Implications of Deep Electrode Insertion on Cochlear Implant Fitting

Using long Med-El Combi40+ electrode arrays, it is now possible to cover the whole range of the cochlea, up to about two turns. Such insertion depths have received little attention. To evaluate the contribution of deeply inserted electrodes, five Med-El cochlear implant users were tested on vowel and consonant identification tests with fittings with first one, two, and up to five apical electrodes being deactivated. In addition, subjects performed pitch-ranking experiments, using loudness-balanced stimuli, to identify electrodes creating pitch confusions. Radiographs were taken to measure each electrode insertion depth. All subjects used each modified fitting for two periods of about 3 weeks. During the experiment, the same stimulation rate and frequency range were maintained across all the fittings used for each individual subject. After each trial period the subject had to perform three consonant and three vowel identification tests. All subjects showed deep electrode insertions ranging from 605° to 720°. The two subjects with the deepest electrode insertions showed significantly increased vowel- and consonant-identification performances with fittings with the two or three most apical electrodes deactivated compared to their standard fitting with all available electrodes activated. The other three subjects did not show significant improvements in performance when one or two of their most apical electrodes were deactivated. Four out of five subjects preferred to continue use of a fitting with one or more apical electrodes deactivated. The two subjects with the deepest insertions also showed pitch confusions between their most apical electrodes. Two possible reasons for these results are discussed. One is to reduce neural interactions related to electrodes producing pitch confusions. Another is to improve the alignment of the frequency components of sounds coded by the electrical signals delivered to each electrode to the overall pitch of the auditory perception produced by the electrical stimulation of auditory nerve fibers.     

Risk factors for premature birth in French Guiana: the importance of reducing health inequalities

Objectives: French Guiana has the highest birth rate in South America. This French territory also has the highest premature birth rate and perinatal mortality rate of all French territories. The objective was to determine the premature birth rate and to identify the prevalence of risk factors of premature birth in French Guiana.

Methods: A retrospective study of all births in French Guiana was conducted between January 2013 and December 2014 using the computerized registry compiling all live births over 22 weeks of gestation on the territory.

Results: During this period 12 983 live births were reported on the territory. 13.5% of newborns were born before 37 (1755/12 983). The study of the registry revealed that common sociodemographic risk factors of prematurity were present. In addition, past obstetrical history was also important: a scarred uterus increased the risk of prematurity adjusted odds ratio =1.4, 95%CI (1.2–1.6). Similarly, obstetrical surveillance, the absence of preparation for birth or of prenatal interview increased the risk of prematurity by 2.4 and 2.3, the excess fraction in the population was 69% and 72.2%, respectively.

Conclusions: Known classical risk factors are important. In the present study excess fractions were calculated in order to prioritize interventions to reduce the prematurity rate.     

Pharmacokinetic interaction between high-dose methotrexate and oxacillin

An 18-year-old man received two high-dose methotrexate cycles for the treatment of an osteosarcoma. Fifteen grams of methotrexate were infused over 6 hours. During the second cycle, co-administration of oxacillin (1g/8h) resulted in prolonged and marked elevation of methotrexate plasma concentrations. The patient experienced acute toxicity with renal failure, myelosuppression, mucitis, fever, and dermatologic abnormalities. After an initial improvement with folinic acid rescue and hemodialysis, the patient died. Oxacillin may thus inhibit the elimination of methotrexate.     

Assessment of a disease-specific muscular impairment rating scale in myotonic dystrophy

OBJECTIVE: To document the intra/interrater reliability and the construct validity of the Muscular Impairment Rating Scale (MIRS) in assessing patients with myotonic dystrophy type 1 (DM1). The MIRS is a ordinal five-point rating scale, established in accordance with the clinically recognized distal to proximal progression of the muscular involvement in DM1, based partly on a manual muscle testing (MMT) of 11 muscle groups. METHODS: To assess the reliability of the MIRS, 55 patients with DM1 were examined by three different observers, one of them evaluating each patient twice. Intra- and interobserver reliability of the MIRS was measured using Cohen's weighted kappa. To assess the construct validity of the MIRS, correlations were made with the Functional Status Index (FSI) and eight timed functional tasks. RESULTS: The intraobserver reliability of the MIRS was excellent (weighted kappa = 0.84), and the interobserver reliability was interpreted as a substantial agreement (weighted kappa = 0.77 to 0.79). The correlation coefficients between MMT scores and MIRS grades were all highly significant (r(s) = -0.81 to -0.88, p < 0.001). The FSI showed a significant progressive increase of the total median dependence score in activities of daily living from 0 in MIRS grade 1 to 39 in MIRS grade 5 (p < 0.001). The time needed to perform the eight functional tasks was also found to significantly increase in relation with the progression of the MIRS grades. CONCLUSION: The MIRS is a quick, simple, and reliable measurement of muscular impairment in DM1. The FSI questionnaire and the timed motor activities supported its construct validity. The MIRS is useful to monitor major stages of DM1 progression, to study the natural history of the disease, and to identify homogeneous groups of patients for clinical trials.     

The prevalence of mycotoxins in Kashin-Beck disease

Mycotoxins are naturally occurring toxic chemical compounds produced by fungi infesting agricultural crops both during their growth and storage. Such secondary metabolites, when ingested, can produce toxic syndromes in humans. As it has been suggested that mycotoxins might be involved in the development of Kashin-Beck disease (KBD), we undertook a survey of barley grains of KBD-affected families and non-affected families in that country. We found, by thin layer chromatography, a hitherto unknown metabolite of Alternaria sp. This was especially common on the barley grains of KBD-affected families.     

Anthropometry and clinical features of Kashin-Beck disease in central Tibet

We compared two different populations living in central Tibet with the purpose of establishing standard values for different anthropometric parameters in a rural population. Later on, these values were used as references for a similar study on a KBD population. One group (KBD) (n=1,246) came from the endemic areas, and the other group, serving as the control population (n=815), came from non-endemic areas. Both groups included children and adults and were of the Mongoloid type; they were farmers or semi-nomads. Height, weight, segment length, joint perimeter, joint diameter, joint movement were recorded. Also more subjective information such as general feeling of tiredness, rapid fatigue at work, work limitation, joint pain, muscle weakness, muscular atrophy, dwarfism, flatfoot, and waddling gate was also collected. Those variables were compared between the two groups.     

An example of detection of heterozygotes and antenatal diagnosis in four families with anhidrotic ectodermal dysplasia

Anhidrotic ectodermal dysplasia is an X-linked inherited skin disorder; only affected males exhibit the complete syndrome, whereas females may have a few mild features. The gene involved in this disease is located in the proximal area of the long arm of the X chromosome, in the q13 position. Molecular analysis is very helpful for calculating the risk of transmission in sisters with normal phenotypes and affected individuals (family 1 provides an example), but cannot solve all problems (example of family 4). The best results are obtained when there are two informative markers, each located on either side of and very close to the mutant gene. Molecular analysis can also be applied to chorionic villi sampled at the tenth week of gestation in order to achieve antenatal diagnosis in male fetuses in high risk families. Until recently, antenatal diagnosis could be performed only at the twentieth week of gestation by the demonstration of inadequate development of skin glands in skin biopsy specimens sampled under fetoscopy. Family 2 provides an example of antenatal diagnosis and highlights the risk of error that always exists in molecular analysis studies.