WBR0241
| Author | [[PageAuthor::Mugilan Poongkunran M.B.B.S [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 3 |
| Main Category | MainCategory::Primary Care Office |
| Sub Category | SubCategory::Musculoskeletal/Rheumatology |
| Prompt | [[Prompt::A 65 year old women comes to see you at the office with complaints of right wrist pain for the past 3 months. She has numbness and tingling sensation in the first two fingers and her symptoms increase with activities requiring prolonged flexion or extension of the wrist. Her other medical problems are hypothyroidism, diabetes, chronic renal failure, coronary heart disease, hypertension and osteoporosis. What is the most appropriate method to make the diagnosis of this condition?
A. Electromyography B. Nerve compression studies C. Phalen maneuver D. The Tinel test E. Ultrasonography]] |
| Answer A | AnswerA::Electromyography |
| Answer A Explanation | [[AnswerAExp::Incorrect : The electrodiagnosis of CTS depends mainly upon the demonstration of impaired median nerve conduction across the carpal tunnel. EMG is most useful to exclude other conditions, such as polyneuropathy, plexopathy, and radiculopathy.]] |
| Answer B | AnswerB::Nerve compression studies |
| Answer B Explanation | [[AnswerBExp::Incorrect : Nerve compression results in damage to the myelin sheath and manifests as delayed distal latencies and slowed conduction velocities. With sustained or more severe compression, axon loss may also occur, resulting in a reduction of the median nerve compound motor or sensory action potential amplitude.]] |
| Answer C | AnswerC::Phalen maneuver |
| Answer C Explanation | [[AnswerCExp::Incorrect : With the Phalen maneuver, the patient fully flexes the palms at the wrist with the elbow in full extension to provide extra pressure on the median nerve. Alternatively, the backs of the hands are placed against each other to provide hyperflexion of the wrist, and the elbows remain flexed. A positive Phalen sign is defined as pain and/or paresthesia in the median-innervated fingers with one minute of wrist flexion. Meta-analyses have shown an average sensitivity of 68 percent and specificity of 73 percent for a positive Phalen's test. Hence this the correct option.]] |
| Answer D | AnswerD::The Tinel test |
| Answer D Explanation | [[AnswerDExp::Incorrect : The Tinel test involves firm percussion performed over the course of the median nerve just proximal to or on top of the carpal tunnel. A positive Tinel test is defined as pain and/or paresthesia of the median-innervated fingers that occurs with percussion over the median nerve. A positive Tinel sign may be less sensitive (50 percent) than the Phalen sign, but has similar specificity (77 percent)]] |
| Answer E | AnswerE::Ultrasonography |
| Answer E Explanation | AnswerEExp::'''Incorrect''' : Imaging studies are not routinely employed in the evaluation for possible CTS. |
| Right Answer | RightAnswer::C |
| Explanation | [[Explanation::Carpel tunnel syndrome (CTS) is a clinical diagnosis. The diagnosis is suspected when the characteristic symptoms and signs are present. The most important of these are nocturnal pain or paresthesia in the distribution of the median nerve. Objective sensory and motor deficits corresponding to the median nerve-innervated regions of the hand may be present, but their absence does not rule out the diagnosis of CTS. Objective weakness can occur in advanced CTS and is limited to muscles of the thenar eminence. This manifests principally as weakness of thumb abduction and thumb opposition. Atrophy of the thenar eminence may be present. Educational Objective: |
| Approved | Approved::Yes |
| Keyword | |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |