In the large vertebral bodies of the back (see the post on Osteoarthritis here), there are bony extensions that come off the sides, called the transverse process. These also have holes where the nerves from the cord exit, and then separate into increasingly smaller nerves that innervate the muscles in the extremities.
The nerves allow the muscles to feel and move. In between the large vertebral bones that look like donuts, is a spongy, disc material. A tough outer ring called the annulus protects the gel-like interior of each disc known as the nucleus pulposus. Due to aging and general wear and tear, the disc loses some of the fluid that made them pliable. They then become flatter and harder. This is what we call osteoarthritis or degenerative joint disease (read the post on Osteoarthritis here). The entire disc material acts as a shock absorber when increased pressures occur within the spine. When too much pressure is applied to the disc, as with lifting or bending while lifting, it compresses and pushes out either towards an exiting nerve root or inward towards the cord. This is a herniated disc. If an exiting nerve is affected in the neck, it radiates into the arms, if it’s in the lumbar region, the legs.
The cord ends at the L1-L2 vertebral bodies, but the lumbar nerves continue below this level. That’s why a cervical injury can impact the cord but not a lumbar one.
A bulging disk only affects the outer perimeter of a disk, not the tough cartilage. A herniated disk, on the other hand, results when a crack in the tough outer layer of cartilage allows some of the softer inner cartilage to protrude out of the disk. Herniated disks are also called ruptured disks or slipped disks, although the whole disk does not rupture or slip. Only the small area of the crack is impacted. Bulges and some herniated discs are often seen in asymptomatic patients on MRI or CT’s when scanned for other concerns. They are not considered clinically relevant, meaning they have no physiological or symptomatic consequence. Ruptured discs that impact a nerve or the cord do have consequences. Acute injuries may cause pain in the spine but also translates into the extremity as it follows the involved nerve root. According to the National Institute for Health, over 70% of patients are pain free at approximately 6 months due to the spontaneous resorption of the herniated disc as seen on MRI (Magnetic Resonance Imaging) studies.
The sciatic nerve is the largest in the body, measuring 2 cm at its beginning as it passes out of the pelvis, into the buttocks to the back of the leg, into the foot. It originates from many nerve roots coming out of the back. It’s like a piece of braided licorice. As it extends into the leg, smaller pieces branch off and innervate motor and sensory areas in the lower extremities. Sciatica is caused by a ruptured disc that impacts this nerve, often due to stenosis in the area of the back where the nerve exits, or spasm in the piriformis muscle. The piriformis muscle is a small muscle deep in the buttock that allows the hip to lift and rotate outwards. The sciatic nerve can run close to, or through, this muscle so when the piriformis is inflamed it can affect the nerve as well.
I know it hurts and the pain seems like it’ll never go away, but in all likelihood, it will. In most cases rushing into surgery is not the answer. If part of the disc space is removed (a discectomy) it has less stability. Once the anatomy has been altered it is changed forever and like a domino effect, can cause further deterioration in the future. Fusions take away the body’s natural balance at each vertebral level, adding increased duties to the ones above and below the fusion. This sets them up for degeneration over time. The body is an incredible machine, in perfect balance and symmetry. When it’s altered for any reason, surgically, genetically, or with age, the ensuing change alters our gait, stance and balance, setting us up for more problems. That’s why it’s imperative not to rush into surgical procedures before making absolutely certain it’s the best treatment. Often these issues will respond to stopping activities that stress the nerve, ice or heat, physical therapy, injections, and medicines such as muscle relaxers, prednisone, and anti-inflammatories. With time and conservative treatment, the pain from the spinal nerve inflammation usually resolves in a few days to several weeks.
I’m a classic example. I’ve had multilevel fusions in my cervical (or neck) and mid thoracic to the lowest lumbar level. This means most of my spine is fused. Add to that, carpal tunnel surgery on both hands, left 1st and 5th toe fusions. All of these have altered the perfect symmetry I was born with, causing each side to now feel stressors differently. The surgeries have altered my gait, which then changes the impact on all the involved muscles. This allows degeneration and breakdown in other areas due to asymmetrical pressures. That’s why it’s important to strengthen and mobilize, ensure activities are safe, and lifting is minimal and performed properly.
When there is a disc impact that causes persistent and unrelenting pressure on a specific nerve root without improvement, surgical intervention is then considered. The first time I ruptured a disc was in my 20’s after a horseback riding accident. Nothing helped to resolve the pain. Before surgery I was able to jog 5 miles a day, horseback ride, exercise and work 12-hour days. After, any kind of activity, even sitting, standing or walking was horrifying. Surgery removed the disc fragment that had been impacting the nerve root and I was given my life back. To those of us helped by a surgeons skills “thank you” is not enough. They will always hold a special place in our hearts.
Regardless of the treatment, seek out professional care when the pain doesn’t resolve quickly, and immediately if you have neurological deficits. Learn which options are best for you.
I’ll go into more depth about diagnosis and treatment options in future posts.