Fluctuating Hearing – Simple to Complex Causes
Hearing that fluctuates over time can cause annoyance and distress, especially when the cause is not yet identified.
Fluctuating hearing may range from mild and transient, to severe and long lasting. Apart from hearing loss, other symptoms may include a feeling of fullness, imbalance/dizziness, tinnitus (noises in the ear) and nausea. The specific combination of symptoms depends on the part of the auditory system affected.
There is a multitude of possible causes of fluctuating hearing, range from simple and treatable, to complex and more permanent. Fortunately in most cases the cause is easily identifiable and treatable.
Starting with the most treatable cause, a simple wax obstruction is quickly confirmed by visual inspection. Ear wax may accumulate gradually and may not produce any obvious symptoms until a 98-100 percent occlusion is reached. Lying or pressing on the ear can easily obstruct the residual opening.
The most common cause of hearing fluctuations is an obstruction of the Eustachian tube, which aerates the middle ear space. Without ongoing replenishment of air, the middle ear space develops a mild vacuum, resulting in a retraction of the eardrum and muffled hearing.
The Eustachian tube is susceptible to mucous blockage from nasal sinusitis, cold/flu and allergic rhinitis. Eustachian tube dysfunction is common in childhood due to the immaturity of the muscles which co-ordinate valve openings at the back of the nose, and also due to the small size and angle of the tube. Most children will grow out of the problem by age seven. Some may need grommets (small valves) placed in the eardrum in the meantime. Enlarged tonsils and adenoids may also affect Eustachian tube function.
Less common in adults, persistent Eustachian tube dysfunction in the absence of cold, nasal sinusitis or allergic rhinitis may raise concerns about the exact nature of blockage in the nasopharynx. Examination by an ENT can confirm the presence of more serious causes of Eustachian tube dysfunction.
Middle ear congestion (otitis media), often associated with poor Eustachian tube function, colds and allergies, may also produce temporary fluctuations in hearing. An accumulation of fluid in the middle ear puts tension on the eardrum, leading to dull or drummy hearing. Whether pain and fever are also present, will depend if the fluid accumulation is caused by an infective process or a chronic dysfunction of the Eustachian tube. Such middle ear problems are often worse on waking, as congestion may build during sleep.
Fluctuations in hearing from inner ear pathology are more complex to treat.
Menieres syndrome involves abnormal regulation of cochlear fluids and is characterized by bouts of vertigo and nausea with stepwise reductions in hearing.
Another source of abnormal fluid regulation in the cochlear is a perilymph fistula (point of leakage). Fistulas may cause loss of cochlear fluids or permit changes in intracranial pressure to damage cochlear structures. Fistulas may be congenital or acquired through disease or trauma.
Auto-immune hearing loss results when the body’s defence mechanisms are misdirected at inner ear microstructures, by an infection occurring elsewhere, causing temporary or permanent hearing loss.
Viral attack, multiple sclerosis, elevated blood lipids, vascular abnormalities and excessive noise have also been identified as potential causes of temporary hearing shifts. In addition, rare syndromes such as Large Vestibular Aqueduct, Susac’s and Pendred’s can cause hearing to fluctuate due to inner ear pathology.