Auditory brainstem activity and development evoked by apical versus basal cochlear implant electrode stimulation in children.

OBJECTIVE: The role of apical versus basal cochlear implant electrode stimulation on central auditory development was examined. We hypothesized that, in children with early onset deafness, auditory development evoked by basal electrode stimulation would differ from that evoked more apically. METHODS: Responses of the auditory nerve and brainstem, evoked by an apical and a basal implant electrode, were measured over the first year of cochlear implant use in 50 children with early onset severe to profound deafness who used hearing aids prior to implantation. RESULTS: Responses at initial stimulation were of larger amplitude and shorter latency when evoked by the apical electrode. No significant effects of residual hearing or age were found on initial response amplitudes or latencies. With implant use, responses evoked by both electrodes showed decreases in wave and interwave latencies reflecting decreased neural conduction time through the brainstem. Apical versus basal differences persisted with implant experience with one exception; eIII-eV interlatency differences decreased with implant use. CONCLUSIONS: Acute stimulation shows prolongation of basally versus apically evoked auditory nerve and brainstem responses in children with severe to profound deafness. Interwave latencies reflecting neural conduction along the caudal and rostral portions of the brainstem decreased over the first year of implant use. Differences in neural conduction times evoked by apical versus basal electrode stimulation persisted in the caudal but not rostral brainstem. SIGNIFICANCE: Activity-dependent changes of the auditory brainstem occur in response to both apical and basal cochlear implant electrode stimulation.     

Traumatic work related fatalities in commercial fishermen in Australia.

OBJECTIVES--To describe the types and circumstances of traumatic work related fatalities in Australian commercial fishermen. METHODS--Work related traumatic fishing fatalities were studied as part of a larger study of all work related traumatic fatalities in Australia from 1982 to 1984. Data on 47 cases were obtained from inspection of coroners' files. RESULTS--The incidence of fatality of 143/100,000 person-years was 18 times higher than the incidence of fatality for the entire workforce, and considerably higher than that of the mining and agricultural workforces. 68% of decedents drowned and 13% died from physical trauma. Rough weather, non-seaworthy vessels, inadequate use of personal flotation devices, and inexperience were associated with many of the fatal incidents. DISCUSSION--Improved vessel and equipment maintenance, better training of workers, greater use of personal flotation devices, and development of improved clothing and personal flotation devices are recommended.     

Reflections of a distance education facilitator.

After nearly a year of preparation, 'Therapeutic Communication', the first nursing unit in our new Bachelor of Nursing degree was taught for the first time in 1988. The unit has developed and grown since this time, with both educational and financial factors determining such things as design of student materials and assessment mode. The geographically scattered--and often isolated--students are formally recognised for their individuality and their personal and professional life experiences, and given choices within the unit of what they want to learn and how they will present this material, through introduction of a learning contract as part of the unit assessment. Difficulties encountered by these students in maintaining their self-esteem when moving from the demanding and complex world of clinical nursing to the arena of tertiary study are discussed. The provision of speedy, comprehensive feedback with general as well as specific guidance with essay writing and referencing, focuses on the process skills many nurses lack as they enter this unit. The applicability of therapeutic communication to clinical practice and the diversity of projects undertaken by students within the limits of the unit demonstrate its appeal to a wide range of registered nurses. Some of the often ignored or minimised factors that differentiate external study from on-campus work are highlighted for both students and unit facilitator, and the creation of an in-house booklet to assist students in developing their skills in external study is outlined.     

Development of the brachial spinal cord in the marsupial Macropus eugenii (tammar wallaby).

The development of the brachial spinal cord was studied in the marsupial Macropus eugenii (tammar wallaby) on postnatal days 1-34. On day 1 the spinal cord was histologically immature, with a deep central canal, proliferating neuroepithelium and roof and floor plates. The lateral motor column had formed, and forelimb muscles contained primary myotubes. The spinal cord gradually attained a mature appearance between days 1-34. The results confirm the suitability of the wallaby spinal cord for studies of early mammalian development.     

Localized cerebral proton MR spectroscopy in HIV infection and AIDS.

PURPOSETo document differences in the cerebral proton MR spectra of patients with early and late stages of human immunodeficiency virus (HIV) infection.METHODWe studied the relative N-acetyl-aspartate (NAA) levels by localized proton spectroscopy of the parietooccipital region of the brain in 43 HIV-seropositive patients, including 26 with an acquired immunodeficiency syndrome (AIDS)-defining diagnosis, and in eight control subjects.RESULTSReduced relative NAA levels were shown in those HIV-1-seropositive patients: 1) with AIDS against HIV-1-seropositive patients without AIDS (P < .04); 2) with HIV-1-associated cognitive/motor complex against neurologically healthy patients (P < .007); 3) with encephalopathic changes on MR against those with normal imaging (P < .001); and 4) on follow-up against their results on initial study (P < .03).CONCLUSIONSBy clinical (Centers for Disease Control classification) and radiologic (MR evidence of white-matter disease) criteria indicating late-stage HIV infection, reduced relative levels of NAA have been demonstrated. Spectroscopic abnormalities can be quantitatively tracked with time. This paper demonstrates the clinical use of detecting NAA as a putative in vivo measure of the neuronal loss that has been demonstrated in postmortem studies of patients with AIDS. This neuronal loss, which is believed to underlie the HIV-1-associated cognitive/motor complex, is thought to be attributable directly or indirectly to the presence of HIV in the brain. Proton spectroscopy may serve as a quantitative noninvasive indicator of this aspect of cerebral involvement in HIV disease.