Hypoparathyroidism

A 16-year-old girl comes to the emergency department because of a panic attack. She began feeling tingling around her mouth and then became nervous at this symptom, causing her to hyperventilate. The tingling has persisted, and she also reports having had muscle cramps and spasms for the past week. A metabolic panel reveals normal electrolytes except for a low serum calcium. A review of the patient's chart reveals thyroid surgery one month earlier due to a suspicious nodule. Which of the following findings is most likely to also be present in this patient?