The median nerve can be tested using several clinical maneuvers and diagnostic tests. These methods assess both sensory and motor function.
Clinical Tests for Median Nerve Function
Several simple tests help evaluate the median nerve:
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Carpal Compression Test (Durkan's Test): This test directly assesses the median nerve within the carpal tunnel. The examiner holds the patient's wrist in slight flexion and applies pressure with their thumbs over the median nerve in the carpal tunnel (just distal to the wrist crease) for 30 seconds. A positive test elicits pain, paresthesia (pins and needles), or numbness in the median nerve distribution (thumb, index, middle, and radial half of the ring finger). [Source: Stanford Medicine 25, UAMS Department of Family Medicine]
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Phalen's Test: This involves flexing the wrists maximally and holding them together for 60 seconds. This position compresses the median nerve. Positive results are similar to the Carpal Compression Test, producing pain, paresthesia, or numbness in the median nerve distribution. [Source: Cleveland Clinic]
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Tinel's Sign: This involves tapping lightly over the median nerve at the wrist. A positive test produces tingling or paresthesia in the median nerve distribution. [Source: StatPearls]
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Thenar Muscle Atrophy: Observe for wasting or decreased bulk of the thenar muscles (muscles at the base of the thumb) indicating possible median nerve damage.
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Testing Motor Function: Assess the patient's ability to perform fine motor tasks involving the thumb, such as opposition (touching the thumb to other fingers), abduction (moving the thumb away from the palm), and flexion. Weakness or difficulty in these movements suggests median nerve involvement. The "OK" sign (touching the thumb to index fingertip) specifically tests the anterior interosseus nerve branch of the median nerve. [Source: NUEM Blog]
Diagnostic Tests
For more definitive diagnosis, consider these:
- Nerve Conduction Studies (NCS): NCS objectively measure the speed and strength of electrical signals traveling along the median nerve. These studies can identify nerve damage and its location. [Source: Johns Hopkins Medicine, Mayo Clinic]
- Electromyography (EMG): EMG assesses the electrical activity of muscles innervated by the median nerve. It helps to determine the extent of muscle damage and can help differentiate between nerve and muscle problems. [Source: Mayo Clinic]
Upper Limb Tension Tests
While not solely focused on the median nerve, Upper Limb Tension Tests (ULTTs), such as UTT1, can help determine if the source of shoulder and arm pain is related to the median nerve or its associated nerve roots (C5, C6, C7). [Source: Physiopedia]
Remember, proper interpretation of test results requires professional medical expertise. These tests are valuable tools in the assessment of median nerve function but should be performed and interpreted by a qualified healthcare professional.
