Electric shock down your leg? What is “sciatica”?
Author: Dr. Grace Lee MD
We often hear about the term – sciatica. It usually refers to the pain, numbness, tingling, or even weakness going down the back of the side of the leg to the foot or ankle – along the sciatic nerve. This neurological symptom is often quite alarming to people which brings them to their doctors.
“Sciatica” happens when there is injury or irritation to the sciatic nerve which is a thick nerve on each side of the body, originating in the buttock area, traveling along the leg, and branching into smaller nerve reaching the foot and toes. The medical term used specifically for symptoms described by “sciatica” is “lumbosacral radiculopathy”, which is a term that covers other nerve irritation in addition to the sciatic nerve. Sciatica often occurs with back pain.
Common Causes
1) Herniated/Bulging Disc
Discs are components of the spine that add cushioning between the bony vertebrae in order to help us bend and twist our backs. Discs have a tough outer shell and jelly-like centre. When the shell breaks, the jelly material can spill out and irritate the surrounding nerves. Sometimes, the disc bulges and presses on the nerves without breaking.
Sciatica from a herniated disc can come on more suddenly. Disc changes can be from an injury, normal wear and tear, or other diseases. Most people who have symptoms from a herniated disc get better on their own.
2) Spinal stenosis (narrowing of the spinal canal)
Inside the bony spine, there is a tunnel where the spinal cord resides called the spinal canal. The spinal cord is the collection of nerves. When the spinal canal becomes narrower (stenosis), the nerves get squeezed and irritated.
Spinal stenosis can be congenital or acquired. Degenerative arthritis is often the most common for people over the age 60. Obesity and family history can increase the risk. Injury can cause spinal stenosis as well. Sometimes it is the vertebrae slipping out of alignment causing the condition (spondylolisthesis). The prognosis for spinal stenosis from degenerative changes is usually benign, with symptoms mostly remaining unchanged or improving without surgical intervention.
3) Osteoarthritis and bone spurs
In addition to making the spinal canal narrower, degenerative changes of the bones (osteoarthritis) from natural wear and tear can also create bone spurs pressing on and irritating the nerves.
4) Degenerative disc disease
These discs that provide cushion between the bony vertebrae sometimes lose their height due to natural wear and tear. Since nerves travel out from between the bony vertebrae, when the vertebrae are stacked closer together because the cushioning is gone, the nerves can become compressed.
5) Other causes include direct injury to the sciatic nerve, tumors pressing on the nerve, or surrounding muscle spasms irritating the nerve (i.e. piriformis syndrome). It is important to check for numbness around anus (saddle anesthesia) and loss of bowel or bladder control because those symptoms may indicate the rare but much more serious condition called cauda equina syndrome which involves all the nerves at the end of the spinal cord.
Diagnosis and Tests
Since there are many potential causes of sciatica, and many symptoms (especially those occurring with back pain) that resemble sciatica can in fact indicate something else, it is best to discuss with a healthcare professional about your symptoms always. After asking many questions and conducting a physical exam, healthcare providers will decide on the plans based on individual situations. Sometimes, imaging tests are not needed for back pain until it has been going on for 4-6 weeks or unless there are red flags. This is because back pain symptoms do commonly get better with conservative treatment. Red flags on the other hand include acute injury, loss of bowel and bladder control, numbness around anus (saddle anesthesia), weight loss, unexplained fevers, history of cancer, HIV, osteoporosis, immunosuppression, on long-term steroid, IV drug use, progressing weakness/numbness, first-ever episode after age 50 – please tell your healthcare provider if you experience any of them. Common imaging tests are X-rays, MRI (magnetic resonance imaging), or CT (computed tomography).
Treatment
Conservative management is often the initial step to treat this condition. Pain medications such as NSAIDs (nonsteroidal anti-inflammatory drugs) like oral ibuprofen (Advil) pills and topical diclofenac gel (Voltaren gel) as well as acetaminophen (Tylenol) are often effective. Activity modification, physiotherapy, and gentle stretches that improve muscle flexibility are highly recommended. Patients are encouraged to reduce exacerbating physical activity especially during the first week of symptom onset and to avoid pain-producing activities. For symptoms that truly involve the sciatic nerve, patients usually find walking, lying down, and doing movements, such as press-ups, that extend the spine to be alleviating. Some patients also find ice and heat packs helpful.
If conservative management remains ineffective, spinal infections with corticosteroid that can decrease pain and inflammation as well as surgeries may be considered.
Legal Disclaimer
These articles are intended for general information purposes only. Readers are recommended to consult with their own healthcare providers regarding their own particular conditions. The views and opinions expressed by the authors do not necessarily reflect the policy or position of Assisting in Medical Expectations.
References
Hsu PS, Armon C, Levin K. “Acute lumbosacral radiculopathy: Pathophysiology, clinical features, and diagnosis” and “Acute lumbosacral radiculopathy: Pathophysiology, clinical features, and diagnosis” UpToDate.
Levin K, “Lumbar spinal stenosis: Pathophysiology, clinical features, and diagnosis” and “Lumbar spinal stenosis: Treatment and prognosis” UpToDate.
Johnsson KE, Rosén I, Udén A. The natural course of lumbar spinal stenosis. Clinical Orthopaedics and Related Research, 1992.
Website References:
HealthLinkBC “Sciatica” https://www.healthlinkbc.ca/health-topics/tp22229spec
Choosing Wisely Canada “Imaging Tests for Lower Back Pain: When you need them and when you don’t” https://choosingwiselycanada.org/imaging-tests-low-back-pain/
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