A 58-year-old previously healthy woman comes to the emergency department due to wrist pain after a fall. The patient was walking her dog when it suddenly ran toward a squirrel, pulling her to the ground. She tried to brace herself with her outstretched hand and injured the wrist. Physical examination shows a gross deformity of the wrist with extensive swelling and bruising. Distal pulses and testing for capillary refill are normal. The patient had no sensory symptoms initially but developed paresthesia in the affected hand while in the emergency department. X-ray results are shown below: Which of the following is most likely to be abnormal due to associated nerve injury in this patient?

Question

A 58-year-old previously healthy woman comes to the emergency department due to wrist pain after a fall.  The patient was walking her dog when it suddenly ran toward a squirrel, pulling her to the ground.  She tried to brace herself with her outstretched hand and injured the wrist.  Physical examination shows a gross deformity of the wrist with extensive swelling and bruising.  Distal pulses and testing for capillary refill are normal.  The patient had no sensory symptoms initially but developed paresthesia in the affected hand while in the emergency department.  X-ray results are shown below:  Which of the following is most likely to be abnormal due to associated nerve injury in this patient?

Quizplus · Accepted Answer

11ec25c8_d966_c316_bc81_e15b933fbcd5_MD0003_00 This patient with significant wrist deformity has a distal radius (Colles) fracture, which commonly occurs after falling on an outstretched hand, particularly in athletes (high-impact falls) or elderly patients with osteoporosis (low-impact falls). Characteristic manifestations include pain, swelling, and dinner fork deformity of the wrist. In addition, severely displaced fractures may result in neurovascular compromise; therefore, careful assessment of pulse, capillary refill, and sensation is indicated. dinner fork deformity Dorsal displacement of the radius (as occurs in Colles fracture) can result in compression of the median nerve, which enters the wrist through the carpal tunnel and provides sensation to the lateral 3½ digits and motor innervation to the thenar muscles (eg, opponens pollicis, abductor pollicis brevis). Compression results in acute carpal tunnel syndrome symptoms, including paresthesia of the affected digits and impaired thumb abduction by abductor pollicis brevis. Furthermore, if compression occurs proximal to the tunnel, the palmar cutaneous branch of the median nerve may be affected, leading to decreased sensation over the anterolateral hand. median nerve (Choices B and E) Adduction of the index, 4th digit, and 5th digit (toward the 3rd digit) is mediated by the palmar interossei, which are innervated by the deep branch of the ulnar nerve. Sensation in the 5th digit (and medial aspect of the 4th) is carried by the ulnar nerve. This nerve can be injured at the elbow due to external compression (eg, hitting the "funny bone") or at the wrist due to a hamate fracture or external compression (eg, bicycle handlebar). However, it is not typically affected by a radius fracture. ulnar nerve (Choices C and D) Injury to the radial nerve at the elbow can cause weakness of hand/finger extensor muscles and sensory loss over the posterior forearm/dorsolateral hand. This is typically seen in supracondylar humerus fractures. Compared to the median nerve, the radial nerve is less likely to be injured in a Colles fracture. forearm/dorsolateral hand supracondylar humerus fractures Educational objective: Distal radius fracture with dorsal displacement can cause median nerve compression, resulting in acute carpal tunnel syndrome symptoms, including paresthesia of the lateral 3½ digits and impaired thumb abduction. In addition, if compression occurs proximal to the tunnel, the palmar cutaneous branch of the median nerve may be affected, leading to decreased sensation over the anterolateral hand.

A 58-Year-Old Previously Healthy Woman Comes to the Emergency Department