Otorhinolaryngology – Head and Neck Surgery: Theoretical Knowledge (Part I Written Exam)
What Part I tests
The written paper uses single-best-answer questions to test applied basic science: temporal bone and skull-base anatomy, sinonasal and laryngeal anatomy, head and neck embryology, audiology and vestibular physiology, oncology biology, microbiology, pharmacology, imaging principles, and evidence interpretation. Questions reward mechanism over lists.
Core rules
- Label units correctly: pure-tone thresholds are dB HL; immittance and otoacoustic emissions use dB SPL. Do not compare across scales without conversion.
- Mask the non-test ear when interaural attenuation is exceeded: about 40 dB for air-conduction headphones and 0 dB for bone conduction. Check for a masking dilemma in bilateral conductive loss.
- Tuning forks screen, not diagnose. Rinne negative with Weber to the affected ear suggests conductive loss; Weber to the better ear suggests sensorineural loss.
- Vestibular physiology follows Ewald laws: excitatory endolymph flow toward the ampulla is stronger in the horizontal canal, while inhibitory flow is stronger in vertical canals. This explains nystagmus direction.
- Laryngeal staging is rule-based: T3 includes a fixed vocal cord, paraglottic-space invasion, or inner thyroid-cartilage cortex invasion; T4a invades through the outer cortex.
- Sensitivity rules out, specificity rules in. Positive predictive value depends on prevalence, so a negative test in a high-prevalence setting does not exclude disease.
Worked example
A 52-year-old has air-conduction thresholds of 40, 50, 60, and 70 dB HL at 500, 1000, 2000, and 4000 Hz. The pure-tone average is (40 + 50 + 60)/3 = 50 dB HL, a moderate loss. Bone conduction is 10 dB HL at the same frequencies, giving a 30–60 dB air–bone gap, so the loss is conductive. If the tympanogram is type B and ipsilateral reflexes are absent, distinguish effusion from ossicular fixation: a type B with normal canal volume suggests effusion, while a small volume suggests perforation or wax. Separate degree (PTA), type (air–bone gap), and site (tympanometry).
Traps
- Calling a loss “moderate” from one 60 dB threshold instead of the PTA.
- Masking the better ear in bilateral conductive loss and creating a false sensorineural result.
- Using tuning forks to quantify hearing.
- Reversing sensitivity and specificity when interpreting screening tests.