An acute time-limited stressor involves a short-term challenge, while a brief  natural stressor involves an event that is normal but nevertheless challenging. A stressful event sequence is a stressor that occurs, and then continues to yield stress into the immediate future. A chronic stressor involves exposure to a long-term stressor, and a distant stressor is a stressor that is not immediate. Psychology
Acute stressful situations where the stress experienced is severe is a cause of change psychologically to the detriment of the well-being of the individual, such that symptomatic derealization and depersonalization, and anxiety and hyperarousal, are experienced. The International Classification of Diseases includes a group of mental and behavioral disorders which have their aetiology in reaction to severe stress and the consequent adaptive response. Chronic stress, and a lack of coping resources available, or used by an individual, can often lead to the development of psychological issues such as delusions, depression and anxiety (see below for further information).Chronic stressors may not be as intense as acute stressors such as natural disaster or a major accident, but persist over longer periods of time, tend to have a more negative effect on health because they are sustained and thus require the bodys physiological response to occur daily. This depletes the bodys energy more quickly and usually occurs over long periods of time, especially when these microstressors cannot be avoided (i.e. stress of living in a dangerous neighborhood). See allostatic load for further discussion of the biological process by which chronic stress may affect the body.
Infants born prematurely can be intubated for a longer amount of time due to the fact that they have more flexible cartilage and a larynx located high in the airway. 90% of acquired cases in children are due to intubation, due to the ring of cartilage in the upper airway. Less commonly, infections, such as bacterial tracheitis, tuberculosis, histoplasmosis, diphtheria, and laryngeal papillomatosis can cause it. Systemic diseases, such as amyloidosis, granulomatosis with polyangiitis, sarcoidosis, inflammatory bowel disease, scleroderma, relapsing polychondritis, and polyarthritis, can also cause it. Other causes may include aspiration of foreign bodies, burns, and exposure to occupational hazards. Very rarely, the condition may also have no known cause, in which case it is known as idiopathic subglottic stenosis. Mechanism
High cuff pressure or long-term intubation can cause damage to the tracheal mucosa, causing inflammation, ulceration, and breakdown of cartilage. When the injury heals, scarring occurs, narrowing the airway. Treatment-related risk factors include repeated intubation, the presence of a nasogastric tube, and size of an endotracheal tube. Person-related risk factors include systemic diseases, the likelihood of infection, and inadequate perfusion. Acid reflux may cause narrowing due to scarring resulting from stomach acid damaging the tracheal mucosa. 10-23% of causes result due to narrowing arising from granulomatosis with polyangiitis. In these cases, it is believed that this is more common in people under the age of 20. Around 66% of sarcoidosis cases involve the airway. Diagnosis
CT scans and MRI (magnetic resonance imaging) can help in diagnosis.