A follow-up study of patients suffering from sudden sensorineural hearing loss.

Sudden sensorineural hearing loss (S-SNHL) is a common problem with a high recovery rate. However, little is known of the long-term prognosis of affected patients. The purpose of this follow-up study was to evaluate the long-term hearing results of S-SNHL patients. The sample consisted of 168 patients with S-SNHL treated with carbogen inhalation and/or anticoagulant therapy during the period 1982-89. A questionnaire was sent to these patients, and audiological investigations were carried out in a selection of these patients in 1997. Comparison of the different treatment methods showed that the difference observed in improvement of hearing was statistically significant between the carbogen inhalation and anticoagulant treatment groups. The hearing improvement achieved was stable for, on average, 8 years of follow-up. During the follow-up period, Ménière's disease was diagnosed in only 1 of the 116 patients who answered the questionnaire and no cases of acoustic neurinoma were diagnosed, indicating that establishment of a careful patient history and clinical and audiological investigations are sufficient for the diagnosis of S-SNHL. In general, the hearing improvement achieved in S-SNHL patients is stable during long-term follow-up.

Wide scope prenatal diagnosis at Kuopio University Hospital 1997-1998: integration of gene tests and fetal karyotyping.

OBJECTIVE: To investigate the applicability of carrier screening in women undergoing invasive prenatal diagnosis. DESIGN: Prospective study. SETTING: University-based clinic. PARTICIPANTS: Two hundred and fifty-six pregnant women. METHODS: Gene tests were offered for fragile X syndrome, aspartylglycosaminuria and infantile neuronal ceroid lipofuscinosis at the time of invasive prenatal testing. RESULTS: The overall uptake of the tests was 92%. Previously unrecognised carriership was found in 10 women: aspartylglycosaminuria (7); infantile neuronal ceroid lipofuscinosis (2) and fragile X (1). Fetal genotyping was carried out in one carrier of aspartylglycosaminuria whose partner was also a carrier, and in one woman who was found to have fragile X premutation. Both fetuses were unaffected. CONCLUSION: Carrier screening for single-gene disorders is feasible and well accepted among pregnant women undergoing invasive prenatal testing. The major benefit is that there is no need to consider extra invasive tests when carriership is detected. Incorporation of genetic testing into fetal karyotyping gives more security to future parents.

Antenatal gene tests in low-risk pregnancies: molecular screening for aspartylglucosaminuria (AGU) and infantile neuronal ceroid lipofuscinosis (INCL) in Finland.

Approximately one in five subjects in Finland carries some gene defect associated with 30 diseases belonging to the Finnish disease heritage, and about one in 500 children born is affected. Almost all carriers, women and men, are unaware of their condition. Recent advances in molecular medicine have offered the possibility of population-based carrier screening for recessive disorders. We studied acceptance and attitudes to antenatal screening for aspartylglucosaminuria (AGU) and infantile neuronal ceroid lipofuscinosis (INCL). From January 1995 until December 1996 carrier tests were offered at Kuopio City Health Center, free of charge to all pregnant women attending maternity care units. Women found to be carriers of AGU (n = 47) or INCL (n = 14) underwent detailed genetic counseling, and their male partners were also offered the test. If both partners appeared to be carriers we offered prenatal testing (n = 1). No affected fetuses were detected. Attitudes towards the gene test were elicited by means of a questionnaire. Altogether 87% of pregnant women elected to undertake the gene tests. Antenatal screening for gene defects was feasible and well accepted, and it provided an effective way to find carriers of genetic diseases and to incorporate prenatal testing into this process.

Antenatal genetic screening for congenital nephrosis.

This study was undertaken to study the applicability of genetic antenatal screening for the Finnish type of congenital nephrosis (CNF), which is a recessive disorder leading to nephrotic syndrome from birth. At Kuopio University Hospital, a total of 1303 pregnant women were offered carrier screening for CNF at the time of first trimester nuchal fold translucency measurement when fetally derived alpha-fetoprotein is still produced by the yolk sac. Two mutations of the nephrin (NPHS 1) gene, accounting for approximately 95% of affected alleles, were tested by two PCR tests. Uptake of the gene test was 91.0% (n=1183). Altogether 38 female carriers were found; a population carrier frequency of 1 in 31. Their partners were tested and two of them were also found to be carriers. In these two pregnancies invasive prenatal diagnosis was offered and accepted, and the results indicated one carrier and one affected fetus. Carrier screening is an effective and well-accepted method for antenatal screening for fetal CNF. Direct mutation analysis involves markedly less invasive procedures compared with serum alpha-fetoprotein (AFP) screening, and the diagnosis was clear-cut. The results indicate that in single-gene disorders genetic testing is suitable for antenatal screening.

Prenatal diagnosis of fragile X syndrome and the risk of expansion of a premutation.

The aim of the present study was to evaluate prospectively the dynamics of the FMR1 gene. The risk of full mutation among pregnant women and the carriers, and the risk of expansion of a premutation allele to a full mutation were estimated. We identified 89 pregnant women with an expanded FMR1 gene seeking prenatal diagnosis. Amniocentesis or chorion villus sampling (CVS) was offered and a DNA test of the FMR1 gene was carried out in such pregnancies. The overall risk of full mutation among women (N = 21) with a repeat size between 60 and 80 was 4.8% (one fetus with mosaicism), and the risk of expansion of the premutation allele to a full mutation was 14% in those offspring to whom the premutation allele was transmitted. The risk of full mutation among the carriers (N = 13) with a repeat size between 81 and 100 was 61.5% (8/13), and the risk of expansion of a premutation allele to a full mutation was 89%. Only one case fell into the category of 101-200 repeats, and expansion to a full mutation was recorded. Fetuses of full mutation mothers inherited the larger allele in 64% (14/22) of the cases. The range of 40-59 repeats was safe: there were no fetal full mutations. The risk of full mutation was also low among the subjects with a repeat size between 60 and 80, whereas the risk increased significantly after 80 repeats. Maternal premutation size was positively correlated with the risk of having a full mutation offspring.

Pregnancy outcome in carriers of fragile X.

OBJECTIVE: To evaluate pregnancy outcome in women who are carriers of fragile X. DESIGN: Cross-sectional case-control study. SETTING: Department of Obstetrics and Gynaecology, Kuopio University Hospital, Finland. SAMPLE: Sixty-three singleton pregnancies in carriers of fragile X who were referred for genetic counselling and prenatal diagnosis to Kuopio University Hospital. METHODS: Logistic regression analysis was used to compare pregnancy outcome in women who are fragile X carrier with outcome of the general obstetric population. RESULTS: Carriers of fragile X often experienced more bleeding in late pregnancy than did the reference group. Otherwise, the course and outcome of pregnancy were comparable in both groups. CONCLUSION: Pregnancy outcome in women who are carriers of fragile X is favourable. There is no need to initiate special fetal monitoring because of the fragile X status of the woman.

Effect of carbogen inhalation on peripheral tissue perfusion and oxygenation in patients suffering from sudden hearing loss.

The effects of repeated carbogen inhalation on peripheral tissue perfusion and oxygenation were assessed in 5 patients suffering from sudden hearing loss by means of continuously measured subcutaneous tissue oxygen and carbon dioxide tension, transcutaneous oxygen tension, laser Doppler red cell flux, and fingertip temperature. The subcutaneous oxygen tension increased clearly during the carbogen inhalation periods, and also, a smaller increase in subcutaneous carbon dioxide tension was simultaneously noticed. The changes in transcutaneous oxygen tension were even greater and the latency was shorter as compared with the subcutaneous gas tensions. The laser Doppler measurements showed no signs of vasoconstriction during the study. In conclusion, carbogen inhalation increases peripheral tissue oxygenation without microvascular vasoconstriction and with only a minor retention of carbon dioxide.

Sudden deafness: a comparison of anticoagulant therapy and carbogen inhalation therapy.

Sudden deafness (SD) is a sudden or rapidly progressive, partial or complete, typically unilateral sensorineural hearing impairment that has no known specific etiologic factor. This study was designed to compare, in a group of 168 consecutive patients with SD, the effect of anticoagulant therapy and carbogen inhalation therapy. Special attention was paid to the shape of the audiogram relative to the clinical outcome and the treatment modality. We found that the configuration of the audiogram of SD patients is prognostic of the outcome, and that patients with a low-frequency-sloping hearing impairment have a better prognosis compared to the patients with a high-sloping loss. Anticoagulant treatment was most effective in low-sloping hearing losses, while carbogen inhalation may be more effective for patients with high-sloping hearing losses.

Betahistine-induced vascular effects in the rat cochlea.

Betahistine (BH) has been used widely to treat cochlear disorders, such as tinnitus and Meniere's disease. The mechanism of action of BH in the cochlea is assumed to be based on its histamine-like effect on H1 receptors in the cochlear vasculature, leading to an increased cochlear blood flow (CBF). Recently it has been shown that BH can strongly affect H3 heteroreceptors (a novel histamine receptor subclass) in the periphery, via an autonomic ligand. This mechanism may also contribute to the BH effects on CBF. This study was to validate BH effects in the cochlear vasculature and to investigate the possible mechanisms of action of this drug in the inner ear vasculature. We assessed the effects of BH on CBF with the laser Doppler flowmeter in 23 rats and concluded that BH affects vascular conductivity in the cochlea in a dose-dependent fashion; betahistine diffuses through the round window, but does not have access to vascular receptors or ligands once in the labyrinthine fluids; and the H1 receptors mediate the systemic and peripheral vascular effects of BH, whereas the cochlear effect involves cholinergic receptors.

The effect of CO2- and O2-gas mixtures on laser Doppler measured cochlear and skin blood flow in guinea pigs.

The effects of carbogen (5% CO2: 95% O2) 10% CO2-in-air and 100% O2 on cochlear blood flow (CBF), skin blood flow (SBP), blood pressure (BP) and arterial blood gases were investigated in the anesthetized, respired or self-respiring guinea pig. In respired animals, CBF and SBF were increased with carbogen and 10% CO2-in-air and decreased with O2. BP was elevated with each gas. In freely breathing animals, only 10% CO2-in-air caused a small increase in CBF; both carbogen and O2 caused CBF to decrease. SPF changes were similar in form, but larger than those seen in respirated subjects. No consistent change in BP was seen during breathing of these mixtures. Arterial PO2 was increased by carbogen and 10% CO2-in-air for both groups. PCO2 increased for both CO2 gas mixtures during forced respiration; but in free-breathing animals PCO2 only increased for 10% CO2-in-air (normal PCO2 values were maintained with carbogen thorough increased breathing rate). The observed changes in CBF were consistent with a balance between a combined vasoconstrictive effect of PO2 and vasodilation effect of PCO2 on cochlear vessels. Analysis of cochlear vascular conductivity (CBF/BP) indicated that vasodilation was significant only with 10% CO2-in-air in respirated animals. In all other conditions the increased CBF apparently reflects the increase profusion pressure associated with respiration of each gas. For clinical purposes, while carbogen does not appear to directly cause vasodilation of cochlear vessels it does lead to an increased oxygenation of the cochlea blood and would appear to avoid the cochlear vasoconstriction caused by 100% O2.

Electronystagmographic findings and recovery of cochlear and vestibular function in patients suffering from sudden deafness with a special reference to the effect of anticoagulation.

The study included 80 patients treated for sudden deafness over the last 5-7 years. Case history, laboratory findings, pure-tone audiogram and electronystagmography (ENG) findings were noted. If any abnormalities had been recorded in ENG studies, the studies were redone. ORL status was redefined and audiograms were obtained in all patients. When becoming ill, the 80 patients had not differed from the normal population in common cardiovascular risk factors. None of them had had signs of viral infection (paired serum samples had been taken at 2-week intervals; routine examinations had been done for common viral antigens). As many as 31 of the 80 patients with acute hearing loss had had abnormalities such as spontaneous nystagmus (PN), hypoexcitability (HE) and directional preponderance (DP) in the bithermal caloric tests (+44 degrees C, + 30 degrees C) of their ENG studies. Twenty of the 31 patients still had abnormal ENG studies after 5-7 years. Only 1 subject had positional nystagmus, and none had subjective vertigo. Patients with an abnormal ENG study showed a poor recovery of the speech reception threshold, whereas those with a normal ENG study showed slightly significant (p less than 0.05) recovery.