Dr. Katherine Mullen, DC, MS
Low back pain is one of the most common injuries someone will experience in their lifetime. According to the American Chiropractic Association (ACA), around 80% Americans will experience low back pain at some point in their lifetime. It is also one of the leading causes for missed work, which can account for over 264 million days lost at work in 1 year. Herniations in the lumbar region are also quite common. Most lumbar disc herniations occur between the ages of 30-55 years old. They can account for around 85% of patients presenting with symptoms of sciatica. Around 25% of adults who are >60 years old will have a herniated disc, but the vast majority of these individuals will be asymptomatic.
What causes a lumbar disc herniation
There are many different ways a disc injury can occur. The most common way to injure the low back is with flexion (bending forward) and a combination of flexion and rotation. It can occur with one incident, such as sudden trauma (weightlifting, sports impact, car accident, lifting an object up off the ground, coughing, sneezing, etc.). Size and weight of the object does not matter, body weight alone is enough to cause a disc to herniate in some circumstances. Disc herniations can also be a result of repetitive microtrauma, such as repetitive lifting with the back, poor biomechanics, or poor ergonomics. Sustained postural load is the most common way to injure the low back.
Anatomically, what happens during a disc herniation?
The intervertebral disc (IVD) sits in between 2 vertebrae of the spine. It absorbs energy like a shock absorber. This allows it to be able to distribute loads along the spine in a more equalized manor. The outer layer of the disc consists of fibers called annular fibers, which consist of 100 alternating concentric rings around this disc. There are inner layers which are closer to the nucleus pulposus (innermost aspect of the disc that is made up of 80-90% water) and move outwardly. In healthy and uninjured discs, only the outer ⅓ is innervated by pain receptors, aka it is poorly innervated. In injured discs, the pain fibers can grow into the inner rings of the fibers at a higher density and distribution than normal, resulting in a higher likelihood of pain perception due to higher ability to transfer nociceptive (perception of a painful stimulus) information compared to a healthy disc.
Positions we put our body in daily such as flexion and lateral flexion create both tensile and compressive forces on the disc. Flexion specifically causes tensile stress on the fibers located on the back (posterior) part of the disc, which is the most common location for a disc herniation to occur. The location of the herniation is actually opposite of the load. So when we sit in a flexed position for a long period of time day after day, we are creating a constant stress in the front of the disc, causing the disc material to protrude posteriorly. This is why sustained postural load over time can create a bulge or herniation, instead of the single traumatic event that most people expect to cause a herniation. The images below illustrate this concept.
Depending on the severity of the tear, the inner disc material (nucleus pulposus) can migrate out and press on the nerve root coming out of the spinal canal. It creates irritation and inflammation and symptoms such as radiating pain to the hip, buttocks, and/or leg. Symptoms of this include general pain, numbness, pins and needle type sensations, or weakness in the legs. Radicular pain starts proximally, aka close to your spine in the glutes or thigh, and expands distally, farther down the leg and even into the toes. The pins and needle type sensation usually starts lower down in the shin, feet or toes and expands up the leg.
A. Photo referenced from University of Western States Tissue Biomechanics III class notes by Dr. Betsy Mitchell
B. Photo referenced from spineuniverse.com
How are disc injuries/herniations diagnosed?
Most of the time, a diagnosis of a disc herniation, bulge, injury, etc. comes from the history and physical exam. When and how the injury occurred, quality of pain, pattern of pain, presence of leg pain, neural tension tests and neurological abnormalities such as reflexes, loss of sensation, and muscle strength all play an important role in diagnosis. We are able to diagnose a likely disc herniation without advanced imaging, but it can be helpful to confirm this diagnosis with an MRI. An MRI can also help us with prognosis and treatment plan as it illustrates the level severity of the herniation.
When bending down to pick something up, putting on socks in morning, or even sneezing can cause a jolt of pain to be sent through your low back. This sensation is usually very unfamiliar so it causes all sorts of thoughts to go through your head as to what could cause so much pain with such a simple movement. You are not alone. As stated above, up to 80% of the US population is in the exact same boat at some point in their lifetime. It is very common to experience this. With that being said, there is great variability with symptom presentation after a disc injury or herniation. This is dependent on where the herniation is located in the spine, severity, size, and if nerve involvement is present. It sometimes even takes a few hours or days for the symptoms to settle in and worsen.
Let’s talk nerve involvement
Not every herniation causes enough tears in the annular fibers to cause the disc material to protrude onto the nerve. In these cases, patients might just have back pain or no pain at all. In other cases where there is irritation or inflammation around the nerve root, there can be leg pain, numbness, pins and needles type sensations, and weakness into the leg. This presentation follows something called a dermatome, which is where branches of a single spinal nerve root supply an area of the skin. This is why you only feel pain, numbness or tingling on the outside of your thigh, inner calf, or just certain portions of the foot and toes.
Is it your sciatica or is that pain pattern actually coming from the back?
It could be either. The pain down the leg could be coming from a lesion of the sciatic peripheral nerve or from irritation or inflammation around the nerve roots of the lower lumbar spine. In most cases, it’s coming from the nerve roots. People categorize their pain as “Sciatica” because it follows the distribution of the peripheral nerve, aka there is pain in the bottock, down the back of the leg and crossing the knee.
What other symptoms come with disc herniations?
Most people describe the pain, especially their leg pain, as sharp, stabbing, electric like pain. It is worsened with bending forward to touch the toes, sitting, standing for long periods of time, laying down, coughing or sneezing, lifting objects off the ground, and bearing down when going to the bathroom. In the acute phase, most patients are stuck in a slightly flexed position and have a decrease in the lumbar lordotic curve due to muscle splinting and compensation of pain.
If you have any symptoms of significant weakness in the lower extremities, loss of sensation in the genital area, and/or no control of your bowel or bladder, immediately go to the emergency room.
What is pain centralization and how does it relate to disc herniations?
Pain originating from the spinal nerve root causes radiation of pain down the leg. Centralization is where the pain retreats back up the leg with movements of repetitive end range loading.
To understand why this happens, we need to back up and think of how the body knows where pain is and how to control the body. In order for your brain to control any part of your body, it has to receive sensory information and that sensory information needs to be mapped out. These maps can be very complex or very simple depending on the needs. For example, the maps of your hands are very complex due to all the different movements they can achieve. Your back, on the other hand, has a very simple map. Inflammation from a disc herniation causes alterations in sensory information going up to the brain. This alteration in sensory information can lead to a smearing of these maps. So while your back is the place of injury, the smeared map can now extend greater areas, i.e your glutes, thighs, etc.
The way we fix sensory maps are 2 fold: 1. Decrease inflammation to stop the alteration of sensory information 2. Use the body part as best we can to remap the back. We do both of those things through movement. Movement pumps in fluid to bring in nutrients such as antioxidants as well as white blood cells while also removing cellular metabolites and cellular debris. Movement also helps us remap the back by providing proprioceptive stimulation, aka allowing your brain to know where your back is or positioned in space. This is primarily achieved through extension, but that is not always the case. It varies person to person.
Timeline and treatment
The Numbers: The timeline of improvement varies person to person and the severity of disc injury. The timelines listed are averages. You can get better faster than the average or take a little bit longer, it just depends. Mild herniations tend to improve within 4-6 weeks, moderate tend to improve within 6-12 weeks, and severe herniations will improve in 6+ months. Leg pain can last 4-6 weeks and functional improvements may settle in for as long as 1-2 years. Though those numbers might sound scary, most disc injuries and herniations will heal with conservative treatment.
In Office Care:
Adjustments: High velocity low amplitude, also known as HVLA, manipulations in the direction of directional preference can be beneficial in the early phase of treatment. It can help decrease pain, increase motion throughout the joint, and decrease muscular tension around the surrounding tissues. Manipulation can close the pain gait, decreasing increased pain signaling.
Directional preference exercises: these focus on pain centralization, which is described above. The McKenzie Method is one of the most well known protocols for centralizing radicular symptoms and reducing pain through repetitive end range loading. If you are suffering from low back pain and radicular symptoms, you can ask your doctor the next time you’re in if this is an appropriate exercise for you and your presenting symptoms.
Manual therapy: reduction of muscle hypertonicity around the injury and help reduce pain. This is achieved in our office through Instrument Assisted Soft Tissue Mobilization (Graston, FAKTR, etc.), myofascial release, cupping, and therapeutic massage.
Acupuncture: this can help reduce pain through resetting pain patterns as well as reducing hypertonicity of surrounding tissue and musculature.
Class IV Laser: this 5 minute treatment can help decrease inflammation and pain through emission of energy within the infrared spectrum in order to promote healing. This is achieved through increasing the temperature of the targeted tissue for temporary relief of muscle and joint pain and muscle spasms. It also helps relax the muscle tissue around the targeted area.
Decompression: This involves a computerized table equipped to stretch the spine with controlled increments of pressure and time based on your body and condition. The table helps to facilitate faster healing by opening the joint space, reversing the effects of gravity, and relieving excess pressure on the spine. Decompression introduces healthy movement back into the joints by creating the pumping effect needed for healthy movement to the injured region. This provides the injured area with increased hydration, nutrients, and oxygen to the injured disc, while also providing relief if there is degeneration present.
Nutrition: this plays a vital role in our ability to heal. Nutritional support can help decrease inflammation and support the body while it heals. If you want to learn more about supplements and dietary changes that can help you, set up a consultation with our nutritionist Kebbie.
At Home Care
Once again, this is going to vary person to person. Some people might respond well to directional preference exercises and some might now. There is no one size fits all. To start off, it is recommended that the aggravating positions be avoided as much as you can. If you need to sit for work and don’t have access to a sit/stand desk, try rolling up a dishrag and place it vertically along your low back when you sit in a chair. This creates more support of the low back and keeps the back out of the flexed position. Leaning back in the chair, if your chair has the ability to do this, can reduce the load on the low back. These are little things you can do at home or in the office to help reduce some of the stress and pain.
Creating a home care plan is a very individualized process, especially because every patient can respond differently and there is variability in their presentations and progressions. Reach out to one of our providers to see what the best plan is for you.
Katherine Mullen, DC, MS is a chiropractic physician with a masters in sports medicine. She has a special interest in the treatment of athletes through chiropractic and rehabilitative care. She is also certified to perform pre-participation physical exams (PPEs). Stay connected with Dr. Mullen on Instagram @washparkchiro or @katherinemullen
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