T. Van Den Abbeele

Pathophysiology and diagnostic approach to laryngomalacia in infants

Laryngomalacia is defined as collapse of supraglottic structures during inspiration. It is the most common laryngeal disease of infancy. Laryngomalacia presents in the form of stridor, a high-pitched, musical, vibrating, multiphase inspiratory noise appearing within the first 10 days of life. Signs of severity are present in 10% of cases: poor weight gain (probably the most contributive element), dyspnoea with permanent and severe intercostal or xyphoid retraction, episodes of respiratory distress, obstructive sleep apnoea, and/or episodes of suffocation while feeding or feeding difficulties. The diagnosis is based on systematic office flexible laryngoscopy to confirm laryngomalacia and exclude other causes of supraglottic obstruction. Rigid endoscopy under general anaesthesia is only performed in the following cases: absence of laryngomalacia on flexible laryngoscopy, presence of laryngomalacia with signs of severity, search for any associated lesions prior to surgery, discrepancy between the severity of symptoms and the appearance on flexible laryngoscopy, and/or atypical symptoms (mostly aspirations). The work-up must be adapted to each child; however, guidelines recommend objective respiratory investigations in infants presenting signs of severity.

Oxygen modulates Na+absorption in middle ear epithelium

The physiology of the middle ear is primarily concerned with keeping the cavities air filled and fluid free to allow transmission of the sound vibrations from the eardrum to the inner ear. Middle ear epithelial cells are thought to play a key role in this process, since they actively transport Na+ and water. The PO2 of the middle ear cavities varies from 44 to 54 mmHg in healthy human ears but may be lower in the course of secretory otitis media. The effect of chronic hypoxia on ion transport was investigated on a middle ear cell line using the short-circuit current technique. Chronic hypoxia reversibly decreased the rate of Na+ absorption across the MESV cell line. Although a decrease in cellular ATP content was observed, the decrease of Na+ absorption seemed related to a primary modulation of apical Na+ entry. As revealed by RNase protection assay, the decrease in the rate of apical Na+ entry strictly paralleled the decrease in the expression of transcripts encoding the alpha-subunit of the epithelial Na+ channel. This effect of oxygen on Na+ absorption might account for 1) the presence of fluid in the middle ear in the course of secretory otitis media and 2) the beneficial effect of the ventilation tube in treating otitis media that allows the PO2 to rise and restores the fluid clearance.The physiology of the middle ear is primarily concerned with keeping the cavities air filled and fluid free to allow transmission of the sound vibrations from the eardrum to the inner ear. Middle ear epithelial cells are thought to play a key role in this process, since they actively transport Na+ and water. The [Formula: see text] of the middle ear cavities varies from 44 to 54 mmHg in healthy human ears but may be lower in the course of secretory otitis media. The effect of chronic hypoxia on ion transport was investigated on a middle ear cell line using the short-circuit current technique. Chronic hypoxia reversibly decreased the rate of Na+absorption across the MESV cell line. Although a decrease in cellular ATP content was observed, the decrease of Na+ absorption seemed related to a primary modulation of apical Na+entry. As revealed by RNase protection assay, the decrease in the rate of apical Na+ entry strictly paralleled the decrease in the expression of transcripts encoding the α-subunit of the epithelial Na+channel. This effect of oxygen on Na+ absorption might account for 1) the presence of fluid in the middle ear in the course of secretory otitis media and 2) the beneficial effect of the ventilation tube in treating otitis media that allows the[Formula: see text] to rise and restores the fluid clearance.

Management of laryngomalacia

Laryngomalacia is the most common laryngeal disease of infancy. It is poorly tolerated in 10% of cases, requiring assessment and management, generally surgical. Surgery often consists of supraglottoplasty, for which a large number of technical variants have been described. This surgery, performed in an appropriate setting, relieves the symptoms in the great majority of cases with low morbidity. However, few data are available concerning the objective results: preoperative and postoperative objective assessment of these infants is therefore necessary whenever possible. Noninvasive ventilation (NIV) may be indicated in some infants with comorbid conditions or failing to respond to surgical management.

Modulation of Middle Ear Epithelial Function by Steroids: Clinical Relevance

The efficacy of steroid therapy for the treatment of otitis media in children remains controversial, and a putative modulation of the middle ear epithelial function has to be demonstrated. Using the MESV cell line, short-circuit current (ISC) technique was used to evaluate changes in ion transport induced by glucocorticoids. Dexamethasone (DXM) produced a dose- and time-dependent increase in ISC in MESV cells. This effect was inhibited by specific glucocorticoid antagonist (RU-38486) and was related to a sodium transport, since the DXM-induced increase in ISC could be prevented or abolished i) by apical addition of the specific Na+ channel inhibitor benzamil; or ii) by substitution of sodium with N-Methyl-glucamine in the incubation medium. RNase protection assay revealed that DXM increased the expression of the alpha subunit sodium channel mRNA, which changes paralleled the modulation of ion transport. These data demonstrate that steroids up-regulate the trans-epithelial sodium transport in the middle ear epithelium. As far as these experimental data can be extrapolated to the in vivo situation, a component of the beneficial effect of steroid therapy for the treatment of otitis media may result from a corticosteroid-induced improvement in fluid clearance from the middle ear.

Extracellular ATP Modulates Ion Transport via P2Y Purinoceptors in a Middle-Ear Epithelial Cell Line

Mucus and cellular debris are eliminated from the middle-ear cavity through the E-tube by the mucociliary system. Depth of the periciliary fluid layer is thought to be regulated by epithelial ion transport activity. Since impairment of the mucociliary system is a key step in the development of otitis media with effusion, we investigated the ion transport mechanisms of the middle-ear epithelium using the middle-ear MESV cell line. ATP has been shown to modulate ion transport as well as various cellular functions in several cell types via purinoceptors. In order to investigate a possible modulation of the transport activity of MESV cells, we evaluated short-circuit current (Isc) changes in response to specific stimulation of putative purinoceptors by ATP and its various analogs. ATP dramatically increased Isc, while adenosine had no effect, thus demonstrating the presence of P2 receptors according to the original classification by Burnstock. The rank order of potency of purinoceptor agonists for stimulation of Isc on the apical side (ATP > UTP > gamma-SATP >> beta-SADP > 2-methylthio-ATP, 2MeSATP > beta, gamma-methylene-ATP, beta,gamma-MeATP) and on the basolateral side (ATP > gamma-SATP > UTP >> beta-SADP > 2 MeSATP > beta,gamma-MeATP), along with studies using selective antagonists and intracellular calcium measurements are consistent with a P2Y receptor subtype. The ATP-induced increase in Isc was related to sodium transport. This modulation might be of importance in stress conditions such as inflammation.

Luminal non-selective cation and outwardly rectifying chloride channels in cultured strial marginal cells from gerbil

Ionic channels located on the luminal side of strial marginal cells (MCs) of gerbil in culture were investigated using the patch-clamp technique. Two types of channels were identified. The most frequently recorded single-channel activity corresponded to a non-selective cation (NSC) channel with a conductance of 23.7 +/- 0.2 pS (n = 18) in symmetrical NaCl conditions. The channel was activated by internal Ca2+ and inhibited by internal adenine nucleotides and flufenamic acid. Spontaneous activity of NSC channels was found in 16% of the cell-attached patches and with a very high density (9 +/- 2 levels/patch, n = 28) in 100% of the excised patches. An outwardly rectifying chloride (ORC) channel was also identified in 14% of the patches but only after excision. The channel exhibited at 0 mV a unit conductance of 26.8 +/- 1.3 pS (n = 8) and a strong outward rectification in symmetrical NaCl conditions, and the open probability increased with depolarization. The luminal NSC channel and the ORC channel evidenced in this study might participate in the production of endolymph. Although extrapolation of the presents results to the in vivo situation should be made with caution, this study suggests that culture of strial MCs may be a suitable model for investigation of endolymph physiology.

Fetal airway management on placental support: Limitations and ethical considerations in seven cases

The aim of this study was to evaluate the paediatric and maternal outcome after ex utero intrapartum treatment (EXIT). A retrospective review was carried out of the medical charts (gestational age, circumstances of diagnosis, multidisciplinary prenatal decision, date of surgery, paediatric and maternal outcome) of all the fetuses eligible for/delivered via the EXIT procedure in our paediatrics and obstetrics tertiary care and teaching centre, between October 2004 and May 2011. Seven fetuses with cervical teratoma, epignathus tumour or congenital high airway obstruction syndrome (CHAOS) were included in our study. Two pregnancies were terminated and five fetuses were delivered alive. The airway was secured in all five cases (two endotracheal intubations and three tracheostomies). No maternal complications were observed. On average, babies were delivered at 32 gestational weeks, and spent 31 days in the intensive care unit. All but one baby were ventilated for 18 days. Long-term paediatric outcome was favourable. It is concluded that airway management by the EXIT procedure has become an efficient technique. A multidisciplinary prenatal assessment is essential in order to select appropriate cases.

Malformaciones congénitas del oído externo y del oído medio

Las malformaciones del oido externo y medio son relativamente infrecuentes y en la mayoria de los casos aparecen de forma aislada y unilateral. Sin embargo, pueden integrarse en asociaciones sindromicas que conviene detectar para buscar malformaciones asociadas y aportar un posible consejo genetico. En la mayoria de las ocasiones es necesario un tratamiento multidisciplinario en el que participen pediatras, genetistas, audiologos y cirujanos, para proponer a los padres un programa terapeutico adecuado.

Mastoiditis aguda en la infancia

La mastoiditis es una osteitis bacteriana del penasco que aparece como complicacion de una otitis media aguda en los lactantes y los ninos pequenos. En los ninos mayores, este cuadro puede revelar la presencia de un colesteatoma. Los principales microorganismos responsables son Streptococcus pneumoniae, Streptococcus pyogenes , Staphylococcus aureus y algunas bacterias anaerobias. Debido a su topografia, la infeccion puede difundirse hacia el exterior, causando un absceso subperiostico, o hacia el cuello, a lo largo del musculo esternocleidomastoideo. Las otras complicaciones extracraneales son la paralisis facial y la laberintitis aguda. La infeccion tambien puede difundirse al nivel intracraneal y causar una meningitis, un absceso intracraneal o una trombosis del seno lateral. Las pruebas de imagen permiten confirmar el diagnostico, buscar una complicacion intracraneal o signos sugestivos de un colesteatoma, asi como guiar un posible tratamiento quirurgico. El pronostico suele ser favorable. Las medidas terapeuticas consisten en un tratamiento antibiotico solo o asociado a la colocacion de un drenaje transtimpanico, un drenaje del absceso subperiostico o una mastoidectomia. Desde hace varios anos, la indicacion quirurgica es menos sistematica, pero esto sigue siendo motivo de debate.

Mastoidite acuta infantile

La mastoidite e un’osteite batterica della rocca che complica un’otite media acuta nel neonato e nel bambino piccolo. Nei bambini piu grandi, puo essere indicativa di colesteatoma. I principali organismi responsabili sono Streptococcus pneumoniae, Streptococcus pyogenes, Staphylococcus aureus e alcuni batteri anaerobi. Grazie alla sua topografia, l’infezione puo diffondersi verso l’esterno, dando un ascesso sottoperiosteo, o verso il collo, lungo il muscolo sternocleidomastoideo. Altre complicanze extracraniche includono la paralisi facciale e la labirintite acuta. La diffusione dell’infezione puo anche essere intracranica e produrre una meningite, un ascesso intracranico o una trombosi del seno laterale. Le tecniche di imaging permettono di confermare la diagnosi, di ricercare una complicanza intracranica o dei segni a favore di un colesteatoma e di guidare un eventuale intervento chirurgico. La prognosi e, di solito, favorevole. La gestione consiste nel trattamento antibiotico da solo o associato a un areatore transtimpanico, a un drenaggio dell’ascesso sottoperiosteo o a una mastoidectomia. Negli ultimi anni, l’indicazione alla chirurgia e diventata meno di routine ma rimane aperta al dibattito.