The general population has been led to believe that if you have numbness in the hand it must be coming from a herniated disc. An MRI is performed. A herniated disc in the cervical region is found and you are now on your path to epidural nerve blocks, pain medication and worst of all, an unnecessary surgery or two. I have heard this story so many times, it is sickening. But with a little knowledge, I believe you can prevent yourself from going down this very slippery path. Understanding what nerves innervate different parts of the hand and what can cause these nerves to trigger numbness is the key to getting the appropriate treatment versus taking a path to surgery because no other treatment protocol worked so surgery is your last resort.
Let's start with the premise that the cause of your numbness is coming from a herniated disc. Herniated discs cannot cause a symptom in the hand. It can only create a symptom in the hand if it is impinging on a cervical nerve root. These are the extensions of the spinal cord that come out at every level of the spine and innervate only a very specific area of skin. The nerve roots that affect the hand are C6, C7 and C8. The C6 nerve root could create an altered sensation only in the thumb. The C7 nerve root in the middle finger and and C8 the pinky. That is it. If your numbness is in any other part of the hand, the numbness cannot be coming from a nerve root impingement caused by a herniated disc at the cervical spine.
Most of the patients I have treated complained numbness at the whole hand. The only area where nerves exist that innervates the whole hand is at the front of the neck where all the nerve roots of the cervical spine come together to then go down the arm. This is called the anterior triangle of the neck and this group of nerves that can impinged here are called the brachial plexus. They get impinged by a muscle called the anterior scalenes straining and thickening impinging on the brachial plexus. Resolution can be accomplished by strengthening the back of the shoulder muscles, the muscles between the shoulder blades, the back of the arm muscles and the rotator cuff muscles.
Numbness at the top of the hand can come from impingement of the radial nerve as it passes through the forearm extensor muscles. If these muscles strain and thicken, they can impinge the radial nerve and create symptoms at the top of the hand and fingers. Resolution comes from strengthening of the forearm extensor muscles and the shoulder muscles described above.
Numbness of the thumb, second, third and half the fourth finger on the palm side comes from impingement of the medial nerve as it goes through the carpal tunnel; typically known as carpal tunnel syndrome. The true cause of this is straining of the forearm and finger flexor muscles that also go through the carpal tunnel. The thickened muscles impinge on the median nerve in the carpal tunnel and create the numbness. Resolution of these symptoms is achieved through strengthening of the forearm extensor muscles and the shoulder muscles described above.
Numbness of the pinky and half the fourth finger typically results from impingement of the ulna nerve as it passes through the forearm flexor muscles near the elbow. Resolution of these symptoms is achieved through strengthening of the forearm flexor muscles and shoulder muscles described above.
These are the key possible methods of creating numbness in the hand. The odds of herniating a disc and creating a nerve root impingement are very low. You have to have had a pretty substantial incident to the neck to create the kind of force necessary to injure these tissues. Next you have to have your numbness in the right location to match the nerve root. In 17 years I may have seen one or two cases out of thousands where a person had the correct symptoms to match a nerve root impingement.
It is more likely that the numbness you are experiencing is the result of an impingement of a nerve by a strained muscle than a variation to a structure such as a disc or a nerve.
Understanding your symptoms and what the potential causes of the symptoms might be will protect you from becoming another statistic of an unnecessary surgery that had no reason to be performed because the symptom could never be caused by a herniated disc or nerve root impingement.