Low back pain and sciatica: radicular pain

Type of pain
Radicular pain is often referred to as radiculopathy, and in lay terms is often described as sciatica. This type of pain is often deep and steady, and can usually be reproduced with certain activities and positions, such as sitting or walking. The pain usually follows the involved dermatome (the area of distribution of the leg covered by the specific nerve) – in the leg, this is usually the sciatic nerve. Radicular pain can be accompanied by numbness and tingling, muscle weakness and loss of specific reflexes.

Area of pain distribution
Radicular pain radiates into the lower extremity (thigh, calf, and occasionally the foot) directly along the course of a specific spinal nerve root. The most common symptom of radicular pain is sciatica (pain that radiates along the sciatic nerve - down the back of the thigh and calf into the foot). Sciatica is one of the most common forms of pain caused by compression of a spinal nerve in the low back. It may result from compression of the lower spinal nerve roots (L5 and S1). With this condition, the leg pain is typically much worse than the low back pain, and the specific areas of the leg and/or foot that are affected depends on which nerve in the low back is affected. Compression of higher lumbar nerve roots such as L2, L3 and L4 can cause radicular pain into the front of the thigh and the shin.

Diagnosis of radicular pain
A radiculopathy is caused by compression, inflammation and/or injury to a spinal nerve root in the low back. Causes of this type of pain, in the order of prevalence, include:

Herniated disc with nerve compression - by far the most common cause of radiculopathy
Foraminal stenosis (narrowing of the hole through which the spinal nerve exits due to bone spurs or arthritis) – more common in elderly adults
Diabetes
Nerve root injuries
Scar tissue from previous spinal surgery that is affecting the nerve root

Sciatica, the term that is commonly used to describe radicular pain along the sciatic nerve, describes where the pain is felt but is not an actual diagnosis. The clinical diagnosis is usually arrived at through a combination of the patient’s history (including a description of the pain) and a physical exam. Imaging studies (MRI, CT-myelogram) are used to confirm the diagnosis and will typically show the impingement on the nerve root.

Treatment of radicular pain
It is usually recommended that a course of conservative treatment (such as physical therapy, medications, and selective spinal injections, among others) should be conducted for six to eight weeks. If conservative treatment does not alleviate the pain, decompressive surgery, such as laminectomy and/or discectomy/microdiscectomy, may be recommended. This type of surgery typically provides relief of radicular pain/leg pain for 85% to 90% of patients. For patients with severe leg pain or other serious symptoms such as progressive muscle weakness, this type of surgery may be recommended prior to six weeks of non-surgical treatment. Back surgery for relief of radicular pain (leg pain) is much more reliable than for relief of low back pain.

The decision to proceed with back surgery is based on severity of leg pain and/or the presence of significant muscle weakness. It is important to note that if definitive nerve compression cannot be documented on an MRI or CT-myelogram, then back surgery is ill advised and unlikely to be successful.

Complete treatment options for radicular pain is beyond the scope of this article. More can be read about surgical and non-surgical treatments for radicular pain (sciatica) in the Sciatica and Microdiscectomy/discectomy sections of this site.

By: Ari Ben-Yishay, MD
Updated December 13, 2005
September 25, 2000