What is Sciatica?

Jul 29

Sciatica refers to a sharp burning pain that radiates down the back of the leg. It follows the path of the sciatic nerve, which runs from the lower back through the buttocks and down each leg. In most cases sciatica is present on one side of the body.

Sciatica usually develops from a lumbar disc herniation that compresses one of the roots of the nerve. This can cause inflammation, pain, numbness, and weakness in the leg and foot. Nearly 85% of sciatica cases are associated with a lumbar intervertebral disc disorder (1).

Most sciatica can resolve with conservative care, however more severe cases can significantly impair function. Leg weakness and changes in bowel or bladder function may require surgical intervention.

How Common is Sciatica?

Estimates of sciatica prevalence range widely, with studies claiming that as many as 43% of individuals will experience sciatica during their lifetimes (27). Sciatica is more common in those who live with chronic back pain.

Low back pain (LBP) is the leading cause of years lived with disability worldwide (7), and one of the most common reasons for seeking healthcare for musculoskeletal pain (8). Approximately 60% of patients visiting primary care with LBP report back-related leg pain (9).

What Causes Sciatica?

The sciatic nerve is a large structure, about the thickness of your thumb, that runs from the lumbar spine deep to the gluteal muscles and down the back of the leg. It splits into the posterior tibial and common peroneal nerves at the level of the knee. It supplies motor inputs to the muscles of the posterior thigh, and all the muscles of the leg and foot. It is composed of nerve fibers that originate in the lumbosacral nerve roots of the lower spine. The fourth and fifth lumbar nerve roots and the first two sacral nerve roots join in the lumbosacral plexus to form the peroneal and tibial nerves. These nerves join and exit the pelvis as the sciatic nerve, the largest nerve in the body (1).

Sciatica is overwhelmingly caused by an injury to an intervertebral disc. Discs sit between the bodies of vertebrae, and act as shock absorbers. They consist of an outer thick, fibrous annular layer, and a gel-like inner nuclear layer. Discs can be injured or degenerate with age. When the annular layer of a disc tears, the inner nuclear material can bulge and begin to irritate or compress nearby spinal nerve roots. Compression of a nerve root is called radiculopathy, and thus sciatica is also known as lumbosacral radiculopathy.

In most cases sciatica is caused by a herniated lumbar disc where the nerve root is compressed by disc material that has ruptured through its surrounding annulus (12). Rarer causes include degenerative spinal conditions including spondylolisthesis, lumbar stenosis, and foraminal stenosis. Cancer and malignancy can also cause radicular findings. In all these causes the lumbar or sacral nerve roots are compressed, which triggers inflammatory processes. Evidence suggests that it is not so much the pressure on the nerve root that causes sciatica, but rather a combination of pressure-related, inflammatory and immunological processes (10).

Current evidence indicates that proinflammatory chemicals called cytokines are a key mediator in the process of disc degeneration, as well as in the pain experienced by those afflicted with lumbar herniated discs. Activated immune cells release proinflammatory cytokines, which signal the brain about tissue damage. The brain responds by altering neural activity and promoting further production of proinflammatory cytokines within the brain and spinal cord. Increased local cytokine production by disc tissue irritates spinal nerve roots, resulting in pain and functional changes in neural activity (12).

What are the Symptoms of Sciatica?

The most common symptom of sciatica is sharp, shooting, or burning pain radiating down your buttocks and into the back of your thigh, and possibly into the foot. Pain can be dull and aching or debilitating for those who experience sciatica. Some individuals also experience muscle weakness in the affected limb as well, with foot drop being a common finding in advanced sciatica (26).

What are the Risk Factors for Sciatica?

Factors that increase the risk of developing acute sciatica include:

Age (peak 45-64 years)
Increasing risk with height
Smoking
Mental stress

Occupational factors that contribute to the development of sciatica include:

Strenuous physical activity—for example, frequent lifting, especially while bending and twisting
Driving, including vibration of whole body (11).

How Does Sciatica Affect the Brain?

Studies show only a weak correlation between the size of the prolapsed disc and the presence of sciatic pain. Since it is the brain that ultimately interprets pain, the research community has focused on studying pain-induced changes in the brain. A large body of new evidence supports the idea that chronic pain not only signals an altered functional state, but is also a consequence of central plasticity. This is to say that aspects of the brain that process pain become more sensitive, and more efficient, and thus harder to shut back off once a pain loop has wound up.

Imaging studies have shown structural alterations in the dorsolateral prefrontal cortices, basal ganglia and hippocampus of the brain, which have been implicated in abnormal pain processing.

This process is called central sensitization, a form of (maladaptive) central synaptic plasticity, and is a main cause for the development of chronic pain. Once chronic pain is generated, the increased sensitivity usually persists for an extended period of time, even though the underlying cause of the pain may have long since disappeared (6).

Chronic low back pain has been shown to promote neuronal cell loss and brain degeneration. Imaging studies of lumbar disc herniation patients have demonstrated significantly reduced gray matter volume in the right anterolateral prefrontal cortex, the right temporal lobe, the left premotor cortex, the right caudate nucleus, and the right cerebellum as compared to healthy controls. Increased gray matter volume was also found in the right dorsal anterior cingulate cortex, the left precuneal cortex, the left fusiform gyrus, and the right brainstem. Small subcortical decreases of the white matter were found adjacent to the left prefrontal cortex, the right premotor cortex and in the anterior limb of the left internal capsule. (13).

Additional neurodiagnostic studies have shown functional changes in the default mode network in chronic low back and sciatica patients (14). The default mode network is a widespread interconnected system in the brain that plays important roles in resting state cognitive and emotional regulation (15).

The decrease in functional activity and connectivity seen with chronic low back pain has been shown to lead to advancing neurodegenerative changes. Chronic low back pain sufferers have been shown on imaging studies to have lower cerebellar grey matter density compared to healthy individuals. Brain age is associated with lower gray matter density in numerous brain regions, and chronic lower back pain has been associated with greater brain aging (16).

How is Sciatica Usually Treated?

Sciatica is usually treated conservatively at first, with chiropractic manipulation, physical therapy, massage, and acupuncture. If these are unsuccessful, anti-inflammatory medications and analgesics are usually employed next, along with imaging studies including x-rays and lower back MRIs. If a disc herniation is identified, interventions may range from steroid injections to epidural and disc injections, nerve block injections, and ultimately, nerve decompression and discectomy surgeries.

How is the NeuroRescue Program Different?

We take both a comprehensive and a conservative approach to the management of sciatica. We generally begin by restoring appropriate biomechanical function with spinal manipulation and exercise therapies. Research shows benefits of combining spinal manipulation and a home exercise plan (3). More significantly, neuroscience literature shows that spinal manipulation is not only effective at reducing pain, but also at restoring brain activation and function. Research shows that the negative changes in the brain’s default mode network can be reversed by spinal manipulation in chronic low back pain and sciatica patients (17).

We employ additional structural therapies including lumbar traction to reduce nerve root compression by bulging or herniated discs. Studies show significant results with reducing back and leg symptoms from using lumbar traction therapy (4,5).

We often employ photobiomodulation strategies in the treatment of low back pain and sciatica, including low-level and high intensity laser and LED therapies. Research demonstrates that laser therapy can improve neuromuscular repair processes (18), accelerate the regeneration process of injured peripheral nerves (19), and be effective in the reduction of chronic lower back pain, particularly when combined with spinal manipulation (20).

We may also employ electrical therapies that have proven effective in reducing lower back pain and sciatica (21), or transcranial magnetic stimulation to reduce pain, as well as reduce depression and insomnia associated with chronic low back pain and sciatica (22). We may also address the inflammatory aspects of your condition with supplementation of polyphenols and associated nutraceuticals to further control your pain (23).

We may engage you in vestibular rehabilitation exercises to address the subclinical balance dysfunction seen in patients with lumbar instability (24), or eye movement exercises to address the vertical eye position anomalies and postural control deficiencies seen in low back pain patients (25).

Every nervous system is different, and so is every NeuroRescue Program. We do not take a cookie-cutter approach to treating sciatica and low back pain. Your protocol will be determined by the specifics of your neurodiagnostic findings and the unique factors of your case.

How Does the NeuroRescue Program Work?

We design your unique NeuroRescue Program to be among the most comprehensive diagnostic and therapeutic protocols available today. We create individual NeuroRescue Programs based on a comprehensive analysis of every relevant neurological system and pathway, using gold-standard, cutting edge neurodiagnostic technologies and examination procedures and state-of-the-art therapies.

We begin with your Discovery Day, wherein we perform a comprehensive history of not only your condition, but your life on a timeline. This allows us to dive deeply into your case and see all of the factors that led to where you are now. It helps us uncover hidden problems and associated conditions that may be making it difficult for you to move your recovery forward.

Our examination allows us to identify the areas and pathways of your brain that are involved in your sciatica and back pain. In all of our cases of lumbosacral radiculopathy, we begin by making certain that there are no central nervous system factors contributing to your symptoms. We do this by precisely quantifying the function of your visual, vestibular, and proprioceptive systems through computerized analysis of your eye movements, your inner ear reflexes, and your balance in a host of different sensory conditions.

We employ technologies including Videooculography and Saccadometry to measure several classes of eye movements. We use Video Head Impulse Testing to measure the function of your inner ear, and Computerized Dynamic Posturography to assess your balance in different sensory conditions.

We use NeuroSensoryMotor Integration testing to evaluate hand-eye coordination and cognition, and Virtualis testing to assess dynamic eye tracking and perception of vertical in a virtual reality environment.

We combine all of this with a comprehensive physical and neurological examination of your sensory, motor, autonomic, and cognitive systems. We review any relevant laboratory testing, radiological imaging, and prior neurodiagnostic testing, and integrate that information with our findings.

We use this information to identify which parts of your nervous system are working properly, which systems are struggling, and the precise point at which your systems fatigue.

We can then design a NeuroRescue Program that is unique and specific to your brain, and yours alone. Your NeuroRescue Program works to rejuvenate and reintegrate the damaged neurons and pathways in your central and peripheral nervous systems. It works to improve energy, endurance, and functional capacity within your involved fragile systems.

We use our technologies and procedures to not only see what we need to address, but also when it is time to stop and let you rest. We address your impaired neurological function from multiple angles of therapy, and provide metabolic support to improve neurological recovery.

While we cannot bring back neurons that have been lost, your NeuroRescue Program allows us to take the pathways that remain and maximize their efficiency and endurance. And by focusing on the integration of systems, we can do more than just get pathways working better, we can get them working together again. This gives us our best opportunity to return you to living a healthy, vibrant, and fulfilling life.