Correct Answer: C. Left Conductive Hearing Loss
Central perforation of the tympanic membrane is a classic cause of conductive hearing loss because it disrupts the mechanical transmission of sound vibrations through the ossicular chain. The key to solving this question is interpreting the tuning fork findings correctly. Rinne negative on the left ear means bone conduction (BC) > air conduction (AC) on that side—the hallmark of conductive loss. Weber lateralizing to the left indicates that the left ear (the affected ear) perceives the vibration better, which occurs because in conductive loss, the inner ear is normal and bone conduction bypasses the defective middle ear. The right ear shows Rinne positive (AC > BC, normal), confirming normal hearing on that side. Therefore, the left ear has conductive hearing loss secondary to the tympanic membrane perforation. In Indian clinical practice, central perforations from recurrent otitis media (common in our population due to upper respiratory tract infections and poor drainage) are managed conservatively initially, with tympanoplasty reserved for persistent cases affecting quality of life.
Why the other options are wrong
A. Right Conductive Hearing Loss — This is wrong because the right ear shows Rinne positive (AC > BC), which is normal hearing, not conductive loss. Additionally, Weber does not lateralize to the right; it lateralizes to the left (the affected ear). The clinical findings and otoscopy (perforation on left) both point to left-sided pathology, not right. B. Left Sensorineural Hearing Loss — This is wrong because Rinne negative on the left (BC > AC) is pathognomonic for conductive, not sensorineural loss. In sensorineural loss, Rinne would be positive (AC > BC) but both would be reduced. Weber lateralizing to the affected ear (left) also favors conductive loss; in sensorineural loss, Weber lateralizes to the better-hearing (right) ear. The perforation is a mechanical defect, not a neural one. D. Right Sensorineural Hearing Loss — This is wrong because it misidentifies both the side and the type of loss. The right ear has normal Rinne (AC > BC), ruling out any loss on that side. Weber lateralizes to the left, not the right. The otoscopic finding of central perforation on the left confirms left-sided conductive pathology. This option represents a fundamental misinterpretation of all three tuning fork parameters.
High-Yield Facts
- Rinne negative (BC > AC) = conductive hearing loss; Rinne positive (AC > BC) = normal or sensorineural loss.
- Weber lateralizes to the affected ear in conductive loss (inner ear is normal, bone conduction bypasses the block); lateralizes to the better ear in sensorineural loss.
- Central perforation of tympanum causes conductive loss by disrupting ossicular chain transmission; common in India from recurrent otitis media secondary to upper respiratory tract infections.
- Tympanoplasty is the definitive treatment for persistent central perforations affecting hearing; conservative management with dry ear precautions is initial approach in India.
- Conductive loss is reversible if the mechanical defect is corrected; sensorineural loss is permanent and requires hearing aids or cochlear implants.
Mnemonics
WEBER LATERALIZATION Conductive loss → lateralizes to Conductively affected ear (the bad ear). Sensorineural loss → lateralizes to the Sound-perceiving ear (the good ear). Remember: conductive loss 'traps' the vibration on the affected side. RINNE INTERPRETATION Positive Rinne = AC > BC (normal or SNHL). Negative Rinne = BC > AC (conductive loss). In conductive loss, bone conduction bypasses the middle ear block and is heard better than air conduction.
NBE Trap
NBE pairs central perforation with Rinne positive to trap students who confuse the side of loss; the question requires careful integration of otoscopy (left perforation), Rinne findings (left negative = conductive), and Weber lateralization (left = affected ear in conductive loss) to avoid choosing right-sided or sensorineural options.
Clinical Pearl
In Indian outpatient ENT practice, central perforations from recurrent otitis media are common in children and young adults; tuning fork examination (Weber and Rinne) is the bedside screening tool that confirms conductive loss before audiometry, guiding the decision between conservative management (dry ear precautions, antibiotics) and surgical repair (tympanoplasty).
_Reference: Bailey & Love Ch. 39 (Otology); Harrison Ch. 29 (Hearing and Balance Disorders)_