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There is controversy over whether a critical period in the development of olfaction exists, as there is in hearing and vision, whereby early stimulation of the olfactory nerve is necessary for normal olfactory performance later in life. Children who undergo tracheotomy early in life are deprived of airflow through the nasal cavity during a critical period of development. Persistent olfactory dysfunction in this patient group after decannulation would provide evidence that postnatal stimulation of the olfactory nerve is critical to normal development.
To determine whether children who undergo early tracheotomy have persistent olfactory dysfunction following decannulation and to validate a prior study showing olfactory deficits in cannulated patients.
Design, Setting, and Participants
This was a cross-sectional study of smell function in pediatric patients with either long-term tracheostomy (cannulated), decannulated patients after long-term tracheostomy, and healthy age- and sex-matched controls, conducted in a tertiary care academic referral center, using data that were collected between 2013 and 2015. All patients were without coexisting nasal abnormalities or developmental delay that would prevent completion of testing.
Administration of a validated pediatric smell test to all 3 patient groups.
Main Outcomes and Measures
Mean percentage correct on a validated pediatric smell test.
In 18 patients ages 6 to 18 years, there was a statistically significant difference (P = .007) in mean percentage of correct responses on the smell test between cannulated (67%; 95% CI, 54%-79%, N = 6), decannulated (61%; 95% CI, 42%-80%, N = 6), and age-matched controls (94%; 95% CI, 90%-99%, N = 6). Analysis between groups showed statistically significant differences between both control and cannulated patients (P = .002) and between control and decannulated patients (P = .006). There was no significant difference between scores in the cannulated and decannulated groups (P = .64).
Conclusions and Relevance
This pilot study suggests that olfactory deficits from early chronic tracheostomy persist following decannulation and provides early data suggestive of a critical period in the postnatal development and neuroplasticity of olfaction.
Kennedy WP, Lewis CP, Stow J, Sobol SE. A Critical Period in Postnatal Neuroplasticity of OlfactionA Pediatric Tracheostomy Model. JAMA Otolaryngol Head Neck Surg. 2016;142(2):127-131. doi:10.1001/jamaoto.2015.2946