The Diagnostic Value of Nerve Ultrasound in an Atypical Palmar Cutaneous Nerve Lesion.

Detailed knowledge of the fascicular anatomy of peripheral nerves is important for microsurgical repair and functional electrostimulation.We report a patient with a lesion on the left palmar cutaneous branch of the median nerve (PCBMN) and sensory signs expanding outside the PCBMN cutaneous innervation territory. Nerve conduction study showed the absence of left PCBMN sensory nerve action potential, but apparently, no median nerve (MN) involvement. Nerve ultrasound documented a neuroma of the left PCBMN and a coexistent lateral neuroma of the left MN in the carpal tunnel after the PCBMN left the main nerve trunk.Nerve ultrasound may offer important information in patients with peripheral nerve lesions and atypical clinical and/or nerve conduction study findings. The present case may shed some light on the somatotopy of MN fascicles at the wrist.