Your Guide to Carpal Tunnel Syndrome
read time: 5 minutes
It’s 2:36 a.m. Laurie has no idea why she’s awake.
No, wait, that’s not true. Her hand is densely numb and it burns. It feels like she just pressed it into the brand-new griddle she got last week for her birthday.
Wait. Was that last week? Or the week before?
She hasn’t been thinking clearly since this hand started waking her up three or four times a night for the past month. She’s been trying to get in to see her doctor, but the current wait time for an appointment is six weeks.
Laurie gives her hand a few aggressive shakes and the pain softens briefly as she dozes back to sleep…
Carpal tunnel syndrome (CTS), in its most basic form, is an extremely common and painful pinched nerve at the wrist.
Specifically, the median nerve is pinched as it passes through, well, the carpal tunnel. The technical term for a pinched nerve is peripheral nerve compression.
Note: This post will be part of a family of Rules of Thumb posts about carpal tunnel syndrome. If you’d like to follow those, search for “carpal tunnel” in the Rules of Thumb archive.
So...what is the carpal tunnel?
The carpal tunnel refers to an anatomic space in the wrist. If you imagine a literal tunnel, the floor beneath you and the walls on either side are made up of the bones in your wrist (drawing below). The roof of the tunnel is a thick ligament known as the transverse carpal ligament (in orange).
Notice that the tubular contents of the tunnel include the median nerve (yellow) and nine flexor tendons (navy). When activated, these are the tendons that bend your fingers into a fist.
Carpal tunnel syndrome = pinched median nerve
Now, if anything compresses the median nerve in this tunnel, you will feel the symptoms of carpal tunnel syndrome.
Here are a few ways this pinch might happen:
SLEEP: When we sleep, we all naturally flex our wrists. Conversely, when we type, most of us extend our wrists. These changes in wrist position alter the volume of the carpal tunnel, resulting in higher pressure within the carpal tunnel.
AGE: The thick ligament (in orange above) that forms the roof of the carpal tunnel will naturally thicken with age. As the ceiling of the carpal tunnel slowly collapses, the median nerve will be the first to squish, leading to carpal tunnel syndrome.
INFLAMMATION: Less common but serious inflammatory conditions such as rheumatoid arthritis can lead to swelling of the nine flexor tendons in the carpal tunnel. If the flexor tendons swell, they have nowhere to expand within the tunnel, and the carpal tunnel pressure skyrockets. Yet again, a pinched median nerve.
PREGNANCY: In pregnancy, hormone shifts can cause an increased volume of fluid in the tissues of the carpal tunnel. Again, more volume within the tunnel means higher pressure on the nerve. Pregnancy-induced carpal tunnel syndrome is very common.
The pinky finger is your guide
So far we’ve talked about how carpal tunnel syndrome occurs. But what are the symptoms?
Classic carpal tunnel syndrome symptoms are some combination of numbness, tingling, burning, or shooting pains felt on the palm side of your thumb, index finger, middle finger, and sometimes part of your ring finger.
These symptoms are typically worse at night and can wake you up from sleep, sometimes multiple times a night.
Carpal tunnel syndrome does NOT involve your pinky finger. Notice in the drawing below how the yellow nerve branches don’t travel to the pinky or half of the ring finger.
If severe or longstanding, carpal tunnel syndrome can even result in weakness or atrophy (loss of muscle) of the muscles at the base of your thumb called your thenar muscles (see photo below). If these muscles look smaller compared to your other hand, please run (don’t walk) to a hand surgeon.
I need sleep. How do I cure these awful symptoms?
As common as carpal tunnel syndrome is, there are infinite myths regarding how to treat it.
Before I mention some of your options, I have one hard and fast rule if you decide to seek relief on your own. It’s ok to try a few things at home first. But do not ignore longstanding nerve symptoms.
This is how you get into the territory of permanent nerve damage that not even surgery can fix. The loss of muscle I mentioned above? Permanent. Irreversible.
So give a few months of treatment a try on your own first if you like, but if it doesn’t work, you do need to get yourself to a hand surgeon for formal care.
Currently, the mainstays of treatment include nighttime wrist bracing (remember, we all bend our wrists at night, which pinches the nerve all night long), a steroid injection into the carpal tunnel, or a relatively minor surgery to decompress the nerve.
Unfortunately, in most circumstances, treatments like therapy or oral medications don’t provide any meaningful relief of carpal tunnel symptoms.
Takeaways:
Carpal tunnel syndrome is caused by a pinched median nerve at the wrist
Symptoms include numbness, burning, or tingling in the thumb, index finger, middle finger, and half of the ring finger
There are some nonoperative treatments worth trying, but it is not safe to ignore these symptoms for extended periods of time
There is much, much more to discuss about carpal tunnel syndrome. Entire textbooks have been written about this condition.
But hopefully you now feel a little more comfortable with the basics and can apply what you know to your specific symptoms. We will build on this in future posts.
I hope you join me.
