Challenges in Diagnosing the Cause of Sciatica

The unique set of symptoms that describe sciatica can be produced by a wide range of lower back conditions, making it difficult to pinpoint a single test to detect the underlying cause. Masquerading symptoms, such as from piriformis syndrome or sacroiliac joint dysfunction, may feel like and clinically present as sciatica, making the diagnosis even more challenging.

Sciatica is characterized by a combination of symptoms and signs (radiculopathy) that originate from a problem in the lumbar and/or sacral spinal nerve roots. Research indicates that 60% to 84% of patients who seek treatment for sciatica have true radiculopathy, suggesting others have symptoms that simply mimic nerve root-related conditions. ¹ Trager RJ. Lumbosacral radiculopathy: Causes and mimics of sciatica and low back nerve root disorders. Integrated Clinics, LLC; 2015.

Diagnostic difficulties for the common causes of sciatica

Every potential cause of sciatica has its own set of challenges and possibilities for misdiagnosis.

Sciatica is often caused by a herniated disc or degenerative spinal stenosis in the lower lumbar spinal segments. ² Davis D, Maini K, Vasudevan A. Sciatica. [Updated 2020 Apr 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507908/ The challenges in diagnosing these conditions are:

• Symptoms may not match medical image test results. The medical image findings may not match the patient’s symptoms and signs. For example, during the initial stages of disc herniation, small tears in the disc’s outer layers, the annulus fibrosus, may leak out inflammatory chemicals that inflame the nearby nerve root. This inflammation may produce sciatica, but a confirmatory diagnostic finding may not support the symptoms. ¹ Trager RJ. Lumbosacral radiculopathy: Causes and mimics of sciatica and low back nerve root disorders. Integrated Clinics, LLC; 2015.
• Two conditions may be present at the same time. Sciatica from a lumbar herniated disc may produce similar symptoms as from degenerative spinal stenosis at the same level. It is possible for the image findings to show both conditions, but symptoms may be produced by only one of the conditions. ¹ Trager RJ. Lumbosacral radiculopathy: Causes and mimics of sciatica and low back nerve root disorders. Integrated Clinics, LLC; 2015.

Accurately diagnosing the cause of sciatica is essential for long-term pain relief because the treatment options primarily depend on the underlying cause.

Masquerading sciatica symptoms from pelvic and leg conditions

A variety of common and uncommon conditions affecting the lower back and legs may mimic sciatica pain and symptoms. A few common examples are listen below.

• Pelvic disorders related to the sciatic nerve. Piriformis syndrome and sacroiliac joint dysfunction originate in the pelvis and can cause pain similar to sciatica because they affect the sciatic nerve in this region. During an initial assessment, however, it may be difficult to differentiate true sciatica from these conditions.
• Peroneal neuropathy in the leg. When a branch of the sciatic nerve—the peroneal nerve—is affected, the symptoms may mimic those from a herniated lumbar disc or lumbar spinal stenosis at the L4-L5 or L5-S1 spinal segments. For example, L5 radiculopathy and peroneal neuropathy can result in a foot drop, leading to misdiagnosis. ³ Reife MD, Coulis CM. Peroneal neuropathy misdiagnosed as L5 radiculopathy: a case report. Chiropr Man Therap. 2013;21(1):12. Published 2013 Apr 22. doi:10.1186/2045-709X-21-12

Rarely, tumors, cysts, infections, cauda equina syndrome, and bone disorders may cause sciatica-like symptoms, which must be addressed on an urgent basis to prevent long-term complications. In addition to sciatica pain, these conditions may also cause troubling symptoms, including severe numbness, complete loss of sensation in the legs, and/or inability to control bowel and bladder movements.

See When Sciatica Pain Is a Medical Emergency

Arriving at a Successful Diagnosis for the Cause of Sciatica

Describing the exact symptoms and signs and accurately explaining the origin and course of the lower back and leg symptoms can help a doctor diagnose the underlying cause with precision. Doctors typically use several techniques to diagnose sciatica, ranging from an in-office medical examination to routine and elaborate medical tests, such as clinical tests, radiographs, MRI, and diagnostic nerve block injections.

After the cause of sciatica is diagnosed, a detailed treatment approach for the contributing condition is planned. Treatments typically start with nonsurgical methods but may include surgery for sciatica if nonsurgical methods fail to provide relief or if a medical emergency is identified.

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