About pinched nerves and herniated disks—oh how that hurts!!!

About pinched nerves and herniated disks—oh how that hurts!!!

 

 

Nitin K. Sethi, MD

Assistant Professor of Neurology

New York-Presbyterian Hospital

Weill Cornell Medical Center

New York, NY 10065

 

 

Recently I have seen many patients in my office with complaint of pain, numbness and tingling radiating down either the arms or legs. Most of these patients have pinched nerves due to herniated disks. They have ranged from ages of 25 to 65 and all of them have sought a neurological consultation primarily due to discomfort and pain from the pinched nerves.

I have written about pinched nerves before (we refer to this condition as radiculopathy. If the pinched nerve occurs in the neck i.e. the cervical vertebrae are involved it is called cervical radiculopathy and if it occurs in the lower back and involves the lumbar vertebrae it is called lumbar radiculopathy) but thought this might be a good time to again discuss this relatively common but frequently disabling condition. So what does a pinched nerve actually mean?

Well as you know our spinal cord is enclosed and protected by a rigid structure called the spinal column (commonly we refer to this as the spine. The spinal column is made of small bones called vertebra which are stacked one on top of each other and interconnected to one another by ligaments and other soft tissues. It is the tail (spine) of the vertebra which you can feel when you touch someone’s back. Now this bony spinal column encloses and protects the delicate spinal cord (the spinal cord starts from the base of the brain and contains all the nerve tracts which carry signals from the brain to the periphery of the body and vice versa. As it descends down into the neck, it gives off nerves which supply all the muscles of the arms and in the lower back (lumbar area) nerves to the legs come out from the spinal cord).

SO LET’S GO OVER THIS AGAIN. YOU HAVE THE SPINAL CORD; IT IS ENCLOSED BY A STRUCTURE (we are calling this the spinal column) WHICH IS MADE OF SMALL BONES CALLED VERTEBRA STACKED ONE ON TOP OF OTHER. FROM THE SPINAL CORD THE NERVES COMING OUT AND SUPPLY THE MUSCLES OF THE ARMS AND LEGS.

HOLD ON WE FORGOT ABOUT THE DISKS!!! So what is a disk or more correctly called the INTERVERTEBRAL DISK? As the name suggests the disk is a small cartilaginous tissue which lies in-between two vertebrae (think of it as a cushion between two bones which is what it actually is!!!). As compared to the vertebrae which are bones, the disk is a cartilage and fibrous tissue which is prone to degeneration and rupture.

Now imagine a scenario.  You are lifting a heavy weight. You bend down, squat and strain to lift that heavy box of office supplies. You hear a “pop” in the back and feel “something give”. Well what do you think has happened? One of the cartilaginous disks in the lower back (most common is either the one between the 4th and 5th lumbar vertebrae or between the 5th lumbar and 1st sacral vertebrae. In the neck it is between the 5th and 6th or between the 6th and 7th cervical vertebrae) has herniated (POPPED OUT) and is now compressing (PINCHING) the nerve coming out of the spinal cord and going into the leg (may be the arm if it occurs in the neck). What is the end result of this disk herniation?

Well the next day you are in terrible pain and can barely get out of bed. You make an appointment to see your doctor. You have shooting pain (the pain radiates down your leg or in the case of a cervical disk herniation into your arm). You complain of feeling pins and needles and electric shocks radiating into your leg (or the arm as the case may be). Some people have more “negative” symptoms and complain of numb feeling rather than pain. The doctor examines you and orders a MRI of the lumbar spine (or the neck as the case may be). He gives you some pain medications and asks to take it easy!!!.

Voila you now officially have a herniated disk with a pinched nerve. It sure hurts like crazy. Will this story have a happy ending?

The story continues in the next post……….

 

Back pain

Back pain (radiculopathy/ myelopathy)

Back pain is one of the most common conditions for which patients seek a neurologist’s opinion. There can be protean causes of back pain and before we discuss them here, a brief discussion about the anatomy of the spine shall serve us well.

 

Anatomy of the spine:

The human spinal column is made up of bones called the vertebra stacked one on top of the other (like a column), As the vertebral column is made up of multiple bones articulating with each other, it allows for mobility. We can bend forward (flexion of the spine), arch our back ( extension of the spine) and can also flex our spines laterally in both directions (lateral flexion of the spine). The soft cartilagenous tissue found between two vertebral bodies is called an intervertebral disc. The spinal cord is enclosed in this skeleton of vertebral bones and thus is protected from injury. From the sides of the vertebral bodies the nerve roots come out. These are the roots which later on join to form the big nerves which innervate the muscles of the arms and legs.

 

What is meant by disc herniation?

Other terms used to describe this common condition include “slipped disc” . A herniated or slipped disc refers to the condition where-in the intervertebral disc gets dislodged (herniates out of its right place or slips out of its right place). When the disc herniates out it puts pressure on the nerve roots exiting the spinal cord at that level. Inflammation of the nerve roots results. This can lead to an intense painful condition where-in the patient complains of pain radiating down in the distribution of that nerve root. We in neurology refer to this condition as Radiculopathy.

Depending upon which nerve root is compressed and at which level patients have pain. For example a disc in your neck slips out, you have pain radiating usually into your arms or even into your finger tips, while if a disc in the lower back slips out, patients usually have pain radiating down their leg ( a condition  commonly referred to as sciatica).

Causes of back pain:

As I stated earlier there can be protean causes of back pain. Here I shall list some of the common causes.

1) Slipped or herniated disk.

2) Mechanical trauma to the back resulting in soft tissue injury (injury to the para-vertebral muscles or the soft tissues eg fat).

3) Fracture/ dislocation of the vertebral bodies: sometimes the vertebral bodies may get dislocated or malaligned. One vertebral body may get displaced in relation to the vertebrae below. This condition is referred to as Spondylolisthesis. The vertebral body itself or any of its parts (arch, pedicle) may get fractured resulting in pain. Fractures of the vertebral column can either be traumatic (occuring in the setting of significant trauma) or they can be secondary fractures. Secondary fractures occur when the vertebral body is weakened by an infectious or malignant (cancerous) process.

4) Spondylosis: is one of the most common causes of back and neck pain especially in the middle aged and elderly population. In its most simplistic defination, spondylosis refers to degeneration of the vertebral column. This degeneration of the bones of the spine becomes more apparent as we age, spur formation may occur (osteophytes). These osteophyted may compress the exiting nerve root leading to pain (radicular symptoms). Further on the spinal canal may get narrowed. When this occurs the spinal cord does not have enough space, a condition referred to as spinal canal stenosis. Spinal canal stenosis classically presents with pain which radiates into the buttocks. Patient complains of pain when he walks, with relief of pain on sitting or when he bends forward (flexion). This condition is referred to as neurogenic claudication.

It is important that spinal canal stenosis be diagnosed correctly as it responds to surgical intervention with good relief of pain and discomfort.

 

For one who has conquered the mind, the Supersoul is already reached, for he has attained tranquillity. To such a man happiness and distress, heat and cold, honor and dishonor are all the same

Lord Krishna in the Bhagavad Gita