Carpal tunnel syndrome (CTS) remains the most common compressive neuropathy. The following reviews recent trends in the preoperative evaluation, anesthesia, surgical approaches, and opioid prescribing patterns for patients with CTS.
The diagnosis of CTS is made primarily by a physical exam and the patient’s medical history. A combination of history and physical exam have been combined in the Carpal Tunnel Syndrome 6 (CTS-6) questionnaire, a validated clinical diagnostic tool that has shown to be both sensitive and specific for the diagnosis of CTS. It consists of six clinical questions with s 26-point weighted scale. A score of 12 points or more is defined as positive for CTS. Electromyography (EMG) studies have been reserved for confirmatory diagnosis of CTS, or if a confounding diagnosis exists from alternative sites of compression.
Unfortunately, the diagnostic utility of EMGs may be limited for several reasons: Asymptomatic patients can also have positive EMGs; 70 percent of postsurgical EMGs do not normalize after clinically successful carpal tunnel release (CTR); and patients with inflammatory causes of compression do not have clear normal values for EMGs. Additionally, EMGs are expensive, time intensive, and painful, putting into question the necessity for such tests. As a result, many surgeons are choosing to forgo EMGs except in equivocal cases. However, some would argue that since EMG is cheaper than surgery, performing the study preoperatively to reduce unnecessary CTRs would be cost effective.
The 2016 AAOS CTS Clinical Practice Guideline (CPG) provides a moderate recommendation for the use of EMG to aid in diagnosis. The guideline no longer recommends EMG for all patients. EMG is to be used in addition to history, physical examination, and diagnostic questionnaires only when necessary. Additional studies will need to be conducted to determine the cost-effectiveness and necessity of using EMG preoperatively for patients with CTS.
Ultrasound has been used preoperatively as an alternative to EMG to confirm the diagnosis of CTS. Evaluators measure the median nerve’s cross-sectional area (CSA) just proximal to the pisiform. A CSA greater than 10 mm2 is considered positive. Studies of patients with a positive CTS-6 score have shown a higher specificity and equivalent sensitivity for ultrasound relative to electrodiagnostic studies (EDS). Additional studies have shown that EDS have the lowest specificity and sensitivity relative to CTS-6 and ultrasound in the diagnosis of CTS.
No agreement exists on the gold standard for diagnosis of CTS. In fact, when performed in isolation, diagnostic questionnaires such as the Katz hand diagram and the CTS-6 performed poorly when correlated with EDS.
The AAOS guideline does provide strong recommendations for splinting and corticosteroid injections, as well as moderate recommendations for oral steroids for treatment. For patients failing those modalities, the guidelines also provide strong recommendations for surgical release of the transverse carpal ligament.
Alternative forms of anesthesia for CTR have also been investigated to reduce cost and streamline surgical throughput. Numerous studies have shown that the wide awake, local anesthesia, and no tourniquet (WALANT) technique reduces costs as it does not require preoperative labs, additional nursing services, IV medications, and operating room-associated costs. Monitored anesthesia care (MAC) and WALANT have had equivalent outcomes and patient satisfaction for CTR and can be considered based on patient and surgeon preferences.
Surgical alternatives to traditional open CTR have been developed for the treatment of CTS to improve patient outcomes and reduce recovery time. Less-invasive approaches include the mini-open, endoscopic, and thread CTR (Fig. 1). The percentage of endoscopic CTRs performed has increased as more surgeons have become comfortable with performing the procedure.
Additionally, the costs associated with endoscopic CTR have decreased. Studies have also shown no significant differences between endoscopic and open CTR at early and late follow-up, except for increased sensitivity during the early post-operative period with mini-open procedures.
The thread CTR was devised to percutaneously loop a thread to transect the transverse carpal ligament. Ultrasound guidance is used to evaluate carpal tunnel anatomy to prevent damage to surrounding neurovascular structures, such as the superficial palmar arch, the Berrettini branch, and common digital nerve branches. Thread CTR has been shown to be a safe and effective alternative with faster return to work and reduced postoperative pain, tenderness, and weakness.
Providers often perform extended releases for patients with severe CTS when conservative nonsurgical management is no longer an option. Recent studies have shown no significant differences in postoperative strength and symptom severity between extended and mini-open techniques. In fact, some studies have shown greater improvement in numbness with endoscopic CTR relative to open CTR in patients with severe CTS.
Postoperative pain control
Given the current opioid epidemic in the United States, opioid prescribing practices have come under scrutiny. After family medicine and internal medicine providers, orthopaedic surgeons are the third highest prescribers of narcotics.
Numerous studies have examined risk factors for increased opioid consumption following CTR. Results have shown that male patients and patients older than 80 years of age consume fewer narcotics and that CTR patients who are on narcotics preoperatively, those who use tobacco or alcohol, and those who have a history of substance abuse, mood disorders, or anxiety often require narcotics longer postoperatively. In addition, narcotic consumption does not differ based on the type of anesthesia provided (WALANT versus MAC) or the type of insurance (Medicare, private, or worker’s compensation).
On average, CTR patients take five to 10 pills for two days postoperatively. Yet, studies show that significantly more, up to five times as many opioid tablets as are typically taken. Consequently, the excess narcotics become available for diversion and abuse. A prescription of 10 pills should be adequate for most patients, and additional follow-up visits should be scheduled to evaluate patients who need refills.
Attempts have been made to find alternative ways to control pain postoperatively. Studies have found that NSAIDs have been equally effective in pain control and postoperative outcomes, and they have recommended that fewer narcotics should be prescribed postoperatively for CTR.
Counseling has been shown to reduce the rates of opioid consumption. Having an open dialogue, assessing risk factors for abuse, attempting nonopioid pain medications, providing expectations about the duration of therapy and treatment goals, and coordinating with the primary care physician or other providers prescribing narcotics are all important parts of the counseling process.
It is important for the surgeon performing CTR to be well-versed in the multiple diagnostic, surgical, and anesthetic techniques for this procedure. A patient-based decision centered on the patient’s pathology and goals is crucial for determining the appropriate treatment and postoperative management for CTS.
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Anil Akoon MD, MBA, is an orthopaedic surgery resident at Geisinger Medical Center in Danville, Pa.
Liam Dwyer MD, is an orthopaedic hand and upper extremity surgeon at Geisinger Medical Center in Danville.