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More than half of patients regain thumb opposition after carpal tunnel release
A greater percentage of younger patients regained thumb opposition than older patients.
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Although researchers from Japan found that overall 52.3% of patients who underwent release for carpal tunnel syndrome recovered thumb opposition, this recovery was unpredictable in patients older than 50 years.
“More than 90% of hands recovered in patients younger than 50 years of age,” Tatsuki Ebata, MD, of Chiba University, said. “On the other hand, only about half of hands recovered in the patients 50 years of age and older. Recovery of thumb opposition still remains unpredictable in these patients and further study, such as second lumbrical compound muscle action potentials, may be required to better predict the recovery of thumb opposition in severe carpal tunnel syndrome.”
Ebata and the researchers studied 109 hands with undetectable abductor pollicis brevis compound muscle action potentials (APB-CMAPs) that were treated with carpal tunnel release between 2001 and 2010 and had at least 1-year follow-up. Patients had a mean age of 62.1 years and mean follow-up of 30.2 months. The investigators excluded patients from the study who underwent hemodialysis or had neuropathic or degenerative diseases. Ebata and colleagues conducted clinical and electrophysiological examinations to determine APB-CMAPs, thumb opposition, disease duration and distal motor latency. They assessed thumb opposition by having patients perform a pulp pinch between their thumbs and middle fingers.
A 55-year-old woman had extensive thenar atrophy and was unable to perform a pulp pinch.
Images: Ebata T
Eighteen months after surgery, thenar muscle atrophy disappeared and she was able to perform a pulp pinch.
Of the 52.3% of hands that recovered thumb opposition, Ebata noted that all showed detectable APB-CMAPs. However, he said that 27 of the hands that did not recover thumb opposition had detectable APB-CMAPs and 25 had undetectable APB-CMAPs. A mean amplitude of 3.72 mV was found in the hands that recovered thumb opposition vs. 1.1 mV in the hands that did not recover this motion. Distal motor latency was shorter in hands that recovered thumb opposition, but investigators found no significant difference regarding the disease duration between hands that recovered this ability (26.9 months) and hands that did not recover (30.3 months) it. Patients younger than 50 years showed better recovery of thumb opposition than patients older than 50 years.
Ebata said the researchers could not use the disease duration to predict recovery of thumb opposition because 30% of patients did not know the duration of their disease.
This patient had an opponensplasty and is able to perform a good opposition of the thumb. Bowstringing of the transferred tendon can be observed.
“If recovery of thumb opposition is predicted at the time of carpal tunnel disease, we can determine whether opponensplasty should be performed at the same time,” Ebata said. “In this study, the duration of disease was not used to predict the recovery of thumb opposition. The reason for that may be, in some patients, that carpal tunnel syndrome progresses rapidly and, in some patients, slowly or that the patient does not accurately remember the duration of the disease because it is longstanding.” – by Renee Blisard Buddle
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Disclosure: Ebata has no relevant financial disclosures.
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Kevin C. Chung, MD, MS
This study challenges our traditional belief about limitation in thenar atrophy and no functional muscle with opposition to the middle finger and that these patients will have little chance of recovery. However in this series, 53% of the patients, despite having no electric signal on needle insertion, retained some type of muscle function on clinical examination. This is an interesting finding that challenges traditional belief.Click Here to Manage Email Alerts