Herniated Disc (or Disk)

Reminder: If you have not done so, please read the Initial Post and  Blog Information.  At the upper left of this page above my picture click on the button, Initial Post and  Blog Information.

The space between two vertebrae (vertebras) is filled by a disc.  This disc is made up of several parts.  The central portion is the nucleus.  When we are young this is a viscous material not that much different in consistency from silly putty.  As we get older, the nucleus tends to dry out.  If a disc is injured, then this drying out takes place quicker than it would with just aging. 

The outer portion of the disc is called the annulus.  It is made up of fibrous connective tissue.  Outside the annulus there is a thin layer of stronger connective tissue known as ligament.  Depending upon which direction you look, the ligamentous tissue can be very thick or very thin or somewhere in between.

Gravity tends to squeeze vertebrae together.  Because of this, almost everyone on planet Earth will have bulging discs as they age.  This process is generally painless.  Should you squeeze a double stuff Oreo (TM) cookie, you will see how the white filling bulges out in all directions.  If we kept our spine straight, our discs would bulge in all directions, too, but we don't.  When we sit, or bend forward, we put much more pressure on the front of the disc, pushing the nucleus backward.

Fortunately, one of our strongest ligaments is directly behind the disc and helps to prevent large bulges in that direction, since this is where the spinal cord is located.  Unfortunately, this strong ligament doesn't protect the entire rear portion of the dics.  The edges closest to the sides of the disc are relatively weak.  It's in these areas that the disc will occasionally rupture, allowing a portion of the nucleus to escape.  This is known as a herniated disk.  A herniated disc can be painless, too.  Sometimes, however, the nucleus will put pressure on nerves causing pain.

Stenosis

We have all seen the little old man who walks slowly, leaning forward on a cane or a walker.  Frequently, that is a sign of stenosis.  Stenosis means narrowing.  People can have stenotic coronary arteries, for which they receive stents or by-passes in order to increase blood flow to the heart and prevent heart attacks.  What we are talking about here is different.  It is stenosis (narrowing) of the canals through which the nerves in your lower back pass.

There are two main type of stenosis, central and foraminal.  Central stenosis is the narrowing of the central spinal canal.  This is usually caused by a combination of arthritis, increased thickness of ligaments, and bulging discs.  Most commonly it is found in older men, who are more likely to have those conditions.  Women can also have stenosis, as can young people, especially if they are cursed by inheriting short spinal pedicles.  With short pedicles, the spinal canal is narrow to begin with, and it is easy to narrow it further with arthritis, thickened ligaments, and/or bulging discs.

Foraminal stenosis is the narrowing of the canal in which the major nerve roots leave the spinal cord and go to the peripheral nervous system.  It is usually caused by the same things that cause central stenosis.

Now, the reason the old man walks bent forward is this: that opens the space in his spine between the vertebrae, taking pressure off the spinal card and/or peripheral nerve roots, relieving his pain.  If you remember the little guy Arty Johnson played on Laugh-in, with the white hair and mustache and leaning on the cane, you'll have an idea of what stenosis looks like.  If you picture him, you can make the diagnosis, too.

Sciatica

Well, I'm two days late this week.  Maybe I shouldn't have a deadline for myself.  But without deadlines, how does anything ever get done on time, or late? ;-D

The sciatic nerve is the biggest nerve in your body.  Pain in this nerve results from compression of the nerve from swollen or displaced tissue.  That tissue can be a herniated disc, a pulled muscle, a torn ligament or tendon, a hematoma, or a fracture. 

The hallmark of sciatica is the radiation of discomfort, usually pain, from the lower back down the leg.  The sciatic nerve is a bundle of nerves that starts near your lower spine and branches all the way to the tips of your toes.  Most people with sciatica suffer with pain that radiates some distance down the nerve.  Most doctors would agree that if your pain radiates below your knee, then the sciatic nerve is involved.  But, you can suffer other problems with compression of a nerve. 

Nerves not only send pain information, they send information to your brain about body position, touch, hot, cold, vibration, and compression.  In addition they send information from the brain to the muscles, telling them to contract or relax.  Sciatica could therefore involve not only pain, but numbness, loss of position sense, inability recognize vibration, heat or cold, or to contract or relax a muscle.

Loss of communication between the brain and your leg via the sciatic nerve may cause many different symptoms: pain, stumbling, foot drop, or injury due to cold or heat, depending upon which nerve fibers are compressed.

Back Exercises

Reminder: If you have not done so, please read the Initial Post and  Blog Information.  At the upper left of this page above my picture click on the button, Initial Post and  Blog Information.

Doing specific back exercises is championed by any number of back gurus.  However, most people do not need to strengthen their backs.  They need to become active.  Aerobic activity by itself can decrease back problems.  As an Atlanta neurosurgeon says, “Motion is the lotion.”  Immobility leads to increased pain.

In his research, as reported in his book Low Back Disorders, exercise physiologist Stuart McGill makes a good case for not doing a number of exercises.  These are frequently the same exercises doctors tell their patients with low back pain to do.  Don’t do them!!  They are listed below.  He also shows why certain exercises are better at rehabilitating an injured back than others.  He compares the back to a tall tower with supporting guy wires.  The tower supports itself against gravity by the way it is constructed, i.e., it isn’t easily compressed.  The guy wires keep the tower from buckling or falling over.  The tower is your vertebral column.  The guy wires are your back and abdominal muscles.

If you think you need specific exercises or think they may help your back, take the following advice from McGill into account: there are some specific exercises to avoid.  Any exercise that increases intra-abdominal pressure increases compression of the discs and the facet joints, increasing the likelihood of injury or irritation of these structures.  Even though strong abdominal muscles contribute to back stability, true sit-ups and bent leg sit-ups can be injurious.  They increase the compressive force between vertebrae to unacceptable limits.  Unless you are an athlete bent on competition and willing to take that risk in order to improve your performance, avoid doing them.  For the rest of us, endurance in those muscles is more important than strength.  Pull-ups, believe it or not, also compress your discs.  Most extension exercises are a bad choice.

All exercises should be done with the back in a neutral position, including any stretching such as hamstring, quadriceps, and psoas stretches.  McGill also goes over nerve flossing (a way of decreasing the compression on segmental nerves), but it has the potential to worsen pain.  It is best to receive specific instructions from a physical therapist who has a lot of experience with the technique.

Back exercises that are acceptable include the cat-camel, partial squats, curl-ups, side bridge, plank, push-up, and bird dog.  These increase core strength and back stability by strengthening the rectus abdominis, obliquus externus abdominis, and obliquus internus abdominis muscles (the guy wires to your towering vertebral column).  Aerobic exercises, like brisk walking, jogging, swimming, and – depending upon your posture – riding a bike are also good for your lower back.  They increase your overall stamina and the stamina and strength of the muscles in your back.