When circumstances cause overall body fat to diminish, the tissue surrounding the Eustachian tube shrinks and this function is disrupted.Activities and substances which dehydrate the body have the same effect and are also possible causes of patulous Eustachian tube. Examples are stimulants (including caffeine) and exercise. Exercise may have a more short-term effect than caffeine or weight loss in this regard. Pregnancy can also be a cause of patulous Eustachian tube due to the effects of pregnancy hormones on surface tension and mucus in the respiratory system.Granulomatosis with polyangiitis can also be a cause of this disorder. It is yet unknown why. PET can occur as a result of liquid residue in the Eustachian tube, after suffering a middle ear infection (otitis media). Radiation therapy
High levels of estrogen
Nasal decongestants
Stress
Sudden weight loss
Neurological disorders

Diagnosis
Upon examination of a suspected case of patulous Eustachian tube, a doctor can directly view the tympanic membrane with a light and observe that it vibrates with every breath taken by the patient. A tympanogram may also help with the diagnosis. Patulous Eustachian tube is likely if brisk inspiration causes a significant pressure shift. Patulous Eustachian tube is frequently misdiagnosed as standard congestion due to the similarity in symptoms and rarity of the disorder. Audiologists are more likely to recognize the disorder, usually with tympanometry or nasally delivered masking noise during a hearing assessment, which is highly sensitive to this condition.When misdiagnosis occurs, a decongestant medication is sometimes prescribed.
Other medications and treatments are available, but have only anecdotal evidence.Medications that may worsen RBD and should be stopped if possible are tramadol, mirtazapine, antidepressants, and beta blockers.In addition to medication, it is wise to secure the sleepers environment by removing potentially dangerous objects from the bedroom and either place a cushion around the bed or move the mattress to the floor for added protection against injuries. In extreme cases, an affected individual has slept in a sleeping bag zipped up to their neck, wearing mittens so they cannot unzip it until they awake.Patients are advised to maintain a normal sleep schedule, avoid sleep deprivation, and keep track of any sleepiness they may have. Treatment includes regulating neurologic symptoms and treating any other sleep disorders that might interfere with sleep. Sleep deprivation, alcohol, certain medications, and other sleep disorders can all increase RBD and should be avoided if possible. Prognosis
Patients with RBD are at risk for sleep-related injury.Almost 92% of patients with idiopathic RBD will go on to develop a neurodegenerative disorder. The disorders most strongly associated with RBD are the synucleinopathies, particularly Parkinsons disease, dementia with Lewy bodies, and to a lesser extent, multiple system atrophy. Most people with RBD will convert to a synucleinopathy—usually Parkinsons disease or dementia with Lewy bodies—within 4 to 9 years from diagnosis of RBD, and 11 to 16 years from onset of symptoms. Epidemiology
RBD prevalence as of 2017 is estimated to be 0.5–2% overall, and 5–13% of those aged 60 to 99.