Page 9 - MSK assignment

9 F. Elahi

Sonographically, cubital tunnel
syndrome presents with a sudden
narrowing and relocation of the ulnar
nerve in the tunnel. This can be
accompanied by a thickened
retinaculum or a lesion which is causing
the narrowing. The nerve proximal to
this area appears enlarged with a loss
of its typical fascicular pattern.
Alongside the enlargement, there is
hypervascularity seen in some cases.
Furthermore, the sonographer can
measure the cross-sectional area of the nerve since it will be larger in patients with cubital
tunnel syndrome. 7.9mm 2 is the maximum threshold for a normal ulnar nerve at the level of the
epicondyle (Bianchi & Martinoli, 2007). Figure I shows a patient present with a mass in the
elbow. The ulnar nerve is seen bending to the shape of the mass in this image (Bianchi &
Martinoli, 2007).

Snapping Triceps Syndrome
When the elbow is flexed, the patient can have a dislocation of the medial head of the
triceps muscle which leads to the dislocation of the adjacent ulnar nerve. The muscle and nerve
are in sequence, therefore when the muscle is affected, so is the nerve. Each dislocation
causes a palpable area over the medial elbow. The first palpable area is representative of the
ulnar nerve. The second palpable area is representative of the dislocation of the triceps muscle.
The etiology of snapping triceps syndrome is undetermined. Patients may present with medial
elbow pain, snapping sensation, ulnar neuropathy, or be asymptomatic (Bianchi & Martinoli,
2007).

Dynamic assessment in ultrasound is effective in diagnosing dislocation of both
structures during active flexion and extension of the elbow. A normal appearance would consist
of the nerve within the cubital tunnel when extended. As flexion occurs, the nerve goes over the
medial epicondyle. Eventually the nerve crosses fully over and lies superficial to the common
flexor tendon origin (Bianchi & Martinoli, 2007).