Have you ever had your hand(s) fall asleep? It’s a weird, awful, and awkward sensation – like having a “dead” weight attached to the end of your arm. Then comes the uncomfortable “pins and needles” or “tingling” as sensation returns and you begin to be able to wiggle your fingers again.
So, what’s really going on?
Essentially, the nerve is just ‘unhappy’. A nerve can get compressed anywhere – from the neck or all the way down into the hand.
Mini-Biology Lesson:
1) Neurons (= nerve cell) are the longest cells in the body. A single neuron and its threadlike axon (think ‘tail’) reach all the way from the neck to the patch of skin (or muscle) that it wires. This could mean a single neuron may go down to your elbow for turning on/off the biceps or could reach all the way to the tip of your finger to provide sensation for it!
2) Commonly, nerves are compared to as wires – a neuron (wire), wrapped in layers of connective tissue (similar to the insulative plastic covering) and to a certain extent, this is true.
In fact, on average, approximately HALF of a nerve is actually made of connective tissue!
As each nerve is made of many bundles of neurons.
And each nerve is wrapped in connective tissue (like “saran wrap”)
And then each bundle is wrapped in more connective tissue
…and then each neuron is wrapped in even MORE connective tissue!
Which is a good thing – as this “saran wrap” provides protection to the precious neurons (as well as the tiny blood vessels) contained inside the nerve.
3) However, nerves are actually a whole lot stretchier and more mobile than the “wire” analogy implies… The median nerve (one of the 3 major nerves that wire the hand & arm) can glide & stretch – lengthening by 10 centimeters (or 3.9 inches) from the position where your hand is touching your shoulder to when your elbow is straight & wrist bent back (open palm).
Therefore, I like to think of nerves as more like bungee or shock cords as they have some “give” and stretch to them.
But there’s only so much compression and/or stretch that a nerve can handle. With 6-8% strain, the blood flow inside the nerve is slowed. With 15% strain, this blood flow is completely stopped. No blood = no oxygen + no nutrients that the neurons need to function. So, the brain receives no signals from the nerves = the “numbness” and “dead weight” feeling.
Once the pressure is relieved, this blood flow to the nerve (and inside the nerve) returns! However, the nerve is only partially working at this point = “tingling” or “pins and needles” sensation felt.
Where exactly you experience your numbness can help figure out which nerve is being compressed (and sometimes even WHERE along the nerve it’s being compressed). This is because each nerve has its own patch of skin that it “wires” – just ask Spock!
For compression occurring somewhere in the arm/hand along the peripheral nerve…
Or if the compression occurs at the root of the nerve (at the neck)...
As long as these symptoms are temporary (ie. go away within a few minutes) and are relieved by a change in your position, this is normal and nothing to be concerned about.
However, if your numbness:
Is worsening in intensity
Is lasting longer each time
Becomes constant
OR you feel like you have a weaker grip and/or are dropping things.
Then you should follow-up with your doctor and/or see a physiotherapist… It’s only logical!
If you have more questions about hand numbness or any hand, arm, or shoulder issue, feel free to book a Telehealth appointment with me at InReach Physiotherapy!
By: Susan Herdman, Registered Physiotherapist – Specializing in Upper Extremity and Hand Telerehabilitation. Book a telephysio / online physio / virtual physio appointment with a registered physiotherapist in British Columbia. InReach Online Physio services communities in northern and rural BC, such as Masset, Queen Charlotte, Fraser Lake, Fort Nelson, Fort St James, Dease Lake, Fort St John, Dawson Creek and more. Learn more
References:
Butler, D.S. The Sensitive Nervous System. Noigroup Publications, Adelaide, Australia, 2000.