Review Question - QID 210879

A 29-year-old woman presents to the clinic complaining of exquisite pain in her finger. The pain is located at the tip of her left index finger and is described as intermittent, 10/10 in intensity, and is exacerbated by cold temperature. The patient denies trauma to the area and cannot recall any other inciting factor. Her past medical history is significant for gastroesophageal reflux disease (GERD) for which she takes a proton pump inhibitor. A review of systems was non-contributory. Her temperature is 98.7°F (37°C), blood pressure is 117/68 mmHg, pulse is 80/min, respirations are 12/min, and oxygen saturation is 98% on room air. The appearance of her left index finger is shown in Figure A. What is the pathophysiology of her condition?