Symptoms and Diagnosis of Carpal Tunnel Syndrome

Symptoms

Patients often say that their entire hand feels numb. However, on closer examination, the sensation on the back of the hand and on the half of the ring finger next to the little finger is normal. They also say that sensation is reduced in the thumb, index finger, middle finger, and the thumb-side half of the ring finger, as well as in the connected skin of the palm. In advanced cases, the muscles of the thenar eminence (the thumb pad) atrophy and become flattened. In people whose jobs require extensive use of the hands, the symptoms tend to be more severe, and the following symptoms generally occur.

1. Main symptoms of carpal tunnel syndrome

· Tingling or a burning sensation at the fingertips, along with numbness or pain, occurs.

· Sensation is reduced in the thumb, index finger, middle finger, and the thumb-side half of the ring finger, as well as in the connected skin of the palm.

· The hand becomes numb while driving.

· Because the pain is especially severe at night, sleep is often disturbed. In such cases, rubbing or shaking the hand often relieves the symptoms.

· The hand feels stiff or cramps in the morning.

· As the condition gradually progresses, muscle atrophy occurs in the proximal part of the thumb-side muscles (the thenar eminence or thumb pad), and this area becomes flattened.

· Fine motor tasks become difficult, and delicate movements in daily life, such as buttoning clothes, may become impaired.

· Grip strength decreases, causing objects to be dropped often or making chopstick use difficult; the strength needed to turn bottle caps weakens, and the strength to wring laundry may also decrease.

· The skin on the palm becomes shiny or dry.

· Some people also complain that the numbness and pain spread to the elbow, shoulder, the entire arm, and the neck.

Diagnosis

1. Medical history review

The overall details are checked, including the pattern of symptoms, when they started, how severe they are, past medical history, and general health status. For any disease, an accurate diagnosis is essential for proper treatment, and carpal tunnel syndrome is no exception. It must be clearly distinguished from various conditions that can compress nerves, and systemic diseases such as chronic renal failure, obesity, diabetes, and thyroid dysfunction can also cause symptoms similar to this condition. It should also be considered that it may appear temporarily during pregnancy. Carpal tunnel syndrome tends to worsen when the wrist is excessively bent or extended, along with the clinical symptoms mentioned above. When the backs of both hands are placed together and the wrists are bent, numbness in the palms and fingers tends to worsen; this examination method is also useful as a self-diagnosis method.

2. Physical examination

The following examination methods are necessary for diagnosing carpal tunnel syndrome.

1. Wrist flexion test (Phalen test)

If the hand becomes numb within 1 minute while the wrist is bent (with the backs of the hands facing each other), carpal tunnel syndrome may be suspected.

2. Nerve percussion test (Tinel sign)

If a tingling sensation occurs in the fingers when the area through which the median nerve passes is tapped, carpal tunnel syndrome may be suspected.

3. Median nerve compression test

If the front part of the wrist on the palm side, where the median nerve passes, is pressed deeply with the finger and abnormal sensation or pain appears in the area supplied by the median nerve, carpal tunnel syndrome may be suspected.

4. Two-point discrimination test (Tow point discrimination test)

Using a pointed pin at the fingertip, the shortest distance at which two simultaneously pressed (or pricked) points can be clearly distinguished as separate points is measured. If the distance at which the thumb, index finger, and middle finger can distinguish two points is greater than that of the little finger, carpal tunnel syndrome may be suspected.

5. Thumb opposition test

If the bulging muscle on the palm side of the thumb becomes atrophied and flattened while the thumb and little finger are brought together and force is applied, the compression of the nerve is likely already quite advanced.

6. Tourniquet test

If a tourniquet is wrapped around the arm and a pressure of about 60-80 mmHg is applied so that arterial blood flows in but venous blood cannot return, the carpal tunnel may be compressed by venous congestion, causing nerve symptoms.

3. Nerve conduction and electromyography test (EMG)

Because clinical symptoms alone cannot completely rule out the possibility of other diseases, electrophysiological tests such as nerve conduction and electromyography are helpful for an accurate diagnosis. EMG is the correct term for nerve conduction and electromyography testing, because EMG is only part of the nerve conduction and electromyography test. Nerve conduction and electromyography tests are used to assess the condition of nerves and muscles. They include EMG, nerve conduction studies, and evoked potential tests, and are useful for determining whether there is a nerve disorder or a muscle disorder, where the lesion is located, how severe it is, and whether the disease is present, progressing, or recovering.

To perform nerve conduction and electromyography testing, the nerves and muscles are artificially stimulated. This stimulation is done with electrical stimulation using surface electrodes or needle electrodes. When stimulated with needle electrodes, mild pain may cause discomfort, but it is a safe test that can be performed without side effects or special sequelae. The test takes about 30 minutes to 1 hour. Even if symptoms appear in only one hand, abnormal findings are often observed in both hands on testing. On the other hand, if the symptoms are mild, such as when nerve compression does not persist and the temporary compression is relieved, or in the early stage of carpal tunnel syndrome, no abnormal findings may appear on nerve conduction and electromyography results.

4. Plain radiography

It is advisable to take frontal and lateral images of the wrist and carpal tunnel view to evaluate for arthritis in the wrist joint, abnormalities of the carpal bones, and calcification of soft tissues. It is also advisable to take frontal and lateral images of the cervical spine (neck bones) to evaluate whether degenerative cervical arthritis and intervertebral disc disease are also present. This is because abnormalities in the cervical spine can also cause hand numbness. In other words, depending on the patient, hand numbness may be caused by carpal tunnel syndrome, but it can also be caused by problems in the cervical spine, so an accurate differential diagnosis is necessary.

5. Other tests

Other tests that may be performed include the following.

1. Blood tests

To check for coexisting conditions related to carpal tunnel syndrome, blood tests can be performed through blood collection, including complete blood count, thyroid function tests, blood glucose tests, rheumatoid factor tests, as well as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), which reflect the degree of inflammatory response.

2. Ultrasound examination

It can help with diagnosis by observing thickening or bulging of the transverse carpal ligament, local nerve compression, and edema proximal or distal to the compression site. It can also assess nerve compression caused by tumors or other causes within the carpal tunnel. Recently, with the use of high-resolution ultrasound, the diagnostic accuracy of ultrasound for carpal tunnel syndrome has become comparable to that of electromyography, and its use for diagnostic purposes has been increasing.

So far, we have explained the symptoms and diagnosis of carpal tunnel syndrome.

In the next part, we will look at the treatment of carpal tunnel syndrome.

Source: Korea Disease Control and Prevention Agency, National Health Information Portal