What is your differential diagnosis for atraumatic lateral elbow pain?

The differential for atraumatic lateral elbow pain is broad and lengthy. More common diagnoses include lateral epicondylitis (tennis elbow) and arthritis. Less commonly seen are cervical radiculopathy, thoracic outlet syndrome, posterior interosseous nerve (PIN) compression syndrome, and radial tunnel syndrome (RTS).

What is the most likely diagnosis?

The diagnosis in the case at hand is most likely RTS. This diagnosis is of debate as some believe it is symptomatic irritation of the radial nerve resulting from common extensor tendinopathy. However, as in this rare case, it can result from direct compression of the radial nerve. It is typically a diagnosis of exclusion.

• Pearl: Risk factors for radial tunnel include repetitive prono-supination and resisted elbow flexion such as with heavy weight lifting [1].

• Pearl: This is differentiated from lateral epicondylitis by location of point tenderness. In lateral epicondylitis the point of maximal tenderness is directly over the lateral epicondyle [1].

What physical exam findings are expected?

Aching dorsoradial forearm pain, tenderness to palpation over the painful region that is about 3-5 cm distal to the lateral epicondyle, absence of motor deficits or weakness (though may be present and resulting from pain) [1,2]. 

Provocative physical exam maneuvers include passive elbow extension with forearm pronation and wrist flexion (this increases the pressure within the radial tunnel approximately 200 mm Hg above baseline), resisted supination, and resisted long finger extension [1,2].

• Pearl: This is differentiated from PIN compression syndrome based on symptoms. PIN compression syndrome is painless and the predominant feature is motor deficits such as weakness [1,2].

Which imaging modalities can be used?

Patients that present to the emergency department (ED) for lateral elbow pain will almost always have an x-ray of the elbow performed to rule out fracture or dislocation. In cases where tendinopathy or neuropathic etiology is suspected, ultrasound may be useful in identifying pathology and localizing the origin or source of pain [1-3].

• Pearl: EMG and MRI are often ordered on an outpatient basis to help establish the correct diagnosis in patients with ED work-up findings that are indeterminate [2].

What is the management in the ED? Do you need to consult Orthopaedics?

Conservative treatment is firstline for RTS. This may include any or all of the following:

• Activity modification, including rest from activities which place one in persistent elbow extension with forearm pronation and wrist flexion [1,2].

• Anti-inflammatory medications, including local corticosteroid injections and/or oral NSAIDs [1,2].

• Removable/temporary splints such as Velcro closed wrist splints that maintain wrist extension with use at night time are recommended.

• Physical and occupational therapy to assist with splint fitting, activity modification, and other ergonomic education as indicated on formal assessment [1,2,4].

Emergent Orthopaedics evaluation is not necessary. These can be followed up by Sports Medicine or Orthopaedics as an outpatient. 

• Pearl: Counsel patients that symptoms may take a long time to improve. Usually, at least 2 months of conservative treatments are tried before more invasive interventions are offered such as surgical decompression. [1,2,5].