of growth hormone. A common anatomic variant is an air-filled cavity within a concha known as a concha bullosa. In rare cases a polyp can form inside a bullosa. Usually a concha bullosa is small and without symptoms but when large can cause obstruction to sinus drainage. Some drugs can be nasally administered, including drug delivery to the brain, and these include nasal sprays and topical treatments. The septal cartilage can be destroyed through the repeated inhalation of recreational drugs such as cocaine. This, in turn, can lead to more widespread collapse of the nasal skeleton. Sneezing can transmit infections carried in the expelled droplets. This route is called either airborne transmission or aerosol transmission. Surgical procedures Badly positioned alar cartilages lack proper support, and can affect the function of the external nasal valve. This can cause breathing problems particularly during deep inhalation. The surgical procedure to correct breathing problems due to disorders in the nasal structures is called a rhinoplasty, and this is also the procedure used for a cosmetic surgery when it is commonly called a "nose job". For surgical procedures of rhinoplasty, the nose is mapped out into a number of subunits and segments. This uses nine aesthetic nasal subunits and six aesthetic nasal segments. A septoplasty is the specific surgery to correct a nasal septum deviation. A broken nose can result from trauma. Minor fractures may heal on their own. Surgery known as reduction may be carried out on more severe breaks that cause dislocation. Several nasal procedures of the nose and paranasal sinuses can be carried out using minimally-invasive nasal endoscopy. These procedures aim to restore sinus ventilation, mucociliary clearance, and maintain the health of the sinus mucosa. Some non-nasal surgeries can also be carried out through the use of an endoscope that is entered through the nose. These endoscopic endonasal surgeries are used to remove tumours from the front of the base of the skull. Swollen conchae can cause obstruction and nasal congestion, and may be treated surgically by a turbinectomy. Society and culture Some people choose to have cosmetic surgery (called a rhinoplasty) to change the appearance of their nose. Nose piercings, such as in the nostril, septum, or bridge, are also common. In certain Asian countries such as China, Japan, South Korea, Malaysia, Thailand and Bangladesh, rhinoplasties are commonly carried out to create a more developed nose bridge or a "high nose".