Introduction:
Inner ear infections have become very common among the general population. Our inner ear is prone to bacterial, viral, and fungal infections, which seek immediate attention. Normally, our inner ear has hair cells (present in the cochlea), which bend on receiving sound waves from the middle ear. This will generate electrical impulses that are transferred by the acoustic nerve (nerve supply to the ear) to the brain, which detects these signals as a sound. Any infections to the inner ear can disrupt the hearing pathway resulting in gradual progression into sensorineural (damage to the nerve transmitting electrical signals to the brain to perceive sound) hearing loss if left untreated. In severe cases, the infection can also spread from the inner ear to the temporal bone (lateral part of the skull bone) and the brain. Inner ear infections also lead to loss of balance due to damage to the vestibular nerve (the eighth cranial nerve).
What Are the Causes of Inner Ear Infections?
Inner ear infections are caused by:
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Bacterial Infections: Bacteria like Streptococcus and Neisseria can result in damage to the inner ear. Labyrinthitis (swelling of the labyrinth - part of the inner ear that helps to control balance) can occur due to bacterial infections.
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Viral Infections: Viruses like cytomegalovirus (CMV) and the rubella virus affect the inner ear and can cause damage or swelling of the vestibulocochlear nerve (the eighth cranial nerve).
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Fungal Infections: Fungus like Aspergillus niger and Candida can result in inner ear infections.
What Are the Signs and Symptoms of an Inner Ear Infection?
Signs and symptoms associated with inner ear infections are:
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Hearing impairment.
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Dizziness.
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Vertigo (spinning sensation in the head).
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Deafness.
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Loss of balance.
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Tinnitus (ringing sensation in the ears).
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Pressure changes in the ears.
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Drainage from the ears.
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Nausea and vomiting.
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Disorientation.
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Pain in the ears.
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Disbalance while walking.
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Nystagmus (involuntary eye movements).
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Blurred vision.
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Meningitis (swelling of the brain tissue if the infection spreads to the brain).
How to Diagnose Inner Ear Infections?
Inner ear infections can be diagnosed by :
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History and Clinical Examination: A detailed history of the patient for the symptoms present are recorded. The ear is examined clinically by an ENT (ear, nose, and throat specialist) by using an otoscope (an instrument with attached light used to check the inner part of the ears) to rule out the presence of any infections, ear discharge, and swelling in the ears.
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Computed Tomography (CT) Scan: CT scan is done to rule out the presence of any inner ear infections, swelling, or growth.
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An Otoacoustic Emission Test: It is done using a tiny speaker to produce sounds in the ear, and the response of the cochlear hair cells to the sound is recorded.
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Auditory Brain Response (ABR) Test: It is done to detect the response of the nervous system (brain) to the sound produced in the ear by a mini earphone. It helps to identify the swelling or damage to the vestibulocochlear nerve (the eighth cranial nerve) causing a defect in the hearing pathway.
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Vestibular Test Battery: It is done to assess the functions of the labyrinth (part of the inner ear) and vestibulocochlear nerve (the eighth cranial nerve) to rule out loss of balance due to infection.
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Electrocochleography (ECOG): It is done to assess the inner ear functions in response to the sound. It can detect abnormal fluid pressure build-up in the ear.
What Is the Treatment for Inner Ear Infections?
Inner ear infections can be managed by:
1. Medicinal Therapy:
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Antibiotics and Anti-Inflammatory Drugs: These drugs are started for the patient to reduce or stop the infections. Oral, intravenous (through a vein), and intramuscular (through muscles) routes for drug take time to reach the target site (ear) and can cause systemic adverse effects on the other organs of the body, so local drug delivery by intratympanic (within the tympanic membrane of the ear) injections is preferred to avoid these complications. Intratympanic drug administration increases the efficacy of the drug in the target area. Delivery of drugs directly into the inner ear by passing the needle through the oval window and depositing it in the inner ear is another technique that is followed, but it is quite invasive (risky).
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Antifungal Drugs: Antifungal drugs like Gentamicin injections are given through the tympanic membrane to reduce the frequency and intensity of vertigo by destroying the vestibular (sensory receptors in the inner ear) hair cells.
2. Nanoparticles-Mediated Treatment: It is one of the current trending techniques to treat inner ear infections. Nanoparticles of small size (less than 1 micrometer) are used as targeted drug therapy to treat inner ear infections. These methods allow the drug to act effectively and specifically in the target areas by slow diffusion of the drug through the oval window in the inner ear. Nanoparticles like titanium dioxide (acts against fungal infections), zinc oxide (acts against bacterial infections), and copper oxide (acts against viral infections) are used to treat inner ear infections effectively. Chitosan (linear polysaccharide composed of randomly distributed β- (1→4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit)) is another polymeric nanoparticle that has been tested to treat inner ear disease effectively. Research for various nanoparticle-based drug delivery systems is still ongoing.
3. Cochlear Implants: Hearing loss induced by inner ear infections is managed by the use of cochlear implants (a small electronic device that stimulates the nerve for hearing) that helps in hearing sounds.
What Research Is Ongoing for the Treatment of Inner Ear Infections?
Further studies are ongoing for the development of biocompatible (ear-friendly) and multifunctional nanoparticles that can release or deliver the drug in a controlled manner without causing harm or toxicity to the ears due to uncontrolled drug delivery (drug overdose).
Conclusion:
Inner ear infections most likely occur from bacterial or viral infections and are rarely caused by fungus. Inner ear infections can cause hearing loss and loss of balance and can also spread to the brain if left untreated. Any signs and symptoms of ear infections noticed should be reported to the doctor for early diagnosis and management of the infection. Early management of ear infections can prevent permanent hearing loss and further complications associated with the infection.
