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Patients with CHARGE association: a model to study saccular function in the human
1Department of Otolaryngology-Head and Neck Surgery, University Hospital, Geneva, Switzerland.
Insights
CHARGE association, a condition causing congenital malformations, can lead to severe vestibular deficits. This case study shows a child with CHARGE association walked despite profound visual and vestibular impairments.
Area of Science:
- Otolaryngology
- Developmental Pediatrics
- Genetics
Background:
- CHARGE association is a complex syndrome with diverse congenital malformations.
- Key features include coloboma, heart defects, choanal atresia, growth/CNS anomalies, genital hypoplasia, and ear anomalies.
- Inner ear malformations in CHARGE association often involve Mondini dysplasia and absence of the superior vestibular structures.
Observation:
- A longitudinal case study of a child with CHARGE association up to age 10.
- The child exhibited a complete absence of nystagmic response to standard vestibular tests (caloric, rotatory pendular).
- A positive nystagmic response was observed during off-vertical axis rotation, indicating saccular macula stimulation.
Findings:
- The study identified a specific inner ear dysplasia in CHARGE association, with only the saccule functioning as a vestibular organ.
- Severe bilateral sensorineural visual and vestibular deficits were present.
- Despite these deficits, the child achieved independent walking at two years of age.
Implications:
- This case reaffirms the saccule's role as a vestibular organ, located in the pars inferior.
- The findings suggest that delays in motor development, such as walking, in CHARGE association may be primarily due to sensory deficits rather than central nervous system anomalies.
- Understanding these specific sensory impairments is crucial for targeted developmental support in children with CHARGE association.
Abstract:
The term CHARGE association refers to a combination of congenital malformations, the mnemonic CHARGE designating the most frequently occurring anomalies in the constellation. "C" indicates coloboma of the retina, "H" heart defects, "A" choanal atresia, "R" retarded growth and/or central nervous system anomalies, "G" genital hypoplasia, and "E" ear anomalies and/or deafness. The inner ear anomaly consists of a specific form of labyrinthine dysplasia that includes Mondini dysplasia of the pars inferior (cochlea and saccule) and complete absence of the pars superior (utricle and semicircular canals). We observed the development of a child with CHARGE association up to the age of 10 years. There was complete absence of nystagmic response to bithermal caloric and rotatory pendular stimuli. A nystagmic reaction was elicited by the off-vertical axis rotation test, indicating stimulation of the saccular macula, the sole remaining vestibular sense organ in this dysplasia. This reaffirms that the saccule is a vestibular organ, even though it is located in the pars inferior. In spite of the severe bilateral vestibular deficit and coloboma of the retina, the child was able to walk at the age of 2 years. The delay in the development of walking was not due to central nervous system anomalies, as suggested by the "R" of the acronym CHARGE, but rather, to the severe sensorineural visual and vestibular deficits.