A 17-year-old male presents to the office with the complaint of a persistent dry cough that worsens when he is exposed to cold air. He reports a desire to participate in winter sports such as snowboarding and skiing but has difficulty breathing outside during cold weather. Physical examination reveals expiratory wheezes bilaterally. Structural examination reveals a flattened thoracic spine and bilaterally restricted movement of the occipitomastoid suture.

Which of the following would be the most appropriate to specifically address his cranial restriction?