Carpal tunnel syndrome diagnostic study of choice
Overview
CTSs Symptoms include numbness, pain, or paresthesia in the median nerve distribution.
Commonly used provocative tests include wrist flexion (Phalen), nerve percussion (Tinel), and carpal compression (Durkan) tests.
Electrodiagnostic studies (EDS) and imaging evaluations are used in order to confirm diagnosis.
Diagnosis
Clinical assessment by history taking and physical examination can frequently diagnose CTS. Diagnostic criteria of CTS:
- numbness and tingling in the median nerve distribution
- weakness and/or atrophy of the thenar musculature
- nocturnal numbness
- loss of two point discrimination
- Phalen's maneuver is performed by flexing the wrist gently as far as possible, then holding this position and awaiting symptoms. A positive test is one that results in numbness in the median nerve distribution. The quicker the numbness starts, the more advanced the condition.
- Tinel's sign, a classic, though less specific test, is a way to detect irritated nerves. Tinel's is performed by lightly tapping (percussing) the area over the nerve to elicit a sensation of tingling or "pins and needles" in the nerve distribution.
- The carpal compression test, or applying firm pressure of the palm over the nerve to elicit symptoms has also been proposed.
Other conditions may also be misdiagnosed as carpal tunnel syndrome. Thus, if, based on history and physical examination, a CTS diagnosis is suspected but not clear, patients will likely be tested electrodiagnostically with nerve conduction studies and electromyography; MRI or ultrasound imaging are also used.
Diagnostic Value of History and Physical Examination Findings for Carpal Tunnel Syndrome
D'Arcy CA, McGee S. The rational clinical examination. Does this patient have carpal tunnel syndrome? [published correction appears in JAMA. 2000;284(11):1384]. JAMA. 2000;283(23):3110–3117.
| FINDING | SENSITIVITY (%) | SPECIFICITY (%) |
|---|---|---|
| Flick sign | 93 | 96 |
| Hypalgesia | 39 | 88 |
| Square wrist sign | 53 | 80 |
| Classic or probable pattern on hand symptom diagram | 64 | 73 |
| Abduction weakness | 65 | 65 |
| Thenar atrophy | 16 | 90 |
| Tinel sign | 36 | 75 |
| Phalen maneuver | 57 | 58 |
| Nighttime or morning symptoms | 70 | 43 |
| Electrodiagnostic | 49–84 | 95–99 |
| Ultrasonography | 82 | 92 |
| MRI | 63-83 | 78-80 |
| Computed tomograph | 67 | 87 |