Naunton's Masking Dilemma Revisited.

BACKGROUND: Pure-tone audiometry is essential in diagnosing clinical hearing loss. Masking of the nontest ear is mandatory for determining accurate hearing thresholds in the presence of asymmetrical levels between the two ears and for ascertaining the presence of a conductive hearing loss. Paradoxically, over masking occurs when the intensity of the required masking noise to the contralateral ear is such that it exceeds interaural cranial attenuation by an amount sufficient to mask the test ear. Ralph F Naunton was the first to describe this phenomenon, which has since been known as "Naunton's masking dilemma." METHODS: A formula was derived mathematically to predict when Naunton's masking dilemma might occur in air and bone conduction. Review of Ralph F Naunton's primary works and related publications was performed. RESULTS: Our derived mathematical formulae predict when "Naunton's masking dilemma" may occur. During air conduction testing, a masking dilemma may occur when the sum of the air/bone gaps is greater than or equal to twice the interaural attenuation minus 15 dB (Σ ABGNTE+TE ≥ 2 × IA - 15 dB). During bone conduction testing, a masking dilemma may occur when the air-bone gap of the nontest ear is greater than or equal to the interaural attenuation minus 15 dB (ABGNTE ≥ IAAIR - 15 dB). CONCLUSION: Naunton's masking dilemma imposes a significant limitation to conventional audiometric testing. To the best of our knowledge, we think this is the first time that Naunton's masking dilemma has been represented in a simplified mathematical equation.

Does microbial colonisation of a neck drain predispose to surgical site infection: clean vs clean-contaminated procedures.

PURPOSE: The study was designed to assess the difference in microbiological colonisation and growth that may occur in drains, in the setting of clean-contaminated compared to clean head and neck surgery. METHODS: A prospective observational cohort study was performed. Surgical drain tips upon removal were sent for bacterial culture and the culture results were compared between clean-contaminated and clean procedures using mixed effects logistic regression. In all statistical analyses, a priori, p < 0.05 (two-tailed) was calculated to indicate statistical significance. RESULTS: One hundred and ten drains were examined in both clean-contaminated and clean procedures. Drains from clean-contaminated procedures had a significantly longer time in situ (11 vs 5 days, p < 0.001). Overall, significant evidence was seen for an association between procedure type and drain growth rates: 68% of clean-contaminated procedures; and 45% of clean procedures. Although not statistically significant, there was an increase in normal skin flora contaminated drains in clean-contaminated procedures (41 vs 25%). Rates of pathogenic skin organisms (15 vs 16%) and pathogenic oropharyngeal organisms (2.9 vs 0%) were similar for clean-contaminated vs clean procedure patients. CONCLUSION: This preliminary study demonstrated a higher rate of microbial contamination of neck drains that were placed during procedures that involved continuity with the upper aero-digestive tract and neck. Retrograde migration of skin flora along the drain is common but of no clinical significance. Similar rates of pathogenic microbial growth have been demonstrated thus far. However, selection of nosocomial pathogens due to extended antibiotic prophylaxis may pose a risk for infection. LEVEL OF EVIDENCE: 1b.

Frontal sinus surgery and sinus distribution of nasal irrigation.

BACKGROUND: Effective mucus lavage and delivery of topical pharmaceuticals are central to successful management of chronic rhinosinusitis (CRS). The frontal sinus remains difficult to penetrate with topical therapies. This study evaluates the benefit of Draf III frontal dissection compared to traditional Draf IIa for distribution of topical therapies. METHODS: Fresh human cadaver heads were dissected sequentially with Draf IIa frontal sinusotomy and then Draf III procedures. Each cavity was irrigated with pediatric (120 mL) and adult (240 mL) irrigation bottles with 1/1000 10% fluorescein-labeled free water in 2 fixed positions (vertex and Frankfort horizontal). An endoscope at a fixed position within the frontal sinus recorded frontal sinus and frontal recess penetration. The images then underwent blinded evaluation of fluid distribution scored as 0 to 4 (nasal cavity only, frontal recess, medial one-half, lateral one-half, and lavage). Ordinal distribution score was analyzed with Kendall's tau-b. RESULTS: Eight specimens (age 76 ± 11.2 years; 50% female) were assessed. Draf III was superior to Draf IIa in ability to achieve frontal sinus distribution of irrigation (90.6% vs 50.1%, p < 0.001). Vertex head position improved distribution (90.6% vs 50.1%, p < 0.001), was synergistic with Draf III (100% with 87.5% lavage, p < 0.001), but was unable to overcome Draf IIa (81.2% with 25% lavage, p < 0.001). Irrigation volume trended toward improved distribution with larger volume irrigations. CONCLUSION: Successful treatment of sinonasal disease may require postoperative delivery of topical therapies. Draf III frontal sinusotomy achieves superior topical access, and access to the frontal sinus with Draf IIa appears limited, despite large volumes and positioning.