Angioplasty and stenting for intracranial atherosclerotic stenosis: position statement of the Hong Kong Society of Interventional and Therapeutic Neuroradiology.

As a means of preventing secondary ischaemic stroke, angioplasty and stenting are considered potentially beneficial for patients with severe intracranial atherosclerotic stenosis. However, the role of stenting has been challenged since the publication of the first randomised controlled trial on Stenting versus Aggressive Medical Management for Preventing Recurrent stroke in Intracranial arterial Stenosis (SAMMPRIS). This indicated that aggressive medical management was superior to stenting using Wingspan to prevent recurrent stroke, because stenting has a high peri-procedural stroke and death rate. In this paper, we review the management of intracranial atherosclerosis, revisit the skepticism on stenting, and state our position on the topic in the form of recommendations. These are based on the prevalence of the disease in Hong Kong, the high risk of recurrent stroke despite medical therapy in the presence of haemodynamic intracranial stenosis without sufficient collaterals, an analysis of the weak points of SAMMPRIS, and results of clinical studies in Hong Kong.

Bypass surgery or percutaneous transluminal angioplasty to treat critical lower limb ischaemia due to infrainguinal arterial occlusive disease?

OBJECTIVES: To define the role of bypass surgery and percutaneous transluminal angioplasty to manage critical limb ischaemia due to infrainguinal arterial occlusive disease. DESIGN: Retrospective review. SETTING: Regional hospital, Hong Kong. PATIENTS: Consecutive patients treated for critical limb ischaemia, for whom data were prospectively collected in those who underwent: (i) infrainguinal percutaneous transluminal angioplasty first, or (ii) infrainguinal bypass surgery. RESULTS: Among patients with critical lower limb ischaemia, 364 consecutive individuals having infrainguinal bypass operations and 100 having percutaneous transluminal angioplasty first were compared. The latter patients were older (77 vs 74 years, P=0.014) and had more co-morbidities but higher ankle pressure than those having bypass surgery. In the angioplasty-first group, 74% had favourable lesions (classified as TransAtlantic Inter-Society Consensus A/B). In the bypass group, operative mortality was higher (4% vs 1%, P=0.03) than that in the angioplasty-first group. Hospital mortality was comparable (8% vs 3%, P=0.15). In the bypass group, median hospital stay was longer than that in the angioplasty-first group (24 vs 4 days, P<0.001), and postoperatively they also had a higher median ankle-brachial index (0.92 vs 0.70, P<0.001) and superior long-term patency. In the bypass group, American Society of Anesthesiologists class 4 patients suffered very high operative and hospital mortality (15% and 31%, respectively). Long-term patency of percutaneous transluminal angioplasty depended on the TransAtlantic Inter-Society Consensus class of the treated lesion. Limb salvage rates at 3 years were 89% and 78% for percutaneous transluminal angioplasty first and surgical bypass, respectively (P=0.046). Long-term survival was poorer in the percutaneous transluminal angioplasty-first group (21% vs 51% at 5 years, P=0.04). CONCLUSION: Infrainguinal bypass and percutaneous transluminal angioplasty are complementary. For TransAtlantic Inter-Society Consensus A and B lesions, percutaneous transluminal angioplasty should be offered first. For American Society of Anesthesiologists class 4 patients, percutaneous transluminal angioplasty should be considered first, regardless of the TransAtlantic Inter-Society Consensus class.

Electromagnetic ray tracing model for line structures.

In this paper, a model for electromagnetic scattering of line structures is established based on high frequency approximation approach - ray tracing. This electromagnetic ray tracing (ERT) model gives the advantage of identifying each physical field that contributes to the total solution of the scattering phenomenon. Besides the geometrical optics field, different diffracted fields associated with the line structures are also discussed and formulated. A step by step addition of each electromagnetic field is given to elucidate the causes of a disturbance in the amplitude profile. The accuracy of the ERT model is also discussed by comparing with the reference finite difference time domain (FDTD) solution, which shows a promising result for a single polysilicon line structure with width of as narrow as 0.4 wavelength.

Microalbuminuria prevalence study in hypertensive patients with type 2 diabetes mellitus in Singapore.

INTRODUCTION: Microalbuminuria is a marker of increased cardiovascular morbidity and mortality. It represents the earliest clinical evidence of diabetic nephropathy. Its early detection allows for implementation of individually-tailored cardiovascular risk reduction management programmes. Despite this, information on the prevalence of microalbuminuria in hypertensive patients with type 2 diabetes mellitus in Singapore is limited. METHODS: The Microalbuminuria Prevalence Study (MAPS) assessed the prevalence of macroalbuminuria and microalbuminuria in consecutively-screened hypertensive adult patients with type 2 diabetes mellitus in ten Asian countries. This paper presents the results of a sub-analysis of data from patients in Singapore. RESULTS: Singapore contributed seven percent of the overall enrolment into MAPS; a total of 499 patients were enrolled and 388 constituted the per-protocol population (patients with bacteriuria and haematuria were excluded). Overall, the prevalence of diabetic kidney disease was high. In our study population, 23.5 percent of patients had macroalbuminuria (95 percent confidence interval [CI] 21.3-25.6), and 48.5 percent of patients had microalbuminuria (95 percent CI 45.9-51.0). Only 28.1 percent (95 percent CI 25.8-30.4) of patients were normoalbuminuric. Associated factors were poor glycaemic control and poor blood pressure control. CONCLUSION: The high prevalence (72 percent) of microalbuminuria and macroalbuminuria found in hypertensive patients with type 2 diabetes mellitus in Singapore is a cause for concern. These findings highlight the need to screen for microalbuminuria and better manage hypertensive patients with type 2 diabetes mellitus, if we are to avoid a major increase in end-stage renal disease.

Dissolution and swelling behaviors of random and cross-linked methacrylic acid-ethyl acrylate copolymers.

The neutralization behaviors of random and cross-linked methacrylic acid-ethyl acrylate (MAA-EA) copolymers were examined as a function of degree of neutralization (alpha) using potentiometric titration and laser light scattering techniques. The random MAA-EA copolymers exhibit a conformational transition from a compact latex particle to a swollen randomly coiled aggregate upon neutralization over a certain range of alpha. With further addition of NaOH, the swollen aggregates dissociate into several smaller clusters. This conformational change is controlled by the balance between electrostatic repulsion within ionized MAA groups and hydrophobic attraction of EA. The cross-linked MAA-EA copolymers do not undergo a drastic conformational change during neutralization. The polymer latex particles swell slightly upon neutralization, and the extent of chain expansion is proportional to MAA molar composition and inversely proportional to cross-linked density. The electrostatic Gibbs energy (DeltaG(el)) obtained from the potentiometric titration data indicates that a higher MAA portion is favorable for the deprotonization of both the random and cross-linked MAA-EA copolymers, suggesting that the dissociation is mainly dominated by polymer structure instead of the electrostatic attraction between H(+) and -COO(-). Moreover, static and dynamic light scattering results confirmed that the cross-linked latex particle exists as monodispersed hard sphere in the collapsed state, whereas in its swollen state the latex particle possesses a core-shell structure.

Binding of dodecyltrimethylammonium bromide to pH-responsive nanocolloids containing cross-linked methacrylic acid-ethyl acrylate copolymers.

The binding of dodecyltrimethylammonium bromide (DoTab) to cross-linked methacrylic acid-ethyl acrylate (MAA-EA) copolymers with various MAA/EA molar ratios at different degrees of neutralization (alpha) was quantitatively studied using isothermal titration calorimetry, dynamic light scattering, surfactant selective electrode, and electrophoresis techniques. The surfactant binds to the polymers at all degrees of neutralization, but via different mechanisms. When alpha is sufficiently high, the binding is primarily electrostatic interaction between the surfactant and ionized polymer chains, which is reinforced by the micellization of electrostatically bound surfactant molecules. The saturation takes place at charge ratio ([DoTa(+)]/[ approximately COO(-)]) close to 1, indicating that the binding is a one-to-one charge neutralization between the cationic surfactant headgroups and anionic carboxylate sites of the polymers. When alpha is low, the binding of DoTab to the unneutralized polymers is driven by the hydrophobic interaction. The onset of hydrophobic binding takes place at DoTab concentration as low as 0.01 mM in 0.05 wt % polymer solution, where the saturation occurs at C(DoTab) approximately 0.19 mM and the amount of bound surfactant is approximately 0.09 mmol of DoTab/(g of polymer) at saturation concentration. The binding results in the formation of the polymer-surfactant complex. For the polymer with low MAA/EA molar ratio, the complex coagulates at a higher DoTab concentration that leads to phase separation; however, for polymers with high MAA/EA molar ratio, the complex remains dispersed and the mixture is stable even at high DoTab concentration.

Growth and spontaneous regression of a middle cerebral artery aneurysm after surgical clipping.

SUMMARY: We present a case of growth and spontaneous regression of a middle cerebral artery aneurysm after surgical clipping. A 36-year-old woman who presented with grade II subarachnoid haemorrhage was found to have a right middle cerebral artery aneurysm. The aneurysm was surgically clipped in view of the morphology of the aneurysm. Second clipping was performed four months later as there was re-growth of the neck of the aneurysm. Again re-growth of the aneurysm was noted five months after the second clipping. As further clipping of the aneurysm would be difficult, external and internal carotid arteries bypass was the treatment option but unfortunately, the by-pass operation was unsuccessful. Interestingly, angiogram performed after the bypass surgery revealed partial thrombosis and decreasing size of the aneurysm. Complete obliteration of the aneurysm was noted without further intervention one month after the failed by-pass surgery.

Tongue deviation in acute ischaemic stroke: a study of supranuclear twelfth cranial nerve palsy in 300 stroke patients.

It is generally believed that the supranuclear innervation of the hypoglossal nucleus is bilateral and symmetrical. The aim of this work is to study the frequency and clinical characteristics of supranuclear tongue palsy in unilateral stroke. 300 patients with acute unilateral ischaemic motor strokes (excluding those in the lower brainstem) and an equal number of normal controls were studied for the presence of tongue deviation in a standardised manner. 29% of stroke patients and 5% of controls had tongue deviation (p < 0. 00001). Deviation was always to the side of the limb weakness. In patients with a history of stroke, it occurred more frequently in those with previous stroke on the contralateral side. Tongue deviation was most common in patients with clinical features of the non-lacunar stroke subtype (56%) or in those with cortical or large subcortical infarctions on brain CT scan (55 and 45%, respectively). All tongue deviations were associated with supranuclear 7th nerve palsy. Dysphagia and dysarthria occurred in 43 and 90% of patients with tongue deviation. Weakness of the arm was significantly associated with presence of tongue deviation. Tongue deviation in unilateral stroke most likely results from asymmetrical supranuclear control of the 12th cranial nerve in many individuals. The finding that it occurs relatively commonly in large (non-lacunar) infarcts and its association with dysphagia may have clinical utility.

Clinics in diagnostic imaging (47). Huntington's disease.

A 38-year-old man presented with progressive worsening of choreiform movements. Serum biochemistry analysis did not reveal any abnormality. Magnetic resonance imaging demonstrated symmetrical caudate nucleus atrophy and generalised cerebral strophy. Huntington's disease was diagnosed in view of the clinical presentation and the characteristic imaging findings. The clinical, pathological and imaging features of this disease process are discussed.

Nipah viral encephalitis or Japanese encephalitis? MR findings in a new zoonotic disease.

BACKGROUND AND PURPOSE: An epidemic of suspected Japanese encephalitis occurred in Malaysia in 1998-1999 among pig farmers. In neighboring Singapore, an outbreak occurred among pig slaughterhouse workers. It was subsequently established that the causative agent in the outbreak was not the Japanese encephalitis virus but a previously unknown Hendra-like paramyxovirus named Nipah virus. METHODS: The brain MR images of eight patients with Nipah virus infection were reviewed. All patients tested negative for acute Japanese encephalitis virus. Seven patients had contrast-enhanced studies and six had diffusion-weighted examinations. RESULTS: All patients had multiple small bilateral foci of T2 prolongation within the subcortical and deep white matter. The periventricular region and corpus callosum were also involved. In addition to white matter disease, five patients had cortical lesions, three had brain stem involvement, and a single thalamic lesion was detected in one patient. All lesions were less than 1 cm in maximum diameter. In five patients, diffusion-weighted images showed increased signal. Four patients had leptomeningeal enhancement and four had enhancement of parenchymal lesions. CONCLUSION: The brain MR findings in patients infected with the newly discovered Nipah paramyxovirus are different from those of patients with Japanese encephalitis. In a zoonotic epidemic, this striking difference in the appearance and distribution of lesions is useful in differentiating these diseases. Diffusion-weighted imaging was advantageous in increasing lesion conspicuity.

Aberrant regeneration of the third nerve.

We describe three patients with aberrant regeneration of the third nerve secondary to traumatic brain injury. The full blown features of the syndrome include horizontal gaze-eyelid synkinesis, pseudo-Graefe sign, limitation of elevation and depression of the eye with retraction of the globe on attempted vertical movements, adduction of the involved eye on attempted elevation or depression, pseudo-Argyll Robertson pupil and absent vertical optokinetic response. The 'misdirection' incidence in our study is 15%.

The feasibility of three-dimensional guglielmi detachable coil for embolisation of wide neck cerebral aneurysms.

SUMMARY: The three-dimensional Guglielmi detachable coil is a modification of the conventional Guglielmi coil. It has a unique complex structure, with alternating small and large loops at 90 degrees angle to each other during deployment. The enhanced coil complexity optimizes coil purchase on the aneurysm wall, promoting coil stability within the aneurysm sac. It may be the solution of the single catheter technique in the embolisation of wide neck aneurysms.We report our early experience in the embolisation of wide neck aneurysms using these complex coils.

Palatal myoclonus--a case report.

Palatal myoclonus is usually due to a brainstem or cerebellar lesion disrupting the dentato-rubro-olivary pathway. Rarely it may be caused by a cortical lesion. The precipitating factor in 70% of all cases is an infarct. We describe an unusual case of a patient with palatal myoclonus who had an old ipsilateral cerebellar infarct and a new contralateral subcortical (corona radiata) infarct. We postulate that the new infarct caused disinhibition of the old cerebellar infarct, resulting in palatal myoclonus. Magnetic resonance imaging (MRI) of the brain did not show any hypertrophy of the inferior olivary nucleus. Her myoclonus proved refractory to clonazepam, valproate and phenytoin.

The neurological manifestations of Nipah virus encephalitis, a novel paramyxovirus.

A novel Hendra-like paramyxovirus named Nipah virus (NiV) was the cause of an outbreak among workers from one abattoir who had contact with pigs. Two patients had only respiratory symptoms, while 9 patients had encephalitis, 7 of whom are described in this report. Neurological involvement was diverse and multifocal, including aseptic meningitis, diffuse encephalitis, and focal brainstem involvement. Cerebellar signs were relatively common. Magnetic resonance imaging scans of the brain showed scattered lesions. IgM antibodies against Hendra virus (HeV) were present in the serum of all patients. Two patients recovered completely. Five had residual deficits 8 weeks later.

Paradoxical seizures in phenytoin toxicity.

Phenytoin toxicity is an uncommon problem seen in clinical practice. The predisposing factors for toxicity are hypoalbuminemia, chronic renal failure, hepatic dysfunction and drugs which interfere with phenytoin metabolism. Common manifestations of toxicity, like confusion and ataxia, are well known. A less well known phenomenon is paradoxical seizures. In this condition, seizures develop as the serum phenytoin level rises and decrease in frequency as levels drop. It may or may not be accompanied by other features of toxicity. We present three patients with paradoxical seizures; their serum phenytoin levels were 43.5 mcg/mL, 46.5 mcg/mL and 38.3 mcg/mL. In all cases, seizures were controlled by withdrawal of phenytoin and reduction of drug levels.

Why do patients complain? A primary health care study.

BACKGROUND/AIM OF STUDY: Patient complaints are indications of their dissatisfaction with the service received. With increasing patient expectations, we need to address this issue for a more satisfying relationship between healthcare provider and user. The objective of this study was to analyse the basis of patients' complaints and to make recommendations to reduce its incidence. METHOD: This is a retrospective descriptive study of all complaints to the Family Health Service between January 1994 and December 1995. All complaints, investigations and replies to complainants were examined and analysed by the authors to determine the reasons for complaints and their justification. RESULTS: There were 226 complaint cases out of 5,620,834 attendances in two years, giving the complaints rate of 4 per 100,000 attendances per year. The complaint rate was highest for the 20-59-year age group and lowest in the 10-19-year age group (3.7 and 2.0 per 100,000 attendances respectively). Sixty-four percent of complaints were verbal and the rest were written. Forty-seven percent of the complaints were made by relatives and 46% were self-complaints. The main reasons for complaints were related to attitude/conduct (28.8%), professional skills (17.8%), patient expectations (16.2%), waiting time (10.0%) and communication (7.8%). Forty-three percent of complaints were evaluated as justifiable, 38% not justifiable and 19% inconclusive. There were no particular sex or ethnic group differences. CONCLUSION: The rate of complaints in Family Health Service was low. Healthcare personnel need to pay attention to areas related to attitude/conduct, professional skills, patient expectations, waiting time and communication.

A case of bilateral ulnar nerve palsy in a patient with traumatic brain injury and heterotopic ossification.

Heterotopic ossification after head injury may occur in the elbow joint. Rarely does this lead to entrapment of the ulnar nerve. We describe the case of a 20-year-old patient who developed heterotopic ossification 6 weeks after a traumatic brain injury. She subsequently developed bilateral ulnar nerve palsy which was confirmed by electrodiagnostic studies and treated by transposition of the ulnar nerve.

The syndrome of painful legs and moving toes--a case report.

The syndrome of painful legs and moving toes is an uncommon and distressing condition with pain in the feet or legs and involuntary movements of the toes. It can follow spinal cord or cauda equina trauma, lumbar radiculopathy, injury to the feet, peripheral neuropathy or without any preceding causes. Ephaptic transmission in damaged nerve roots or peripheral nerves with central reorganisation may be the underlying mechanism of the syndrome. Treatment is difficult. We report a case of this syndrome following peripheral neuropathy, with a good early response to the GABA agonists baclofen and clonazepam. The role of different GABA agonists in the treatment of this condition needs to be better defined.

Sciatic neuropathies--a retrospective review of electrodiagnostic features in 29 patients.

Sciatic neuropathy is an uncommonly diagnosed focal mononeuropathy. We reviewed the aetiology and electrodiagnostic features of 29 patients studied at the Neurodiagnostic Laboratory, Tan Tock Seng Hospital from January 1989 to April 1995. External nerve compression was the most common cause (38%) followed by trauma (21%). Other rare causes in this series included intragluteal injections, hip surgery and diabetic mononeuropathy while 24% had uncertain aetiology. Electrodiagnostic studies showed preferential involvement of the peroneal division in 51%. Axonal loss was found in 97%. We conclude that sciatic neuropathy often mimics distal peroneal nerve dysfunction and neurophysiological studies are essential for diagnosis. Furthermore, these studies are necessary for assessing prognosis in relation to axonal loss.