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September 3, 2013 Issue

Clinical Practice Points

Methylprednisolone Injections for the Carpal Tunnel Syndrome. A Randomized, Placebo-Controlled Trial

Steroid injections are often used to alleviate symptoms of the carpal tunnel syndrome and prevent the need for surgery. This trial in patients with mild to moderate carpal tunnel syndrome despite wrist splinting found that methylprednisolone injection temporarily improved symptoms but did not obviate the need for surgery.

Use this study to:

  • Start a teaching session with a multiple-choice question! We’ve provided one below.
  • Review when to consider and how to diagnose the carpal tunnel syndrome. You can use PIER’s Carpal Tunnel Syndrome for its succinct review, tables, and figures to help teach.
  • Discuss what your residents’ initial recommendations should be for their patients with the carpal tunnel syndrome. How do patients get wrist splints?
  • Review the results of this randomized trial (which are summarized in Table 2). Ask your residents if they will recommend injections for their patients with an inadequate response to wrist splinting.

The Ankle–Brachial Index for Peripheral Artery Disease Screening and Cardiovascular Disease Prediction Among Asymptomatic Adults: A Systematic Evidence Review for the U.S. Preventive Services Task Force

and

Screening for Peripheral Artery Disease and Cardiovascular Disease Risk Assessment With the Ankle–Brachial Index in Adults: U.S. Preventive Services Task Force Recommendation Statement

The systematic review found limited evidence on the added value of the ankle–brachial index (ABI) in current coronary artery disease or cardiovascular disease (CVD) risk prediction. Accordingly, the USPSTF concluded that the current evidence is insufficient to assess the balance of benefits and harms of peripheral artery disease (PAD) screening in adults. The recommendation applies to asymptomatic adults without a known diagnosis of PAD, CVD, severe chronic kidney disease, or diabetes.

Use these reports to:

  • Review how the ABI is determined. What do the results mean?
  • Since an ABI less than 0.9 is associated with increased morbidity and mortality, why does the USPSTF conclude that we lack enough information to decide if ABI screening is beneficial? An editorialist answers that question by summarizing what we know, and still need to know.
  • These articles and the editorialist point out that ABI adds little to the evaluation of risk over the use of the Framingham Risk Score. Review how the FRS is calculated. Why does that matter? The editorialist points out that most patients identified with PAD with ABI have other indications for treatments to prevent CVD.
  • Get CME for yourself! Log on and complete the short quiz that accompanies the USPSTF recommendation statement.

Screening for Hepatitis C Virus Infection in Adults: U.S. Preventive Services Task Force Recommendation Statement

The USPSTF now recommends screening for hepatitis C virus (HCV) infection in all asymptomatic persons at high risk for infection and recommends offering 1-time screening for adults born between 1945 and 1965 without known liver disease or functional abnormalities.

Use this clinical guideline to:

  • Discuss the risk factors for HCV infection.
  • Discuss what tests should be ordered for screening.
  • What are the potential benefits and harms of screening for HCV infection? The Task Force discusses these on pages 353 to 355.

In the Clinic: Obesity

How is obesity defined, and what is the evidence that it harmful? When can the body mass index be misleading? What history and examination findings are important in the evaluation of obesity? What tests should be ordered? What pharmacologic treatments are available, and when should they be considered? What about surgery? Use this concise and eminently practical review to answer these questions. It includes MKSAP questions—structure an interactive teaching session around them—as well as already prepared teaching slides. Log on to answer the questions and get more CME for yourself!


Humanism and Professionalism

A Day in the Life of a Corporate Retail Pharmacist

Play an audio recording of this issue’s On Being a Doctor, in which Dr. Dore describes just one busy day on the job at a retail pharmacy. Ask your house officers if they ever think about how patients get their prescriptions. Who answers their patients’ questions? What dangers are there in the system described by Dr. Dore? Do your house officers feel they face similar challenges? How do they handle them?


mksap16

A 45-year-old woman is evaluated for a 3-month history of worsening discomfort in the right forearm, right wrist, and right hand accompanied by numbness and tingling in the hand that she can “shake away.” The pain is worse at night, at times disrupting her sleep.

On physical examination, vital signs are normal. Neurologic examination shows weakness in her pinch grip and subtle numbness in the second, third, and fourth distal fingers.

Which of the following is the most appropriate next step in management?

A. Electromyography and nerve conduction study
B. MRI of the wrist
C. NSAIDs
D. Surgical release of the median nerve

Answer:
A. Electromyography and nerve conduction study

Key Point:
In patients with symptoms of suspected entrapment neuropathy, electromyography and a nerve conduction study are useful when the diagnosis is uncertain, when a patient is not responding to therapy, or when surgery is under consideration.

Educational Objective:
Manage carpal tunnel syndrome.

Electromyography (EMG) and a nerve conduction study are indicated for this patient with probable carpal tunnel syndrome, the most common peripheral neuropathy. Symptoms include aching and paresthesias in the hand and forearm (particularly at night) and weakness of grip strength in advanced cases. On physical examination, there is loss of sensation in the median nerve territory (including the palmar surface of the first three fingers and the radial aspect of the fourth) and thenar atrophy. The Phalen and Tinel signs have limited ability to discriminate carpal tunnel syndrome from other causes of hand dysesthesia. An EMG and a nerve conduction study are useful when the diagnosis is uncertain, when a patient is not responding to therapy, or when surgery is under consideration. In this patient with forearm symptoms, other causes need to be excluded, including a more proximal nerve entrapment or cervical radiculopathy. Therefore, an EMG and nerve conduction study would evaluate the severity of a carpal tunnel diagnosis and exclude other possible diagnoses.

MRI of the wrist has been advocated by some as the imaging study to evaluate for carpal tunnel syndrome. However, the diagnostic utility of MRI is unclear and is not recommended as a first management step. Although NSAIDs are recommended and widely used as the initial drug therapy, there is no strong evidence that they are useful.

Carpal tunnel release surgery is indicated for severe carpal tunnel syndrome (by clinical or EMG evidence) but is not indicated in this patient pending confirmation of the diagnosis, categorization of its severity, and possibly pending response to more conservative intervention.

Bibliography
D’Arcy CA, McGee S. The rational clinical examination. Does this patient have carpal tunnel syndrome? [Erratum in: JAMA 2000;284(11):1384.] JAMA. 2000;283(23):3110-3117. PMID: 10865306

This question was derived from MKSAP® 16, the latest edition of the Medical Knowledge Self-Assessment Program.

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