Early radial digital neuropathy of the thumb due to flexor pollicis longus tendinitis: value of ultrasound in an uncommon mild neuropathy.

Introduction: A 50-year-old man developed intermittent paresthesia of the outer portion of the right thumb. Paresthesia increased with thumb abduction and flexion. The remainder of the physical examination was normal.

Methods: Routine motor and sensory examinations of the median and ulnar nerves were within normal ranges.

Results: Ultrasonographic studies revealed that a tenosynovitis of the flexor pollicis longus of the right thumb was compressing the radial digital nerve of the thumb.

Conclusions: Ultrasonographic evaluation was used in conjunction with nerve conduction studies to diagnose digital neuropathy. Ultrasound is a beneficial, complementary tool to electrodiagnostic studies, especially for uncommon focal neuropathies.