Testing for ulnar carpal tunnel syndrome (also known as Guyon's canal syndrome) involves a combination of physical examination and sometimes imaging techniques. There isn't a single definitive test; rather, diagnosis relies on a thorough assessment of symptoms and clinical findings.
Physical Examination
A physician will conduct a physical examination focusing on several key aspects:
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Sensory Testing: They will assess sensation in the little and ring fingers, the areas innervated by the ulnar nerve. This helps determine the extent of nerve involvement. As noted in the AAOS OrthoInfo resource, "[They will test the sensation in your fingers, focusing on the little finger and ring finger. They may ask you to try to tell the difference when they touch your…]"
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Pressure Provocation: The doctor may apply pressure directly over the ulnar nerve at the wrist (Guyon's canal) to see if this exacerbates the numbness or tingling. This helps localize the source of compression. One reference states that physicians "may apply pressure over the ulnar nerve at your wrist to see if this makes your numbness and tingling worse."
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Tinel's Sign: The physician may tap (percuss) over the ulnar nerve at the wrist. A positive Tinel's sign—tingling or paresthesia in the distribution of the ulnar nerve—suggests nerve irritation or compression. This is also mentioned in a resource which explains that clinicians "may tap their finger over the ulnar nerve at the wrist to determine whether this causes a tingling sensation (Tinel sign), which is a sign of nerve compression."
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Muscle Strength Testing: The doctor might assess the strength of muscles controlled by the ulnar nerve in the hand. The Johns Hopkins Medicine resource mentions a test which checks "[nerve and muscle function and may be used to test the forearm muscles controlled by the ulnar nerve."
Imaging Studies
While a physical exam often suffices, imaging may be necessary in some cases to rule out other conditions or to visualize the extent of nerve compression. These may include:
- X-ray: To identify bone fractures or bone spurs that might be compressing the nerve.
- CT scan: To look for growths or other structural abnormalities in the wrist.
- MRI: To provide a detailed visualization of the soft tissues, including the ulnar nerve and surrounding structures.
- Ultrasound: To assess the nerve's structure and detect any compression or abnormalities. WebMD lists these as possible diagnostic tools: "[X-ray to look for a fracture or a bone fragment pressing on the nerve · CT scan to look for a growth · MRI · Ultrasound.]"
It's crucial to remember that these tests are used in conjunction with a patient's reported symptoms and medical history to arrive at an accurate diagnosis.
