Carpal tunnel syndrome without numbness

Abstract

Introduction: Numbness/paresthesia in the median nerve distribution are hallmark symptoms of carpal tunnel syndrome. An atypical case with just thenar muscles atrophy and thumb pain is reported. Methods: Case report A 66-year old woman with diabetes, hyperlipidaemia and obesity attended a GOPC in October 2019 complained of an insidious onset of right thumb pain since 6 months ago. The pain had been worsening. Atrophy of her right thenar eminence noticed. She reported no numbness over her fingers nor wrist. Examination showed right thumb metacarpophalangeal joint tenderness without abnormal mass. There was marked wasting of her right thenar muscles with weakness of the thumb. X-ray right thumb: satisfactory alignment; Degenerative changes at interphalangeal joint. CXR was unremarkable. She was referred to the orthopaedic specialist. Her right thumb’s abduction power was graded as 2/5; Tinel’s, Durkan’s and Phalen’s tests were all positive upon being seen by O&T a few months later. No abnormality was detected over her right elbow, other myotomes nor dermatomes. The impression was carpal tunnel syndrome. Early NCV/EMG were arranged and she was put on list for surgical release. Meanwhile, she was referred to occupational therapist for wrist splint. Results: The patient was diagnosed to have carpal tunnel syndrome eventually. Discussion: Carpal tunnel syndrome is a common disorder with an estimated prevalence of 1-5% in the general population. The patient described in this case presented atypically with right thumb joint pain and atrophy of thenar muscles only. She did not volunteer any numbness. Nonetheless, early referral to orthopaedics is mandatory. Apart from carpal tunnel syndrome, family physicians should also beware of Pancoast tumor as an important differential diagnosis when patients present with small muscles of hand atrophy. Conclusion: Family physicians should be alerted to the finding of thenar muscles atrophy and proceed with referrals and further investigations to find out the cause.