Iatrogenic benign paroxysmal positional vertigo: review and personal experience in dental and maxillo-facial surgery.

The post-traumatic origin of benign paroxysmal positional vertigo remains the most likely, from a patho-physiologic point of view. Benign paroxysmal positional vertigo due to surgical "traumas" has been described in the medical literature. According to personal experience, these iatrogenic cases represent a rare possibility and may be the consequence of surgical interventions differing according to the anatomical district involved and surgical technique performed. The temporal relationship with the surgical action and clinical features may be involved in some of these cases, even if it is not possible to define any real cause-effect link. Herewith some cases of paroxysmal positional vertigo are described, strongly held to be of iatrogenic origin, focusing on dental and maxillo-facial surgery as risk factors for benign paroxysmal positional vertigo.

Iodine deficiency in Calabria: characterization of endemic goiter and analysis of different indicators of iodine status region-wide.

The distribution of goiter prevalence in schoolchildren (no.=13,984, age 6-14 yr), the neonatal TSH results obtained from the congenital hypothyroidism screening program and the urinary iodine excretion values (no.=284) were employed for the assessment of iodine deficiency in Calabria, a Southern Italy region. Data were collected during the years 1990-1996. In the inland territory, goiter prevalence ranged from 19 to 64%. At sea level, there was a great variability of goiter prevalence, with values varying from 5.3 to 25.7%. The analysis of the neonatal hypothyroidism screening program data (no.=21,078) showed a 14.8% frequency of TSH levels >5 microU/ml whole blood in newborns from the inland territory and a 14.1% frequency at sea level. Urinary iodine excretion resulted (mean+/-SD) 53.8+/-43.4 microg/l (range: <20 to 189 microg/l) in the inland territory and 89.6+/-59.8 microg/l (range: 26 to 333 microg/l) at sea level. Median urinary iodine excretion values in 13 villages or small towns of the inland territory ranged from 31 to 57 microg/l. In 2 major towns located at sea level, the median iodine excretion values were 72 microg/l in Crotone main city and 94 microg/l in Reggio Calabria main city. The data indicated that moderate, with pockets of severe iodine deficiency is present in the inland region while iodine supply varies from sufficient to marginally low in the coastal areas. Mild iodine deficiency was found in a major town located at sea level.

A large family with hereditary MTC: role of RET genetic analysis in differential diagnosis between MEN 2A and FMTC.

Germline mutations of the RET proto-oncogene cause three different cancer syndromes: multiple endocrine neoplasia type 2A (MEN 2A), multiple endocrine neoplasia type 2B (MEN 2B) and familial medullary thyroid carcinoma (FMTC). In the absence of biochemical and/or clinical evidence of pheochromocytoma and hyperparathyroidism, patients with MEN 2A disease display the same phenotype of FMTC disease, although prognosis and clinical management in both affected and unaffected familial members are quite different. We studied a family with hereditary MTC, whose proband was referred to us because of enlarged cervical nodes and increased calcitonin serum levels 28 years after the total thyroidectomy for MTC. Cervical node dissection was carried out and subsequently the presence of MTC metastasis was histologically confirmed. A RET genomic mutation at codon 634 (TGC-->TTC) was identified in the proband and in seven out of 19 familial members studied. Accordingly, a hereditary disease was suggested. However, the strong association of RET mutation at codon 634 with the presence of pheochromocytoma in MEN 2 disease suggested a more rigorous management in all gene carriers. Indeed, during the follow-up pheochromocytoma was subsequently identified in the proband. This finding suggests that all families with a pedigree suggestive of FMTC should be regarded at risk from MEN 2A disease, at least when a critical mutation in the RET cysteine domain is detected.

Percutaneous ethanol injection may be a definitive treatment for symptomatic thyroid cystic nodules not treatable by surgery: five-year follow-up study.

We present a prospective study on the long-term efficacy of percutaneous ethanol injection (PEI) treatment for thyroid cystic nodules. Among patients referred for symptomatic thyroid cystic nodules who had relapsed after two aspirations or whose nodules could not be aspirated due to the thickness of the cystic fluid, PEI was given when surgery was either refused or contraindicated. Forty-three patients were treated; the mean basal volume of the cysts was 38.4 mL. The purpose of the study was to evaluate long-term efficacy of PEI treatment on: (1) amelioration of symptoms and signs of local compression and (2) nodule volume reduction. In three subjects (7%), PEI failed to induce a significant (>50%) nodule reduction, so that surgical treatment was performed. In 40 patients (93%), an impressive nodule shrinkage was observed, reaching a plateau after 24 months (volume reduction = 91.9%+/-11.4%). A new PEI session was needed in two patients in whom a recurrence was noted within the first 6 months. After 6 months, no significant (> or =1 mL volume) nodule regrowth was observed up to 60 months. Both symptoms and tracheal displacement rapidly (within 1 month) and significantly (p<0.01) improved. After PEI, mild pain was the only side effect observed. No suspicious cytology was observed in any residual nodule greater than 1 mL 6 and 24 months after the last PEI session. Our data suggest that PEI is a first-line safe, effective, probably definitive, treatment for cystic thyroid nodules for which surgery is either refused or contraindicated.

The statistical analysis of neonatal TSH results from congenital hypothyroidism screening programs provides a useful tool for the characterization of moderate iodine deficiency regions.

TSH data from the congenital hypothyroidism screening program were analyzed in a mild to moderate iodine deficiency region. Neonatal TSH levels were measured at day 4-5 of life in 22,384 infants (99% coverage; 51.1% males, 48.9% females). The cut off TSH value for recall was established at 20 microUl/ml whole blood. TSH values > 20 microUl/ml were excluded from further analysis of the data. The frequency distribution analysis showed that the median neonatal TSH level was 2 microUl/ml and the mode (28% of newborns) corresponded to neonatal TSH values < 1 microUl/ml. TSH levels above 5 microUl/ml were observed in 14.4% children and the 97% cut off was 11 microUl/ml. When examined in relation to the areas of newborn origin, the individual 97% cut off values varied from 8 to 14 microUl/ml. Accordingly, the frequency of TSH levels above the 97% cut off value calculated for the entire newborn series (> 11 microUl/ml) ranged from 2.1% to 4.6%. A significant correlation was found between the frequency of neonatal TSH levels > 11 microUl/ml and both goiter prevalence (r2 = 0.88; p = 0.0019) and median urinary iodine excretion (r2 = 0.86; p = 0.0077) observed in those areas for which epidemiological data were available (n = 7). The results indicate that neonatal TSH data from the congenital hypothyroidism screening programs can be used for monitoring mild to moderate iodine deficiency regions.

Interaction between the aortic valve leaflets and a Millar dual-micromanometer catheter during recording of the aortic component of the second heart sound in dogs.

The influence of the closure of the aortic valve leaflets on a dual-micromanometer Millar catheter is investigated with respect to the power spectrum of the aortic component (A2) of the second heart sound in dogs. The catheter inserted through the aortic valve is used to simultaneously record A2 in the left ventricle and in the aorta and to study the transmission of A2 up to the body surface. Results indicate that the interaction of the valve leaflets with the Millar dual-micromanometer catheter during the closure and vibration of the aortic valve does not produce a clapping artefact. The main effect is a change in the natural modes of vibration (resonant frequencies) of the aortic valve resulting from a modification of the vibrating structure (combined structure composed of the catheter, the aortic valve and the surrounding blood and tissues) because of the tight mechanical coupling between the aortic valve leaflets and the catheter. In addition, this modification of the natural modes of resonance does not invalidate the estimation of the frequency response of the transfer function between the aortic root and the thoracic recording site, even if the mean gain of the transfer function is affected and the phase slightly increased with frequency. On the contrary, the interaction of the aortic valve leaflets with the catheter seems to slightly increase the spectral contribution (coherence) of the intra-aortic A2 to the thoracic A2.

Acoustic transmission of the aortic component of the second heart sound within the ascending aorta of dogs.

The spectral characteristics of the acoustic transmission of the aortic component of the second heart sound within the ascending aorta was studied using a Millar dual-micromanometer catheter. The tip micromanometer was located close to the aortic valve leaflets while the second micromanometer was located 3 cm above the aortic valve. The frequency response of the transmission properties (amplitude and phase) of the blood and the aortic wall was modelled by an equivalent acoustic transmission system. The signal recorded by the tip micromanometer located near the aortic valve was considered to be the input signal of the equivalent system and the signal recorded by the second micromanometer was used as the output signal. Results of the spectral analysis of the input and output signals show that the acoustic transmissibility of blood in the ascending aorta is high at 20 Hz (the attenuation is negligible). Between 20 and 60 Hz, the transmissibility decreases at a rate of -3 dB per octave while between 60 and 120 Hz it decreases at a rate of -14 dB per octave. Above 120 Hz the transmissibility is low and the resulting attenuation is greater than 20 dB. The phase of the transfer function is shifted by -60 degrees at 20 Hz and decreases at a mean rate of -2.0 degrees Hz-1 between 20 and 100 Hz and -0.75 degrees Hz-1 up to 400 Hz. The phase velocity of the sound transmission is relatively constant (5.5 ms-1) between 40 and 100 Hz and increases up to 9 ms-1 at 300 Hz.

Spectral analysis and acoustic transmission of mitral and aortic valve closure sounds in dogs. Part 3. Effects of altering heart rate and P-R interval.

A surgical protocol was designed to implant, in seven dogs, a programmable sequential atrioventricular pacemaker after destruction of the bundle of His to produce a chronic heart block. The heart rate and P-R interval were then varied independently and their influence on the spectra and acoustic transmission of the mitral M1 and aortic A2 valve closure sounds was studied. Results indicate that the major effects of varying the P-R interval are a strong change in the intensity of M1 and modifications of its acoustic transmission across the heart/thorax acoustic system. No similar influence is observed on the intensity and acoustic transmission of A2. Varying the heart rate has a small effect of the intensity of M1 but none on the intensity of A2. In addition, changes in either the P-R interval or the heart rate do not seem to modify the spectral profile of the intracardiac and thoracic M1 and A2 components.

Spectral analysis and acoustic transmission of mitral and aortic valve closure sounds in dogs. Part 4: Effect of modulating cardiac inotropy.

A surgical protocol was designed to implant in dogs a programmable atrioventricular pacemaker and to destroy the bundle of His with one to four 0.1 ml formaldehyde injections. The heart rate and P-R interval were paced at 100 beats min-1 and 75 ms, respectively. Cardiac inotropy was then varied in five animals by using injections or infusions of cardiotonic drugs (Dobutamine, Betalol and Quinidine). Their effect on the spectra and acoustic transmission of the mitral M1 and aortic A2 closure sound components produced within the left heart and transmitted up to the body surface was studied. Results indicate that changes in cardiac inotropy strongly modify the intensity of M1 and A2 but do not markedly affect their spectral distribution. They also affect the transfer function of the heart/thorax acoustic system, but this influence is small compared with that of a 12 min reference interval. In addition, it was shown that the intensity of M1 is more sensitive to the cardiotonic agents than the intensity of A2.

Spectral analysis and acoustic transmission of mitral and aortic valve closure sounds in dogs. Part 1. Modelling the heart/thorax acoustic system.

A system model based on the simultaneous recording and analysis of the intracardiac and thoracic phonocardiograms to estimate the time-varying properties of the heart/thorax acoustic system of the dog is described. The presence of instrumental noise in the recording of intracardiac phonocardiograms is characterised, and it is demonstrated that its effect on the estimate of the transfer and coherence functions of the system can be quantified and corrected. Application of the model to study the spectral characteristics and the acoustic transmission properties of the mitral component M1 of the first heart sound and of the aortic component A2 of the second heart sound in the dog shows that the heart/thorax acoustic system acts like a bandpass filter having a higher attenuation for A2 than for M1. Between 20 and 100 Hz, the mean attenuation of M1 is 30 dB while that of A2 is 46 dB. Above 100 Hz, the attenuation slope is -12 dB per octave for M1 and -6 dB per octave for A2.

Spectral analysis and acoustic transmission of mitral and aortic valve closure sounds in dogs. Part 2. Effects of neuromuscular blockade, sternotomy and pacemaker control, and a two-week recovery period.

The paper describes the effects of neuromuscular blockade, sternotomy and atrio-ventricular pacing, and a two-week recovery period on the spectra and acoustic transmission of mitral M1 and aortic A2 sound components in dogs. Results indicate that neuromuscular blockade does not affect the attenuation properties of the heart/thorax acoustic system even if it modifies the intensity of M1 and the phase of the transfer function. The immediate effect of sternotomy and cardiac pacing is an important increase in the attenuation of the heart/thorax acoustic system. This increased attenuation is different for both sounds (20 dB for M1 and 11 dB for A2) and disappears after a two-week recovery period. However, the resulting controlled dog model shows slightly different acoustic characteristics than those of the normal animal model.