Is Sciatica A Diagnosis Or A Symptoms Of An Underlying Medical Condition?

Sciatica is a pain radiating along the course of the sciatic nerve which runs from the lower back to the buttock, through the back of the thigh and into the lower leg and foot. Sciatic pain usually affects one side of the body. This pain is sometime called Lumbar radiculopathy or True Sciatica.

Sciatica is not a diagnosis as many people think but rather, it is a symptom of an underlying condition.

The sciatic nerve is a huge nerve which originate or arises from L4, L5, S1, S2, and S3 nerve. These five (5) nerve roots join together to form one huge nerve called the sciatic nerve. Each of the 5 nerves has its own dermatomel distribution, (ie, the sciatic nerve branches out in the thigh and the leg to give multiple muscular (motor) and sensory functions to specific areas and specific muscles in the leg and the foot). When a nerve is compressed, it gives pain and symptoms in a specific area depending on the nerve affected. This pain is called Sciatica or Sciatic pain.

Sings of sciatica

1. Patient experience pain that radiate from the lower back to the thigh, leg and foot.
2. Pain is worse when sitting {this is because, sitting places tension on the nerve or stretching which aggravate the sciatic nerve and worsened the pain }
3. The pain maybe sharp, shooting pain like electric shock that radiate to the leg and foot.
4. There may be burning, tingling pain and some numbness.
5. Patient may be unable to stand or walk and they may be some weaknesses.

Sudden movements, sneezing or coughing may also aggravate the sciatic nerve and make the pain worse.

The pain is better during walking or lying down, and the pain is worsened while sitting and standing.

Note: the symptoms of sciatica are felt in different areas of the leg and into the foot depending on where the sciatic nerve is compressed and which nerve root is involved.

Causes of Sciatica

1. Lumber disc herniation

 A disc is a cushion between the vertebrae. These vertebrae have a soft inner material that may leak out or herniate from the disc through a tear in the outer fibrous layer, becoming a disc herniation. Sciatica is one common symptoms of a lumber disc herniation. Usually, the disc will herniate in a posterolateral directions. The most commonly affected level is the L5-S1 which involves the S1 nerve root.

Note: the best examination for lumber disc herniation is the straight leg raising sign (Tension Sign).

There is pain and parathesia at 30 degree to 70 degree of the elevation. This elevation will reproduce the leg pain but not the back pain. The straight leg raising sign will usually diagnosis L5 or S1 radiculopathy.

MRI is the best study for diagnosing lumber disc herniation.

90% of the patient will improve within about one month with non-operative care such as

Rest, physiotherapy, and anti-inflammatory medication.

2. Degenerative disc disease

Osteophyte formation at the back of the spine is one of the disc degenerative diseases. Osteophyte forms because of the increase in the dermis joint surface area. It is most common form of unsatisfied arthritis. Osteophyte usually limit joint movement and causes pain. It forms naturally at the back of the spine as one ages and more sign of degeneration.

Symptoms includes pinch of the nerves as the osteophyte rotate. Pain radiate from spinal nerves to the extremities (leg or arm). Pain is associated with numbness, soreness or weakness in that same area.

Treatment includes, conservative approach, weight loss and exercise, anti-inflammatories and pain management.

3. Lumber spinal stenosis

Stenosis refers to an anatomical narrowing of the space between the vertebrae such as the spinal canal and nerve foramen.

Hypertrophy of the facet joints, hypertrophy of the ligamentum flavum, disc degenerative or arthritis are all example of conditions which constrict the nerve root canals causing compression of the spinal nerves and sciatica.

Note: patient will have back pain that is better with flexion, or leaning forward. The pain will be worse with the extension of the back. Patient will have leg pain, weakness, cramps, burning and heavy sensation.

Neurological examination is normal in over 50% of the patient and straight leg raising is rarely positive.  

      Differential diagnosis

Hip disease or arthritis

Metastatic disease

Vascular problems

Note: every case that you suspect to be lumber stenosis, suspect vascular problems (vascular claudication) and examine the pulse. In both of this cases, walking will cause symptoms. Sitting will relieve the symptoms of both conditions. Standing still will cause symptoms of lumber spinal stenosis but this relieve the symptoms for vascular claudication. Using a stationary bicycle will relieve symptoms of lumber spinal stenosis, however, it will aggravate the symptoms in vascular claudication.

4. Isthmic spondylolisthesis

This is characterized as anatomical slipping of one vertebrae in relation another. Typically in the lower spine, this condition can be developmental or acquired.

In other words, spondylolisthesis is a vertebral condition where one bone slides forward over the bone below it.

Note: it is not the disc slipping but rather the vertebral body. It usually occurs at L5-S1. Slippage occurs in 90% of pediatric cases. In adult, the slippage rarely exceeds 30% and it usually affects the L5 nerve root. 15% of patients with pars defect will progress to forward slippage.

This slippage places tension on the nearby nerve causing sciatica or sciatic pain. 

5. Piriformis syndrome

In this condition, the sciatic nerve can become irritated where it runs under the piriformis muscle in the buttock region. When the pirisformis muscle irritate the sciatic nerve, it causes sciatica. This is not a true lumber radiculopathy (true sciatica), however, it’s called sciatica.

Note: true sciatica is caused from the irritation of the verve roots due to disc problems (lumber disc radiculopathy). Pirisformis syndrome causes sciatica due to irritation of the sciatic nerve.  

6. Sacroiliac joints dysfunction (SI joint pain)

This does not cause true radiculopathy, however, the symptoms sometimes mimic radiculopathy or mimic pirisformis syndrome.

Note: the clinician should be aware that the symptoms associated with these 3 conditions which may overlap in symptoms and clinical presentation.

All the causes of sciatica indicate clearly that, sciatica is not a disease or diagnosis but rather a symptoms of an underlying condition.