The cochlear blood flow in relation to noise and cervical sympathectomy

The effect of noise and unilateral transection of the cervical sympathetic trunk on cochlear blood flow was studied in anesthetized cats. The sound pressure level was 100 dB and the exposure time 6 min. Neither noise nor sympathectomy were found to affect the blood flow.

Development of craniofacial and dental arch morphology in relation to sleep disordered breathing from 4 to 12 years. Effects of adenotonsillar surgery

OBJECTIVES

To study the development of craniofacial and dental arch morphology in children with sleep disordered breathing in relation to adenotonsillar surgery.

SUBJECTS AND METHODS

From a community-based cohort of 644 children, 393 answered questionnaires at age 4, 6 and 12 years. Out of this group, 25 children who were snoring regularly at age 4 could be followed up to age 12 together with 24 controls not snoring at age 4, 6 and 12 years. Study casts were obtained from cases and controls and lateral cephalograms from the cases. Analysis regarding facial features and dento-alveolar development was performed.

RESULTS

Children snoring regularly at age 4 showed reduced transversal width of the maxilla and more frequently had anterior open bite and lateral cross-bite than the controls. These conditions persisted for most cases at age 6, by which time 18/25 had been operated for snoring. In most of the cases, surgery cured the snoring temporarily, but their width of the maxilla was still smaller by age 12-even when nasal breathing was attained. At age 12, the frequency of lateral cross-bite was much reduced and anterior open bite was resolved, both in cases and controls. The children who snored regularly at age 12 operated or not operated, showed a long face anatomy and were oral breathers (this applied even to those who were operated). The seven cases who were not operated and the five who were still snoring in spite of surgery at age 12, did not have reduced maxillary width as compared to the controls.

CONCLUSION

Dento-facial development in snoring children is not changed by adenotonsillar surgery regardless of symptom relief. If snoring persists or relapses orthodontic maxillar widening and/or functional training should be considered. Collaboration between otorhinolaryngologist, orthodontists and speech and language pathologists is strongly recommended.

The development of sleep disordered breathing from 4 to 12 years and dental arch morphology

OBJECTIVE

To track the development of sleep disordered breathing (SDB) as well as dento-facial morphology in cohort of children by having them complete a questionnaire at ages 4, 6 and 12. Clinical examination, sleep studies (at ages 4 and 12) and orthodontic evaluation were carried out on all who were reported to snore regularly and children who did not snore at all.

RESULTS

Out of the original group of 615 children, 64% (393) answered the inquiry on all three occasions. Of those, 27 snored regularly and 231 did not snore at all at the age of 12. There were differences between those groups on all answers, especially prevalence of oral breathing: 78% versus 5% (p<0.001). The prevalence of OSA decreased from 3.1% at the age of 4 to 0.8% at age 12 and the severity decreased from a mean AHI 14.8 at 4 to a mean AHI of 1.95 at age 12. The minimum prevalence of snoring regularly was estimated to 4.2% at 12 years compared to 5.3% at 4, calculated for the original cohort of 644 children. The odds for a child who snored regularly at 4 or 6 years to be snoring regularly also at age 12 was 3.7 times greater than for a not snoring child in spite of surgery (OR 3.7, 95% CI 2.4-5.7). 63 children had undergone surgery due to snoring by age 12. 14 of them never snored and 17 snored regularly at the age 12. The dental arch was narrower in the children snoring regularly at 4, 6 and 12 years compared to not snoring children. Cross-bites were more common among snoring children than among non-snoring children, at 4 and 6 as well as at 12.

CONCLUSION

The prevalence of regular snoring is about the same from 4 to 12 years independent of surgery, but the prevalence of OSA decreased considerably. The children snoring regularly generally have a narrower maxilla compared to children not snoring. Surgery in young children is necessary but "cures" the snoring only temporary.

Tonsillectomy or tonsillotomy?--A randomized study comparing postoperative pain and long-term effects

BACKGROUND

tonsillectomy (TE) is currently the most common treatment for children with snoring and sleep apnea. Many of these children have not had any severe throat infections. To cure such children from their obstructive problems, without influencing the immunological function of the tonsils, tonsillotomy (TT) with CO2-laser was performed in a randomized study comparing it to regular tonsillectomy, with special attention to postoperative pain and symptom recurrence.

METHOD

41 children 3.5-8 years-old were included--21 'TT's' and 20 'TE's'. They were all operated under the same anesthesia and followed the same postoperative scheme for analgesia. A visual analogue scale for pain measurements with faces was used for the first 24 h. After that, each day until pain-free, the parents registered the child's pain on a three graded scale, what the child was able to eat, and the amount of analgesic drugs used.

RESULTS

all the children were cured from their breathing obstruction. The mean time used for the surgery was the same and no postoperative bleeding was seen in either group. 'TT children' were pain-free after 5 days and 'TE children' after 8 days. Eight to ten days after surgery, the TT-children had gained weight and the TE children lost weight significantly. The TE group used twice as much analgesic drugs as the TT group during the first postoperative week. The TT group was healed with normal-looking, but small tonsils after 8-10 days; the TE group often still showed edema and crusts. At the one-year follow-up 2/21 among the 'TT-children' snored, but did not require re-surgery.

CONCLUSION

tonsillotomy is much less painful than TE and children recover more quickly. Results with respect to breathing obstruction are almost the same for both methods at 1-year follow-up.

Using the carbon dioxide laser for tonsillotomy in children

Carbon dioxide laser tonsillotomies were performed on 33 children aged 1-12 years for the relief of obstructive symptoms due to tonsillar hyperplasia. As opposed to conventional tonsillectomy, only the protruding part of each tonsil was removed. A carbon dioxide laser delivering 20 W was used for the excision. Twenty-one children were seen in active short-term follow-up and the records of all the children were checked for possible surgery related events up to 20-33 months after surgery. Laser tonsillotomy was uniformly effective in relieving the obstruction, with good hemostasis. The tonsillar remnants healed completely within 2 weeks. No major adverse events occurred. Post-operative pain appeared slight and easily controlled. There was no gain in operating time compared with conventional tonsillectomy. The laser tonsillotomies were in most cases done in day surgery. No recurrence of obstructive problems was reported up to 20-33 months after surgery. It was concluded that tonsillotomy, using a carbon dixoide laser, is a valid treatment for obstructive symptoms caused by enlarged tonsils, which can be performed with little bleeding and post-operative pain. The improved hemostasis may enable a shift from in-patient to day surgery.

[Many persons with snoring problems and apnea are untreated. A review of therapeutic methods]

As sleep apnoea and snoring are very disabling conditions both for patients and their families, and hazardous for drivers and others in traffic, there is good reason to treat snoring problems. Treatment should be individualised, always beginning conservatively--i.e., positional training, weight reduction if necessary, more sleep if sleep deficiency is present, and a review of any muscle-relaxant or mucolytic medication. Sleep registration will demonstrate the extent of any sleep apnoea syndrome, which is of decisive importance for further choice of treatment. Mild apnoics and social snorers may initially be offered an occlusal splint if their dental status allows. Otherwise, in such cases surgery is a form of treatment yielding immediate results, though the patient must be forewarned of the discomfort which can occur in isolated cases. For patients with sleep apnoea syndrome of marked or intermediate severity, continuous positive airway pressure (CPAP) treatment should be available. If the patient can not tolerate CPAP treatment, the occlusal splint alternative can be tried. For patients who can not have CPAP or occlusal splint treatment, tracheostomy is a possibility. This treatment may be lifelong, but if weight reduction is achieved postoperatively, it may be possible to remove the tracheostomy.

Breathing obstruction in relation to craniofacial and dental arch morphology in 4-year-old children

The prevalence of breathing obstruction was determined in a cohort of 4-year-old children. Craniofacial morphology was studied in obstructed children and compared with data from a control group of 4-year-old children with ideal occlusion. Dental arch morphology was compared in obstructed and non-obstructed children in the group. Parents of 95.5 per cent of the study base of 644 children answered a questionnaire concerning their child's nocturnal behaviour and related questions. The 48 children who, based on parental report, snored every night or stopped breathing when snoring (the 'snoring group'), showed a higher rate of disturbed sleep, mouth-breathing, and a history of throat infections as compared with the rest of the cohort. These children were examined by both an orthodontist and an otorhinolaryngologist and, when indicated, they were also monitored in a sleep laboratory. Twenty-eight of the children were diagnosed as having a breathing obstruction (4.3 per cent of the cohort) and six children (0.9 per cent) had sleep apnoea (mean apnoea-hypopnoea index of 17.3), using the same definition as that for adults. Cephalometric values among the obstructed children differed from those of a Swedish sample of the same age with ideal occlusion. Thy had a smaller cranial base angle and a lower ratio of posterior/anterior total face height. Small, but not significant differences were seen for NSL-ML and NL-ML. Compared with 48 asymptomatic children from the same cohort, the obstructed children had a narrower maxilla, a deeper palatal height, and a shorter lower dental arch. In addition, the prevalence of lateral crossbite was significantly higher among the obstructed children.

The effect of uvulopalatopharyngoplasty without tonsillectomy using local anaesthesia: a prospective long-term follow-up

This paper presents the long-term effect of restricted surgery for snoring and sleep apnoea. Patients with obstructive sleep apnoea (OSAS) (19) or heavy snoring (HS) (36) were studied prospectively for five to seven years after uvulopalatopharyngoplasty without tonsillectomy performed by regular surgical technique using local anaesthesia (LUPP). Five years after surgery, 90 per cent answered a questionnaire. All OSAS patients were offered a polysomnography, and the HS patients were offered a sleep study. Eighty per cent still showed a positive effect on daytime somnolence, and 77 per cent on snoring. Side-effects were reported by 40 per cent; most common was choking (20 per cent) the first year. Eighteen per cent had local problems such as globus sensation. The polysomnography showed that 80 per cent were still 'responders' with an apnoea index (AI) reduction of > 50 per cent. None of the HS patients had developed OSAS. In conclusion, LUPP in selected patients with OSAS or HS has a good long-term effect. Side-effects are common, but diminish with time.

[Medical aspects of diving--a sport for both women and men]

As interest in scuba diving is increasing in both sexes, doctors need to be aware of the risks encountered when diving and about gender-related differences in these risks. Individuals prone to panic attacks, claustrophobia or reckless risk-taking should avoid diving. In tolerating cold, muscle mass is more important than the amount of subcutaneous fat. The risk of decompression disease seems to be slightly greater among women, probably due to their fat distribution. Pregnant women are recommended not to dive, because the risk of birth defects seems to be greater among those who do, and there is a serious risk of fetal decompression disease. All participants in the sport must be responsible for their own diving safety.

Long-term follow-up of patients with obstructive sleep apnea treated with uvulopalatopharyngoplasty

OBJECTIVE

To study the long-term outcome after treatment with uvulopalatopharyngoplasty (UPPP).

DESIGN

Long-term follow-up (4-8 years) with polysomnography.

SETTING

Referral center for patients with sleep-disordered breathing.

PATIENTS

Thirty-four consecutive patients of whom 25 (22 men and 3 women; mean age, 49 years) participated in the follow-up. All patients had obstructive sleep apnea syndrome.

INTERVENTION

Uvulopalatopharyngoplasty.

MAIN OUTCOME MEASURES

Symptoms and apnea-hypopnea index (AHI) before and after UPPP. Response to treatment defined as a 50% or more reduction in AHI and a postoperative AHI of 10 or less.

RESULTS

Reduced prevalence of snoring and daytime sleepiness and reduction in AHI (mean [+/-SD], 40 +/- 26 to 21 +/- 21) at follow-up (P < .001). Sixteen patients (64%) were responders after 6 months and 12 (48%) at the long-term follow-up. Responders had a lower preoperative AHI (25 +/- 7) than did nonresponders (48 +/- 29) (P < .05). None of the 7 patients with preoperative AHI of more than 40 were responders (P < .01). No difference was seen in preoperative body mass index, lung function, ventilatory response to carbon dioxide, computed tomography scan of upper airways, or change in body mass index between responders and nonresponders.

CONCLUSIONS

Four to 8 years after UPPP, about half of our patients were clinically and objectively improved. Uvulopalatopharyngoplasty should be reserved for patients with mild or moderate obstructive sleep apnea. After UPPP, long-term follow-up is recommended because some initially successfully treated patients will relapse in the long term.

The epidemiology of sleep related breathing disorder in children

An epidemiological study of sleep obstruction and its orthodontic consequences is under way on a cohort (500) of 4-year-old children. The parents are asked about the child's snoring, sleep apnea, sucking habits, infections and 'genetic clues'. Dental casts have been made from the first 100 children and the group of children who snore are being compared to the non-snorers. A sleep study, a lateral cephalogram and dental casts are done on all snorers in the cohort. Preliminary results show that 6.2% snore every night by age 4 and another 18% when infected. More children use pacifiers among the snorers than in the non-snoring group (60% vs. 35%). Tonsillar angina is 3 times more common in the snorer group and twice as many of their parents have been adenoidectomized (A) and/or tonsillectomized (T). The dental casts show a significant difference in width of the maxilla and length of the mandible. The children are treated for their breathing obstruction with A or A+T. Two years later, the same cohort will be examined again. The prevalence of snoring and sleep apnea among 4-year-olds will be known as will whether and how treatment for breathing obstruction influences facial development.

Excessive daytime sleepiness and fatigue in nonapnoeic snorers: improvement after UPPP

Even in the absence of sleep apnoea, heavy snoring may be a cause of excessive daytime sleepiness (EDS) and fatigue. The aim of this investigation was to study whether uvulopalatopharyngoplasty (UPPP) is effective in relieving snoring and excessive daytime sleepiness in nonapnoeic snoring patients. UPPP was assessed in 155 nonapnoeic, snoring patients (136 men and 19 women, mean age 45 yrs). Postoperative evaluation was made after 3 months in 105 patients, and after 12 months in 50 patients. Fifty four patients were evaluated after both 3 and 12 months. In 49 patients, a further evaluation was made after 2 yrs. The results were compared with those of 76 conservatively-treated, nonapnoeic, snoring patients, who were reinvestigated 12 months after their initial examination. The proportion of patients with frequent loud snoring had decreased postoperatively from 96 to 18%. A highly significant improvement was reported in EDS and daytime fatigue. The proportion of patients who reported problems staying awake when driving had decreased from 29 to 7%, and the number who felt rested when awakening in the morning had increased from 23 to 78 after the operation. The patients in the UPPP group had somewhat more severe symptoms before treatment than those treated conservatively. One year after treatment the situation had been reversed, with significantly more snoring and excessive daytime sleepiness in the conservatively-treated group. In conclusion, these results indicate that UPPP is effective in relieving snoring and EDS in nonapnoeic snorers.

Excessive daytime sleepiness and fatigue in nonapnoeic snorers: improvement after UPPP

Even in the absence of sleep apnoea, heavy snoring may be a cause of excessive daytime sleepiness (EDS) and fatigue. The aim of this investigation was to study whether uvulopalatopharyngoplasty (UPPP) is effective in relieving snoring and excessive daytime sleepiness in nonapnoeic snoring patients. UPPP was assessed in 155 nonapnoeic, snoring patients (136 men and 19 women, mean age 45 yrs). Postoperative evaluation was made after 3 months in 105 patients, and after 12 months in 50 patients. Fifty four patients were evaluated after both 3 and 12 months. In 49 patients, a further evaluation was made after 2 yrs. The results were compared with those of 76 conservatively-treated, nonapnoeic, snoring patients, who were reinvestigated 12 months after their initial examination. The proportion of patients with frequent loud snoring had decreased postoperatively from 96 to 18%. A highly significant improvement was reported in EDS and daytime fatigue. The proportion of patients who reported problems staying awake when driving had decreased from 29 to 7%, and the number who felt rested when awakening in the morning had increased from 23 to 78 after the operation. The patients in the UPPP group had somewhat more severe symptoms before treatment than those treated conservatively. One year after treatment the situation had been reversed, with significantly more snoring and excessive daytime sleepiness in the conservatively-treated group. In conclusion, these results indicate that UPPP is effective in relieving snoring and EDS in nonapnoeic snorers.

Sudden deafness: a retrospective evaluation of dextran therapy

A retrospective evaluation was performed in 112 patients treated during a 10-year period as inpatients with the diagnosis idiopathic sudden hearing loss. Excluding all patients in whom later other diagnosis were established, like Ménière's disease, collagenoses, mumps etc., 101 patients remained. 80 of them had been treated consistently according to a protocol as having idiopathic sudden hearing loss. These patients had all 5-day treatment with low molecular weight dextran and nicotinic acid and vitamin B during 1 month. 68% did completely recover or were markedly improved (> 30 dB), another 19% were fairly improved (10-30 dB). Statistical analysis showed that all retrocochlear signs or nystagmus made the prognosis less favorable. To wake up with the hearing loss was more favorable than a daytime debut. A mid-frequency loss had always a good prognosis. Because no untreated controls were included in the study, it was not possible to evaluate the specific effect of the treatment. The results obtained from this study have changed the treatment policy in our clinic.

The cochlear blood flow: a comparison between the laser Doppler and the microsphere surface methods

Since the introduction in the early 1980s, of the laser Doppler (LD) method for measuring cochlear blood flow (CBF) it has been debated whether the measured changes reflect the total or regional blood flow and whether the method per se influences the CBF. In order to answer those questions, the effect of one vasodilating drug, sodium nitroprusside, was investigated after topical application on the round window membrane (RWM) with respect to its influence on CBF. Two different techniques, the microspheres surface method and the LD method, were used. Untreated animals and animals which received saline or nicotine acid on the RWM were used as controls. The effects on CBF and blood pressure (BP) were continuously registered with LD. When a maximal flow had stabilized, 6 x 10(6) microspheres were injected into the left side of the heart. After the microspheres had been distributed within the body, the animals were killed. Both cochleae were microdissected and the microspheres counted turn by turn in the lateral wall. The number of spheres in the two ears was compared and the difference was recorded as the increase caused by the drug. The percentage change in CBF measured using the LD was compared with that obtained by using the microsphere surface method (MSM). No change in CBF measured by the two techniques was registered in the untreated animals, or after saline or nicotinic acid, while sodium nitroprusside induced a substantial increase in CBF. The mean percentage change of CBF measured with the LD method was compared with the calculated mean percentage change of microspheres for all turns in the cochlea, and in the first turn. Student's t-test and the linear correlation coefficient were calculated.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of topical application of vasodilating agents on cochlear electrophysiology

The aim of this investigation was to study whether increased blood flow has beneficial effects on the ear or whether it is damaging to the auditory function, expressed as the auditory gross neural response. Four vasodilating agents were examined after topical application with respect to their influence on cochlear blood flow (CBF), blood pressure, and auditory function in the normal guinea pig. CBF was recorded with laser-Doppler. The drugs used were sodium nitroprusside, hydralazine, nicotinic acid and histamine. Sodium nitroprusside and hydralazine increased CBF and induced concentration dependent loss of auditory function. Neither nicotinic acid nor histamine had any effect on CBF. Nicotinic acid had varying effects: in some cases a negative influence on threshold shifts was seen, and in others a positive one. In most cases histamine caused improvement of the auditory function. The data indicate that topical administration of drugs to the inner ear is effective to influence both CBF and auditory function.

Body growth in relation to tonsillar enlargement and tonsillectomy

Severe airway obstruction caused by tonsillar enlargement can result in disturbances in body growth. The effect of this interference and of tonsillectomy in the child with only moderate symptoms have been less satisfactoril evaluated. In this study, 122 children with symptoms and signs of tonsillar obstruction were investigated concerning the height and weight before and after tonsillectomy. None of the individuals demonstrated cardiopulmonary complications of tonsillar obstruction. Altogether 10% of the children exhibited abnormalities in body weight and/or length prior to surgery. Especially during the first postoperative year, the weight and height gain exceeded the expected in 75% of the patients. The accelerated weight gain increased with tonsil size, but there was no relation to the extent of difficulties in swallowing or sleeping disruptions. The results support the hypothesis that tonsillar hypertrophy frequently is associated with disturbances in body growth and that this is seldom demonstrable prior to tonsillectomy.

Cochlear blood flow in response to dilating agents

Reduced cochlear blood flow (CBF) has been implicated in various pathologies of the inner ear, including sudden deafness, noise-induced hearing loss and Meniere's disease. Thus the aim of some current therapeutic regimens to treat these conditions is to increase CBF and thereby improve oxygenation of the inner ear tissues. Most of the vasodilating agents in clinical use, however, do not have specific experimental evidence to support their effects on CBF. The hypotension which can follow systemic administration may limit their local effectiveness and general utility, just as it complicates the interpretation of the data in animal experiments. In the current study we investigated the effect of six agents, known for their systemic cardiovascular actions, on CBF: hydralazine, sodium nitroprusside, papaverine, nicotinic acid, verapamil and histamine. The effect of these drugs was studied after topical applications on the round window membrane (RWM) and systemic intravenous administrations. CBF was monitored with a laser Doppler flowmeter (LDF). Topical administration of sodium nitroprusside was the most effective in increasing CBF, followed, in order, by hydralazine and histamine. No change in CBF was observed for papaverine, verapamil or nicotinic acid. Systemic administrations of all the agents caused a marked decrease in blood pressure and variable effects on CBF. We discuss the CBF changes in relation to the different pharmacological mechanisms of action of each drug. The study demonstrates the effectiveness of topical application of vasodilating agents in increasing CBF.

The influence of tonsillar obstruction and tonsillectomy on facial growth and dental arch morphology

Children, who were tonsillectomized because of sleep apnea were examined with respect to facial growth and dental arch morphology. Dental casts and lateral roentgencephalograms were analysed before surgery and two years after tonsillectomy. The findings were compared to data from children without tonsillary obstruction. A higher proportion of malocclusion than normal, especially open bite and crossbite, was noticed before surgery. Two years after surgery, 77% of the open bites were normalised and 50-65% of the buccal and anterior crossbites. The best results were seen in children operated before the age of 6.

Down syndrome and sleep apnea--a therapeutic challenge

This case report describes 3 patients with Down syndrome and obstructive breathing problems, ages: 5 months, 15 months, and 22 years. The youngest one had normal cardiopulmonary function at birth, but soon developed a pulmonary hypertension. The next had a severe atrioventricular defect and additional pulmonary hypertension and there was little hope for her to survive heart surgery. The oldest one had had apneas since childhood with increasing severity, but was regarded as having normal heart function. All 3 were operated to relieve their breathing obstruction. The 5-month-old boy improved only slightly after an initial UPPP and had to be tracheotomized, which solved his problems. The tracheotomy could be removed when he was one year. The 15-month-old girl was cured of her breathing problems through an A + T and survived her heart surgery one month later. Tonsillectomy and UPPP was performed on the oldest patient. Following surgery, he had an episode of life-threatening bleeding and developed a DIC syndrome, and was critically ill for 18 days. After he recovered, his sleep apnea had improved. Once a myxoedema was diagnosed and treated, he made further progress. These cases stress the significance of early recognition of sleep apnea in children with Down syndrome and the importance of a careful preoperative investigation in collaboration with cardiologists.

Symptoms in heavy snorers with and without obstructive sleep apnea

Five hundred and eighty persons who were heavy snorers filled in a questionnaire regarding symptoms on a 5-grade scale. Of these, 178 had a complete polysomnography investigation while 402 patients underwent oxymetric screening during the night only. On the basis of these investigations. 217 were classified as suffering from the obstructive sleep apnea syndrome (OSAS) and 363 as snorers without OSAS. The symptom scores differed between the two groups, but the range was wide and some persons with OSAS claimed only minor daytime sleepiness, somnolence, etc., while a high proportion of persons without OSAS frequently suffered from such symptoms. Thus, it was not possible to discriminate between patients with and without OSAS on the basis of their symptoms only. Furthermore, there are many persons who are "only" heavy snorers but who have symptoms that affect their career and social life and who so far have only received scant interest from the medical profession. Excessive daytime sleepiness and somnolence thus do not seem to be secondary to hypoxemia at night but rather to poor quality of sleep, which may be the case in association with heavy snoring even without appreciable deterioration of oxygen saturation.

Clinical treatment of vascular inner ear diseases

A multitude of general disorders of the vascular system may also affect the blood circulation of the cochlea and cause symptoms such as fluctuating or permanent hearing loss. Such is the case for arteriosclerosis combined with hypertension or hypotension, collagenosis, and diabetes. Blood disorders, like leukemia, sickle cell anemia, and polycythemia, and infectious diseases involving the blood vessels, such as lues, may also present their primary symptoms in the ear. The otorhinolaryngologist must be able to establish the correct diagnosis and refer patients requiring more general treatment to other specialists. The use of specific vasoactive treatment should be continued to those patients with symptoms of acute or fluctuating hearing loss, vertigo, or tinnitus who exhibit no other signs. Modern techniques for cochlear blood flow measurements have verified that several of the treatment protocols in use, which have a sound theoretical background, do indeed increase cochlear blood flow.

Children with tonsillar obstruction: indications for and efficacy of tonsillectomy

One hundred and twenty-two children between 1 1/2 and 14 years of age with symptoms suggesting tonsillar obstruction have been investigated. Each patient's history was analysed and the symptoms scored according to their incidence and severity. In addition, the size of the tonsils was evaluated. Eighty-five patients were chosen for tonsillectomy. The children with signs and symptoms of tonsillar obstruction improved greatly immediately after tonsillectomy. Severe symptoms of obstruction were observed in children with nearly normal tonsil size, as well as in those with very large tonsils. It is therefore just as important to obtain a careful history as it is to evaluate the size of the tonsils before deciding about surgery.

Cochlear blood flow increases after systemic hemodilution: comparison of simultaneous laser Doppler flowmetry and radioactive microsphere measurements

Guinea pig cochlear blood flow was measured before and after systemic normovolemic hemodilution with high molecular weight dextran. Absolute determinations of blood flow (in the cochlea, brain, kidney and lung) were accomplished by use of radioactive-labeled (85Sr or 141Ce) microspheres. Relative measurements of the cochlear blood flow changes were made simultaneously by the use of a laser Doppler flowmeter. The flowmeter probe was placed on the first cochlear turn. Hemodilution to an average systemic hematocrit of 20% increased cochlear blood flow by 250% as measured with microspheres. The laser Doppler instrument significantly underestimated the actual flow increase giving an indication of 148%. Furthermore, the data, when analyzed on an individual trial basis, showed a very poor correlation between the two methods. The theoretical basis for these findings in relation to the use of the laser Doppler instrument is discussed.

Sleep apnea in children without hypertrophy of the tonsils

Two 12-year-old boys with severe sleep apnea syndrome but normal-sized tonsils were satisfactorily corrected by tonsillectomy and uvulopalatopharyngoplasty. One of the boys had muscular hypotony as contributing cause of the condition. The other had mandibular hypoplasia in combination with a long soft palate. Thorough preoperative anamnesis and examination in a sleep laboratory are necessary to determine which cases will benefit from surgery in spite of normal-sized tonsils and which surgical procedure will be most helpful.

The microsphere method for studies of inner ear blood flow

The microsphere method was adapted in 1974 for studies of cochlear blood flow. Since then it has been used in Uppsala, Sweden, at the Department of Otolaryngology, University Hospital, for investigations of the blood flow circulation in the inner ear. The experience with the technique, the subjects, the actual projects and the results are presented and discussed.

Cochlear blood flow in relation to age in normotensive and spontaneously hypertensive rats

Cochlear blood flow was studied with the microsphere method in young and old normotensive and spontaneously hypertensive rats. The young animals were 3-6 months old and the old ones 18-24 months. The cochlear blood flow in young rats was 1.64 microliter/min/cochlea for the normotensive and 1.51 for the spontaneously hypertensive rats. In the old rats, the cochlear blood flow rates were 1.40 and 1.29 microliter/min/cochlea, respectively. The differences were not significant between the age groups, nor between the normotensive and spontaneously hypertensive rats. However, there was a tendency towards lower cochlear blood flow with increasing age, especially among the spontaneously hypertensive rats. The difference between young normotensive and old spontaneously hypertensive rats was significant (p less than 0.05). The group of old hypertensive rats was also the only one with evident morphological changes in the organ of Corti.

Cochlear blood flow in noise-damaged ears

Cochlear blood flow was measured in rats with a known noise-induced hearing loss, using the microsphere technique. The animals were exposed to simulated industrial noise for 3 months. The rats were divided into four groups: young and old; normotensive (N) and spontaneously hypertensive (SH). The mean values of the cochlear blood flows were compared with those of rats from matched groups not exposed to noise. The mean cochlear blood flow in the noise-exposed groups was lower than in the non-exposed groups. The decrease in cochlear blood flow was significant for all groups except young SH rats and was more pronounced in the older age group. Cochleas from the groups of old N and SH rats were investigated in the scanning electron microscope. Extensive changes were far more common in SH than in N rats.

Effect of hemodilution on cochlear blood flow measured by laser-Doppler flowmetry

The effect of hemodilution on cochlear blood flow was studied in guinea pigs. Hypervolemic hemodilution was accomplished by infusion of 10 mg/kg of body weight of dextran 40 (as a 10% solution in normal saline), which resulted in an average hematocrit decrease from 43 to 32%. Normovolemic hemodilution was accomplished by repeated exchange of 3 ml of whole blood with 3 ml of dextran 75 (6% solution in normal saline) every 5 minutes until the hematocrit reached approximately 5%. The cochlear blood flow was measured by laser-Doppler flowmetry. Irrespective of the dilutional technique, the cochlear blood flow increased as hematocrit decreased to a maximum of approximately 200% of original value at a hematocrit near 20%. The blood pressure was not significantly influenced by the hemodilution until hematocrit values below 15% were reached. The enhancement of cochlear blood flow is consistent with the expected reduction of blood viscosity and increase of cardiac output. Normovolemic hemodilution with dextran 75 causes a smaller disturbance of systemic circulation physiology and has a more lasting effect than dextran 40 infusion.

The effect of cervical sympathectomy on cochlear electrophysiology

The purpose of this study was to examine the electrophysiologic responses to sound from guinea pig cochleas, 3--6 days after a unilateral cervical sympathectomy. After recovery from surgery the guinea pigs developed a Horner's syndrome on the sympathectomized side. Some days later their bullas were opened and electrodes were placed bilaterally on the round windows. Most of the sympathectomized cochleas showed signs of decreased sensitivity to sound. They had a smaller dynamic range for the click- and tone-burst evoked compound action potential (CAP) compared with the non-sympathectomized cochleas. The threshold sound levels for the CAPs and the sound levels to produce 1 muV of cochlear microphonic potentials were unaffected. In other animals with chronic implanted electrodes, the same electrical responses were measured with only light sedation before and after sympathectomy and showed the same results. In additional animals the crossed olivocochlear bundle (COCB) was electrically stimulated and a similar inhibition of the CAP was registered on both the intact and the sympathectomized side. The results suggest that the sympathetic nerves to the cochlea, coming from the ipsilateral cervical ganglion and ending near the habenula perforata, may be important for the sound perception as they influence the CAP.

Cochlear blood flow related to hyperosmotic solution

Glycerol and urea can induce positive threshold shifts in Menire's disease whereas mannitol and ethanol do not seem to possess this ability. As an impaired blood supply is suspected to be part of the mechanism behind Menière's disease, the difference in ability of the various hyperosmotic solutions to improve hearing might depend on different effects on the cochlear blood flow. The microsphere method was used to study the cochlear blood flow in albino rabbits before and after administration of hyperosmotic solutions of glycerol, urea and mannitol. The cochlear blood flow increased by about 30% after administration of all solutions. As no difference was found in the effect on cochlear blood flow by the different substances and as the increase in cochlear blood supply was only modest, it would appear that the increment of cochlear blood flow is not a main factor behind the hearing improvements in Menire's disease after glycerol and urea ingestion.

Effect of nicotinic acid on cochlear blood flow

Effects of nicotinic acid on cochlear blood flow were studied in rats by the microsphere method. One measurement was performed before drug administration and the second after i.v. injection of the nicotinic acid 25 mg/kg body weight. No measurable effect on cochlear blood flow was observed in normal animals. In one group of animals the cervical sympathetic trunks were cut and the distal part on one side was electrically stimulated during the measurements. On the unstimulated side the cochlear blood flow was significantly higher than in intact animals, but uninfluenced by nicotinic acid. On the sympathetically stimulated side a significant increase of the cochlear blood flow occurred after nicotinic acid administration.

The effect of glycerol on cochlear blood flow

Cochlear and cerebral blood flows were measured in albino rabbits by the microsphere method before and 15 min after intravenous administration of glycerol. Both cochlear and cerebral blood flow were significantly increased. The increase in cochlear blood circulation is interpreted as a contributory factor in producing the improvements in hearing threshold seen in the positive glycerol test in Ménière's disease.

Does loud sound influence the intracochlear oxygen tension?

The effect of loud sound on the perilymphatic oxygen tension was studied in anesthetized guinea pigs. Pure tone (4 kHz) and broad-band noise were given at 85-130 dB SPL for 3-8 min. No effects were seen either in the animals exposed to pure tone or in the animals exposed to 85 dB broad-band noise. In the animals exposed to noise at 130 dB SPL both increases and decreases of perilymphatic oxygen were measured but the changes were only of about 12% or less. The response to anoxia was normal. In animals with hypotension ( less than 8 kPa) the perilymphatic PO2 fluctuated with the blood pressure. When the sound was delivered directly into the opened bulla the measured PO2 dropped immediately but was found to be caused by the cooling effect of an air current produced by the noise. Flushing the opened bulla with nitrogen, air or oxygen caused the same temperature-induced drop of measured PO2. The results and the artifacts are discussed.

Effect of ethanol on cochlear blood flow

The cochlear and cerebral blood flow was studied in rabbits with the microsphere method before and 15 min after i.v. administration of ethanol. In a series of control experiments only saline was injected. No alteration was measured in the cochlear and cerebral blood flow after the administration of saline, whereas both cochlear and cerebral blood flow showed an increase after ethanol administration. The results are discussed in relation to changes in serum osmolality and hearing in patients with Menière's disease.

The effect of CO2-breathing on cochlear blood flow

The cochlear blood flow was measured with the microsphere methods, before and during CO2-inhalation, in anesthetized rabbits. Different gas mixtures and exposure times were used. The greatest increase of cochlear blood flow was measured after 5 min inhalation of 7% CO2 in air (115%) and the least increase (44%) in animals breathing 7% CO2 in oxygen. The difference is explained as due to a vasoconstriction caused by a high oxygen tension counteracting the vasodilating effect of CO2.

Early effects of cervical sympathetic stimulation on cerebral, ocular and cochlear blood flow

Autoregulatory mechanisms may be expected to modify effects of vasomotor nerve stimulation in many tissues. Attempts were made to reveal a distinct early, but transient effect of cervical sympathetic stimulation on cerebral, retinal and cochlear blood flow. The labelled microsphere method was used to determine regional blood flow during electrical stimulation of the cervical sympathetic chain for 15-25 s and 5 min. At a frequency of 6 Hz there was 5% reduction in cerebral flow at 15-25 s and 7% at 5 min. In the choroid plexus the mean reduction was 22% at 15-25 s but decreased 10% after 5 min. In the cerebellum, optic nerve and retina, sympathetic stimulation had no appreciable effect on the blood flow. In the cochlea and iris, the blood flow reductions were 25 and 32%, respectively, on both occasions. In the choroid, vasoconstriction increased with time, whereas in the masseter muscle there was a decrease. Thus in the present experiments no indication was found of an autoregulatory escape phenomenon in the brain, the eye or the cochlea. Some escape was noted in the masseter muscle.