What's Causing That Numbness in Your Hand?

Dr. Steven Scappaticci, B.Sc. (Hons.), CSCS, DC, FRCms

            Numbness or tingling of the hand is a common symptom. Anecdotally, many seem to attribute this more often than not to Carpal Tunnel Syndrome. In reality, there are many potential causes for someone to experience numbness in their hand. Some of these reasons are innocent and fixable; some are manageable, while some others are life-threatening. Lets remember which conditions are more common & use a full clinical picture to identify other possible causes for numbness.
 
            A few important points to remember is that anytime there is sensation changes, such as numbness there will be involvement of one or multiple nerves. This may be a direct or indirect piece of the puzzle as to what is truly causing the problem. It means something very different if the numbness is constant versus intermittent as well as if it is in one hand compared to being experienced in both hands. 
 
            The nerves in our arms and hands actually originate in the neck. They leave the neck by exiting between the vertebra, through the neck muscles, and course down the arm going over, under, and even through some muscles. As they travel, they split and divide many times until they reach the fingertips! You can see that there are many potential sites where something can become compromised. 
 
            So what’s on this long list of possible reasons for hand numbness? We can systematically break this down into musculoskeletal(MSK) causes and systemiccauses for simplicity. All the causes are bolded below.
            Under the MSK category we’ll start at the neck with cervical spondylosis, simply recognized as degeneration. Now this is often painless but if severe enough, it can lead to stenosis– a narrowing of the space housed by the spinal cord and the exiting nerve roots that can lead to numbness. A similar mechanism is if those exiting nerve roots become significantly irritated, one may experience a cervical radiculopathy. There are many causes of cervical radiculopathy but one that stands out is a cervical disc herniation. This presentation can vary from sharper pains to weakness but can also include numbness in the arm/hand. 
            Continuing along, Thoracic Outlet Syndromecan be the culprit of arm/hand numbness. A much more involved condition, compression/irritation of the affected nerve (95% of the time as there is a small percentage that is of a vascular cause) that can occur in a few different places in and around the neck and chest/upper arm. Whether it’s tight musculature in the neck/arm or the presence of a cervical rib, the compression can cause hand numbness. A related diagnosis that can cause hand numbness is that of Double-Crush Syndrome. It is here that the nerve or nerves are compressed at two sites along its path. Muscles, bones, or even cysts, such a Ganglion Cyst, can irritate nerves in the arm/hand. These Ganglion cysts exist in the wrist and although usually asymptomatic can cause issues and create sensory changes in the affected hand. 
            Further down the arm we can have what we’ll refer to as “Tunnel Syndromes”. As mentioned earlier, nerves can run between muscles in “tunnels”. Specific nerves take residence in specific tunnels. For example, the median nerve courses through the carpal tunnel. The ulnar nerve passes along the cubital tunnel at the elbow. There are numerous “tunnels” (i.e. radial tunnel, Guyon’s Canal) within the body, both in the upper and lower limb and these can often be superficial and prone to irritation. When irritated, guess what can occur…numbness!
            Lastly, numbness symptoms can be due to posturaltractioning of nerves as well as positional/occupationalfactors. There are some nerves that we mention actually pass through muscles. If the muscles are overused or injured it can compromise the nerve that pierces it as well (i.e. Pronator Teres Syndrome). 
 
            We’ve spent a considerable amount of time speaking about MSK causes of hand numbness. There are also many non-MSK causes for hand numbness. We’ll refer to this category as systemic reasons. These causes may start insidiously with no known cause or warning. Some here may also be present on both sides of the body. 
            People commonly know that a heart attackcan present with pain down the left arm.  Lets first clear up the fact that it does not have to be the left arm. It can be the jaw, neck, and even the right arm that presents with pain. Also, women’s signs/symptoms of a heart attack can be quite atypical. However aside from pain, numbness may be felt/perceived in the arm. It’s best not use this symptom alone to dictate further management, use the full clinical picture!
            Sticking with the cardiovascular system, a strokemay also cause numbness. Once again, the hallmark sign may be weakness of the face and/or arm, but numbness is a cardinal sign as well.
            Diabetic neuropathiescause numbness. They may commonly start in the feet first but can spread to the hands in the classic “glove & stocking distribution” to give about numbness. There are other medical conditions such as Multiple Sclerosis, Guillain-Barre Syndrome, & even Raynaud’s Syndromethat can cause hand numbness. These are examples of some of the neurologic & autoimmune conditions that create numbness but are not the entire list. Lastly, there are some lifestyle factors that can cause numbness. One in particular is excessive alcohol use, or Alcoholic Neuropathy.
 
            Now that you know what can cause numbness in the hand, you may be asking yourself what can you do to prevent it from happening? First off, some of these you can’t prevent but for the ones that you can, there are a few things to help lower the risk of occurrence. Be sure to live a healthy lifestyle. A life that includes a healthy diet with moderate indulgence, and being active! Do not let things build up. Go for your routine exams. Seek manual therapy from a qualified professional when you have lingering aches and pains! Be proactive with your health!
 
Note that the systemic causes listed above are not in the realm of chiropractic treatment. For diagnosis & management of such systemic conditions, please seek care from a medical doctor.
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