You examine a 17-year-old female whose chief complaints include episodic bilateral chilly index and middle fingers, with each episode lasting for about 15 minutes. The episodes seem precipitated by vibration, emotional distress, and cold, but the patient cannot remember when they started. Previous medical testing has ruled out any vessel-obstructing disease, and no cervical rib is present. The patient is a non-smoker.

Upon observation, there are no trophic changes, but palpation reveals that the hands fluctuate between feeling cold and warm over 20 minutes. The rest of the examination is unremarkable – normal strength, sensation, flexibility, pulses, reflexes, negative Allen test, Adson test, and costoclavicular maneuver. Finally, no symptoms were reproduced by cervical compression-distraction. Given these findings, at this stage of your examination, which of the following would be the most likely working hypothesis?

1. Thoracic outlet syndrome
2. Carpal tunnel syndrome
3. Raynaud’s syndrome
4. Thromboangiitis obliterans

 The solution will be posted in a few days.