Week 4: Carpal Tunnel Syndrome
This week I’d like to talk about carpal tunnel syndrome and hopefully educate you on some of the facts associated with carpal tunnel syndrome as well as review options for treatment. I treat a lot of carpal tunnel syndrome in my clinic and I think we do a good job at it. As always, we use imaging as a primary modality for diagnosis and treatment as well as determining the stage of the disease process.
With technology advancing as it is, most of the medicine world is not keeping up with all the available options in treating carpal tunnel syndrome, so I’d like to take time to review the available options with you as well as some statistics.
There are about 12 million people in the United States with carpal tunnel syndrome. Of those, 1.2 million receive a new diagnosis of carpal tunnel syndrome every year. About 6 million suffering with carpal tunnel syndrome are recommended for surgery, but only 650,000 get the surgery, so there seems to be a big void between those recommended for surgery and those that actually follow through with surgery.
Currently the general standard of care - or the majority of the surgeries that are done for carpal tunnel syndrome - are what’s called a mini-open procedure where a small incision measuring about 2 cm is made through the palm of the hand. The surgeon then dissects down on the carpal tunnel ligament and transects it, which does have some downsides to it. The biggest problem associated with this particular procedure is the healing time as it is a 2 - 6 week recovery. If you work with your hands, life can be difficult if you have to be out of work for four weeks. If you have bilateral carpal tunnel syndrome, then you’re looking at double that time as they will generally do one hand at a time. I believe that is one of the primary reasons why people are not getting the surgery. Many are intimidated by a surgery in general, and then they can’t take the needed down-time for recovery, nor can they afford the economic burden of the cost of surgery in addition to the cost of time off work. Because there are so many challenges standing in their way, most people just go on living with carpal tunnel syndrome. The reality is, most people can live with carpal syndrome for quite awhile, sometimes even years. However, the problem with waiting is that due to the anatomy, the condition will worsen over time and can lead to permanent damage.
Understanding the Anatomy
Image taken from https://www.neurosurg.org/
To try and better explain what causes carpal tunnel syndrome, imagine a small circular tunnel like a PVC pipe that is a hard surface all the way around and you stick a bunch of pencils into that tunnel. The pencils are also fairly rigid and they represent your flexor tendons - the tendons that allow you to move your fingers. Along with the pencils, imagine a cooked noodle - like penne pasta.If the pencils grow in size or if the tunnel decreases in size, the thing that’s going to take the beating is that noodle. In this case, that noodle represents the median nerve - which is very soft and pliable and it is prone to injury. The median nerve flows like a river. It goes from your spinal cord out down your arm and to your hand through your carpal tunnel. When the nerve arrives at the tunnel, if there is some form of restriction, it compresses the nerve and everything flowing down the nerve backs up just like a dam in the river proximal to (or above) the nerve. That swelling over time can become permanent - it is called scarring. With a carpal tunnel release, the goal is to decrease that swelling or enlarged size of the nerve, but even with a release, the damage may have reached a point that the scarring is not reversible. Now you can understand a little better why it’s worrisome from a physician standpoint that a lot of people who need carpal tunnel release are not doing it or putting it off. They could be causing permanent damage to that nerve. With a carpal tunnel release, a surgeon will go in and cut the top of that cylinder (or PVC pipe from our example) to allow for more space for everything trying to fit into that tunnel - specifically for the nerve. A release of the transverse carpal ligament is very effective at treating that compression syndrome, and it is a very common and generally safe procedure.
Symptoms and Progression of Carpal Tunnel Syndrome
Most often, the symptoms of carpal tunnel syndrome start out as nighttime symptoms. You’re usually woken up at night with numbness or tingling in your hand, so you end up shaking your hand out to relieve that numbness or tingling. Some of you will notice while driving with a hand on the steering wheel - or really in any type of fixed position - your hand goes numb. This numbness is usually specific to the thumb, index finger, middle finger, and part of the ring finger. The little finger is generally not affected. These primary symptoms usually respond well to using night splints - or braces that are worn while sleeping to prevent the hand and wrist from kinking - keeping pressure off the median nerve. If you notice your symptoms early enough and begin utilizing splinting possibly in conjunction with physical therapy, this might be enough to resolve symptoms.
However, if that nerve continues to swell and can’t fit through the tunnel and continues to back up the chain like that dam we talked about, symptoms increase and bring you to a point of going to the doctor . For diagnostic purposes, you may get a nerve conduction study, which basically measures the velocity or how the message travels up and down the nerve - this will help determine the severity of the disease to know what steps come next. At our office, we will measure the size of the nerve - this will show how much swelling/scarring has actually occurred and this can also tell us the severity of carpal tunnel syndrome to know what next steps are.
Once conservative options have been tried and failed, and you are unsure about jumping to surgery, an option would be to try a steroid injection into the carpal tunnel around the median nerve which can reduce swelling of that nerve. This can also be a pretty good test to know if surgery is the best option. If you get an injection and it lasts for three weeks and the symptoms return right back, then this is pretty indicative of the fact that you need surgery. However, if your symptoms are resolved following the injection for 6 months to a year, then you could probably just do a repeat injection and with the time of decreasing that swelling, symptoms may resolve.
With newer technology today, we can actually utilize ultrasound imaging to see the nerve and measure its size to help determine the extent of abnormality and scarring the nerve has. We can also get a pretty good estimate as to how much of that scarring will resolve with a carpal tunnel release. With this technology, it allows us to diagnose carpal tunnel syndrome without the need of a nerve conduction study. We know that symptoms in the presence of a swollen nerve is carpal tunnel syndrome. A normal nerve measures 5-9mm² - which is about the size of a pencil. When a nerve gets over 10mm², it’s no longer within the normal range and it’s starting to get sick. When a nerve reaches 15 mm², we know that the symptoms are probably not going to be treated or resolved with conservative methods and that surgery is going to be the best outcome.
You might be asking how long do I wait and how many conservative options do I try before I embrace surgery? That answer is going to be gauged on an individual basis, but you definitely want to get surgery before you begin to experience permanent numbness in your thumb, index finger, middle finger, and ring finger. Or you want to address it before the thenar muscle - the muscle attached to your thumb - gets weak. If your symptoms have reached this point, it’s not necessarily too late. You can still save a lot of the nerve, but there’s a lot of damage already done that’s most likely not going to be resolved with a carpal tunnel release. Oftentimes, it will even take months to a year to resolve some of the numbness symptoms.
Treatment Options
I’ve drawn three marks on my left hand with labels 1, 2, and 3 to illustrate the various treatment options for carpal tunnel syndrome.
Number one represents the current standard of care that I previously discussed, which is called a mini-open release. It’s about a 2 cm incision across the palm of your hand. As far as outcomes go, they are great and the risks are fairly minimal. In my opinion, the biggest draw back from that procedure is the amount of downtime. Following the procedure, you’ll have stitches that usually come out 10 days following the procedure. Once the stitches are out, you’ll do some physical therapy and then you can return to work. Generally, if you’re a manual laborer and use your hands a lot, you’re usually out of work for about four weeks.
Number two, you can see, is aligned in a different direction than number one and it represents the entry site for what is called an endoscopic release. This technique is not used as readily as the mini-open procedure, because it’s generally done by surgeons with lots and lots of experience because there’s some portion to the procedure that you can’t see until you put a device in it. The benefit to this procedure is the down-time is minimized by usually a couple weeks less than the mini-open procedure. However, you’re still out about two weeks before returning to work or participation in daily activities.
Number three is a newer procedure that I’ve been doing since 2017 - it is called the micro-invasive technique utilizing a tool that is called the Sx-1 MicroKnife.
You can clearly see one of the biggest differences between all three procedures is the size of the incision site. Obviously, the bigger incision is with a mini-open, which is reduced with the endoscopic, and then even greater reduced with the micro-invasive technique. With the mini-open release, a surgeon has to open the hand up in order to see the targets and dissect down slowly and then carefully to transect or cut the transverse carpal ligament. This is the goal of all the procedures - to release that ligament - because it is the roof of the tunnel. So if we can pop open that roof and allow more space for the median nerve - it can then return to its normal health. With the endoscopic release, you put a device down down and look up through an endoscope - or a small camera - at the transverse carpal ligament that is then cut from the bottom up. As I had mentioned, the surgeon can visualize the ligament as they go underneath that ligament, but all that is seen are the structures that are in view of the camera. Anything outside of that view cannot be visualized.
Due to the advances in ultrasound technology, we are now able to see dynamic changes in the carpal tunnel. The means that I can look inside the tunnel and I can see your flexor tendons, I can see your median nerve, and I can also see the branches of your median nerve. These branches are at risk during an operative carpal tunnel release. So if a patient has a variance in their anatomy or a remarkable structure, I can see that beforehand utilizing ultrasound. With the Sx-1 MicroKnife, we can make a 4-5 mm incision which is half a cm or less. Through that small incision, we run a device up through your wrist and underneath the transverse carpal ligament all while visualizing the nerve, the artery, the ligament, as well as the device in real time. This complete visualization allows for a very safe procedure.
As for outcomes with this micro-invasive technique, most patients are generally back at work within four days. So if we do the procedure on a Thursday, they will be back to work by Monday. This even applies to manual labor situations where people use their hands a lot. With this option of decreased recovery time, it should reduce the reason why people are not getting a carpal tunnel release. It’s a very slick procedure and it works very well and patients are generally quite happy with the results. Of course it is still a surgical procedure that inherently has its risks, but those risks are minimized secondary to visualization of structures.
Clearing Up Some Myths
As some of you who have read or watched my first week’s post for the Weekly Peak, you will know that one reason I decided to start these weekly educational conversations is because of my frustration at the amount of misinformation found online in regards to a lot of the conditions I treat. This is no different with carpal tunnel syndrome. I recently saw a YouTube video about treating carpal tunnel syndrome and it was a practitioner stating that carpal tunnel syndrome can be treated by adjusting the neck. After having reviewed the anatomy and what carpal tunnel syndrome is, you can clearly see that is a fallacy. Carpal tunnel is the entrapment of the median nerve at the wrist, not the neck. If you have entrapment of a nerve root at the neck, you can get symptoms similar to those of carpal tunnel syndrome, but it is not carpal tunnel syndrome. In some instances, people will have entrapment of a nerve at the neck which goes down to the wrist and they will also have entrapment at the wrist - this is called double crush syndrome. Theoretically, you could treat the cervical spine which would help with any restriction or entrapment at the neck, but it’s not going to do anything for true carpal tunnel syndrome.
So let me clear that carpal tunnel syndrome does not come from the neck - it comes from the wrist. I will, however, add an “although.” Although it comes from the wrist, people with carpal tunnel syndrome can have pain going to their elbow, to their forearm, up into the shoulder, and all the way into the neck. In scenarios like this where symptoms reach to the neck and a diagnosis that needs to be looked at or ruled out is that of a nerve root impingement, such as a herniated disc or arthritis in your neck, then an MRI should be considered to see if there’s impingement in the cervical region to explain those symptoms. Another option to help rule that out would be a nerve conduction study or EMG that I talked about earlier that can be used in diagnosing carpal tunnel syndrome. This test can determine whether the symptoms are stemming from the neck or hand or possibly both.
Hopefully, I have been able to clear up any misinformation you may have received about carpal tunnel syndrome, and you can better understand the disease and the options available to you.