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PubMed1988

Transcutaneous bilirubinometry. Evaluation of accuracy and reliability in a large population.

A total of 576 transcutaneous bilirubin measurements were performed on 336 Japanese full-term breast-fed newborn infants during the first twelve days of life. Our present study revealed that transcutaneous bilirubin measurements obtained from the forehead, chest, and sternum correlated well with serum bilirubin concentrations measured by AO bilirubinometer (0.910-0.922, p less than 0.001, n = 576). The 95% confidence limits were +/- 3.04 mg/dl for the forehead, +/- 2.85 mg/dl for the chest, and +/- 2.84 mg/dl for the sternum readings. The overall mean of values from the forehead, chest and sternum, when compared with individual means, was found to correlate better with serum bilirubin concentrations (r = 0.930, p less than 0.001, n = 576) and improve the 95% confidence limits to +/- 2.68 mg/dl. These results demonstrated that the accuracy and reliability of TcB measurement could be increased further with multiple site measurement. The study clearly indicates that transcutaneous bilirubinometry is useful for clinical screening of serum bilirubin levels in Japanese full-term newborn infants.

Bilirubin↗
PubMed1988

Transcutaneous bilirubinometry in preterm very low birthweight infants.

Transcutaneous bilirubinometry using the Minolta Airshield TcB was performed on 40 preterm VLBW Chinese infants during the first 7 days of life; altogether 614 observations were made on the forehead and sternum, respectively. A positive correlation between the TcB index and plasma bilirubin concentration was obtained on the forehead and sternum. Positive plasma bilirubin-TcB index correlations were also observed for each individual day. The plasma bilirubin-TcB index (forehead) regressions were fairly similar for the individual days and the combined overall regression except for 2 days (days 5 and 7). A slight improvement was observed when only bilirubin concentrations less than or equal to 200 mumol/l were evaluated. The intercepts were however different for individual days requiring correction factors to the combined overall regression intercept if the regression is to be used for the respective days. However, the plasma bilirubin-TcB index (sternum) regression for the individual days were significantly different one from another, and from the overall combined plasma bilirubin-TcB index (sternum) regression. This significant difference was still observed when only plasma bilirubin concentrations less than or equal to 200 mumol/l were evaluated. Hence, transcutaneous bilirubinometry has major limitations in preterm VLBW infants.

Bilirubin↗
PubMed1996

Postnatal hypothermia and cold stress among newborn infants in Nepal monitored by continuous ambulatory recording.

AIMS: To describe the pattern of hypothermia and cold stress after delivery among a normal neonatal population in Nepal; to provide practical advice for improving thermal care in a resource limited maternity hospital. METHODS: The principal government funded maternity hospital in Kathmandu, Nepal, with an annual delivery rate of 15,000 (constituting 40% of all Kathmandu Valley deliveries), severe resource limitations (annual budget Pounds 250,000), and a cold winter climate provided the setting. Thirty five healthy term neonates not requiring special care were enrolled for study within 90 minutes of birth. Continuous ambulatory temperature monitoring, using microthermistor skin probes for forehead and axilla, a flexible rectal probe, and a black ball probe placed next to the infant for ambient temperature, was carried out. All probes were connected to a compact battery powered Squirrel Memory Logger, giving a temperature reading to 0.2 degree C at five minute intervals for 24 hours. Severity and duration of hypothermia, using cutoff values of core temperature less than 36 degrees C, 34 degrees C, and 32 degrees C; and cold stress, using cutoff values of skin-core (forehead-axilla) temperature difference greater than 3 degrees C and 4 degrees C were the main outcome measures. RESULTS: Twenty four hour mean ambient temperatures were generally lower than the WHO recommended level of 25 degrees C (median 22.3 degrees C, range 15.1-27.5 degrees C). Postnatal hypothermia was prolonged, with axillary core temperatures only reaching 36 degrees C after a mean of 6.4 hours (range 0-21.1; SD 4.6). There was persistent and increasing cold stress over the first 24 hours with the core-skin (axillary-forehead) temperature gap exceeding 3 degrees C for more than half of the first 24 hours. CONCLUSIONS: Continuous ambulatory recording identifies weak links in the "warm chain" for neonates. The severity and duration of thermal problems was greater than expected even in a hospital setting where some of the WHO recommendations had already been implemented.

Adult↗
PubMed1976

Relationship between evaporation rate of sweat and mean sweating rate.

The rate of evaporation of sweat under a step change of ambient temperature (30-45 degrees C) was compared with the mean sweating rate (MSR) computed from five simultaneous resistance hygrometric measurements. Empirical equations derived for the conditions studied enabled a direct conversion from hygrometric measurements into real evaporative sweat losses and skin wetness for all phases of sweat evaporation. From five chosen skin areas, forehead, forearm, chest, thigh, and calf, it was found that none of these sites gave a local sweating response close to the MSR. In the subjects with a forehead sweating rate within +/- 39% of the MSR, at least four hygrometric sensors were needed to predict the rate of sweat evaporation. For subjects with higher forehead sweating rates, at least five sensors were necessary to calculate the evaporative sweat loss.

Adult↗
PubMed2006

Ethnic variation in vellus hair follicle size and distribution.

It is a given fact that hair follicles play an important role in the penetration process of topically applied drugs and cosmetics. Since exact knowledge of the potential follicular reservoir is essential for understanding and calculating the penetration process, this knowledge may indeed help to optimize the development of topically applied drugs and cosmetic products. We know that variability in skin properties exists among the human population, but it is the deciphering and quantification of these differences that may help to explain racial disparities in dermatological disorders and provide a basic approach for treatment and prevention. Data pertaining to structural and functional differences within ethnic skin types (reviewed in this paper) support the assumption that hair follicles in the various skin types are not equal. Thus, the need to investigate follicular morphology in non-Caucasian skin types becomes more than apparent. The aim of the present study was to determine the potential reservoir of vellus hair follicles in non-Caucasian skin types in order to estimate their contribution to the penetration of topically applied substances. Cyanoacrylate skin surface biopsies were taken from seven body sites of Asians and African-Americans. To determine the follicular reservoir, the samples were evaluated under the light microscope. Follicular parameters were measured with the help of a digital imaging software program. In the evaluation and comparison of the results with those of Caucasians, significant differences were detected. Compared with Whites, follicular density on the forehead is significantly lower in Asians and African-Americans. Smaller values were detected for volume, surface, follicular orifice and hair shaft diameter on the thigh and in calf regions in Asians and African-Americans. Furthermore, the follicular reservoir, characterized by follicular volume, is generally higher in Caucasians. In comparison to African-Americans, larger follicular volumes on the forehead, back and on the upper arm were determined in Asians. The fairly similar density in these sites revealed that Asians have a higher follicular reservoir in these sites. Due to significant ethnic differences in the follicular reservoir, particularly on the calf and forehead, prospective skin absorption experiments need to be performed on different skin types in order to be representative. Likewise, the development of topically applied drugs should take place under adequate consideration of ethnic differences in skin physiology.

Adult↗
PubMedDate not supplied

Circulatory effects caused by intra-arterial infusion of AMP, ADP and ATP in the canine facial and nasal vascular beds.

The effects of the intra-arterial infusion of ATP, ADP and AMP into the internal maxillary artery (IMA), which provides the blood supply to the nasal and forehead regions of the dog, were analyzed. Total blood flow and perfusion pressure measurements in the IMA after administration of each adenyl compound indicated dose-dependent and active vasodilatory responses that were restricted to the ipsilateral vessels. The rank order of potency was ADP > or = ATP > AMP. In order to determine the microcirculatory effects caused by ADP, the tracer microsphere technique combined with absolute blood flow measurement was used. Intra-arterial infusion of ADP in the range 1-200 nmol/min produced elevations in the IMA flow on the stimulated side that ranged between 11 and 74%. The responses to low doses of ADP were mainly confined to the capillaries (CAP), whereas the arteriovenous anastomoses too were sensitive to high doses. The relative contributions of the anatomically and functionally different compartments of the forehead and nose to ADP-produced relaxations of the CAP were dependent upon their location. The CAP flows in the tissues which play a crucial role in conditioning the inspired air increased significantly, while the compartments of the furred surfaces were less sensitive to ADP. The results suggest that, since ATP, ADP and AMP are effective vasodilatory agents in all the regions examined, purines could have a regulatory or modulatory role in the complex vascular regulation of the nasal and forehead regions.

Adenosine Diphosphate↗
PubMed1997

Cardiovascular reactivity to stress and left ventricular mass in youth.

We studied the relationships of cardiovascular reactivity during mental stress with left ventricular mass index in a group of prepubertal children 8 to 10 years old and in a group of peripubertal or postpubertal adolescents 15 to 17 years old. One hundred fifteen participants, varying in age group, sex, and race (black and white), took part in a laboratory stress protocol consisting of a reaction-time task, a mirror tracing task, a cold forehead challenge, and a stress interview. Cardiovascular measures included blood pressure and heart rate, as well as cardiac output, stroke volume, total peripheral resistance, and preejection period obtained noninvasively with impedance cardiography. Measures of left ventricular mass were made by echocardiography. Results indicated that across all participants, left ventricular mass index was associated with cardiovascular responses during the mirror tracing and cold forehead tasks, especially with those responses reflecting increased vasoconstriction. Subgroup analyses showed that these associations were significant for males and sometimes adolescents but not for females and children. As mirror tracing and cold forehead tasks most consistently produce alpha-adrenergic activation, the results suggest a model in which vasoconstriction due to mental stress is related to increased left ventricular mass in susceptible individuals, even at a young age.

Adolescent↗
PubMed2000

Consistency of hemodynamic responses to cold stress in adolescents.

Laboratory research on hypertension often is performed with cold stress to elicit vasoconstriction and increases in blood pressure. Several studies have shown that cardiovascular responses to the cold pressor test predict the development of hypertension. We extended this research by comparing cardiovascular responses to a traditional forehead cold pressor test and a naturalistic whole-body cold exposure. We evaluated blood pressure and impedance cardiographic measures of cardiac output and total peripheral resistance in healthy black (n=69) and white (n=47) adolescents (mean age, 14.7 years) during forehead cold pressor (3 degrees C to 4 degrees C) and passive whole-body exposure to a cold chamber (8 degrees C to 10 degrees C). Both tasks elicited increases in vascular resistance and blood pressure, but forehead cold elicited an increase in cardiac output, whereas whole-body cold elicited a decrease in cardiac output (P<0.05). Consistent with previous research, there was a tendency toward greater vasoconstrictive reactivity to cold stress in blacks than in whites, particularly during whole-body cold exposure (P<0.05). Cardiovascular reactivity correlated significantly between tasks, but substantial intertask consistency occurred only for cardiac and vascular reactivity in male subjects (r>0.30) but not in female subjects (r<0.15). These gender differences might reflect diminished adrenergic receptor function in female subjects. We conclude that whole-body cold exposure offers a viable, relatively naturalistic alternative to traditional cold pressor tests for the assessment of cardiovascular reactivity.

Adolescent↗
PubMed1994

Cold or warm start of cardiopulmonary bypass--influence on microcirculatory blood flow.

In a randomized study of 30 patients undergoing elective aortocoronary bypass grafting, either cold start of cardiopulmonary bypass (CPB) (prime: room temperature [approximately 20 degrees C], n = 15) or normothermic start of CPB (prime: warmed up to the patients' blood temperature, n = 15) were performed. After warm start, CPB was continued using almost normothermia (lowest nasopharyngeal temperature: 35.8 +/- 0.4 degrees C), after cold start hypothermia was used (lowest nasopharyngeal temperature: 28.8 +/- 0.2 degrees C). Changes in microcirculatory perfusion were assessed by measuring skin capillary blood flow at the patient's forearm and forehead using laser Doppler technique. Laser Doppler flow (LDF) was continuously monitored before onset of CPB (= baseline values), 30 seconds, one, five, 10, 15 and 20 minutes after start of CPB. Mean arterial blood pressure (MAP) and systemic vascular resistance (SVR) were reduced by CPB in both groups, with the more pronounced reduction in the normothermic patients. Haemoglobin and plasma viscosity were without differences between the groups. The lowest blood temperature in the hypothermic patients was 21.0 +/- 0.3 degrees C, and the lowest rectal temperature in these patients was 29.0 +/- 0.3 degrees C (20 minutes after start of CPB). Forehead- and forearm-LDF increased significantly in both groups by start of CPB. In the hypothermic patients, this increase was significantly lower, and LDFs were already reduced below baseline values five to 10 minutes after onset of CPB (LDF-forehead -18%, LDF-forearm -72%).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed2005

Aberrant neural responses to cold pressor challenges in congenital central hypoventilation syndrome.

Patients with congenital central hypoventilation syndrome (CCHS), a condition characterized by impaired ventilatory responses to chemoreceptor stimulation, do not show the normal increase in respiratory rate and respiratory-related heart rate variation to cold forehead stimulation, a challenge that bypasses central chemoreceptors. We hypothesized that a forehead cold pressor challenge would reveal abnormal neural response patterns, as assessed by functional magnetic resonance imaging, in brain regions that are responsible for the integration of cold afferent stimulation with respiratory and cardiovascular output in patients with CCHS. Primary sensory thalamic and cortical areas for the forehead showed diminished responses in 13 patients with CCHS (ventilator dependent during sleep but not waking, no Hirschsprung's disease) compared with 14 control subjects, despite initial signal changes in the cortex being similar in both groups. Cerebellar cortex and deep nuclei; basal ganglia; and middle to posterior cingulate, insular, frontal, and temporal cortices showed reduced signal rises in patients with CCHS. Areas within the frontal and anterior cingulate cortices exhibited marked signal declines in control subjects but little change in patients with CCHS. No response occurred in either group in the dorsal medulla, but medial and ventral medullary areas showed enhanced signals in patients with CCHS. The cold pressor stimulation did not recruit dorsal medullary sites that would be affected by PHOX2B (a mutation of which is associated with the syndrome) expression in either group but demonstrated deficient cerebellar and medial medullary influences that, by action on rostral sites, may underlie the loss of respiratory responses.

Adolescent↗
PubMed1994

1-year stability and prediction of cardiovascular functioning at rest and during laboratory stressors in youth with family histories of essential hypertension.

Blood pressure (BP). heart rate, cardiac index, and total peripheral resistance index were measured at rest and in response to postural change, forehead cold stimulation, and a video game challenge in a sample of 128 White and 155 African-American normotensive youth with family histories of essential hypertension (EH). These measurements were readministered 1 year later (12.5 +/- 3.2 months). Moderate temporal stability was observed for all resting and absolute stress responses. Reliability estimates for reactivity change scores were lower, although some were within acceptable ranges. African-American youth exhibited greater BP and peripheral resistance index reactivity to forehead cold on both evaluations. After controlling for various anthropometric and demographic parameters and the pertinent previous year's resting cardiovascular (CV) parameter, mean video game systolic blood pressure (SBP) responses were predictive of resting SBP whereas absolute forehead cold and video game diastolic responses predicted resting diastolic blood pressure (DBP) 1 year later. Mean video game DBP responses were also predictive of resting peripheral resistance index after controlling for significant demographic and anthropometric measures. CV reactivity is discussed with regard to possible value in prediction of changes in resting BP and cardiac structure prior lo establishment of EH.

Journal Article↗
PubMed2005

Cuvier's beaked whale (Ziphius cavirostris) head tissues: physical properties and CT imaging.

Tissue physical properties from a Cuvier's beaked whale (Ziphius cavirostris) neonate head are reported and compared with computed tomography (CT) X-ray imaging. Physical properties measured include longitudinal sound velocity, density, elastic modulus and hysteresis. Tissues were classified by type as follows: mandibular acoustic fat, mandibular blubber, forehead acoustic fat (melon), forehead blubber, muscle and connective tissue. Results show that each class of tissues has unique, co-varying physical properties. The mandibular acoustic fats had minimal values for sound speed (1350+/-10.6 m s(-1)) and mass density (890+/-23 kg m(-3)). These values increased through mandibular blubber (1376+/-13 m s(-1), 919+/-13 kg m(-3)), melon (1382+/-23 m s(-1), 937+/-17 kg m(-3)), forehead blubber (1401+/-7.8 m s(-1), 935+/-25 kg m(-3)) and muscle (1517+/-46.8 m s(-1), 993+/-58 kg m(-3)). Connective tissue had the greatest mean sound speed and density (1628+/-48.7 m s(-1), 1087+/-41 kg m(-3)). The melon formed a low-density, low-sound-speed core, supporting its function as a sound focusing organ. Hounsfield unit (HU) values from CT X-ray imaging are correlated with density and sound speed values, allowing HU values to be used to predict these physical properties. Blubber and connective tissues have a higher elastic modulus than acoustic fats and melon, suggesting more collagen structure in blubber and connective tissues. Blubber tissue elastic modulus is nonlinear with varying stress, becoming more incompressible as stress is increased. These data provide important physical properties required to construct models of the sound generation and reception mechanisms in Ziphius cavirostris heads, as well as models of their interaction with anthropogenic sound.

Adipose Tissue↗
PubMed1978

Compound frontal sinus injuries with intracranial penetration.

Extensive trauma to the forehead, resulting in large penetrating wounds of the frontal sinus that extend into the frontal lobes of the brain, has traditionally been treated by frontal sinus ablation. Although this operation eliminates dead space, it leaves the patient with a depressed area in the forehead with little protection for the brain. The success of Nadell and Kline in replacing skull fragments following compound depressed skull fractures yet avoiding infection has spurred us to attempt this technique in penetrating injuries of the frontal sinus. By preserving the anterior frontal sinus wall, we have not only afforded protection for the frontal lobes of the brain, but, at the same time, avoided the cosmetic defect that would be left by an ablation procedure. This procedure has been performed on two patients at our institution. After a two-year follow-up, excellent forehead profile preservation has been achieved and there has been no evidence of bone absorption or infection at any time since surgery.

Adolescent↗
PubMed1985

Surgical management of cutaneous carcinomas at the inner canthus.

Surgical management of carcinomas at the inner canthus is based on three criteria which are listed in a descending order of importance: tumor resectability with adequate margins, preservation of vision, and acceptable cosmetic result. The lesions resected are to create trapezoid or rectangular defects which can be closed simply with primary closures or with Z- or W-plasties. In medium sized defects skin is borrowed from the glabella, upper nasal dorsum, or nasolabial sulci and used as rotational flaps. In more extensive lesions, through and through defects, or when lined flaps are required, nondelayed midline forehead pedicled or island flaps are employed. For very large defects, sliding cheek flaps, sickle forehead flaps, horizontal forehead flaps, and (in rare instances) scalping flaps where the distal segment is the temporal, hairless skin is used. Tumors which extend intracranially and are deemed resectable are removed with a combined intracranial approach. The latter may be via a transfrontal sinus resection or a combined lateral rhinotomy and frontal craniotomy resection. Regional lymph node metastasis normally requires a superficial parotidectomy, radical neck dissection (including submaxillary, angular, and mandibular nodes), and occasionally postauricular lymph node dissection. Distant metastases are contraindications for major surgical procedures.

Carcinoma↗
PubMed2004

Cerebral oxygenation during exercise in cardiac patients.

BACKGROUND: Until recently, compensatory mechanisms have been believed to regulate adequately cerebral blood flow in humans. However, this has been called into question by a series of new investigations suggesting that patients with left ventricular dysfunction suffer from cerebral hypoperfusion. We compared cerebral oxygenation during incremental exercise between patients with valvular heart disease and normal subjects. METHODS: Thirty-three patients with valvular disease and 33 normal subjects performed a symptom-limited incremental exercise test using a cycle ergometer. Oxyhemoglobin at the forehead was continuously monitored during exercise using near-infrared spectroscopy. Respiratory gas measurements were performed on a breath-by-breath basis. RESULTS: The increase in oxyhemoglobin during exercise was significantly lower in the patients with valvular disease than in normal subjects. The change in oxyhemoglobin during exercise (DeltaO(2)Hb) at the forehead was negatively correlated with the slope of the increase in minute ventilation to the increase in carbon dioxide output (DeltaE/DeltaCO(2)), and positively correlated with the peak oxygen uptake (O(2)), gas exchange threshold (GET), and slope of the increase in O(2) to the increase in the work rate (DeltaO(2)/DeltaWR). Among the patients with valvular disease, 15 patients showed a decrease in oxyhemoglobin at the forehead during exercise. When compared with the patients with increased oxyhemoglobin, those with decreased levels exhibited a higher DeltaE/DeltaCO(2) and a lower peak O(2), GET, and DeltaO(2)/DeltaWR. CONCLUSIONS: The present findings strongly suggest that cerebral oxygenation during exercise is dependent on the cardiovascular and pulmonary systems. The study also indicated the presence of cerebral hypoperfusion during exercise in cardiac patients whose cardiac output fails to increase normally.

Adult↗
PubMed2000

Skin barrier properties in different body areas in neonates.

OBJECTIVE: The aim of the study was to investigate skin barrier function in neonates in different anatomic sites during the first 2 days of life. DESIGN: The study population consisted of 44 healthy full-term newborn infants. Transepidermal water loss (TEWL), stratum corneum hydration (SCH), and skin surface pH were measured in different anatomic sites (forehead, flexor part of forearm, upper back, abdomen, inguinal region, palms, and soles) during the first 10 hours of life and 24 hours later. Measurements were recorded with a Tevameter, a Corneometer, and a skin pH meter with a flat glass electrode. Results were compared with those in 20 healthy adults. RESULTS: TEWL was lower in infants than in adults in the forehead, palms, soles, and higher in the forearms. It was significantly higher on day 1 than on day 2 in the soles, palms, and forearms, and in the forearm, palms, and inguinal region compared with the other anatomic sites. SCH was significantly lower in the infants on the forehead, back, and abdomen, and higher on the forearms and palms; it was significantly higher on the first day of life on the forearms and palms, and lower in the inguinal region. Skin surface pH was significantly higher in the infants in all body sites (>6.6 in most measurements). On day 2, it was significantly lower than on day 1, but still higher than in adults. SCH correlated positively with TEWL in the neonates but not in the adults. None of the variables were related to gestational age, sex, mode of delivery, or body weight. CONCLUSIONS: Changes take place in SCH, water loss, and pH in the first 2 days after birth, suggesting that the stratum corneum barrier is still in the process of adapting to extrauterine life. The significant anatomic variability in TEWL and SCH should be taken into account in evaluating the permeation of skin care products and topical medications in newborns.

Adult↗
PubMed2000

Increased eumelanin expression and tanning is induced by a superpotent melanotropin [Nle4-D-Phe7]-alpha-MSH in humans.

Seven normal volunteers (six males and one female) with tanning skin types III or IV (Fitzpatrick scale) were given 10 daily subcutaneous injections of a superpotent synthetic analog of alpha-melanocyte stimulating hormone (alpha-MSH) over two weeks. This agent, [Nle4-D-Phe7]alpha-MSH, also called Melanotan-I (MT-I), was administered at a dose of 0.16 mg/kg/day (Monday-Friday), over a two week period. Tanning was measured serially using computerized light reflectance. This regimen induced tanning at 3 of 8 anatomic sites including the face, neck and forearm by comparison of baseline to (1) the end of the daily dosing period, (day 14), and (2) one week later, (day 21). Shave biopsies of the forearm taken at baseline and day 21 were analyzed by high performance liquid chromatography for eumelanin content which was measured as the permanganate oxidation product, pyrrole-2,3,5-tricarboxylic acid or PTCA. Pheomelanin content was measured as the hydroiodic acid digestion product, aminohydroxyphenylalanine (AHP). Eumelanin was also measured in the forehead skin samples of three subjects. The HPLC results show that mean (+/- SD) baseline eumelanin (PTCA) levels in forehead skin (n = 3) averaged 1.38 (+/- 0.87) ng/mg of wet skin tissue weight. Higher mean baseline levels of PTCA were detected in forearm skin (2.06 +/- 0.28 ng/mg wet weight, n = 7). One week after MT-I treatments ended, there was a mean (SD) 49% (+/- 17.6%) increase in forehead skin PTCA levels compared to baseline (P = 0.019, n = 3, by paired sample T-test). The mean (SD) increase in forearm skin PTCA levels was 98% (+/- 25.4%) over the same period (P = 0.003). In contrast, forearm pheomelanin expression following MT-I treatment did not significantly change from baseline. Overall, the MT-I regimen increased the eumelanin: pheomelanin ratio in forearm skin from 51:1 at baseline to 86:1 following MT-I (P = 0.054 by paired sample T-test). These results show that the tanning induced by MT-I in the face and forearm is associated with a significant increase in the eumelanin content of the human skin.

Adult↗
PubMed2005

Which is mightier, the tuning fork or the bone oscillator?

INTRODUCTION: It is important to differentiate cochlear implant candidates with profound sensorineural hearing loss from those with profound mixed hearing loss. The latter include patients with far advanced otosclerosis and chronic otitis media who may be better treated with ossiculoplasty and conventional amplification than with cochlear implantation. Otologists have observed that a dentally placed tuning fork can be heard by some patients whose sensorineural thresholds are beyond the limits of a bone oscillator placed on the mastoid. We hypothesized that tuning forks may be able to deliver a strongerintensity bone-conducted signal than a conventional mastoid-placed oscillator. OBJECTIVE: To measure the maximum bone-conduction signal intensities of a mastoid-placed bone oscillator and tuning forks placed on the forehead, mastoid, and teeth. METHOD: The maximum signal intensity of a mastoid-placed bone oscillator and tuning forks at various locations (mastoid, forehead, teeth) was measured using behavioural masking level differences at three frequencies (250, 500, and 1000 Hz). RESULTS: The peak intensity of a dental bone-conducted tuning fork signal is greater than that delivered by a mastoid-placed bone oscillator (at least 20.5 dB HL at 250 Hz, 16.5 dB HL at 500 Hz, and 8.5 dB HL at 1000 Hz; p <.001) at all three frequencies tested. At some frequencies, the bone oscillator's maximum perceived level is greater than the peak perceived level of the tuning fork when placed on the forehead or mastoid. CONCLUSIONS: In addition to pure-tone audiometry, all patients being considered for cochlear implantation should be evaluated with maximally vibrating tuning forks applied to the teeth. If the signal is audible, other surgical procedures may need to be considered before proceeding with cochlear implantation.

Adolescent↗