| Category | Specific Conditions | Mechanism | | :--- | :--- | :--- | | | Narrow or horizontal Eustachian tubes (common in infants/young children) | Poor pressure equalization | | Inflammatory | Acute or chronic sinusitis, hay fever, recent cold | Mucosal swelling blocks the tube | | Iatrogenic | Nasal steroid or decongestant misuse | Rebound congestion | | Environmental | Rapid descent (e.g., military fighter jets, steep landing approach) | Pressure change too fast for tube to open | | Behavioral | Sleeping during descent, not swallowing | No muscle activation to open tube |