Suture restriction of the temporal bone as a risk factor for acute otitis media in children: cohort study

BACKGROUND

Eustachian tube (ET) dysfunction plays an important role in the pathogenesis of acute otitis media (AOM). Unfortunately, there is a lack of knowledge about the exact role of the ET's bony support, the temporal bone, on occurrence of AOM. This study investigates whether severe suture restriction of the temporal bone is a risk factor for development of AOM in young children.

METHODS

Using a prospective cohort design, 64 children aged 6 to 18 months without prior history of AOM were followed during the cold season (September 2009 to April 2010). Temporal bone status (categorized as with or without severe suture restriction) was evaluated using palpation and a cranial bone mobility test. Information about potential baseline confounders and risk factors for AOM (gender, age, birth weight, gestational age, use of pacifier, daycare attendance, presence of siblings, low socioeconomic status, breastfeeding ≥ 6 months, parental smoking and history of upper respiratory tract infection) were also collected. Occurrence of AOM diagnosed by physicians blinded to temporal bone status was the main outcome. Data were analyzed using hierarchical linear and nonlinear (multilevel) models.

RESULTS

Severe suture restriction of the temporal bone was identified in 23 children (35.9%). At least one AOM episode was diagnosed in 14 (48.3%) of the ears associated with temporal bones previously identified as having severe suture restriction and in 28 (28.3%) of those without severe suture restriction. Higher risk for AOM was explained by severe suture restriction of the temporal bone (adjusted relative risk (RR), 2.26, 95% CI 1.43 to 2.91, p<.01), pacifier use (RR, 2.59, 95% CI 1.51 to 3.22, p<.01) and younger age (RR, 0.22, 95% CI 0.10 to 0.52, p=.001).

CONCLUSIONS

The study results indicate that severe suture restriction of the temporal bone is a risk factor for AOM in young children. Subsequent intervention studies are needed to determine if this mechanical risk factor can be modified in young children.

Vocal cord adduction causing obstructive sleep apnea from vagal nerve stimulation: case report

A recognized complication of vagal nerve stimulation is new or worsening sleep apnea. Its pathophysiology is not clearly understood. We report a patient with obstructive sleep apnea that was directly associated with vagal nerve stimulation causing recurring vocal cord adduction. Adjusting the stimulator settings resolved the problem.

Otologic safety of manuka honey

OBJECTIVE

To investigate the possible ototoxic effects of a 50% concentration of manuka honey in a chinchilla animal model.

STUDY DESIGN

A prospective, controlled animal study.

SETTING

The Research Institute of the Montreal Children's Hospital, McGill University Health Centre.

SUBJECTS AND METHODS

Eight animals had myringotomy incisions in both ears. One ear was randomly assigned to receive the 50% manuka honey solution. The contralateral ear received saline and served as the control ear.

OUTCOME MEASURES

Auditory brainstem evoked responses (ABRs) were measured bilaterally for a wide range of frequencies (between 8 and 25 kHz) before and 2 weeks after transtympanic manuka honey and saline application. The animals were sacrificed, and all cochleae were dissected out and processed for light and scanning electron microscopy (SEM).

RESULTS

The measured ABR thresholds after the application of 50% concentration of manuka honey revealed severe ototoxicity in all honey-exposed ears. This was accompanied by gross physical changes and histologic evidence of hair cell toxicity on SEM and light microscopy. The control ears remained unchanged during the period of the experiment.

CONCLUSION

Although 50% concentration of manuka honey is the proven concentration to have bactericidal properties against biofilms of Pseudomonas aeruginosa and Staphylococcus aureus, this concentration appeared to have caused severe or intense inflammatory changes that produced facial paralysis, vestibulotoxicity, and hearing loss.

Radiation-induced xerostomia: is octreotide the solution?

OBJECTIVE

In this study, we looked for evidence that octreotide, a drug used specifically in acromegaly and other digestive pathologies, can have a radioprotective effect on salivary glands. This effect has already been proven on the pituitary gland, which is why we postulated that octreotide could act the same way on rat parotid glands.

METHOD

A prospective randomized controlled study on animals was conducted. With a noninvasive technique, we collected saliva from the parotid glands of 18 anesthetized rats at time 0 (preirradiation) and 1 month (postirradiation). Each sampling technique lasted 40 minutes, with pilocarpine injection at time 0 and 20 minutes. Saliva was collected bilaterally. Eighteen rats, nine in the saline group and nine in the octreotide group, were randomized. The substance was injected 30 minutes before irradiation. Thirty gray were given with the gamma knife on the left parotid gland of each rat following a computerized targeting method. Each gland was examined after the last saliva collection to determine the percentage of five criteria: fibrosis, ducts, fat, vessels, and acini.

RESULTS

Data are available for 17 rats (nine in the octreotide group and eight in the saline group). Statistical analysis was done with a t-test (independent and paired). We noted that the postirradiation secretion in the left (radiated) gland was diminished compared with the right (nonradiated) gland in the saline group (p = .014). Fibrosis was increased in the irradiated (left) gland in both groups (p = .024 in the octreotide group and p = .033 in the saline group). The percentage of duct cells was more important in the left (radiated) gland of the octreotide group (p = .046). A trend appeared for a decrease in acinic cells only in the control group (p = .063).

CONCLUSION

Octreotide acted as a radioprotective agent on rat parotid glands 1 month after irradiation with 30 Gy given with the gamma knife.

Origins of the inhibiting effects of nasal CPAP on nonnutritive swallowing in newborn lambs

The present study investigated the mechanism by which continuous positive airway pressure (CPAP) suppresses nonnutritive swallowing (NNS) during quiet sleep (QS) in newborn lambs. Eighteen full-term lambs were chronically instrumented and evenly distributed into three separate groups to determine the extent to which modulation of NNS may be attributed to stimulation of upper airway and/or bronchopulmonary mechanoreceptors. Six lambs were tracheotomized, six other lambs underwent a two-step bilateral intrathoracic vagotomy, and the remaining six lambs underwent chronic laryngotracheal separation (isolated upper airway group). Forty-eight hours after surgery, each nonsedated lamb underwent polysomnographic recordings on three consecutive days. States of alertness, NNS and respiratory movements were recorded. Results demonstrate that a CPAP of 6 cmH2O inhibited NNS during QS while administered directly on the lower airways and that bivagotomy prevented this inhibition. However, application of CPAP on the upper airways only also inhibited NNS during QS. Finally, the application of a CPAP of 6 cmH2O had no systematic effect on NNS-breathing coordination (assessed by the respiratory phase preceding and following NNS). In conclusion, our results suggest that bronchopulmonary receptors are implicated in the inhibiting effects of nasal CPAP of 6 cmH2O on NNS in all our experimental conditions, whereas upper airway receptors are only implicated in certain conditions.

Obstructive sleep disordered breathing in children: beyond adenotonsillectomy

Traditionally, adenotonsillectomy (AT) has long been the treatment of choice for obstructive sleep disordered breathing (SDB) in children. AT is usually considered a safe procedure, which cures 80% of children with SDB. Accumulated data have however challenged this overly simplistic view. Indeed, AT is invariably associated with significant morbidity, post-operative pain, and a mortality rate which, though low, cannot be ignored. In addition, aside from a recurrence of SDB at adolescence in an unknown percentage of cases, some recent results suggest that complete SDB cure is not achieved in as much as 75% of cases after AT. Interestingly, several treatment options have been recently proposed for replacing or complementing AT. Continuous positive airway pressure (CPAP) is now suggested in children with remaining SDB after AT; however, compliance and suitability of equipment remain important hurdles, especially in small children and infants. Anti-inflammatory treatments, including nasal glucocorticoids and/or the anti-leukotriene montelukast, appear to hold great promise. Finally, orthodontic treatments are an appealing option, with recent results in children suggesting that it is possible to improve or perhaps even cure SDB in a durable manner by enlarging the nasal passages and/or the oropharyngeal airspace. In conclusion, while we are currently in the midst of an exciting time with several new treatments being developed for childhood SDB, randomized controlled trials are urgently needed to delineate their indications. In the meantime, it appears that systematic detection of orthodontic anomalies and better collaboration with maxillofacial specialists, including orthodontists and/or dentists, is needed for deciding the best treatment options for childhood SDB.

Mechanisms of active laryngeal closure during noninvasive intermittent positive pressure ventilation in nonsedated lambs

The present study stems from our recent demonstration (Moreau-Bussiere F, Samson N, St-Hilaire M, Reix P, Lafond JR, Nsegbe E, Praud JP. J Appl Physiol 102: 2149-2157, 2007) that a progressive increase in nasal intermittent positive pressure ventilation (nIPPV) leads to active glottal closure in nonsedated, newborn lambs. The aim of the study was to determine whether the mechanisms involved in this glottal narrowing during nIPPV originate from upper airway receptors and/or from bronchopulmonary receptors. Two groups of newborn lambs were chronically instrumented for polysomnographic recording: the first group of five lambs underwent a two-step bilateral thoracic vagotomy using video-assisted thoracoscopic surgery (bilateral vagotomy group), while the second group, composed of six lambs, underwent chronic laryngotracheal separation (isolated upper airway group). A few days later, polysomnographic recordings were performed to assess glottal muscle electromyography during step increases in nIPPV (volume control mode). Results show that active glottal narrowing does not develop when nIPPV is applied on the upper airways only, and that this narrowing is prevented by bilateral vagotomy when nIPPV is applied on intact airways. In conclusion, active glottal narrowing in response to increasing nIPPV originates from bronchopulmonary receptors.

Pain management after tonsillectomy: morphine is not enough

INTRODUCTION

Tonsillectomy is usually done as day surgery, transferring to the parents most of the postoperative care. They often feel alone and incompetent in front of a child in pain. We developed a guide to help parents for both the evaluation and the management of postoperative pain.

OBJECTIVE

To improve pediatric posttonsillectomy pain management with the implementation of a parental guide and treatment algorithm.

METHODS

Eighty children (5-17 years) were recruited in this randomized clinical trial. Parents and children were assigned to one of the research groups: control or experimental. All received an identical prescription for acetaminophen (15 mg/kg) and morphine (0.3 mg/kg), information about the medication, a visual analogue scale (VAS), and index cards to be filled at home. The experimental group also received a treatment algorithm associating pain scores with analgesics.

RESULTS

Pain scores for the control group and the experimental group were 5.3 and 4.7 on the day of surgery, 4.0 and 3.6 the next day, 2.2 and 2.3 3 days later, and 1.6 and 1.4 1 week after the intervention, respectively. The side effects and the analgesics given were comparable for both groups.

CONCLUSION

No significant difference was demonstrated for the studied parameters, probably because the majority of the parents followed the prescriptions well. The guide was much appreciated. The children understood the VAS easily and liked using it. The combination of acetaminophen-morphine needs to be revisited since pain remains problematic.

Non-nutritive swallowing and respiration coordination among states of alertness in adult sheep

Swallowing is a powerful inhibitor of respiration. Its coordination with respiration is therefore crucial to avoid aspiration and apnea. The aim of this study was to determine the coordination between non-nutritive swallowing (NNS) and phases of the respiratory cycle, including the assessment of the effect of states of alertness in adult sheep. Six animals were surgically instrumented under general anesthesia to record electroencephalography, electro-oculography (state of alertness), diaphragmatic electromyography (EMG), nasal flow (respiration), esophageal EMG, and the thyroarytenoid muscle (NNS). Our results revealed that (1) the highest NNS frequency is observed in rapid eye movement (REM) sleep, especially for bursts of NNS; (2) while NNS begins mainly during inspiration in all states of alertness, REM sleep, however, is responsible for an increase in the proportion of NNS beginning in expiration; (3) the link between inspiration and NNS is not affected by rumination. In conclusion, the link between NNS and inspiration in adult sheep is similar to that of lambs but contrary to previous reports on NNS induced by water in humans. Whether these differences are related to interspecies differences or the experimental techniques clearly needs further studies on spontaneous NNS in humans.

First myringotomy with insertion of a modified Goode T-Tube: changing the perforation paradigm

BACKGROUND

Goode T-Tubes (Medtronic Xomed, Inc) have a bad reputation because of their residual tympanic perforation rate. However, these long-term tubes are mostly used in patients with chronic middle ear problems. On the other hand, "safer," short-term tubes may need to be reinserted in up to 20% of children.

OBJECTIVE

To demonstrate that modified Goode T-Tubes inserted at the first myringotomy in normal children leave a perforation rate comparable to the rate reported in the literature for short-term tubes and may be extracted safely in the outpatient clinic when eustachian tube function is thought to be adequate.

METHOD

This prospective study followed 58 children (100 ears) who had their modified Goode T-Tubes electively removed in the clinic, from October 2003 to November 2004.

RESULTS

We found only one persistent perforation at the third follow-up (mean time 5.2 months). The tubes had been in place for an average of 2.9 years. The perforation healing rate was inversely related to intubation duration. Adenotonsillectomy seemed to favourably influence the speed of healing. The perforations healed faster when tubes were inserted for chronic middle ear effusion compared with recurrent acute otitis media. Age, gender, and the site of intubation were not related to persistent perforation. All of the tubes spontaneously extruded (13) healed without perforation.

CONCLUSION

Modified Goode T-Tubes inserted at the first myringotomy and electively extracted allow for a longer middle ear ventilation period and have a perforation rate comparable to that of short-term tubes.

Cognitive skills analysis, kinesiology, and mental imagery in the acquisition of surgical skills

GOAL

Isolate and evaluate the impact of mental imagery on the acquisition of an emergency surgical technique.

METHOD

We studied 44 first-year medical students performing a cricothyrotomy on a mannequin to determine the impact of teaching using mental imagery (MI) and/or kinesiology (KG) compared to the standard Advandec Trauma Life Support (ATLS) approach. Students were randomly assigned to one of three groups: MI and KG, KG alone or control (ATLS). Two weeks after the one-hour teaching session, they were evaluated with an OSCE testing the performance of the different steps of the technique, the time required and its fluidity.

RESULTS

Total results (maximum: 25 marks) are as follows: KG + MI = 20.3 +/- 1.5 ; KG = 19.3 +/- 2.9 ; ATLS = 18.2 +/- 2.5. The only statistically significant difference for total results was in the use of MI and KG compared to the control group. Kinesiology alone or with mental imagery improved the fluidity of the performance.

CONCLUSION

Many factors influence the acquisition of a surgical technique. This study showed that acquisition and performance of an emergency procedure (cricothyrotomy) was improved when mental imagery and kinesiology were combined to teach it.

Active upper airway closure during induced central apneas in lambs is complete at the laryngeal level only

We tested the hypotheses that active upper airway closure during induced central apneas in nonsedated lambs 1). is complete and occurs at the laryngeal level and 2). is not due to stimulation of the superior laryngeal nerves (SLN). Five newborn lambs were surgically instrumented to record thyroarytenoid (TA) muscle (glottal constrictor) electromyographic (EMG) activity with supra- and subglottal pressures. Hypocapnic and nonhypocapnic central apneas were induced before and after SLN sectioning in the five lambs. A total of 174 apneas were induced, 116 before and 58 after sectioning of the internal branch of the SLN (iSLN). Continuous TA EMG activity was observed in 88% of apneas before iSLN section and in 87% of apneas after iSLN section. A transglottal pressure different from zero was observed in all apneas with TA EMG activity, with a mean subglottal pressure of 4.3 +/- 0.8 cmH2O before and 4.7 +/- 0.7 cmH2O after iSLN section. Supraglottal pressure was consistently atmospheric. Sectioning of both iSLNs had no effects on the results. We conclude that upper airway closure during induced central apneas in lambs is active, complete, and occurs at the glottal level only. Consequently, a positive subglottal pressure is maintained throughout the apnea. Finally, this complete active glottal closure is independent from laryngeal afferent innervation.

Effects of C fiber blockade on cardiorespiratory responses to laryngeal stimulation in concious lambs

The primary aim of the study was to explore cardiorespiratory reflexes originating from laryngeal C fiber endings in the neonatal period. Seventeen lambs were instrumented for recording glottal adductor and diaphragm EMG, heart rate, systemic arterial pressure and respiratory movements. C fiber blockade was induced in eight lambs by 30 mg/kg capsaicin, the remaining nine lambs serving as controls. Cardiorespiratory reflexes were induced in non-sedated lambs by flowing air, menthol or 13% CO2, or by injecting water or 50 microg capsaicin in the laryngeal inlet through an endoscope. Responses to all stimuli but capsaicin were similar between the two groups. While cardiorespiratory responses were induced by capsaicin in control lambs, the responses were significantly inhibited in lambs with C fiber blockade. We conclude that laryngeal C fiber endings are functional and responsible for laryngeal chemoreflexes in newborn lambs.

Active glottal closure during central apneas limits oxygen desaturation in premature lambs

Our laboratory previously reported that active glottal closure was present in 90% of spontaneous central apneas in premature lambs while maintaining a high-apneic lung volume (Renolleau S, Letourneau P, Niyonsenga T, and Praud JP. Am J Respir Crit Care Med 159: 1396-1404, 1999.) The present study aimed at testing whether this mechanism limits postapnea oxygen desaturation. Four premature lambs were instrumented for recording states of alertness, thyroarytenoid muscle and diaphragm electromyographic (EMG) activity, nasal airflow, lung volume changes, and pulse oximetry. One thousand four hundred fifty-two spontaneous central apneas (isolated or during periodic breathing) were analyzed in nonsedated lambs. Apneas, with high lung volume maintained by active glottal closure, were compared with apneas, with a tracheostomy opened at apnea onset. Oxygen desaturation slopes were lower when high-apneic lung volume was actively maintained during both wakefulness and quiet sleep. Furthermore, oxygen desaturation slopes were lower after isolated apneas with continuous thyroarytenoid EMG during wakefulness, compared with apneas with noncontinuous thyroarytenoid EMG (= glottis opened shortly after apnea onset). These results highlight the importance of maintaining high-alveolar oxygen stores during central apneas by active glottal closure to limit desaturation in newborns.

The Larynx and Neonatal Apneas

OBJECTIVE: We sought to review the current literature on the role of the larynx in neonatal apneas. STUDY DESIGN: We conducted a literature search and analysis of the published and other available information on the topic.

RESULTS: Publications on this topic in otolaryngology journals are rare, although more basic sciences-oriented journals have published interesting results from animal studies during the past 20 years. The scarce data on human neonates are also presented.

CONCLUSIONS: The authors follow the phylogenetic and oncogenetic pathways to explain the active role of the larynx in neonatal apneas. Although most of these results are derived from animal studies, they certainly improve our understanding of human neonatal apneas.

The larynx and neonatal apneas

OBJECTIVE

We sought to review the current literature on the role of the larynx in neonatal apneas.

STUDY DESIGN

We conducted a literature search and analysis of the published and other available information on the topic.

RESULTS

Publications on this topic in otolaryngology journals are rare, although more basic sciences-oriented journals have published interesting results from animal studies during the past 20 years. The scarce data on human neonates are also presented.

CONCLUSIONS

The authors follow the phylogenetic and oncogenetic pathways to explain the active role of the larynx in neonatal apneas. Although most of these results are derived from animal studies, they certainly improve our understanding of human neonatal apneas.

Quality of life following surgical treatment of oculopharyngeal syndrome

Oculopharyngeal syndrome is a hereditary disease mostly affecting French Canadians. Cricopharyngeal myotomy and blepharoplasty are commonly performed on these patients. We reviewed the files of 20 patients who underwent these procedures between June 1986 and June 1999. The average perioperative stay was 4.7 days. The nine patients still alive were contacted and answered a telephone survey on their quality of life. None reported postoperative complications. Myotomy significantly improved the medical domain of their quality of life as confirmed by improvement in the dysphagia for solids, food incarceration, duration of meals, and choking during meals. The psychological domain also improved, namely, appetite and interest in food. The effects of blepharoplasty were also notable. Long-term satisfaction is reported by the majority of patients up to a maximum of 10 years postoperatively. In conclusion, simple procedures such as blepharoplasty and cricopharyngeal myotomy greatly improved the quality of life of these patients. We therefore recommend early interventions.

Type III tympanoplasties: the Sherbrooke experience

OBJECTIVES

To review short- and longer-term results of type III tympanoplasties as performed by the senior author and to compare these results with those reported in the literature.

METHOD

Retrospective review of 96 type III tympanoplasties, with and without mastoidectomy, performed between April 1996 and August 2000.

RESULTS

At a mean of 384 days postoperatively, 57.3% of patients had an air-bone gap of less than 20 dB. The average postoperative gap is 21.4 dB. Gap closure is best at 2000 Hz, with an average drop of 51% from initial value, compared with 34%, 39%, and 18% at 500, 1000, and 4000 Hz, respectively.

CONCLUSION

Our results are similar to those published previously. We emphasize the improvement at 2000 Hz, which is an important frequency for speech discrimination. It would be interesting to see if it correlates with an improvement in quality of life.

Active glottal closure during anoxic gasping in lambs

The present study was aimed at assessing laryngeal dynamics and their consequences during anoxic gasping in ketamine-sedated lambs. We first verified that the glottis was closed between gasps during anoxic gasping in seven chronically instrumented lambs, aged 11-15 days. Recording of glottal constrictor muscle electrical activity, subglottal pressure and lung volume, together with endoscopic observation, confirmed the presence of active glottal closure with maintenance of a high lung volume between gasps. Secondly, we tested whether maintenance of a high lung volume between gasps improved autoresuscitation efficiency. Six sedated lambs aged 8-11 days underwent two anoxic runs, including one with an open tracheostomy to prevent maintenance of a high lung volume. Access back to air was allowed for gasping. No significant difference was found in time to eupnea resumption, hemodynamic parameters or arterial blood gases. We conclude that a high lung volume is actively maintained by glottal closure between anoxic gasps in sedated lambs. Further studies are however needed to define the importance of laryngeal dynamics during gasping.

Microvascular anastomosis using histoacryl glue and an intravascular soluble stent

OBJECTIVE

The purpose of this study was to assess a new technique for microvascular anastomosis on small arteries using Histoacryl glue and an intravascular soluble stent.

METHODS

Sprague-Dawley rats were randomly assigned to either of two experimental groups or one control group. The first author (DL, a postgraduate year 4 resident) performed 12 end-to-end anastomoses on rat carotid arteries (1-mm vessel) (group A) using the experimental technique with Histoacryl glue and an intravascular stent. Thirteen microsuture carotid anastomoses performed by the senior author (DD), an experienced microsurgeon, served as control (group C). Permeability was assessed at 1 week for half of the animals and at 6 weeks for the others. Pathologic examination was done on both groups. To evaluate the influence of vessel size on the experimental technique, eight end-to-end anastomoses on rat abdominal aorta (2 mm) (group B) were also done by the first author. Permeability was assessed at 24 to 48 hours for this group.

RESULT

In the experimental groups (A and B), two predictable failures (both in group A) were observed. Median anastomosis times were 11 minutes and 7 minutes, respectively. The control group had no failure and a median time of 17 minutes. Pathologic examination revealed more inflammation in group A than in group C. Coagulative necrosis of the arterial wall was observed exclusively in group A.

CONCLUSION

This new technique is easy to learn and readily accessible to less experienced microsurgeons. The technique is fast and efficient. The calibre of the vessel has a great influence on ease and speed of the technique. However, histotoxicity of Histoacryl glue was observed. This technique can be valuable for free-tissue transfer in head and neck reconstruction. A less toxic glue would be useful.

Radiotelemetry system for apnea study in lambs

Neonatal apneas are being studied in the laboratory using polysomnographic recordings in lambs. Standard equipment, requiring animal restraint, disrupts sleep and prevents development of spontaneous apneas. The aim of the current work was to develop and validate a wireless recording equipment to study freely moving lambs. Firstly, a radiotelemetry equipment composed of a multichannel FM transmitter and a receiver was developed. Secondly, to test the telemetry equipment, each biopotential - [electroencephalogram (EEG), electrooculogram (EOG), electrocardiogram (ECG), electromyograms (EMGs), nasal airflow] - was recorded simultaneously by standard equipment and by telemetry (5 lambs). The results indicated an excellent concordance between signals obtained by both systems. Finally, the 8-channel telemetry prototype was tested for polysomnographic recordings (16 lambs). Results obtained confirmed the possibility of recording frequent REM sleep periods and spontaneous apneas. In conclusion, this radiotelemetry polysomnographic equipment brings new possibilities for research on neonatal apneas.

Retropharyngeal abscesses: a clinical and radiologic correlation

OBJECTIVE

This study evaluates the efficacy at our centre of the lateral neck x-ray and the computed tomography (CT) scan in differentiating retropharyngeal cellulitis from abscess in retropharyngeal space inflammatory process.

METHOD

We reviewed the medical records of 37 patients with the diagnosis of retropharyngeal abscess or cellulitis hospitalized at the Centre Universitaire de Santé de l'Estrie in Sherbrooke between 1986 and 1997. Patients with a positive drainage at surgery were considered as retropharyngeal abscess and the rest as cellulitis. We measured the sensitivity, specificity, and positive and negative predictive values for the lateral neck x-ray and CT scan. Demographic and clinical data were also extracted for each patient.

RESULTS

Twenty-five patients were classified as retropharyngeal cellulitis and only six patients as retropharyngeal abscess, although 13 patients went to the operating room for drainage. Results for the sensitivity and specificity were 80% and 100% for the lateral neck x-ray and 100% and 45% for the CT scan. Positive and negative predictive values for lateral neck x-ray were 100% and 94%, respectively. Forty percent and 100% were the values calculated for the CT scan. Clinical data were consistent with what has been reported in the literature.

CONCLUSION

CT scan is helpful in the management of retropharyngeal abscess but has limits in differentiating cellulitis and abscess. Lateral neck x-ray was found to be very specific when the air sign was present.

Vagal afferents and active upper airway closure during pulmonary edema in lambs

The present study was undertaken to gain further insight into the mechanisms responsible for the sustained active expiratory upper airway closure previously observed during high-permeability pulmonary edema in lambs. The experiments were conducted in nonsedated lambs, in which airflow and thyroarytenoid and inferior pharyngeal constrictor muscle electromyographic activity were recorded. We first studied the consequences of hemodynamic pulmonary edema (induced by impeding pulmonary venous return) on upper airway dynamics in five lambs; under this condition, a sustained expiratory upper airway closure consistently appeared. We then tested whether expiratory upper airway closure was related to vagal afferent activity from bronchopulmonary receptors. Five bivagotomized lambs underwent high-permeability pulmonary edema: no sustained expiratory upper airway closure was observed. Finally, we studied whether a sustained decrease in lung volume induced a sustained expiratory upper airway closure. Five lambs underwent a 250-ml pleural infusion: no sustained expiratory upper airway closure was observed. We conclude that 1) the sustained expiratory upper airway closure observed during pulmonary edema in nonsedated lambs is related to stimulation of vagal afferents by an increase in lung water and 2) a decrease in lung volume does not seem to be the causal factor.

Effects of capsaicin pretreatment on expiratory laryngeal closure during pulmonary edema in lambs

The present study, performed in nonsedated, conscious lambs, consisted of two parts. In the first part, we 1) examined for the first time whether a respiratory response to pulmonary C-fiber stimulation could be elicited in nonsedated newborns and 2) determined whether this response could be abolished by capsaicin pretreatment. Then, by using capsaicin-desensitized lambs, we studied whether pulmonary C fibers were involved in the sustained, active expiratory upper airway closure previously observed during pulmonary edema. Airflow and thyroarytenoid and inferior pharyngeal constrictor muscle electromyographic activities were recorded. In the first set of experiments, a 5-10 microg/kg capsaicin bolus intravenous injection in seven intact lambs consistently led to a typical pulmonary chemoreflex, showing that C fibers are functionally mature in newborn lambs. In the second series of experiments, eight lambs pretreated with 25-50 mg/kg subcutaneous capsaicin did not exhibit any respiratory response to 10-50 microg/kg intravenous capsaicin injection, implicating C fibers in the response. Finally, in the above capsaicin-desensitized lambs, we observed that halothane-induced high-permeability pulmonary edema did not cause the typical response of sustained expiratory upper airway closure seen in the intact lamb. We conclude that functionally mature C fibers are present and responsible for a pulmonary chemoreflex in response to capsaicin intravenous injection in nonsedated lambs. Capsaicin pretreatment abolishes this reflex. Furthermore, the sustained expiratory upper airway closure observed during halothane-induced pulmonary edema in intact nonsedated lambs appears to be related to a reflex involving stimulation of pulmonary C fibers.

Complete glottic closure during central apnea in lambs

OBJECTIVE

The objectives of this study were threefold: to document complete glottic closure during artificially induced central apnea in lambs; to unequivocally confirm that thyroarytenoid muscle electrical activity during central apneas in lambs reflects complete glottic closure; and to evaluate the physiologic significance of this phenomenon in artificially induced central apneas in lambs.

METHODS

We recorded thyroarytenoid (TA) muscle EMG, subglottic pressure, and lung volume simultaneously with direct endoscopic vision of the glottis from beneath on nine 11- to 15-day-old lambs during artificially induced central apneas.

RESULTS

Thirty-eight central apneas were induced. Complete glottic closure was present on 35/38 (92%) of these apneas. Complete glottic closure was always paralleled by thyroarytenoid muscle electromyogram (EMG) activity (35/38). In no instance was TA EMG recorded without complete glottic closure. Moreover, positive subglottic pressure and maintenance of lung volume above functional residual capacity were observed in 27/30 (90%) and 18/19 (95%), respectively, of these apneas where complete glottic closure was present.

CONCLUSIONS

Complete glottic closure is present throughout most artificially induced central apneas in lambs. Complete glottic closure is paralleled by TA EMG in artificially induced central apneas. Thyroarytenoid muscle electromyographic activity is a reliable way to document complete glottic closure during apneas, especially in the presence of positive subglottic pressure. These observations suggest that complete glottic closure could be a physiologic mechanism aimed at maintaining higher lung volumes to improve gas exchange during central apneas.

Coordination between glottic adductor muscle and diaphragm EMG activity in fetal lambs in utero

It has previously been reported that active glottic adduction is present during prolonged apneas but absent during periods of breathing movements in fetal lambs in utero. The present study was aimed at examining the precise coordination between fetal breathing movements [diaphragm electromyographic (EMG) activity (Di EMG)] and glottic adduction [thyroarytenoid muscle EMG activity (TA EMG)]. Electrodes for electroencephalogram, eye movements, TA EMG, and Di EMG and an arterial catheter were surgically implanted in fetal lambs 123-142 days postconception. Polygraphic recordings were performed without sedation while the ewe breathed room air (n = 11) or various gas mixtures (hypoxia, n = 5; hyperoxia, n = 4; hypercapnia, n = 5; hypercapnia+hyperoxia, n = 5). Tonic TA EMG was observed throughout >90% of apneas (>6 s) in both non-rapid-eye-movement and rapid-eye-movement sleep, and when Di EMG frequency decreased in rapid-eye-movement sleep. In all but two fetuses, TA EMG was immediately inhibited when Di EMG appeared. Altering blood gases did not modify these results. In conclusion, Di EMG and TA EMG are well coordinated in late gestation in fetal lambs, except in a few cases. These findings may have consequences for understanding the pathogenesis of mixed/obstructive apneas of prematurity.

[Ameloblastic carcinoma. Apropos of a case]

Ameloblastic carcinoma is an exceptionally rare odontogenic tumor. Ameloblastoma is considered malignant if there is evidence of metastasis or histological features of malignancy. Present classification of these tumors is debated. Several authors use the term malignant ameloblastoma for tumours that metastasize despite "benign" histological features whereas ameloblastic carcinoma is referred to as a tumor with malignant histological features regardless of its metastatic potential. We report a case of mandibular ameloblastic carcinoma with cervical lymph node metastasis in a 70-year-old man, documented by MRI and CT. We discuss current knowledge on these tumors.

[Intra-parotid neurogenic tumors of the facial nerve. Value of MRI]

Facial nerve intraparotid neuromas are rare. We report two cases with no facial paralysis. In the first case, the clinical protocol for the evaluation of a parotid mass did not suggest the intramastoid tumor extension. This extension was shown by CT and MRI and confirmed by gross and microscopic appearance. In the second case, no intrapretrous extension was observed with MRI. The diagnosis of neuroma was made during surgery. With a literature review, we discuss the diagnostic difficulties encountered in the investigation of parotid facial nerve tumors, emphasizing on the usefulness of CT and MRI in its diagnosis.

How I do it: Zenker's stapler diverticulectomy

Zenker's diverticulum is an outpouching of the hypopharyngeal mucosa through Killian's area, a dehiscent or weak area between the cricopharyngeus muscle and the inferior constrictor muscle. Although this entity was described more than a century ago, these pulsion diverticuli continue to challenge surgeons to this day. The authors would like to reintroduce a method of resection that has proved useful in our practice.

Role of xanthine oxidase in reperfusion injury of ischemic skeletal muscles in the pig and human

We investigated whether xanthine oxidase (XO) is a major source of oxygen-derived free radicals (oxy-radicals) in the pig and human skeletal muscles. It was observed that xanthine dehydrogenase and XO activities in nonischemic pig latissimus dorsi (LD) and gracilis muscles and human LD and rectus abdominis (RA) muscles were < 0.5 mU/g wet wt. The pig LD muscle hypoxanthine content increased significantly from 0.33 +/- 0.02 to 2.33 +/- 0.44 mumol/g dry wt after 5 h of warm ischemia, but the muscle uric acid content remained unchanged up to 2 h of reperfusion. Similarly, the hypoxanthine content in the human LD and RA muscles increased from 0.33 +/- 0.03 to 0.84 +/- 0.23 mumol/g dry wt after 2.0-3.5 h of warm ischemia, and the muscle uric acid content remained unchanged at the end of 15-90 min of reperfusion. Furthermore, 5 days of allopurinol treatment (25 mg/kg iv twice daily) starting 2 days before ischemia or 3 days of oxypurinol treatment (25 mg/kg iv twice daily) starting 15 min before reperfusion did not attenuate the extent of skeletal muscle necrosis in pig LD muscles subjected to 5 h of ischemia and 48 h of reperfusion. However, deferoxamine treatment (250 mg/kg iv twice daily) starting before or after ischemia, as described above, significantly reduced the extent of pig LD muscle necrosis. Finally, at 2 and 48 h of reperfusion significantly higher muscle neutrophil contents were seen in ischemic than in nonischemic control pig LD muscles. Neutrophil depletion with mechlorethamine (0.75 mg/kg iv) significantly reduced the extent of necrosis in pig LD muscles. These observations indicate that XO is not a major source of oxy-radicals in ischemia/reperfusion injury in the pig gracilis and LD muscles and human RA and LD muscles.

Augmentation of transmidline skin perfusion and viability in transverse rectus abdominis myocutaneous (TRAM) flaps in the pig

The aim of this experiment was to design a clinically relevant TRAM flap in the pig and to use this flap model to study the effectiveness of preoperative ligation of the dominant vascular pedicle in augmentation of muscle and skin capillary blood flow and skin viability in the TRAM flap. This TRAM flap model was based on the deep inferior epigastric vascular pedicle, with the center of the transverse skin paddle attached to the underlying rectus abdominis muscle at the superior end of the muscle and extending bilaterally from its attached muscle. The transverse skin paddle (8 x 30 cm) included a contralateral and ipsilateral random portion of skin. This flap model was based on the deep inferior epigastric rather than the superior epigastric vascular pedicle because the deep inferior epigastric vascular pedicle is the smaller of the two in the pig and augmentation of its blood supply by ligation of the dominant superior epigastric vascular pedicle resembles more closely the clinical situation. It was observed that ligation of the dominant superior epigastric vascular pedicle 14 days prior to raising the TRAM flap significantly (p less than 0.05; n = 5) increased the total muscle and skin capillary blood flow and skin viability in the transverse skin paddle compared with the sham-operated control (n = 5).(ABSTRACT TRUNCATED AT 250 WORDS)

[Vascular territory expansion: a surgical technique for augmenting survival of an animal model of a musculocutaneous flap]

Ischemia-induced flap failure remains a major concern for reconstructive surgeons. A porcine rectus abdominis musculocutaneous (TRAM) flap was designed and subsequently used to study our hypothesis of vascular territory expansion whereas the perfusion territory of a previously ligated vessel is taken over by the remaining vessel(s). Specifically, we observed that ligation of the superior epigastric (SE) vessels two weeks prior to raising the TRAM flap significantly (p less than 0.05) increased the length and area of the viable skin in the transverse skin paddles of the treatment flaps compared to the contralateral sham manipulated control flaps. This significant increase in skin viability was seen to be accompanied by a significant (p less than 0.05) increase in skin and muscle capillary blood flow in the treated flaps compared with the controls (n = 9). The mechanism of vascular territory expansion is unclear. We postulate that hypoxia resulting from the ligation of the SE vessels prior to the flap surgery may play a role in triggering the deep inferior epigastric (DIE) artery to take over some of the territory previously perfused by the SE artery.

Surgical augmentation of skin blood flow and viability in a pig musculocutaneous flap model

A porcine rectus abdominis musculocutaneous (TRAM) flap model was designed and validated in nine pigs. This TRAM flap was based on the deep inferior epigastric (DIE) vessels with an 8 x 18 cm transverse skin paddle at the superior end of the rectus abdominis muscle. The model was subsequently used to test our hypothesis of surgical augmentation of flap viability by vascular territory expansion. Specifically, we observed that ligation of the superior epigastric (SE) vessels at 4, 7, 14, and 28 days (N = 6 to 8) prior to raising the TRAM flaps significantly increased (p less than 0.05) the length and area of the viable skin in the transverse skin paddles of the treatment flaps compared with the contralateral shammanipulated control flaps. This significant increase in skin viability was seen to be accompanied by a significant increase (p less than 0.05) in skin and muscle capillary blood flow in the treatment TRAM flaps compared with the controls (N = 9). The mechanism of vascular territory expansion is unclear. We postulate that hypoxia resulting from the ligation of the superior epigastric vessels prior to the flap surgery may play a role in the triggering of the deep inferior epigastric artery to take over some of the territory previously perfused by the superior epigastric artery. This would then increase the skin and muscle capillary blood flow in the transverse paddle when the TRAM flap was raised on the deep inferior epigastric vascular pedicle.