Thenar hammer syndrome: a case report

BACKGROUND: Raynaud's phenomenon occurs among automobile mechanics secondary to long-term use of vibrating hand-held tools. It can also occur from traumatic injury to the upper extremity. AIM: This report describes a case of single digit Raynaud's phenomenon in an automobile mechanic due to focal arterial impact trauma. CASE REPORT: A 38-year-old right-handed transmission mechanic complained of paraesthesia and blanching of the right index finger on exposure to cold and eventually developed a transient necrotic ulcer at the tip of the digit. He had a long history of occupational exposure to vibrating hand-held power tools. Evaluation for common causes of Raymond's phenomenon was negative. The diagnosis of hand-arm vibration syndrome (HAVS) was rejected because of the rapidity of progression and severity of the symptoms restricted only to the index finger without corresponding symptoms of the other digits of the right hand as would be expected. Angiography revealed an obstructive lesion of the distal right radial artery at the wrist and he was diagnosed with thenar hammer syndrome. This uncommon condition was due to focal injury of the distal radial artery caused by repeated slamming of transmission parts on a work table. CONCLUSIONS: Not all cases of Raynaud's phenomenon in workers using vibrating hand-held tools are due to HAVS. Alternative aetiologies should be considered especially if symptoms are asymmetrical and unilateral.