Lady has B/L hearing loss since 4 years which worsened during pregnancy. Type of impedence auditometry graph will be –
**Core Concept:** Impedance audiometry is a non-invasive method used to evaluate the hearing status of a patient by measuring the resistance of the auditory system to sound waves. Impedance audiometry produces an impedance (Z) vs. frequency (f) curve, which can be used to diagnose conductive hearing loss, sensorineural hearing loss, or mixed hearing loss. The type of impedance audiometry graph depends on the type of hearing loss.
**Why the Correct Answer is Right:** In this case, the patient has bilateral hearing loss (B/L) that worsened during pregnancy. This suggests a possible inner ear pathology, such as Meniere's disease or viral infections like rubella, cytomegalovirus (CMV), or herpes simplex virus (HSV). Both Meniere's disease and viral infections can lead to sensorineural hearing loss, which is characterized by a type B impedance audiometry graph.
**Why Each Wrong Option is Incorrect:**
A. A type A graph is expected for a normal hearing individual. The correct answer is not A because the patient's hearing loss has worsened during pregnancy.
B. A type C graph is seen in a patient with a mixed hearing loss, which is not consistent with the given case.
C. A type D graph is associated with a conductive hearing loss, which is not consistent with the described worsening of hearing during pregnancy.
**Why the Correct Answer is Right:** The correct answer is a type B graph because sensorineural hearing loss, as seen in Meniere's disease or viral infections, results in a type B impedance audiometry graph. This graph is characterized by a steep decrease in impedance at low frequencies followed by a gradual decrease at higher frequencies. The worsening of hearing during pregnancy is due to the increased blood flow and fluid volume in the inner ear, which exacerbates the underlying pathology.
**Clinical Pearl:** A type B impedance audiometry graph should prompt further evaluation for possible inner ear pathology, such as Meniere's disease or viral infections, considering the patient's history of worsening hearing during pregnancy.