Thierry Van Den Abbeele

Predictive Factors for Success After Transnasal Endoscopic Treatment of Choanal Atresia

OBJECTIVE To analyze the different factors affecting the outcome of transnasal endoscopic repair of choanal atresia (CA) in children. DESIGN Retrospective study. SETTING Academic tertiary care childrens hospital. PATIENTS Eighty patients (48 girls and 32 boys) aged 3 days to 17 years (mean age, 3 years 8 months) who presented with unilateral (n = 53: 37 right, 16 left) or bilateral (n = 27) CA and underwent surgery between September 1996 and December 2005. INTERVENTION All patients underwent transnasal endoscopic surgery with telescopes and a microdebrider. Nasal tubes in neonates and nasal packing in older children were removed after 48 hours. Systematic endoscopic revision was performed under local or general anesthesia a week after surgery. Patients were then clinically and endoscopically monitored for nasal obstruction and healing for a mean follow-up of 43 months. RESULTS A total of 30 patients presented with associated malformations: 9 with CHARGE (coloboma, heart disease, choanal atresia, retardation of postnatal growth()and mental development, genital hypoplasia, and ear anomalies), 1 with Treacher-Collins syndrome, 1 with Kabuki syndrome, 1 with facial cleft, 1 with Down syndrome, 12 with nonsyndromic malformations, and 2 with 22q11 microdeletion. Three children had heart malformations not related to CHARGE association. One child had a congenital nasal piriform aperture stenosis. Twenty-four children had undergone previous surgery; 10 underwent a second procedure with success. Gastroesophageal reflux disease (GERD) was systematically treated in cases of restenosis. Topical mitomycin C was used in 3 patients with relapse. Two patients underwent laser treatment to reduce stenotic scarring. Of the 10 patients who needed revision surgery, 6 had bilateral CA, and 4 had unilateral CA. Age younger than 10 days and presence of GERD increased the chances of restenosis (P = .03). Postoperative stenting negatively affected the outcome. Associated anomalies and previous surgery had no effect on outcome. The bony nature of the CA and bilaterality were not significant (P = .08). However, surgeon learning curve was an important element positively influencing the results (P = .04). CONCLUSIONS Transnasal endoscopic repair of CA is a safe and successful technique. Predictive factors of restenosis are the presence of GERD, age younger than 10 days at the time of surgery, and insufficient postoperative endoscopic revision. However, previous surgery and associated malformations are not predictive of a poor surgical outcome.

Congenital Nasal Pyriform Aperture Stenosis: Diagnosis and Management of 20 Cases

The objective of this study was to review the characteristics of congenital nasal pyriform aperture stenosis (CNPAS) in a series of 20 children seen between 1993 and 1996. The diagnosis was made by physical examination and computed tomography scan. A single central maxillary incisor was detected in 12 cases (60%). Three children had morphological abnormalities of the pituitary gland shown on magnetic resonance imaging. One child had an antidiuretic hormone deficiency, and another child had a growth hormone deficiency. Two children had craniosynostoses, 1 of which was Aperts syndrome. All patients underwent operation by a sublabial approach, and 1 was referred for a columellar necrosis after nasal stenting. After surgery, all patients showed improvement, and the nasal stenting was usually removed 1 week after surgery. Follow-up revealed normal breathing. In conclusion, CNPAS was previously considered to be an unusual cause of nasal obstruction in neonates and infants. The number of cases treated recently in our department suggests that this newly recognized entity is more common than expected.

A cationic nonselective stretch-activated channel in the Reissner's membrane of the guinea pig cochlea

The Reissners membrane (RM) separates in the mammalian cochlea the K(+)-rich endolymph from the Na(+)-rich perilymph. The patch-clamp technique was used to investigate the transport mechanisms in epithelial cells of RM freshly dissected from the guinea pig cochlea. This study shows a stretch-activated nonselective cationic channel (SA channel) with a linear current-voltage relationship (23 pS) highly selective for cations over anions [K+ approximately Na+ (1) > Ba2+ (0.65) > Ca2+ (0.32) >> Cl- (0.14)] and activated by the intrapipette gradient pressure. The open probability-pressure relationship is best fitted by a Boltzmann distribution (half-maximal pressure = 37.8 mmHg, slope constant = 8.2 mmHg). SA channels exhibit a strong voltage dependency and are insensitive to internal Ca2+, ATP, and fenamates but are blocked by 1 microM GdCl3 in the pipette. They are reversibly activated by in situ superfusion of the cell with hyposmotic solutions. Kinetic studies show that depolarization and mechanical or osmotic stretch modify the closed and open time constants probably by a different mechanism. These channels could participate in pressure-induced modifications of ionic permeability of the RM.

Balloon dilation laryngoplasty for subglottic stenosis in children: eight years' experience.

OBJECTIVE To evaluate outcomes of balloon dilation laryngoplasty for laryngeal stenosis in children. DESIGN Retrospective study. SETTING Academic tertiary care department of pediatric otolaryngology. PATIENTS All children treated with laryngeal balloon dilation (primarily or secondarily following laryngeal surgery) from 2002 to 2010. MAIN OUTCOME MEASURES Stenosis severity, measured using the Cotton and Myer classification. RESULTS A total of 44 children ranging in age from 1 month to 10 years (14 [32%] with grade II stenosis, 25 [59%] with grade III stenosis, and 4 [9%] with grade IV stenosis) were included. Twelve children [27%] had congenital laryngeal stenoses, and the in other 32 [7 3%], stenosis was acquired. A total of 52 balloon dilation laryngoplasties were performed, and 37 (71%) were deemed successful. Twenty of the 31 patients undergoing primary dilation (65%) had successful outcomes, and in the other 11 [35%], outcomes were unsuccessful (4 had grade II stenosis and 7 had grade III stenosis) and required either laryngotracheal reconstruction or tracheotomy. Twenty-one balloon dilations were performed as a secondary procedure after recent open surgery; 17 of the procedures (81%) were successful, and thus surgical revision was avoided. CONCLUSION Balloon dilation laryngoplasty is an efficient and safe technique for the treatment of both primary and secondary pediatric laryngotracheal stenosis.

A calcium-activated nonselective cationic channel in the basolateral membrane of outer hair cells of the guinea-pig cochlea

The patch-clamp technique was used to investigate ion channels in the basolateral perilymph-facing membrane of freshly isolated outer hair cells (OHCs) from the guinea-pig cochlea. These sensory cells probably determine, via their motile activity, the fine tuning of sound frequencies and the high sensitivity of the inner ear. A Ca2+-activated nonselective cationic channel was found in excised inside-out membrane patches. The current/voltage relationship was linear with a unit conductance of 26.3±0.3 pS (n=15) under symmetrical inger conditions. The channel excluded anions (PNa/PCl=18 wherePNa/PCl denotes the relative permeability of Na to Cl); it was equally permeant to the Na+ and K+ ions and exhibited a low permeability toN-methyl-D-glucamine and Ba2+ or Ca2+. Channel opening required a free Ca2+ concentration of about 10−6 mol/l on the internal side of the membrane and the open probability (Po) was maximal at 10−3 mol/l (Po=0.72±0.06,n=12). Adenosine 5′mono-, tri- and di-phosphate reducedPo to 29±14 (n=5), 42±10 (n=8) and 51±12 (n=5) % of controlPo, respectively, when they were added at a concentration of 10−3 mol/l to the internal side. The channel was partially blocked by flufenamic acid (10−4 mol/l) and 3′,5′-dichlorodiphenylamine-2-carboxylic acid (DCDPC, 10−5 mol/l). This type of channel, together with Ca2+-activated K+ channels, might participate in the control of membrane potential and modulate the motility of OHCs.

A ubiquitous non-selective cation channel in the mouse renal tubule with variable sensitivity to calcium

Basolateral membranes of microdissected collagenase-treated fragments of renal tubules from the mouse were examined using the cell-attached and the cell-free variants of the patch-clamp technique. With a K+-rich solution in the pipette, a highly active, inwardly rectifying K+ channel was observed on intact cells of the cortical collecting tubule (CCT). The mean inward and outward conductances were 38.5±3.1 pS and 17.3±1.8 pS, respectively (n=4). In contrast, cell-attached patches were usually inactive when a Na+-rich solution filled the patch pipette. However, another type of channel with a conductance of 20–30 pS exhibited a sparse activity in 4/20 CCT. In excised, inside-out patches, the most frequent channel in CCT had an ohmic unit conductance of 27.1±1.2 pS (n=17), excluded anions (PCl/PNa=0.09), discriminated little between NH4+, K+ and Na+ (PNH4/PNa=1.5;PK/PNa=0.9), and was much less permeable to Ca2+ and Ba2+ than to Na+ (PCa/PNa=0.09;PBa/PNa≈0). The cation channel was moderately voltagedependent, showing a decreased open probability (Po) at negative voltages. It was activated by internal calcium (threshold: 1 μmol/l–0.1 mmol/l calcium), and inhibited by the adenine nucleotides ATP, ADP and AMP with half-maximal inhibition ofPo at 1.2 umol/l AMP. As in other cell models, 3′,5′-dichlorodiphenylamine-2-carboxylic acid blocked channel activity when added to the internal surface of the membrane patch. Extending our study to other parts of the renal tubule, we found that the basolateral membranes of the proximal (pars recta), distal convoluted, connecting and outer medullary collecting tubules, the thin descending limb and the medullary thick ascending limb all contained a similar Ca- and ATP-sensitive cation channel. The calcium sensitivity varied from one part to another.

Detection of bacterial biofilm on cochlear implants removed because of device failure, without evidence of infection.

Objective: To investigate the formation of bacterial biofilms on the surface of the electrode array of cochlear implants (CI) explanted because of device failure, without evidence of infection, by use of scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Study Design: Prospective study. Setting: Patients from 2 tertiary-care referral centers. Patients and Methods: CIs were explanted from 9 patients because of device failure. Specimens were immediately snap-frozen in cold isopenthane, stored at −80°C and examined with SEM and CLSM by 3 investigators. Main Outcome Measure: Presence of bacterial biofilm ascertained by SEM and CSLM. Results: One specimen showed the formation of a bacterial biofilm on the middle ear part of the electrode array. No biofilm formation was found in the inner-ear part of electrode arrays. In the middle-ear part of the electrode array, a cylindrical cover of human muscular tissue was seen plugging the cochleostomy. Conclusion: This is the first study demonstrating that bacterial biofilms may exist on the surface of the electrode array of CIs explanted because of device failure but not infection. We found 1 case of biofilm formation in 9 explanted CIs. Further studies with larger series of CIs are required to investigate biofilm formation on the surface of CI electrode arrays to address both the pathophysiology of bacterial biofilms and prevention of device-related infections in CI patients.

Severe Snoring in a Child With Pycnodysostosis Treated With a Bilateral Rib Graft

Pycnodysostosis is a rare osteopetrotic disorder. This report describes a case of a 3½-year-old boy with pycnodysostosis who presented with severe snoring. The snoring was the result of a pharyngeal narrowing due to a hypoplastic mandible. Surgery consisted of a bilateral rib graft, which allowed an enlargement of the pharynx by acting both on an anterior projection of the chin and a decrease of the glossoptosis. A significant reduction of the snoring and an excellent mouth aperture were obtained. This technique is ideal for such patients presenting a high risk of infection, nonunion, and secondary fracture.

Potassium channel ether à go-go mRNA expression in the spiral ligament of the rat

Identification of the K+ transporters located in the lateral wall of the cochlea is essential for a better understanding of the mechanisms by which a positive endocochlear potential and a high K+ concentration are achieved in endolymph. In this study, we have determined the distribution of the K+ channel rat ether à go-go (eag) mRNA in the cochlea. After reverse transcription of adult rat cochlear tissues, cDNA was amplified with primers specific to eag channel. The eag mRNA was localized in cochlear tissues by in situ hybridization using specific oligonucleotide probes tailed with digoxigenin conjugated UTP. Eag mRNA was detected in the organ of Corti but mainly in the fibrocytes of the spiral ligament but not in spiral prominence or in stria vascularis. The expression pattern of rat eag transcript in spiral ligament is complementary to the Na+,K+-ATPase distribution in the cochlear lateral wall. The localization of eag mRNA suggests that eag potassium channel may be produced in the corresponding cells. Considering the importance of the K+ gradient in the cochlea, the result reported here suggests that eag channel may play a role in the control of K+ fluxes in the spiral ligament.

Antibodies to myelin protein zero (P0) protein as markers of auto-immune inner ear diseases.

Background/Aims: The inner ear can be the target of autoimmune disorders. Recognition of autoimmune inner ear disease is important, as it is one of the very few forms of sensorineural hearing loss (HL) that can be successfully treated by medical therapy. The aim of this study was to evaluate whether the detection of antibodies to myelin protein P0 (MPZ) could be a diagnostic test for inner ear disease of autoimmune cause. Methods: This multicentric prospective study included 129 patients: patients with progressive sensorineural HL or with Menières disease, together with their control group corresponding to patients with similar symptoms, but of presumably known origin. Detection of antibodies to myelin P0 protein was performed by using western blots. Normal: The prevalence of antibodies to myelin P0 protein in patients with rapidly progressive HL was not statistically different from that of the control group corresponding to genetic HL patients (30 versus 28%). In patients with Menières disease, the prevalence was lower than that of the control group corresponding to patients with benign paroxysmal positional vertigo (5.4 versus 18.7%). No patient with auto-immune disease had antibodies to myelin P0 protein. Conclusions: The sole presence of antibodies to myelin P0 may not be used as a marker of inner ear disease of autoimmune origin.