors

Causes:
Irritation or inflammation of the sciatic nerve causes sciatica. The following reasons could cause this irritation:

1. Pinching or stretching of sciatic nerve

2. A herniated disc or slipped disc.

3. Narrowing of the canal containing the spinal cord due to aging and overgrowth of bone is called spinal stenosis. This spinal stenosis puts pressure on the sciatic nerve leading to sciatica on both the sides of the back.

4. Sciatic nerve may experience pressure due to Spondylolisthesis, which is slipping of one backbone forward over another.

5. In Piriformis syndrome, the sciatic nerve gets trapped deep in the buttocks by the piriformis muscle causing symptoms of sciatica.

6. Osteoarthritis and osteoporosis caused due to aging can also lead to Sciatica.

7. The disease such as Lyme disease, fibromyalgia, pelvic infections, Reiter syndrome and various bacterial, viral or fungal infectious causing arthritis leading to sciatica.

8. Sciatica could also be caused due to tumor, blood clot or abscess (boil) (4).

Risk Factors:
Various risk factors could cause sciatica such as:

1. Age: Changes in the spine due to aging is one of the most common risk factors leading to herniated disk between 30 years to 40 years.

2. Occupation: People with jobs that strain the back, carry heavy loads, and drive motor vehicles for a long duration with limited rest are at risk of developing sciatica.

3. Physical activity: Walking and jogging is associated with sciatica. People with sedentary lifestyle and sitting for prolonged periods are likely to develop sciatica as compared to active people.

4. Genetic Factors: Two genes have been identified to cause disk problems.

5. Diabetes: Inappropriate blood sugar levels can cause a nerve damage leading to sciatica (5).

Signs & Symptoms

Common symptoms of sciatica are radiating pain from the lower back and spreading through the buttocks, leg, calf and sometimes the foot. The pain is generally dull, aching or burning - getting worse during nights and aggravated by motion. The pain could also worsen with prolonged sitting, standing, low sitting or standing up suddenly (such as standing up from a toilet seat). Worst pain is experienced by sneezing, coughing, laughing or hard bowel movement. Sciatica could also cause tingling, numbness or muscle weakness in the affected limb. Weakening of leg or foot could also be experienced along with the pain (1) & (4).

Medical Tests & Diagnosis Methods/Tools

Diagnosis of sciatica includes physical examination and medical history:

Physical Examination:
During a physical examination, the doctor tries to look for evidence of sciatic nerve injury or symptoms leading to the pain.

Medical Examination:
Firstly, the doctor reviews all the symptoms and later the medical history such as injury, fever and problems controlling bowels or bladder. In order to correlate the symptoms with that of physical examination the doctor would seek spinal X-rays, Computed tomography (CT) scan, Magnetic resonance imaging (MRI) scan (1).

Article by Kona Vishnu, MS
Medical Writer,
OmniMedicalSearch.com