Patrick Thornley, MD, MSc, FRCSC, London Health Science Centre Combined Neurosurgical and Orthopaedic Spine Program, Schulich School of Medicine, Western University, Ontario, Canada.
Christopher S. Bailey, MD, MSc, FRCSC, London Health Science Centre Combined Neurosurgical and Orthopaedic Spine Program, Schulich School of Medicine, Western University, Ontario, Canada.

Abstract
Lumbar intervertebral disc herniations (IVH) carry a high lifetime prevalence and are the most common cause of sciatica. The vast majority of symptomatic lumbar IVH improve with conservative management though adjuncts such as physiotherapy and epidural steroid injections may play a role in short-term symptom relief. For patients with unresponsive lumbar IVH, discectomy reliably improves symptoms more rapidly than continued conservative care, though there is inconsistent evidence that clinical differences between operative and conservative care are no different at one-year after symptom onset.
Key Words: lumbar radiculopathy, intervertebral disc herniation; lumbar intervertebral disc herniation; lumbar disc herniation; sciatica.

Introduction:
The most common cause of sciatica, better termed lumbar radiculopathy is lumbar intervertebral disc herniation (IVH).^1,2 Lumbar radiculopathy is a common condition, carrying a lifetime incidence of 13 to 40%, with an approximate annual prevalence of 2%.^1,3,4 The most classic clinical presentation of lumbar radiculopathy follows a posterior/posterolateral leg pain distribution along the sciatic nerve distribution and may be accompanied by purely sensory and/or motor and reflex changes.^4,5 Lumbar intervertebral disc herniation refers to the displacement of intervertebral disc material beyond the normal confined margins of the disc space, exposing ruptured nucleus pulposus material to the lumbar neural elements.² In patients with symptomatic lumbar disc herniations, radiculopathy occurs via contact of the nucleus pulposus with a nerve root, which incites an inflammatory cascade that may be necessary for the creation of mechanical nerve root compression to cause pain.²

Most commonly lumbar IVH affects males in their fourth or fifth decade, with only about half of the patients recalling any inciting event.4 Etiologic studies have shown correlations to strenuous activity and smoking while additional research has demonstrated a genetic predisposition.^6,7 The natural history of IVH is clinically favorable for the vast majority of patients, with 70% of patients resolving most leg symptoms by six weeks.^2,3,6,8,9 The lumbar radiculopathy can be expected to improve with conservative care in 90% of patients within four months of symptom onset.⁶