Topographic electroencephalogram in children during mask induction of anaesthesia with sevoflurane.

BACKGROUND: Epileptiform patterns, spikes, polyspikes and periodic epileptiform discharges (PED) have been reported in electroencephalograms (EEGs) during anaesthesia induction with sevoflurane in healthy adults and children. Published recordings have been performed with a limited number of channels, and therefore the topographic distributions of these patterns are not known. METHODS: Twenty ASA I children aged 4-10 years undergoing routine operations were anaesthetized with 8% sevoflurane in 50%/50% oxygen and nitrous oxide using mask induction with controlled normoventilation. An EEG was recorded with a full 10-20 electrode system including orbitofrontal and ear electrodes, and a recording band of 0.016-70 Hz. Beat-to-beat heart rate (HR) was calculated off-line. RESULTS: Nineteen out of 20 children developed multifocal spikes and polyspikes with a maximum over the frontal lobes. Four patients developed suppression, which was almost continuous and lasted several minutes, and thereafter a continuous EEG resumed, a few spikes were seen and then a nonepileptiform pattern. In three children a couple of PED waves were seen at the onset of a continuous EEG. HR increased maximally before the onset of spikes. No motor phenomena were seen. CONCLUSION: These recordings confirm the epileptogenic property of sevoflurane in mask induction. The spikes and polyspikes had frontal multifocal maxima and may be missed in recordings from frontopolar electrodes used by depth-of-anaesthesia monitors. PED and burst suppression were synchronous over the whole cortex. Epileptiform activity was indiscernible from epileptiform waveforms without anaesthesia, such as the patterns seen in status epilepticus.

Post-tonsillectomy pain: a prospective, randomised and double-blinded study to compare an ultrasonically activated scalpel technique with the blunt dissection technique.

Thirty-two patients participated in a study to compare the use of an ultrasonically activated scalpel (Harmonic scalpel) for tonsillectomy on one side and a blunt dissection tonsillectomy on the other. Pain scores at rest and on swallowing expressed as the area under curves (AUC) during the 10 h after surgery, intra-operative blood loss and the need for electrocoagulation for haemostasis were significantly higher on the blunt dissection side than on the Harmonic scalpel side (p < 0.05). However, pain scores expressed as AUC at rest, on swallowing, the day's least, average and worst levels of pain, and the day's worst otalgia during the second week after surgery were significantly higher on the Harmonic scalpel side than on the blunt dissection side. In conclusion, we found that Harmonic scalpel tonsillectomy was associated with decreased severity in pharyngeal pain on the day of the operation but increased pharyngeal pain and otalgia during the second postoperative week.

Carhart notch effect in otosclerotic ears measured by electric bone-conduction audiometry.

The Carhart notch is an elevation in the middle-frequency bone-conduction threshold of an ear with clinical otosclerosis. The study population consisted of 138 patients with clinical otosclerosis. Conventional air-conduction (AC) and bone-conduction (BC) and electric bone-conduction (EBC, with Audimax 500 audiometer) thresholds were measured 2 weeks before and 7 months after stapes surgery. The EBC thresholds were converted from mA values to dB SPL to compare the results obtained with the different methods. The mean differences in the BC thresholds before and after the operation were 3.2 dB (95% CI 1.9-4.6) at 1 kHz and 7.6 dB (95% CI 6.1-9.1) at 2 kHz. The mean differences in the EBC thresholds were 5.4 dB (95% CI 3.8-6.9) at 1 kHz and 5.3 dB (95% CI 3.4-7.1) at 2 kHz. Thus, both methods showed a distinct Carhart notch effect.

Speech perception and functional benefit after multichannel cochlear implantation.

This study was done to investigate the effect of a multichannel cochlear implant on speech perception and the functional benefit of cochlear implantation in Finnish-speaking postlingually deafened adults. Fourteen subjects were enrolled. Sentence and word recognition were studied with open-set tests auditorily only. One year after implantation, the listening performance was assessed by case histories and interviews. Before implantation for subjects with a hearing aid, the mean recognition score was 38% for sentences and 17% for words. One year after switching on the implant, the mean recognition score was 84% for sentences and 70% for words. Before implantation, the majority of the subjects were not aware of environmental sounds and only a few were able to recognize some environmental sounds. One year after switching on the implant, the majority of the subjects were able to use the telephone with a familiar speaker. All the subjects were able to recognize speech auditorily only and had thus gained good functional benefit from the implant.

Cochlear implant patients and quality of life.

During the last two decades, cochlear implants have been available for profoundly hearing-impaired patients who do not benefit from conventional hearing aids. The quality of life of these implantees has not been extensively studied, and has not been studied at all in Finland. To assess their quality of life, the Nottingham Health Profile questionnaire was sent to all adult implanted patients in Finland. Implantees tended to have more favourable average pain, emotional reaction and mobility indexes in each age group studied than the average population. Social-isolation seemed to be more common in the youngest and oldest age groups of implantees. Apparently, implantees are physically healthier than the average population. However, a bias caused by the strict selection of implant candidates cannot be excluded.

The effect of a multichannel cochlear implant on phoneme perception.

This study was done to investigate the effects of a multichannel cochlear implant on phoneme perception in Finnish-speaking postlingually deafened adults. Phoneme recognition was studied with 100 prerecorded nonsense syllables (open-set) presented at 70 dB SPL, auditorily only, in a free-field situation. Ten subjects were tested before implantation both with and without a hearing aid (HA), and 3, 6 and 12 months after switching on the implant. Before implantation without a HA, the subjects did not recognize vowels, consonants or syllables. Four of the subjects used a HA before implantation, and the mean recognition scores of these subjects were 34% for vowels, 28% for consonants and 13% for syllables. One year after switching on the implant, the mean recognition scores were 77% for vowels, 66% for consonants and 46% for syllables. According to phonological analysis vowels appear to be easier to perceive than consonants during the first stage after multichannel cochlear implantation.

Cochllear implants and GSM phone.

Use of a telephone and GSM phones, in particular, was assessed by means of a postal interview sent to all adult Finnish implantees. The response rate was very high (87%). Fifty-one of the 61 respondents used a telephone and 27/61 also used a mobile phone, usually a digital phone. Two GSM phone models from Nokia (3110 and 6110) were tested with three different cochlear implant systems used by nine patients. Definite differences between the processors were found. Nucleus Spectra (two implantees) could not be used with any of the GSM phones under any test condition. Nucleus SPrint was incompatible with both GSM phone models in a poor field, while GSM phone model 6110 could be used in a good field. The Med-El Combi 40+ processor was compatible with both GSM models tested under any condition.

Snoring and obstructive sleep apnea in children: a 6-month follow-up study.

BACKGROUND: Snoring children may present symptoms suggestive of obstructive sleep apnea syndrome (OSAS). Different and controversial methods to establish the diagnosis and to choose the treatment modalities have been proposed. OBJECTIVES: To study children with symptoms raising the suspicion of OSAS with overnight polysomnography (PSG). To evaluate the efficacy of adenotonsillectomy as treatment of pediatric OSAS and to elucidate the natural history of OSAS and primary snoring. DESIGN: A controlled, prospective, nonrandomized clinical trial. SETTING: Academic medical center. SUBJECTS: Fifty-eight snoring but otherwise healthy children aged 3 to 10 years with symptoms suggestive of OSAS underwent PSG twice, 6 months apart. Thirty healthy children served as controls. RESULTS: Twenty-seven children had OSAS with an obstructive apnea/hypopnea index greater than 1, while 31 had primary snoring. There were statistical differences in the symptoms and signs among the 3 study groups. Adenotonsillectomy was curative in the 21 children with OSAS who were operated on. Obstructive apneas and hypopneas in the healthy, nonsnoring children were almost nonexistent in this study. CONCLUSIONS: Half of the children or fewer with symptoms suggestive of OSAS actually had the condition. Clinical symptoms may raise the suspicion, but it is not possible to establish the diagnosis without PSG. Because snoring and obstructive symptoms may resolve over time, a normal PSG finding may help the clinician decide on an observation period. Adenotonsillectomy is curative in most cases of pediatric OSAS. Obstructive symptoms may continue after adenoidectomy alone.

Nasalance scores in snoring children with obstructive symptoms.

OBJECTIVE: Snoring and the sleep apnea syndrome (OSAS) in children are usually caused by adenotonsillar hypertrophy, which may affect air escape into the nose and nasal resonance. A microcomputer-based system makes it possible to objectively determine whether the oral passage is adequately separated from the nasal passage during phonation. The score thus obtained is called nasalance. This study was conducted to verify whether there exists differences in nasalance between primary snorers and OSAS-children. DESIGN: Fifty-three habitually snoring children (31 boys), mean age 6.1 years (range 3.2-10.5 years), were subjected to overnight sleep polygraphy (PG) and nasalance measurements with the Nasometer 6200. The study was successfully repeated 6 months later on 36 children. RESULTS: Nineteen children had obstructive apnea-h ypopneaindex (OAHI)> 1 on overnight polygraphy (OSAS-children), while 32 were considered primary snorers (PS), (OAHI<1). No statistically significant difference in nasalance scores was found between the OSAS- and PS children. Both groups of children had somewhat higher mean nasalance values both for oral and nasal passage sentences than the normative values for Finnish speech. In general, the most habitual snorers had lower nasalance scores than the less frequently snoring children (P=0.05). Earlier adenoidectomy or palatine tonsillar size did not have a significant influence on the nasalance. Adenotonsillectomy did not affect the nasalance scores of the nine children operated on during the follow-up period. CONCLUSIONS: According to the present study, nasalance measurements cannot be used to predict the incidence of OSAS among snoring children.

Cervical headgear therapy as a factor in obstructive sleep apnea syndrome.

PURPOSE: Obstructive sleep apnea syndrome (OSAS) has been a subject of increasing interest from the orthodontic point of view, but less attention has been paid to the possible influence of orthodontic treatment on its occurrence. The aim here was to study possible associations between the use of cervical headgear and nocturnal cessations of airflow and the severity of the latter. METHODS: The subjects were 30 children (12 boys, 18 girls, mean age 8.2, sd 1.61 years), divided into three groups: a group of 10 children undergoing headgear therapy, selected for this examination because of symptoms of OSAS while using headgear, an age-matched control group of 10 healthy children and a group of 10 with OSAS. Standard cephalograms of the headgear group prior to the orthodontic therapy and the corresponding cephalograms of healthy controls were analysed. A polygraphic (PG) sleep evaluation was used to assess the tendency for OSAS. Apnea and hypopnea periods were summated as apnea index (AI) and number of desaturations as desaturation index (ODI). All the subjects spent one night sleeping under laboratory conditions, those with orthodontic treatment spending the first half of the night with the headgear and the latter half without. RESULTS: The position of the mandible was found to be slightly more posterior in the headgear group than in the control group. The children in the headgear group were found to have significantly more apnea/hypopnea periods during the hours when the appliance was used, and the ODI-index showed increased values in this group. CONCLUSIONS: We suggest that headgear therapy may contribute to the occurrence of sleep apnea, when a strong predisposition, such as mandibular retrognathia to the development of upper airway occlusion already exists.

The growth rate of osteomas of the paranasal sinuses.

Paranasal sinus osteomas are benign tumours, occasionally known to cause complications. They have a tendency to grow slowly, but the growth rate has never been evaluated previously. We retrospectively studied 44 patients with paranasal sinus osteomas. In 13 out of the 23 patients who underwent at least two sinus radiographs at different times some growth was seen. The mean growth rate of these 13 osteomas was 1.61 mm/yr, range 0.44 to 6.0 mm/yr. The endoscopic technique is a good method for the removal of osteomas and obliteration of the frontal sinus does not seem to be necessary. Two patients having osteomas with intracranial expansion are described.

Computed tomography data based rapid prototyping model of the temporal bone before cochlear implant surgery.

Rapid prototyping (RP) technique allows automatic fabrication of 3D model parts. This method was applied to make a temporal bone model before cochlear implant surgery. A helical CT scan is used to acquire high resolution data from the middle and the inner ear of the patient. From the scanning data bone structures and soft tissues can be separated because their different grayscale pixel values. By using a guided image processing tool the desired parts of the anatomy can be extracted and 3D data created. The segmented data are processed to the form suitable for creating a high accuracy RP model. The RP model is made in the stereolithography (SLA) process by means of a computer guided HeCd laser beam inducing polymerisation of acrylic solution as it passes layer by layer over the surface of the polymer solution. In this prototype model the anatomy of the temporal bone can be clearly visualised, including, e.g., mastoid cells, tympanic cavity, bony canal of facial nerve, and round and oval windows. The inner ear spaces including vestibule, semicircular canals and cochlear turn are also shaped. The transparent acrylic material allows bonelike mechanical handling. The RP model can be dissected and used in individual surgical planning and simulation prior to cochlear implantation.

Snoring children: factors predicting sleep apnea.

Many snoring children present obstructive symptoms according to their parents. The seriousness of the symptoms and the possibility of the obstructive sleep apnea syndrome (OSAS) in these children may be difficult to judge on the basis of the clinical findings and the patient's history only. In order to evaluate snoring children's relative risk (RR) to have OSAS, their symptoms and signs, as reported by the parents, and clinical findings were compared with the results of overnight polysomnography (PSG). An obstructive apnea index (AI) > or = 1 in PSG was regarded as the criterion for OSAS. The mean AI was 1.55 (range 0-15), and 29 children had a pathological AI, while 49 had a normal PSG recording. Apneic episodes every night detected by the parents was the most important single risk factor for OSAS (RR 3.6, 95% confidence interval (CI) 1.7-7.7). The RR ratio decreased when apneas appeared less frequently, but any detected apnea was still a single risk factor (RR 1.4, CI 1.2-1.8). The other risk factors of night-time symptoms were constant snoring (RR 1.5, CI 1.0-2.1) and restless sleep (RR 2.1, CI 1.1-4.0). Of the daytime symptoms, absence of excessive sleepiness was a protective factor against OSAS (RR 0.3, CI 0.1-1.0). Previous adenoidectomy was found to be a risk factor (RR 1.7, CI 1.1-2.7), as was tonsillar enlargement (RR 1.4, CI 1.1-1.8). These two findings suggest that the epipharyngeal space does not play a central role in the development of OSAS in children. OSAS cannot be reliably diagnosed without PSG, which is the most important examination for snoring children with obstructive symptoms. For clinical decisions, the consideration of risk factors is essential.

Sleeping positions and dental arch dimensions in children with suspected obstructive sleep apnea syndrome.

The present paper analyzed the association between children's sleeping positions and dental arch morphology. The sleeping patterns of 27 children, aged 3 to 10 yr, suspected of having the obstructive sleep apnea syndrome (OSAS) were studied by polysomnography (PSG) and videotape recordings under laboratory conditions. The PSG recordings were used to calculate the apnea index (AI) and the relative time spent sleeping on the back, and the videotapes to categorize distinctly different sleep and head postures. Plaster casts were made for the assessment of dental arch morphology. Sleeping predominantly on one's back, was associated with a reduced maxillary intercanine width, while prolonged head extension during sleep correlated inversely with the overjet. The subjects with the highest AI scores (> 4) had larger dental arches. We suggest that sleeping on the back causes a more posterior tongue position, reducing its moulding effect on the anterior dental arch. As nasopharyngeal airway obstruction in OSAS-patients might trigger an anterior tongue position to secure a free airway passage, there will be increased lingual pressure on the dental arches, leading to their dimensional increase.

Objective real ear measurements of bone-conduction hearing aid performance.

Conventional bone-conduction and bone-anchored hearing aids are tested with skull simulator devices; individual adjustments are reliant on psychoacoustic free-field audiometry, which can be quite demanding for the patient. A method is presented in which the induced skull vibrations are measured with an accelerometer and then analysed with Fast Fourier Transformation (FFT). With this method, frequency characteristics, harmonic distortion and dynamic response can be analysed.

Assessment of bone conduction prosthesis in situ.

Conventional and bone anchored bone conduction hearing aids can be tested with skull simulating devices and the individual adjustment rely on time consuming psychoacoustic audiometry in free-field which can be quite demanding for the patient. A method is presented in which the hearing aid induced skull vibrations are collected with an acceleromotor and recorded on a digital audio tape. The recordings are analysed with Fast Fourier 'Transformation (FFT) by using a signal processor. The free-field test signal can be either narrow-band or white noise. Changes in frequency characteristics can be easily monitored with white noise as signal, harmonic distortion and dynamic response can be analysed reliably by using pure tones. The inter-individual comparisons can be made when calibration is based on skull vibrations at the individual bone-conduction hearing thresholds. Two case reports are presented and discussed.