National Board of Chiropractic Examiners (NBCE) Practice Test

Fixed adduction and internal rotation of the shoulder with pronation of the forearm and no sensory loss is most characteristic of which condition?

1. Wrist drop

2. Erb's Palsy

3. Brachial plexus injury

4. Rotator cuff tear

The correct answer is: Erb's Palsy

The presentation of fixed adduction and internal rotation of the shoulder, along with forearm pronation and the absence of sensory loss, aligns with the characteristics of Erb's Palsy. Erb's Palsy results from an injury to the upper trunk of the brachial plexus, typically occurring during childbirth or trauma that affects the nerves supplying the shoulder and upper arm. In this condition, the affected arm often hangs in a characteristic position: adducted and internally rotated at the shoulder due to weakness of the muscles functioning to lift the arm, primarily the deltoid and rotator cuff muscles, which are innervated by the affected nerves. The forearm being pronated is a result of weakness in the biceps muscle, which is responsible for forearm supination. The lack of sensory loss further supports the diagnosis, as Erb's Palsy primarily affects motor function in the upper trunk region without directly impacting sensory pathways, which would otherwise lead to sensory deficits in cases of more extensive nerve damage or injury affecting the entire brachial plexus. Thus, when considering these specific symptoms and the typical presentation associated with Erb's Palsy, it becomes clear why this option is the most fitting response.