Age / Sex : 66 / F

Chief complaint: chronic lateral elbow pain

1) What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

(Quiz는 quiz일 뿐이오니 답안은 한개만 보내주시기 바라오며, 복수의 답안을 보내주시는 분은 정답이 포함되어 있더라도 부득이 semi-correct answer로 처리토록 하겠습니다.)

Courtesy: 김태은(Tae Eun Kim), 대구파티마병원(Daegu Fatima Hospital)

Radial tunnel syndrome

Discussion

Findings: 
Sonography obtained longitudinally and transversly to posterior
interosseous nerve shows focal nodular swelling just proximal to supinator
muscle, commonly referred to as the arcade of Frohse.

Differential Diagnosis: Clinically, must be
differentiated from lateral epicondylitis.

Diagnosis: Radial tunnel syndrome

Discussion: Radial tunnel syndrome(RTS) and
Posterior interosseous nerve syndrome(PINS) are altogether caused by
compression of the same PIN, but patients with RTS typically present with
lateral proximal forearm pain rather than weakness or paralysis as their chief
complain.  The vast majority of patients
with RTS have normal electrodiagnostic testing.(In this case, NCV-EMG also
showed normal result.) It has been reported that 5% of those with an initial
diagnosis of lateral epicondylitis have RTS. PIN is well visualized on high
resolution ultrasound, so in patient with lateral elbow pain, not only lateral
epicondyle but PIN should be evaluated essentially.

References:

1.    J Hand Surg 2009;34A:1906–1914

2.   
AJR 2003;181:219–221

3.   
Radiology 2006;240:161–168.