Sciatica is pain along the sciatic nerve, which runs from the lower back down each leg. Bilateral sciatica occurs when both sciatic nerves are affected, causing symptoms in both legs simultaneously.
Understanding Bilateral Sciatica
Sciatica results from irritation or compression of the sciatic nerve or its roots. While unilateral sciatica affects one leg, bilateral sciatica involves nerve root compression on both sides of the lower spine, causing symptoms in both legs.
The sciatic nerve forms from roots in the lower lumbar and sacral spine. Bilateral compression of these roots leads to symptoms in the buttocks and legs. This condition is less common than unilateral sciatica and often indicates more significant spinal issues.
Common Structural Causes
Several structural issues within the spine can lead to bilateral sciatica by compressing nerve roots on both sides. These conditions often involve degenerative changes that narrow the space available for the nerves.
Spinal stenosis, a narrowing of the spinal canal, is a common cause of bilateral sciatica. Central narrowing can compress multiple nerve roots on both sides, causing pain, numbness, or weakness in both legs. Age-related changes like thickened ligaments and bone spurs often contribute.
Spondylolisthesis, where one vertebra slips forward over another, can also cause bilateral sciatica. Significant slippage affecting both sides of the spinal canal can compress nerve roots bilaterally, leading to pain in both legs. This condition can result from degenerative changes, trauma, or congenital factors.
A severe central disc herniation can also cause bilateral sciatica. This happens when the disc’s inner material pushes out, directly compressing nerve roots in the center of the spinal canal. A large, centrally positioned herniation can affect nerve roots on both sides simultaneously, causing symptoms in both legs.
Critical Conditions and Other Causes
Some causes of bilateral sciatica are less common but may signify more serious underlying conditions that require prompt medical attention. Recognizing these signs is important for timely intervention.
Cauda Equina Syndrome (CES) is a medical emergency that can present with bilateral sciatica. It involves compression of the cauda equina, a nerve bundle at the lower spinal cord. Symptoms include new or worsening bladder or bowel dysfunction (e.g., difficulty urinating, incontinence) and saddle numbness (around buttocks, genitals, inner thighs). These additional neurological symptoms indicate a medical emergency.
Spinal tumors can also cause bilateral sciatica. Growths within or near the spinal canal can pressure the spinal cord or nerve roots, leading to bilateral symptoms. Their location and size determine the extent of nerve compression.
Spinal infections, like discitis or osteomyelitis, can cause inflammation and swelling within the spinal column. This inflammation can compress nerve roots, resulting in bilateral pain and other neurological symptoms. Infections may also weaken spinal structures.
Severe spinal trauma, such as from falls or accidents, can directly injure the spinal cord or nerve roots, leading to bilateral nerve damage. Fractures, dislocations, or significant soft tissue damage can cause immediate bilateral sciatica. Trauma can also lead to herniated discs or other nerve-compressing changes.
When to Seek Medical Attention
Timely medical attention for bilateral sciatica is important, as some underlying causes are serious and require immediate treatment. If bilateral leg pain develops or worsens, especially with specific accompanying symptoms, medical evaluation is advised.
Immediate medical attention is necessary if bilateral sciatica is accompanied by new onset of bowel or bladder dysfunction (e.g., difficulty urinating, incontinence). Other red flags include progressive weakness or numbness in both legs affecting walking or balance, or saddle numbness (groin and buttocks). These symptoms could indicate Cauda Equina Syndrome, requiring urgent diagnosis and treatment to prevent permanent nerve damage. Also, seek prompt medical assessment for any sciatica symptoms that begin after a traumatic injury, are severe and unrelenting, or are accompanied by fever, chills, or unexplained weight loss.