Sciatica

Sciatica is a spine condition characterized by nerve pain in the leg. The nerve roots, known as radicular nerves, make up the sciatic nerve and arise from the lumbar spine. Consequently, when there is damage to the nerve root, you may feel pain along the distribution of the sciatic nerve which runs, on either side of the body, from the back to the gluteal region and down the leg.    

What is the Cause?    

The most common cause of sciatica is a disc bulge. A disc bulge can cause the wall of the disc, called the annulus, to prolapse outward against the nerve root.    

In other cases, there can be a tear of the annulus and nuclear material exudes out of the disc—called a disc extrusion. This nuclear material is highly inflammatory and can therefore chemically irritate the nerve roots.    

There are many other causes of sciatica. Any spine condition that can injure the nerve root can cause sciatica. These include:  

• spinal canal stenosis,  
• spondylolisthesis,  
• ankylosing spondylitis,  
• and osteophytes (reactive bone growth from mechanical stress).  

What are the Symptoms?  

The symptoms for sciatica may include: 

• Back pain  
• Leg pain along the path of the sciatic nerve 
• Leg weakness especially of the ankles 
• Leg tingling or other nerve sensations in the region supplied by the nerve 

How is It Diagnosed?  

Sciatica is diagnosed by a clinical assessment and studies.  

• Physical Examination. Sciatica pain may with the straight leg-raise test, a maneuver that involves lifting the leg while the patient is lying down. When a disc bulge is the cause, an increase in leg pain from bending the spine is common from the hydraulic pressure upon the front of the disc. Bending the head forward is also common a common pain trigger from the increase in neural tension.  
• MRI. This procedure obtains detailed images of different spine tissues including the vertebrae, discs, nerve roots, and muscles. In many cases, it will visualize the anatomic problem responsible for your nerve pain.  
• Electrodiagnostic Studies. Comprised of electromyography and nerve conduction studies, these tests can assess the health of muscles and nerves affected by sciatica. They are helpful for clarifying the cause when more than one type of nerve problem may be present.  

How is it Treated?  

Non-operative therapy is the most effective form of treatment for most sciatica. There are several common injury mechanisms that worsen sciatica. These include bending the spine forward, compressing the spine, and combining the two. 

In cases of neural foraminal stenosis and spinal canal stenosis, extension is also an aggravator. The reason for this counterintuitive effect is extension narrows both of these regions where nerves travel. So while flexion and compression injuries are the originator of disc injury, extension is a common perpetuator.    

Done correctly, most cases respond best to a combination of physical therapy approaches:  

• Pain-trigger avoidance — avoiding the postures, motions, and loads that cause you pain.  
• Postural coaching 
• Movement coaching  
• Individualized exercise training 

Injections play a Role  

• Epidural steroid injections 
• Platelet-rich Plasma injections  

Decompressive Surgery 

• Discectomy  
• Laminectomy  
• Foraminotomy  

Burning Questions 

I have no leg symptoms—Is it sciatica if the pain is in my back only? 

Maybe.    

Sciatica pain can occur anywhere along the path of the sciatic nerve or the tiny nerve roots that connect together to form that nerve. Keep in mind that the spinal nerve and nerve roots are on the back also, not just the leg. Sciatica pain of this location is usually to one side and feels vaguely uncomfortable. It is readily confused for muscle pain. One indication that you are not having muscular pain is if pressing on the area of pain does not increasing your symptoms.    

I have leg pain only and no pain at all—is this still sciatica?  

Probably.  

Many disc injuries causing sciatica result in gluteal and leg pain only. The presence or absence of back-region pain are both common sciatica presentations.  

The pain is over the buttock only—doesn’t this prove that I have piriformis syndrome?  

Probably not.  

Compared with sciatica, piriformis syndrome is exceedingly rare. I know of seasoned spine clinicians who have seen only a handful of piriformis syndrome for their entire careers. A gluteal-only pain is, by contrast, an exceedingly common sciatica presentation. The clues that you have a sciatica presenting as a gluteal-only pain is evidence of damage to the L5 or S1 spinal nerve or its roots—most typically from a disc bulge.    

However…consider piriformis syndrome in the presence of:  

• Direct trauma to the gluteal region. Patient with piriformis syndrome often report direct trauma. For example, a fall onto their bottom. 
• MRI evidence of an anatomical anomaly in which the sciatic nerve pierces the piriformis. This congenital variation involves the sciatic nerve getting crushed when the piriformis is activated or spasms.  
•  A palpable tightness and your usual pain from pressing the gluteal region. This sign is possible in sciatica too.  
• The absence of nerve compression of the L5 or S1 nerve root. This scenario may suggest that the sciatic nerve is instead getting sensitized from a more distant site away from the spine.  

My MRI report said that I have spinal canal stenosis. But my sciatica is on one side only—isn’t spinal canal stenosis associated with pain to both legs?  

Not necessarily.    

The diagnosis of spinal canal stenosis indicates that there is a constriction within the central canal, where the spinal nerves travel. The constriction might be a bit more to one side of the central canal than the other so that the spinal nerve is affected on only one side.  

My MRI report said something about “neural foraminal stenosis”—what does that mean?  

The neural foramen is Latin for “nerve opening.” This tiny canal is on either side of the spine which forms the pathway for the spinal nerve root to exit the spine.  

To the front of neural foramen is the disc.  

To the back of the canal is the facet joint.  

A disc that bulges into the neural foramen can crowd the nerve root. So too can facet hypertrophy. Quite often, neural foraminal stenosis arises from a combination of both of these problems being present.    

McKenzie-based extension exercises are worsening my sciatica from a disc bulge—why is that?  

It’s complicated.  

One possible reason: extension postures and movements actually constrict the spinal canal and the neural foramen. If you have either of these problems, you are, quite literally, compressing the nerves further.  

Another possible reason: disc injury might cause instability and the extension forces are de-stabilizing the spine.    

There’s other possible reasons, but let’s just leave it at that for now.    

Should I get an epidural steroid injection?    

Maybe.    

An epidural steroid injection entails the placement of steroids, along with a numbing agent, into the region of the spinal nerves or its roots.    

The data for the effectiveness of this procedure is weak. According to Dr. Roger Chou, an epidemiologist from Oregon, the injections result, over average, in only very small and very short-lived pain reductions—less than 10% impact for less than a month.    

However…clinically, I have observed impressive results in a small minority. For the lucky few, an epidural steroid injection resolves most pain for many months.    

But…if you have a limited treatment response, no surprise there as that’s the norm.    

I’ve already tried everything, should I just get surgery?    

Not necessarily.    

Most surgery for sciatica is elective meaning you get the surgery when you can’t put up with the pain anymore.    

I’ve observed that most patients who have previously been told that they need surgery from a spine surgery can still be fixed with more insightful diagnostic and treatment.  
  

Select References 

Berry, James A., et al. “A review of lumbar radiculopathy, diagnosis, and treatment.” Cureus 11.10 (2019). 

McGill, Stuart. Low back disorders: evidence-based prevention and rehabilitation. Human Kinetics, 2015.   

Jim, Lysander. Specific Spine: A Doctor’s Guide to a Healthy Back. M.D. Muse Media, 2023.    

Clark, Rachel, Rachel Palmieri Weber, and Leila Kahwati. “Surgical management of lumbar radiculopathy: a systematic review.” Journal of general internal medicine 35 (2020): 855-864.   

Barr, Karen. “Electrodiagnosis of lumbar radiculopathy.” Physical Medicine and Rehabilitation Clinics 24.1 (2013): 79-91.