HSS Ultrasound Case 70

Clinical History 35 year-old woman with laceration injury to the volar wrist and paresthesias with palpation of the laceration.

The patient was referred for an ultrasound (US) to assess for median nerve injury.

Ultrasound of the Month – Case 70

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Findings Transverse US image of the left wrist in our patient reveals a laceration (arrowheads) at the volar surface of the wrist which extends to the palmaris longus tendon. The palmaris longus tendon is heterogeneous and there is peritendinous edema due to partial thickness laceration injury. The underlying median nerve (circle) is close to the peritendinous edema but is not injured.

Ultrasound of the Month – Case 70

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Diagnosis Partial thickness laceration injury of the palmaris longus tendon

Discussion The palmaris longus is variably absent in between 5 – 27% of the patient population.

When present, the palmaris longus tendon can be found as a long and flat tendon at the volar wrist, coursing over then inserting on the central flexor retinaculum. Its superficial location makes it particularly susceptible to laceration injury.

The palmaris longus tendon is a common source of tendon graft given its length and lack of functional deficit with harvest.

Given its close proximity to the median nerve, injury or irritation to the palmaris longus tendon may cause paresthesias and the median nerve should be closely evaluated for concomitant injury.

When harvesting the palmaris longus tendon, nerve stimulation is performed to confirm the median nerve is left intact.

Ultrasound of the Month – Case 70

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