Carpal Tunnel and Wrist Ultrasound in Ajax
Tingling fingers or a sore wrist? Learn how ultrasound looks at the median nerve and wrist tendons, how to prepare, and what Ajax patients can expect.
· 9 min read
Pins and needles in the thumb and first few fingers. A hand that “falls asleep” while you hold your phone or steer the car. Waking at night and shaking your hand to get the feeling back. Dropping a cup more often than you used to. These are some of the experiences that lead people to mention carpal tunnel syndrome to their family doctor, and they are also some of the reasons a provider in Ajax, Pickering or Whitby might send a patient for an ultrasound of the wrist.
This article explains what the carpal tunnel is, why a sound-wave scan can be a useful look inside it, what the appointment involves, and where ultrasound fits alongside the other ways health-care providers assess hand and wrist symptoms. It is general information, not a diagnosis. Only your own provider can put your symptoms, examination and test results together.
A tight space with a lot passing through
The carpal tunnel is a narrow passage on the palm side of the wrist. Its floor and walls are formed by the small carpal bones, and its roof is a firm band of tissue called the transverse carpal ligament. Through that space run nine tendons that bend the fingers and thumb, and one nerve: the median nerve.
The median nerve carries sensation from the thumb, index finger, middle finger and part of the ring finger, and it helps control some of the small muscles at the base of the thumb. Because the tunnel does not stretch much, anything that crowds it can press on the nerve. Swelling of the tendon linings, fluid retention, changes from arthritis and a range of other factors can all play a part.
When the nerve is squeezed for long enough, it can become irritated and swollen, and that is when the familiar symptoms tend to appear.
Who tends to notice it
Carpal tunnel symptoms are common and can affect people of many ages and occupations. Providers often ask about:
- Repetitive gripping, typing or vibrating tools at work or in hobbies
- Pregnancy, when fluid changes can temporarily crowd the tunnel
- Conditions such as diabetes, thyroid conditions or inflammatory arthritis
- A previous wrist injury or fracture
- Symptoms that are worse at night or first thing in the morning
None of these on their own mean you have carpal tunnel syndrome. They are simply part of the picture your provider builds when deciding what to do next.
Not every tingling hand is carpal tunnel
Numbness in the hand can come from several places along the route a nerve travels. A pinched nerve in the neck, irritation of a different nerve at the elbow, circulation problems and general nerve conditions can all cause similar feelings. That is one reason your provider may examine your neck, elbow and both hands, and why imaging of the wrist is only one possible step.
If neck symptoms are part of the story, our post on cervical spine X-rays explains how the neck is imaged and what those pictures can and cannot show.
A note on urgent symptoms: sudden numbness or weakness in one hand or arm, especially with facial drooping, slurred speech, confusion or trouble walking, can be a sign of stroke. Call 911 right away. A community imaging clinic is not the right place for those symptoms.
What a wrist ultrasound can show
Ultrasound uses high-frequency sound waves to build a live picture of soft tissue. At the wrist, the structures sit close to the skin, which makes them well suited to this kind of imaging. During a carpal tunnel or wrist ultrasound, the sonographer may look at:
- The median nerve itself. The size and shape of the nerve can be measured at and near the tunnel. A nerve that appears enlarged where it enters the tunnel is one finding a radiologist may comment on.
- The tendons and their linings. Thickening or fluid around the finger tendons can crowd the tunnel.
- Space-occupying lumps. A ganglion cyst or other lump near the wrist can press on nearby structures.
- Anatomical variations. Some people have an extra muscle or a nerve that divides earlier than usual, which can matter if a provider is planning further care.
- Movement. Because the picture is live, the sonographer can watch tendons glide as you gently move your fingers.
Ultrasound does not test how well the nerve is sending signals. That is the job of a different test, often called a nerve conduction study, which measures electrical activity. Your provider may order one, the other, both, or neither, depending on your symptoms. The two tests answer different questions, and one is not simply a replacement for the other.
Beyond carpal tunnel
Wrist ultrasound is also used for other soft-tissue questions, such as:
- Swelling on the back of the wrist that may be a ganglion cyst
- Pain along the thumb side of the wrist, where two thumb tendons share a tunnel of their own
- Tendon irritation from overuse
- Fluid around the small joints
If bones are the main concern, for example after a fall onto an outstretched hand, an X-ray is usually the starting point. Our practical guide to hand and wrist X-rays covers that side of things.
Getting ready for the appointment
Preparation for a wrist ultrasound is usually simple, but it is worth confirming any instructions when you book.
- Bring your health card and the requisition your provider gave you. If anything on the form is unclear, the office that wrote it can usually explain.
- Remove rings, bracelets and your watch before the scan, or leave them at home. The sonographer needs clear skin contact and room to move the probe.
- Wear a top with loose sleeves that push up past the elbow without much effort.
- No fasting is needed for a wrist scan in most cases, unlike some abdominal exams. If you have more than one ultrasound booked on the same day, the other exam may have its own preparation, so check each one.
- Make a note of your symptoms. Which fingers tingle, what time of day it is worse and what makes it better can all be useful to the person ordering the test.
If you are pregnant and your provider has asked for a wrist ultrasound, there is no special preparation related to the pregnancy. Ultrasound does not use ionizing radiation.
During the scan
Most people are surprised by how ordinary a wrist ultrasound feels. You are usually seated beside a small table or exam bed with your forearm resting on a cushion or towel, palm facing up.
The sonographer applies a clear gel to the wrist and slides a small handheld probe across the skin. The gel helps the sound waves travel. It can feel cool but should not be painful. You may be asked to:
- Rest your hand completely still while the nerve is measured
- Slowly bend and straighten your fingers so the tendons can be watched as they move
- Turn your wrist slightly so a different angle can be viewed
The sonographer may also scan the other wrist. Comparing both sides can help the radiologist judge what is normal for you. If you have symptoms in both hands, both may be scanned as part of the exam.
Light pressure is needed to get good pictures. If an area is tender, tell the sonographer. They can usually adjust. Once the images are captured, the gel wipes off with a towel and you can put your jewellery back on and leave.
Why the sonographer may not share findings
During the exam, the sonographer is focused on capturing clear, complete images. They are not able to give you a diagnosis. Your images are interpreted and a report is sent to the provider who ordered the test. Our article on how imaging results reach your doctor walks through that process in more detail.
How the results tend to be used
A wrist ultrasound report becomes one piece of information among several. Your provider may consider it alongside:
- Your description of symptoms and how long they have been present
- Physical examination findings, such as sensation in the fingertips and thumb strength
- Results of a nerve conduction study, if one was done
- Other imaging, such as an X-ray if arthritis or an old fracture is a concern
Based on all of that, your provider will talk with you about what the findings mean and what, if anything, should happen next. Decisions about splints, activity changes, referrals or other options are medical decisions made with your provider. A normal-looking ultrasound does not necessarily rule out carpal tunnel syndrome, and an abnormal one does not by itself decide a treatment plan.
Everyday habits worth mentioning to your provider
People sometimes feel they should have “caught it earlier” or done something differently. It is more useful to simply tell your provider about the parts of your day that involve your hands. Things that are often worth mentioning include:
- How many hours you spend typing, using a mouse or holding a phone
- Whether you sleep with your wrists curled under your pillow or body
- Tools, instruments or sports that involve gripping or vibration
- Recent changes, such as a new job, a new baby to carry or a new hobby
Your provider can then decide whether general advice, a referral to a hand therapist or physiotherapist, or further testing makes sense for you. We will not offer specific exercises or treatments here, because what helps one person may not suit another.
Booking a wrist ultrasound in Ajax
Rossland Diagnostic Clinic is at Unit 102, 300 Rossland Road East, with free parking and ground-floor access, which can make life easier if your hand makes it awkward to manage stairs, heavy doors or a long walk from a parking garage. We are open Monday to Friday from 9:00am to 5:00pm and Saturday from 8:00am to 3:30pm. Saturday appointments can be helpful if you work standard weekday hours.
You can read more about the range of scans we offer on our ultrasound service page, including musculoskeletal ultrasound for tendons, ligaments and joints. Patients come to us from across Ajax, Pickering, Whitby and the surrounding area.
When you have your requisition in hand, call us at 905-426-3111 or request an appointment online. If you have questions about preparation before your visit, our team is happy to help over the phone.