in North American and some Australasian centres. Is the use of thesetherapies justified on the basis of the current evidence? Does theimprovement in mortality seen in patients with malignant middlecerebral artery territory infarction undergoing decompressive crani-ectomy come at the cost of increased numbers of patients living withsevere disability? Or is hemicraniectomy a useful therapeutic addi-tion? Other therapies such as transcranial sonolysis or near infraredlaser therapy have also been shown to be of promise in strokepatients. Is the rationale behind these therapies sound and are thepositive study results simply a statistical aberration? These andother controversial new stroke therapies will be presented.

doi:10.1016/j.jocn.2010.07.049

49. Idiopathic intracranial hypertensionJohn King

University of Melbourne and Royal Melbourne Hospital, VIC

Idiopathic Intracranial Hypertension (IIH) presents neurologistswith important diagnostic and therapeutic challenges. There is apotential for misdiagnosis unless thorough clinical assessment, lum-bar puncture and MRI/MRV are carried out.

The aim of treatment is relief of symptoms and preservation ofvision. Most patients can be managed by medical treatment to lowerintracranial pressure, weight reduction and regular follow-up untilthe patient is in remission.

Where medical treatment fails and there is loss of visual acuityand/or field, surgical options should not be delayed. There are no evi-dence-based guidelines to assist the clinician but lumbo-peritonealor ventriculo-peritoneal shunting, optic nerve sheath fenestrationand dural venous sinus stenting have all been reported to be effec-tive. All the procedures have their advantages and disadvantagesand all may fail no matter what procedure is used. Once again regu-lar review by the neurologist is necessary to avoid permanent visualloss.

doi:10.1016/j.jocn.2010.07.050

50. Does the principle of minimum work apply at the carotidbifurcation?G. Das, R. Beare, M. Ren, W. Chong, V. Srikanth, T.G. Phan

Stroke and Ageing Research Group, Monash Medical Centre, VIC

Background: There is recent interest in the role of carotid bifurca-tion anatomy, geometry and hemodynamic factors in the pathogen-esis of carotid artery atherosclerosis. Investigators have drawnparallel between certain anatomical and geometric configuration atthe carotid bifurcation and its exposure to disturbed flow. Anintriguing idea is that the vascular dimensions of the intracranialcarotid artery may be optimally designed such that there is mini-mum work to maintain blood and pump it through a vascular sys-tem. It has been proposed that this occurs when the exponentpower relationship between the radii of the parent artery and thedaughter arteries is 3. In this study, we evaluate if the dimensionsof bifurcation of the extracranial carotid artery follows this principleof minimum work.

Methods: This study involved subjects who had CT angiographyat Monash Medical Centre between 2006–2007. Subjects with lumi-nal stenosis >30% were excluded. Following segmentation of the car-otid artery, the radii and areas of the common carotid/parent artery

and the two daughter arteries (internal and external carotid arteries)were determined. A non-linear equation solver was used to deter-mine the optimum value of power n.

Results: When the equation was solved for radius, the value of nranged from 1.4 to 1.8.

Conclusion: Our findings indicate that the principle of minimumwork (as defined by power n of 3) may not apply at the carotid bifur-cation and may suggest that additional factors play a role in the rela-tionship between the parent and daughter vessels radii.

doi:10.1016/j.jocn.2010.07.051

51. Bilateral frontal periventricular locations of cerebral whitematter lesions show greatest covariance with poorer gaitVelandai Srikanth a, Thanh G. Phan a, Jian Chen a, Richard Beare a,Jenny Stappleton a, David C. Reutens b

a Stroke and Ageing Research Group, Monash Medical Centre, VICb Queensland Brain Institute, University of Queensland, QLD

Background: Ageing is associated with a slowing and hesitancy ofgait, and in some, this may take the form of a more serious gaitapraxia. Greater volume of cerebral white matter lesions (WML) isassociated with poorer gait. One possible causal mechanism for thisis that WML disconnect neural networks specifically involved in gait.We hypothesised that WML associated with gait impairment arepreferentially distributed in regions related to the control of gait.

Methods: High-resolution brain MRI and computerised gait anal-ysis were performed on 385 participants in the population-basedTasmanian Study of Cognition and Gait (TASCOG). A composite gaitfactor was derived using factor analysis. Semiautomated segmenta-tion was used to identify lesion-affected voxels. The multivariatevoxel-based method of partial least squares regression was used todetermine which systems of WML voxels showed greatest covari-ance with gait independent of other WML voxels.

Results: Systems of WML affected voxels in bilateral frontal andperiventricular regions demonstrated greatest covariance withpoorer gait. The location of these voxels corresponded mainly tomajor anterior projection fibres (anterior and superior thalamic radi-ations, corticopontine and corticospinal tracts), adjacent parts ofanterior association fibres (corpus callosum, superior longitudinalfasciculus, short association fibres).

Conclusion: WML may contribute to age-related gait decline bydisrupting frontally located afferent and efferent projection andassociation tracts known to be involved in the execution of plannedmovement.

doi:10.1016/j.jocn.2010.07.052

52. The role of ABCD2 in predicting stroke recurrence in theAustralian settingLauren Sanders a, Velandai Srikanth a, Helen Pshigohios b, KittyWong a, Dave Ramsay b

a Stroke and Ageing Research Group, Monash Medical Centre, VICb Monash Medical Centre,VIC

Background: To determine the accuracy of the ABCD2 tool in pre-dicting stroke outcome in an Australian cohort of patients.

Method: This is a retrospective cohort study. The setting is anurban tertiary referral hospital in Melbourne, Australia. All adultspresenting with suspected Transient Ischaemic Attack (TIA) who

Abstracts / Journal of Clinical Neuroscience 17 (2010) 1610–1638 1625