Skin Dermatomes

Skin Dermatomes

A dermatome refers to a portion of skin in the body that gets its sensation from a single spinal nerve. When I examine people in the office, I will test a dermatome for sensation.  I saw a patient last week who had hip osteoarthritis.

He had pain over his right thigh.  When I examined him, he had a hypersensitivity over the L2,3 distribution.  As it turns out, he has a herniated disc at that level in his lumbar spine that is the source of his pain.  Here are 4 things to take away about  a dermatome and what to know about your body’s innervation pattern.

  1. Spinal cord segments.  The spinal cord, as you can imagine, is highly specialized. It is divided into segments.  Spinal nerve roots arise from the spinal cord in pairs of nerves.  These nerves are numbered based upon where they exit.  For instance, there are 8 cervical, 12 thoracic, 5 lumbar and 5 sacral segments.  Each of these nerve pairs will give motor, sensation and in some cases reflexes to the body.  It is in understanding this wiring that we can identify where a particular problem lies in the spine.
  2. Dermatome and myotome.  Just as a dermatome will give information about a segment of skin, a myotome is a map of motor power for a group of muscles.  In addition to testing your skin at various levels, a motor examination will help confirm if a particular nerve root or nerve roots are affected.  For instance, with a C5 radiculopathy, I will specifically test the deltoid muscle of the shoulder, and the skin over the outside or lateral aspect of the arm.  In addition, I will test the biceps reflex which is a predominately supplied by the C5 nerve root.
  3. A dermatome can explain referred pain.  Because a dermatome is a roadmap of nerves it can also explain referred pain.  Referred pain is a phenomenon where structures in the body can confuse nerve perception.  An example is when someone has an inflamed gall bladder orcholecystitis.  The gall bladder can inflame the diaphragm which is innervated by C3,4 and C5.  The C3,4 dermatome innervate above the shoulder.  Rarely, a patient will come to the office with right shoulder pain but the pain is coming from cholecystitis.
  4. Virus can express themselves in a dermatome distribution.  Viruses can hibernate in the sensory cell bodies.  An example is varicella zoster virus.  Patients can present with severe pain in the back or trunk and this can be a manifestation of a zoster attack. Diagnosis can be confusing because it can be misinterpreted as back or flank pain and not the beginning of shingles.

In medicine you often have to play detective.  The dermatome map is one clue to a diagnosis and hopefully a cure.  I have included a dermatome map here for you to look at further. 

Ravi Ramachandran M.D. Sacramento Spine Surgeon


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by Ravi Ramachandran, M.D.

Recovery after nerve damage

Recovery after nerve damage

Nerve damage.  Not a pleasant thing to think about but important to discuss.  I saw a patient several years ago with a foot drop from a herniated disc in his lumbar spine.  The muscle that moved his ankle had complete atrophy.

As it turns out he had significant nerve damage.  Despite a microdiscectomy, which helped his leg pain, his muscle atrophy never recovered.  What is nerve damage and what are different types you should know?  Here are 5 key points to understand about nerve anatomy and damage.

  1. Nerve anatomy.  A peripheral nerve refers to a nerve that leaves the spinal cord and exits down the extremities or trunk.  A peripheral nerve has several layers.  The outer layer is known as the epineurium.  Inside the nerve are two further linings, the perineurium and theendoneurium. Individual nerve fibers run within the endoneurium and are known as axons.
  2. Axon anatomy.  Around an individual axon are cells that make myelin.  Myelin is like the coating of a wire in your house.  Myelin helps insulate and conduct electrical signals down the nerve to move the muscles in the arms and legs.  The major peripheral nerve, such as thesciatic nerve, have a combination of sensory and motor fibers that are surrounded by myelin.
  3. Nerve injury.  There are three types of nerve injury to know with a peripheral nerve.  These are neuropraxia, axonotmesis and neurotmesis.  In a neuropraxia, there is a bruise to the nerve. This is the most common type of nerve injury I see in the office.  A neuropraxia leads to injury to the myelin because of compression.  This can lead to sensory and/or motor loss of function.  An example would include compression from a herniated disc or from spinal stenosis.  When the compression is removed, the nerve can recover over weeks to months.  Axonotmesis is a more involved type of nerve injury where some of the individual axons die.  The most severe form of nerve injury is when the nerve is actually cut in half.  This is known as neurotmesis.  Fortunately, I don’t see many cases of neurotmesis.
  4. Nerve recovery.  The key point with different types of nerve injury is to provide an optimal environment and time for the nerve to recover.  For a neuropraxia, observation is typically the prescribed treatment.  When I see patients in the office who have a foot drop from a herniated disc, I will recommend surgery if the foot drop does not improve.  This is to remove pressure off the nerve to allow maximal recovery.  If is important to emphasize the point that each nerve injury is different.  Sometimes a herniated disc can cause so much damage that axonotmesis can be extreme.  This is the case I described above.  When I see atrophy in the muscle innervated by the nerve, that is a poor sign.  It means that individual axons in the nerve have been lost.
  5. Prompt diagnosis and treatment.  When you notice in yourself or someone you know weakness or numbness that persists, get evaluated.  If I am concerned regarding a diagnosis or if there is severe nerve damage, an EMG and nerve conduction test may be appropriate.  This is to document what type and degree of nerve injury.

Often with nerve damage, there is a waiting game.  An adult peripheral nerve has been estimated on average to regenerate approximately 1 mm per day.  That’s watching the grass grow.  If on average there is 1 mm per day regeneration, you can understand that many nerve injuries can take over a year to recover.  If requires patience and aligning with a clinician you trust to walk you through the diagnosis and treatment for your individual condition.  So that is a brief introduction to nerve damage and recovery. 

Ravi Ramachandran M.D. - Spine Surgeon in Sacramento, CA

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by Ravi Ramachandran, M.D.

The dangers of smoking tobacco

The dangers of smoking tobacco

We all know that smoking is bad for us.  We tell our loved ones and patients in the office to kick the habit before it kicks them.  Recently the New England Journal of Medicine published a quality article on the hazards of smoking.  The lead author Dr. Jha had some interesting points to illustrate in the article.  Here are the key points of the article as it relates to smoking.

  1. Large database.  Dr. Jha looked at 216,917 smoking histories between 1997-2004.  These patients who were surveyed through 2006 and were followed by the National Death Index.  Current and former smokers were then compared with people who never smoked.  The authors of the paper then determined risks of death and the causes of death in the different groups.
  2. Death rate was three times more in smokers as compared to nonsmokers.  The paper showed if you are a smoker you are 3 times more likely to die.  No surprise but this quantifies the risk of death from smoking for people.
  3. Cause of deaths in smokers were wide and varied.  Smoking causes changes in tissues in a negative manner that can wreak havoc in the body.  In Dr. Jha’s paper, the higher risk of death was due to cancer, stroke, heart attack and lung disease.  It seems that nearly every organ in the body is impacted negatively and this is borne out in this paper.
  4. Life expectancy was shortened by more than 10 years amount current smokers.  If you smoke, you can expect, based on this study, 10 years of your life span.  If you quit smoking earlier in life you get some of those years back.  This statistic illustrates the body’s ability to repair some of the damage associated with smoking.
  5. Stop smoking before 40 years of age.  In Dr. Jha’s paper, if one quits smoking before 40 years of age, there is a 90% reduction in the risk of death compared with active smokers.  The authors were quick to point out that it doesn’t mean you can smoke until 40 and be alright.  They pointed out that the remaining risk in someone’s life is 20% for early death in a former smoker compared with a nonsmoker.

This paper was well written and illustrated the obvious.  Smoking is bad for you and those around you.  From an orthopedic standpoint, it destroys the musculoskeletal system and acceleratesdegenerative disc disease and spinal stenosis.  Smoking cessation requires hard work and a multidisciplinary approach including rethinking habits.  I have included a link from the Heart Foundation on smoking cessation. 

Ravi Ramachandran M.D. - Spine Surgeon in Sacramento, CA

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by Ravi Ramachandran, M.D.

Exercise and low back pain

Exercise and low back pain

Exercising with low back pain.  It seems like an oxymoron but it is common.  I hear this often in the clinic.  ”I can’t exercise because of my back pain.”

Traditional thinking is that low back pain means no exercise and “take it easy”.  In the past, doctors would prescribe several days of bed-rest.  We have learned that movement through exercise is not only important but often is necessary to improve low back pain.  When I see someone in the office with low back pain, I often discuss core strengthening and exercise.  But how do you exercise when your back hurts?  Here are several things you should know about exercising with low back pain.

  1. Warm up before and after.  Stretching before and after an exercise routine is essential.  This gets your back warmed up and ready to go before and after the exercise routine.  Tony Horton who is the modern-day version of Jack LaLanne, has a nice lower back stretching videoto watch on this subject.
  2. Focus on core and gluteal strength.  Strength in the core muscles and the gluteal musclestakes pressure off arthritic joints and aging ligaments in the back.  I emphasize core strength in the office for this reason.  There is a balance between the core muscles that flex your trunk and the back muscles that extend your trunk. In the office, most people with back pain have soft abdominal muscles and very tight back muscles.  That imbalance needs to be addressed.  Some basic core exercises you can do are described here.
  3. Choose a program that fits your comfort level .  With exercise, not everyone fits into the same program.  Some people have significant pain that prevents typical exercise programs.  I recommend people explore all possible options to get the heart rate up and burn calories.  One article I like in particular that discusses this further is referenced here.
  4. Cross train.  Mix up exercise during the week.  It’s important to write down a program before the week begins or speak with a trainer if you have one.  Options include walking, swimming, biking and resistance exercises.  Cross training has the benefit of taking stress of the low back and releasing endorphins.
  5. Take 1-2 days off per week.  It is important for the body to recover after periods of exercise.  The body will be in a rebuilding phase and rest is important.  I encourage patients to stretch during this time period and include foam rolling into their regimen.  If you are not familiar with foam rolling, here is a video link for the gluteus muscle and piriformis.

I understand that there are many examples where someone has had surgery on their back or a bad accident and exercise seems impossible.  Keeping the body moving however is key.  With extreme cases of back pain you should start simple and work your way up to more involved exercise programs over time.  The key is to be realistic about the goals you set.

I also want to emphasize to have your low back pain examined by a qualified professional if you experience prolonged bouts of low back pain.  Having a good understanding of what issues you have in your lower back helps with designing a individual training program.  So there you go.  Exercise can be a wonderful form of prevention and rehabilitation for the back.  Keeping your body stretched out and moving makes you more durable for the long-term

Ravi Ramachandran M.D. - Spine Surgeon in Sacramento, CA

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by Ravi Ramachandran, M.D.

Back Pain Therapy. Understanding Physical Therapy And Your Back.

Back Pain Therapy. Understanding Physical Therapy And Your Back.
As a spine surgeon in Sacramento, I treat many patients without surgery. I send patients with low back pain to physical therapy. I recall a pleasant lady who had severe spinal stenosis. I sent her for back pain therapy and her back and leg pains improved. She wasn’t perfect but she felt that her quality of life was restored. What is back pain therapy and how does physical therapy improve the condition? Here are 4 take home points to remember about back pain therapy. Read more »
by Ravi Ramachandran, M.D.

What Is A Stinger Or Burner? 5 Key Points About A Bruised Nerve In The Neck.

What Is A Stinger Or Burner? 5 Key Points About A Bruised Nerve In The Neck.
A stinger or burner is a bruise to a special highway of nerves in the neck called the brachial plexus.

Several years ago, I was the doctor on the sidelines for a high school football game. The running back had a big collision with a defensive safety. He was slow to get up and came off the sidelines with radiating left arm and neck pain. He sustained a “stinger” or burner to his neck and brachial plexus. He recovered completely from the stinger and went on to finish the season. Many people ask me what is a stinger or burner. Here are 5 key points to understanding a stretch or bruise to the brachial plexus. Read more »

by Ravi Ramachandran, M.D.

Understanding Cervical Neck Surgery

Understanding Cervical Neck Surgery
Cervical neck surgery is often a last resort when patients have cervical radiculopathy from a herniated disc. There are different types of cervical neck surgery to know and understand. A 50-year-old male came to my office with burning pain and numbness in his right arm. We tried nonoperative techniques first but in the end he underwent a cervical discectomy and fusion. This relieved his symptoms and he did quite well. He came to the office well-informed prior to the surgery with questions about different options. What are the options in cervical neck surgery and what should you know? Read more »
by Ravi Ramachandran, M.D.