Ischaemic stroke related to branch artery disease: a missing link?

INTRODUCTION: Clinicians and researchers often classify atherosclerotic cerebral infarctions into large artery atherothrombotic disease (LAD) and small artery lacunar infarction (LACI), but this system of ‘dichotomisation’ cannot account for a substantial proportion of stroke cases. Twenty years ago, a third mechanism for cerebral infarction - branch artery disease (BAD) - was proposed. However, this concept was understudied and still remains an obscure entity. METHODS: Stroke patients admitted under the Neurology Unit of Queen Mary Hospital over a 24- month period were studied retrospectively. Patients with ischaemic stroke presumably due to atherosclerotic disease were classified according to their imaging +/– clinical findings into three groups: LAD, BAD, and LACI. Patients with BAD were further categorised into five BAD stroke syndromes based on radiological criteria. Clinical characteristics, vascular risk factors, results of vascular workup, and outcome among the various stroke subgroups were compared. RESULTS: A total of 720 patients with a diagnosis of stroke were admitted during the study period, including 123 LAD (17% of all stroke patients or 33% of all studied patients), 147 BAD (20% or 40%), and 102 LACI (14% or 27%). Among the BAD patients, the number of cases involving Heubner’s artery, lenticulostriatal arteries, anterior choroidal artery, thalamoperforating/geniculate arteries or paramedian pontine infarction were 0, 47, 45, 15 or 40 (0, 32, 31, 10 or 27%), respectively. Patients with BAD were the youngest among the three groups. As compared to LAD patients, BAD patients had lower NIHSS scores, were less often diabetic, and carotid stenosis was less common, while stenosis of the intracranial arteries were more frequently seen in BAD as compared to LACI patients. Mean follow-up period was 1085 days, and outcome of BAD patients was intermediate between LAD and LACI. Comparison of variables among the BAD stroke syndromes showed that they were a homogenous group of conditions. CONCLUSION: Despite being a rarely applied concept, BAD is the most prevalent subtype of ischaemic stroke in our study. The homogeneity among the BAD syndromes suggests they might represent a distinctive stroke entity. Although patients with BAD and LACI had similar degrees of neurological deficits on presentation, outcome in the former group was significantly worse than the latter.published_or_final_versionThe 15th Medical Research Conference; Department of Medicine, The University of Hong Kong, Hong Kong, 16 January 2010. In Hong Kong Medical Journal, 2010, v. 16 suppl. 1, p. 30, abstract no. 4

Herpes simplex encephalitis: how good are we in diagnosing this condition?

INTRODUCTION: Herpes simplex encephalitis (HSE) is the commonest sporadic infective encephalitis in Hong Kong. Early recognition of HSE, which relies on a high index of suspicion, is important as effective treatment is available. Empirical acyclovir is advocated for all cases of clinically suspected viral encephalitis. Electroencephalography (EEG) is a routine investigation in suspected HSE. METHODS: The EEG database of Neurodiagnostic Unit, Queen Mary Hospital, was reviewed retrospectively. All referrals from April 2006 to March 2009 with a diagnosis of suspected HSE treated with empirical intravenous acyclovir were identified. Their presenting features, imaging and laboratory findings, and final diagnoses were reviewed. RESULTS: During the study period, 60 patients (mean age, 51 years; range, 18-90 years, M:F ratio=13:7) underwent EEG for suspected HSE. Presenting features included fever (n=39), confusion (n=39), impaired consciousness (n=31), focal signs (n=15, seizure in 8), and headache (n=13). All patients underwent brain CT and 45 had MRI. The commonest imaging findings were unrelated old changes (n=20) and normal study (n=16). Lobar inflammation was detected in four patients. EEG was normal, showed diffused abnormalities, or focal/ multifocal abnormalities in 16, 31, or 13 patients, respectively. Lumbar puncture was performed in 59 patients. Total cell count was ≤10×106 /L in 68% of patients and CSF protein was <0.8 g/L in 51% of patients. Polymerase chain reaction for herpes simplex virus was positive in one out of 56 requests. Viral encephalitis was the final diagnosis in three patients (HSE=1, Japanese encephalitis=1, other virus=1). Other common diagnoses included meningitis (n=9), non-CNS sepsis (n=9), psychiatric illnesses (n=8), epileptic seizure (n=6), and acute stroke (n=5). CONCLUSION: Our findings demonstrate that we were exercising a high index of suspicion for diagnosing HSE. Our liberal use of empirical acyclovir was also consistent with the IDSA (Infection Diseases Society of America) recommendations. Despite our low threshold of investigating for HSE, only one case was identified over 3 years, suggesting HSE is an uncommon condition.published_or_final_versionThe 15th Medical Research Conference; Department of Medicine, The University of Hong Kong, Hong Kong, 16 January 2010. In Hong Kong Medical Journal, 2010, v. 16 suppl. 1, p. 29, abstract no. 4

First year of 24/7 Acute Stroke Unit. Part 1: eligibility and utilisation of intravenous thrombolysis

INTRODUCTION: Intravenous recombinant tissue plasminogen activator (IV-rtPA) is the standard therapy for acute ischaemic stroke. Because of its narrow therapeutic time window, eligibility and utilisation rates of this treatment remained low. Our IV-rtPA programme was enhanced to a 24/7 protocol since September 20…published_or_final_versio

Clinical and neuroradiological features of viral encephalitis: a hospital-based study

Oral PresentationThis journal supplement contains abstracts from the 17th MRC; Dept. of Medicine, The University of Hong Kong, Queen Mary Hospital, Hong KongTopics: Basic science, translational and clinical researchINTRODUCTION: Viral encephalitis is an important infection of the central nervous system with significant morbidity and mortality. We studied the clinical, laboratory and radiological characteristics of viral encephalitis patients managed in our hospital, focusing on factors associated with poor prognosis. METHODS: We retrospectively studied the clinical features of patients diagnosed …published_or_final_versionThe 17th Medical Research Conference (MRC), Department of Medicine, University of Hong Kong, Hong Kong, 14 January 2012. In Hong Kong Medical Journal, 2012, v. 18 suppl. 1, p. 31, abstract no. 3

A novel approach to the surgical management of tophaceous gout: early results from a prospective observational pilot study

Concurrent Free Papers 9 - Sports/General Orthopaedics: no. 9.

Ischemic stroke related to intracranial branch atheromatous disease and comparison with large and small artery diseases

Background: The mechanism of ischemic stroke in intracranial branch atheromatous disease (BAD) is different from large artery atherothrombotic disease (LAD) or lacunar infarction (LACI). The concept of BAD is underused in clinical practice and research. Methods: Patients admitted over 24-months with ischemic stroke caused by atherosclerotic disease were reviewed retrospectively and classified according to radiological ± clinical criteria into LAD, BAD and LACI. The BAD cases were further divided into 5 BAD syndromes. Clinical characteristics, vascular risk factors, results of vascular workup and outcome among these subgroups were compared. Results: 123 cases of LAD (17% of all stroke patients or 33% of all studied patients), 147 BAD (20% or 40%) and 102 LACI (14% or 27%) presented during the study period. Compared to LAD, BAD patients had milder neurological deficits, were less often diabetic and carotid stenosis was less common, while stenosis of the intracranial arteries was more frequent in BAD as compared with LACI patients. Outcome in BAD patients was intermediate between LAD and LACI. Comparisons among the BAD syndromes indicated they were homogenous conditions. Conclusions: BAD is the most prevalent ischemic stroke subtype in our cohort. The homogeneity among the BAD syndromes suggests they might represent a distinctive stroke entity. © 2011 Elsevier B.V.link_to_subscribed_fulltex

Myopia as a latent phenotype of a pleiotropic gene positively selected for facilitating neurocognitive development, and the effects of environmental factors in its expression

Myopia has become an almost pandemic problem in many populations. There are compelling evidence to suggest that myopia is a hereditary condition. However, myopia would constitute a definite selection disadvantage during most stages of human evolution, which is incompatible with its moderate to high prevalence in most modern populations. The rapid upsurge of myopia over just a few decades also implies that its inheritance does not follow any of the usual patterns, and environmental factors may have an important role in precipitating its occurrence in those who are genetically predisposed. Previous studies showed that myopes were, on average, more intelligent than non-myopes, and this association had been attributed to a biological link between eye growth and brain development. We propose a pleiotropic genetic model to explain the atypical epidemiologic and inheritance pattern of myopia and its relationship with neurocognitive development. This pleiotropic gene was positively selected for its facilitation of human intelligence. The myopic component is a latent phenotype; myopia will not be expressed unless some novel external factors are encountered (i.e. a "quirk" phenomenon). Therefore, the myopic component was selectively neutral in our ancestral environment. The net gain in Darwinian fitness enables the pleiotropic gene to attain a high frequency in the human population, as reflected by our current prevalence of myopia. © 2005 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex