Perilymphatic Fistula - Causes, Classification, Symptoms, Diagnosis, and Treatment

Introduction:

A fistula is the presence of an abnormal connection between two body parts. Perilymphatic fistula is the presence of an opening between the barrier membrane separating the middle ear from the inner ear. Normally our middle ear is filled with air, and our inner ear is filled with perilymphatic fluid (extracellular fluid), which functions for the transformation of sound waves into the endolymph. Any abnormal communication that develops between these two layers results in leakage of the perilymph fluid from the inner ear to the middle ear resulting in pressure changes in the ear, causing hearing and balance problems.

What Is the Prevalence of Perilymphatic Fistula?

The prevalence of perilymphatic fistula is very rare, accounting for one in 100000 adults.

What Are the Causes of Perilymphatic Fistula?

Various causes for perilymphatic fistula are:

• Head injury.

• Perforated eardrum.

• Long-term ear infections.

• Barotrauma (sudden pressure change during childbirth, sea diving, or flying).

• Trauma to ears.

• History of ear surgery like stapedectomy (surgical removal of stapes).

• Blowing your nose hard.

What Are the Signs and Symptoms of Perilymphatic Fistula?

Perilymphatic fistula presents the following signs and symptoms:

• Hearing loss.

• Loss of balance.

• Dizziness.

• Vertigo (spinning sensation in the head).

• Ear pain.

• Headaches.

• Nausea and vomiting.

• Motion sickness.

• Tinnitus (ringing sensation in the ear).

• Lightheadedness.

• Ear fullness.

• Feeling of pressure changes in the ear.

How to Classify Perilymphatic Fistula?

Based on the cause, the perilymphatic fistula is categorized as:

• Category 1: People with a history of trauma, past ear surgery, and ear infections fall under this category.

• Category 2: People having trauma due to pressure changes in the ear (barotrauma) due to external activities like flying and sea diving fall under this category.

• Category 3: People having trauma from pressure changes due to internal activities of the body like sneezing, coughing hard, or blowing their nose extremely hard are under this category.

• Category 4: Idiopathic (due to unknown causes).

How to Diagnose Perilymphatic Fistula?

Various diagnostic criteria for perilymphatic fistula are:

• History and Clinical Examination: A thorough history of a patient about the previous ear infections, trauma, or surgery of the ear should be recorded. An otoscope (a small instrument with light) is used by the doctor to check the ears for the presence of any fluid drainage or ear infections.

• An Audiogram (Hearing Test): It is done to assess the severity of hearing impairment by producing different sounds in the ears and noting the response from the sounds.

• Tympanometry: This test is done to check the functions of the middle ear. The pattern of movement of the tympanic membrane with respiration can be evaluated. In this test, a soft earbud is placed in the ears, and a probe is used to change the air pressure. These results are recorded on the graph for assessment.

• Computed Tomography (CT) Scans: A high-resolution scan is done for the temporal bone (bone present on the lateral part of the skull). It helps to diagnose the perilymphatic fistula more accurately. These scans show the presence of air bubbles in the vestibule of the ear and displacement of the stapedius footplate, which detects the presence of a perilymphatic fistula.

• Magnetic Resonance Imaging (MRI): These scans show the presence of air in the vestibule (central part of the inner ear) and cochlea (hollow spiral bone in the inner ear), which confirms the presence of a perilymphatic fistula.

• Auditory Brain Response (ABR) Test: In this test, electrodes are attached to the back of the ears and on the scalp. The response of the brain to the sound produced is measured. It helps to identify the presence of any defect in the hearing pathway.

• Electrocochleography (ECOG): This test helps measure the fluid pressure inside the ear by measuring the electrical impulse generated by the eighth cranial nerve (vestibulocochlear nerve) in response to the sound produced in the ears by the earphones.

What Is the Treatment for Perilymphatic Fistula?

Treatment modalities for the perilymphatic fistula are:

• Conservative Management: It includes bed rest, head elevation while sleeping, and avoiding activities that can increase air pressure.

• Blood Patch Injections: In this procedure, the doctor uses the patient's blood and injects it into the middle ear. It helps to regenerate and repair the membrane damage. It has proven to give successful outcomes in many patients. If the patient does not respond to the blood patch injection treatment, they undergo surgical procedures.

• Surgical Repair: If conservative management fails, the repair of the perilymphatic fistula is done surgically. This surgery is done under general anesthesia by lifting the eardrum and placing a tissue graft material in the base of the stapes and the perforated space. This surgery takes around one hour.

What Are the Precautions to Be Taken After Perilymphatic Fistula Repair Surgery?

Precautionary measures to be taken after perilymphatic fistula repair are:

• Avoid strenuous activities like weight lifting and excessive exercise.

• Avoid sports activities till one month after surgery, like scuba diving.

• Avoid air traveling after surgery for one month.

• Follow head end elevation while sleeping.

How to Prevent Perilymphatic Fistula?

Perilymphatic fistula can be prevented by:

• The presence of frequent ear infections should be brought to the notice of the doctor, and treatment should be started for it.

• Try to use earplugs while traveling in a plane.

• Avoid areas with loud noises for a longer duration.

Conclusion:

Perilymphatic fistula is a very rare condition but causes significant disturbances in the person's life by affecting the hearing and balance function. Any symptoms like reduced ability to hear, discharge from ears, vertigo, and loss of balance, if noticed, should be reported to an ENT (ear, nose, and throat) specialist for early diagnosis and management of the perilymphatic fistula before it becomes worse. However, some perilymphatic fistulas get healed by conservative management, but some of them need surgical attention. Although there are various techniques available for treating perilymphatic fistulas, any delay in the diagnosis and treatment of perilymphatic fistula can result in permanent hearing loss.