S.R. Hammond

Multiple sclerosis in Australia: socioeconomic factors.

The data from an epidemiological study on multiple sclerosis in Australia have been analysed to determine the relation between the prevalence of the disease and educational level, and the association between level of disability and employment status. There was a significantly higher frequency of multiple sclerosis in those who left school at an older age and achieved a higher educational level. The explanation of this finding remains speculative and may be related to genetic or environmental factors. The study confirmed the recognised association between moderate-severe disability and divorce-separation and lower rates of employment.

The contribution of mortality statistics to the study of multiple sclerosis in Australia.

Mortality statistics provided a valuable source of support for data obtained from prevalence surveys of multiple sclerosis in Australia. Firstly, multiple sclerosis mortality data for the decade 1971-80 in the States of Australia confirmed the relationship between increasing disease frequency and increasing south latitude shown by State and regional point prevalence surveys based on the national census day 30 June 1981. Secondly, a comparison with mortality data from the decade 1950-59 showed that in most States there had been a substantial fall in multiple sclerosis mortality in the more recent decade and this was clearly an important contributing factor to the rise in prevalence noted between the morbidity surveys of 1961 and 1981. Thirdly, multiple sclerosis mortality in the UK-born migrant population dying in Australia was found to be similar to that of the Australian-born population and very much lower than that found in the UK. This observation corroborated evidence from the 1981 morbidity surveys and suggested that migration from the UK to Australia may lower the risk of developing multiple sclerosis either through a reduction in disease incidence or the operation of environmental factors curbing disease expression.

The epidemiology of multiple sclerosis in Queensland, Australia

An epidemiological survey of multiple sclerosis (MS) in the State of Queensland was undertaken with its prevalence day being the national census day on June 30th, 1981, 20 years after a regional survey within the State. The relationship between increasing prevalence of MS and increasing south latitude within the State of Queensland which was suggested by the 1961 study was confirmed in the present study. The prevalence rate had increased significantly over the 20-year period between the studies but the State remained a medium frequency zone for MS (prevalence rate between 5 and 29 per 100,000 of population). Although a real increase in disease frequency could not be excluded as a contributing factor to the rise in prevalence, it was most likely due predominantly to an increase in life expectancy amongst the MS population and also in differential migration of a population at a greater risk of developing MS than the indigenous population. The proportions of Australian-born patients who had migrated to Queensland from the higher risk southern regions of Australia or travelled overseas to countries known to be high-risk for MS prior to disease onset, had fallen between the two surveys thus exerting, if anything, a negative influence on the change in prevalence. Analysis of MS prevalence rates amongst migrant populations in Queensland as compared to the more southerly city of Perth in Western Australia, suggested that the risk of acquisition of MS may extend over a wider age range than is generally accepted. Finally, there was an absence of MS cases amongst the Aboriginal population in Queensland but it can only cautiously be concluded from this study that the disease is rare in these peoples.

Multiple sclerosis in Australia: prognostic factors

In order to determine the influence of age of onset, sex, onset symptoms, clinical course and interval from onset to first relapse on the subsequent outcome of multiple sclerosis (MS), data from 2934 cases of MS documented in a large population based study undertaken in Australia have been analysed. Disability on prevalence day (30 June 1981) was defined on the Kurtzke disability scale as mild (DSS 0-3), moderate (DSS 4-6) and severe (DSS 7-9). Prognostic factors associated with mild vs moderate/severe, and moderate vs severe disability on prevalence day were identified by logistic regression analysis. A worse prognosis was significantly associated with older age of onset, progressive disease course, onset symptoms that were multiple, pyramidal or cerebellar, and a short interval between onset and first relapse.

The clinical profile of MS in Australia A comparison between medium‐ and high‐frequency prevalence zones

Recent epidemiologic studies of multiple sclerosis (MS) in Australia defined the State of Queensland as a medium-frequency zone and the more southerly placed cities of Perth, Newcastle, and Hobart as high-frequency zones. Clinical profiles in the patient populations of both frequency zones were remarkably similar in most respects to each other and to MS populations in the northern hemisphere. However, male patients in Queensland differed from their counterparts in the three cities by showing a greater tendency to develop a progressive disease course and, hence, more disability. The explanation for these observations is uncertain; we speculate that the hotter climate in Queensland may be relevant.

Variability on serial testing of pattern reversal visual evoked potential latencies from full-field, half-field and foveal stimulation in control subjects

The change in pattern reversal visual evoked potential (PRVEP) latency over time (test-retest variability, TRV) was assessed in 30 (16 males, 14 females) adult control subjects using full-field (FF), half-field (HF) and foveal (central-field, CF) stimulation. The mean test-retest interval (TRI) was 20.5 months with a range of 18-21.5 months. There were no significant test-retest latency differences in either sex and furthermore there were no significant inter-sex differences in any of the test-retest parameters. Because of the latter finding the test-retest upper limit of normal for each parameter as defined by the mean value + 2.5 S.D. was taken as the largest value obtained in either sex. Thus the test-retest upper limits of normal for absolute latency from FF, right HF, left HF and CF stimulation were 6, 7, 9 and 7 msec, respectively; for interocular latency differences (ILD) from FF and CF stimulation were 4 and 5 msec respectively; and for right HF to left HF intraocular latency difference (IOLD) was 7 msec. It is concluded that the TRV was sufficiently small in our control group with each of the stimulus techniques to make all of them potentially useful in serial PRVEP studies. Furthermore the extra information provided by CF and HF stimulation may increase the sensitivity and accuracy with which change can be monitored.

The interaction between sex and click polarity in brain-stem auditory potentials evoked from control subjects of Oriental and Caucasian origin

Brain-stem auditory evoked potentials (BAEPs) were performed on 30 male and 30 female young normal Oriental subjects, using both condensation and rarefaction stimulation. The effects of sex and click polarity on the BAEP latencies and amplitudes were studied. Females had shorter absolute and interpeak latencies and higher absolute amplitudes than the males. These sex-related BAEP differences were independent of the click polarity. Rarefaction clicks produced shorter wave I latency and longer I-III interpeak latency, but the differences were significant in the female only. The polarity-related BAEP amplitude differences were essentially independent of the sex. BAEPs performed on 60 sex- and age-matched young Caucasian subjects produced similar results. The importance of establishing control BAEP values according to the sex and click polarity is emphasised.

A comparison of brainstem auditory evoked responses evoked by rarefaction and condensation stimulation in control subjects and in patients with Wernicke-Korsakoff syndrome and multiple sclerosis☆

Brainstem auditory evoked responses (BAER) evoked by rarefaction and condensation stimulation were compared in patients with Wernicke-Korsakoff syndrome (WKS) and multiple sclerosis (MS) and click polarity-related differences in topodiagnosis were found in 24% of the WKS and 40% of the MS patients. These results suggest the need to record BAER routinely with both stimulus polarities separately if practicable. BAER from rarefaction and condensation stimulation were recorded from control subjects of both sexes to provide control data for the patient study and also to investigate the interaction between sex and click polarity. BAER latency and amplitude differences between males and females were found to be independent of click polarity. However, the study did show an interaction between female sex and click polarity-related BAER latency differences although differences in amplitude and waveform morphology were essentially independent of sex. This further emphasises the importance of taking into account the variables of sex and stimulus polarity in establishing BAER control values.

The prevalence of idiopathic intracranial hypertension and associated co-morbidities in central western new south wales (nsw)

Objectives Over the last 20 years we have been surprised by the large number of patients seen with idiopathic intracranial hypertension (IIH) in Central Western NSW. We therefore performed a study to quantitate the prevalence of this condition. This is the first epidemiological study of IIH performed in Australia and one of the first to investigate a rural population worldwide. The primary objective was to identify the prevalence of IIH in Central Western NSW. Secondary objectives included identifying the prevalence of IIH subtypes, true and venogenic, identifying the prevalence of co-morbidities amongst these patients and reviewing clinical outcomes. Methods The representative population comprised five areas within Central Western NSW defined by postal code. Retrospective analysis was conducted from the two neurology practices in the region. Data collected from patient files included patient demographics, presenting symptoms, imaging results, co-morbidities, treatments received and clinical outcomes. Prevalence was calculated using 2011 census data (2016 data being unavailable). Results We found an overall prevalence of 24.9 per 100 000, with 7.9 true and 17 venogenic. All participants identified were female. A large proportion of individuals were either overweight or obese. The most common co-morbidities amongst IIH patients were migraine (31·8%), depression (30%) and hypertension (22.7%). Overall 81.2% of patients reported symptomatic improvement (75% true and 85.7% venogenic). Of those, 33.3% received stenting (all were patients with venogenic IIH) while 66.7% improved with medical management alone (50% true and 50% venogenic). Conclusions We have identified a higher prevalence of IIH in Central Western NSW compared with the previously reported UK prevalence of 10.9 per 100 000. This disorder is also highly prevalent in obese females thus clinicians should have a high index of suspicion in any obese female patient with headache. Although the majority of patients experience symptomatic relief, randomised controlled trials of treatment modalities are needed.

81. : Adult onset opsoclonus-myoclonus with autonomic dysfunction responsive to intravenous immunoglobulin

We describe a case of idiopathic adult onset opsoclonus-myoclonus syndrome with autonomic dysfunction, and review the clinical features and management of this rare condition. A 23-year-old woman was admitted to a regional hospital in NSW, Australia with opsoclonus-myoclonus syndrome (OMS) and moderate ataxia following a recent influenza-like illness, complicated by autonomic dysfunction. Intensive diagnostic assessment revealed no evidence of a remote neoplasm, and para-infectious OMS was felt the most probable diagnosis. Admission was complicated by autonomic dysfunction requiring critical care unit admission. The symptoms responded to treatment with high dose intravenous Ig (IVIG) and methylprednisolone. Apart from elevated influenza A antibodies, serological tests did not confirm a recent infection. Diagnosis was made of idiopathic OMS. OMS is a rare autoimmune central nervous system disorder in adults. Both parainfectious and paraneoplastic causes must be considered. Autonomic dysfunction in idiopathic OMS is unusual, and is usually associated with identified paraneoplastic antibodies such as NMDA receptor antibodies. As demonstrated in our patient, IVIG and corticosteroids are effective first line therapies in the management of parainfectious or idiopathic OMS with complete recovery.