Accessory abductor digiti minimi

Case contributed by Dr Maulik S Patel

Diagnosis certain

Presentation

Bilateral wrist dorsal nodular swelling for 2-3 years.

Patient Data

Age: 30 years

Gender: Female

From the case: Accessory abductor digiti minimi

Ultrasound

Normal-appearing ulnar artery and nerve in Guyon’s canal. There is an extra structure in left tunnel showing muscle echotexture. It is separating the ulnar nerve from the artery, which normally run in unison. Ulnar artery is patent.

Ultrasonography also showed bilateral scapholunate joint-related ganglia (images not shown).

Case Discussion

The patient's wrist swelling was accounted for by dorsal wrist ganglia.

An accessory abductor digiti minimi muscle was demonstrated in Guyon's canal. There is no symptom of ulnar neuropathy in Guyon's canal due to the presence of an accessory muscle.

The accessory abductor digiti minimi is the most common accessory muscle of the hand, occurring in up to 25% of the population.