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A Critical Period in Postnatal Neuroplasticity of Olfaction: A Pediatric Tracheostomy Model
William P Kennedy1, Cameron P Lewis1, Joanne Stow2
1Children's Hospital of Philadelphia, Philadelphia, Pennsylvania2University of Pennsylvania Perelman School of Medicine, Philadelphia.
Insights
Early tracheostomy in children may cause lasting smell dysfunction, even after the breathing tube is removed. This suggests a critical period for olfactory development is impacted by airflow deprivation.
Area of Science:
- Neuroscience
- Developmental Biology
- Otolaryngology
Background:
- A critical period for sensory development, similar to vision and hearing, is debated for olfaction.
- Children undergoing tracheotomy are deprived of nasal airflow during critical developmental stages.
- Persistent olfactory dysfunction post-tracheotomy could indicate the necessity of early olfactory nerve stimulation.
Purpose of the Study:
- To investigate persistent olfactory dysfunction in children after tracheotomy decannulation.
- To validate previous findings of olfactory deficits in cannulated pediatric patients.
Main Methods:
- A cross-sectional study involving pediatric patients who underwent long-term tracheostomy (cannulated), those decannulated after long-term tracheostomy, and healthy controls.
- Utilized a validated pediatric smell test to assess olfactory function across all groups.
- Data collected between 2013 and 2015 at a tertiary academic referral center.
Main Results:
- Significant differences in smell test performance were observed between controls (94%) and both cannulated (67%) and decannulated (61%) groups.
- No statistically significant difference in olfactory performance was found between cannulated and decannulated patients.
- The study included 18 pediatric patients (ages 6-18) and age-matched controls.
Conclusions:
- Olfactory deficits associated with early tracheostomy appear to persist after decannulation.
- Findings suggest a potential critical period for olfactory development and neuroplasticity.
- Early nasal airflow is likely crucial for normal olfactory system maturation.
Importance:
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.
Objective:
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.
Interventions:
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.
Results:
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.
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