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Dr Andrew Davidson

portrait Andrew DavidsonDr Andrew Davidson - New Approach in AVM Research

Dr Andrew Davidson is a Fellow of the Royal Australasian College of Surgeons but his current PhD research at the Australian School of Advanced Medicine (ASAM) at Macquarie University focuses on a non-surgical cure for arteriovenous malformations in the brain.

An arteriovenous malformation (AVM) is an abnormal connection between low-pressure veins and high-pressure arteries which is probably formed prior to birth. The tangled mesh of vessels can be very fragile and prone to bleeding, causing strokes. 

Dr Davidson is a consultant neurosurgeon with a clinical group of Macquarie Street specialists in Sydney and has been able to draw on a database of 640  AVM patients amassed by one of his PhD supervisors and Dean of ASAM, Professor Michael Morgan. Their database is of a similar size to major multicentre international databases of AVM patients.  

“While AVMs may occur in around two in 10,000 people, there is an over-representation of young patients. AVMs account for only one to two percent of all strokes but are a leading cause of stroke in young people.

AVMs present in a similar demographic of young people as multiple sclerosis but do not have the same public exposure, said Dr Davidson. The average age of patients in the research database is 37 with just over half (52 percent) of them male.

His study reveals that about 50 percent of AVM patients presented with bleeding, 25 per cent with seizures and 10 percent were picked up incidentally with CT scans performed for unrelated problems.

Current treatment to stop bleeding in vessels to prevent death or devastating symptoms are open brain surgery, embolisation or blocking of diseased vessels with a glue-like material, or radiotherapy. Often these treatments are used in combination. 

Obliteration rates using radiotherapy ranged from 75 percent for small AVMs to 53 per cent for medium to 13 per cent for large. 

Dr Davidson is taking a very different approach and working at the interface of two disparate fields of research - focused ultrasound and molecular biology. 

Focused ultrasound, said Dr Davidson, uses heat energy to treat lesions deep within the body without affecting intervening tissue. Using low level focused ultrasound causes molecular changes to cells and tissues but does not permanently damage them. The challenge now is to use this technique on cultures of endothelial cells that line blood vessels and induce changes in their genetic and protein structure. 

The expertise in molecular biology required in this area is provided by colleagues in the Australian Proteome Analysis Facility (APAF Ltd) at Macquarie University - a pioneer in proteomics (the study of proteins expressed by genes), including the rapidly developing field of protein “biomarkers”. 

“Focused ultrasound has evolved from normal ultrasound techniques over the past decade. In Australia and the US oncologists already use ultrasound to treat prostate, uterine, and breast tumours while in the US and Europe there have been preliminary trials on tumours of the brain. The military are investigating the use of focused ultrasound to stem bleeding in the field, but the intensity of treatment required to stop bleeding also causes significant tissue damage,” said Dr Davidson.

The interdisciplinary research at ASAM and APAF is being closely followed by overseas neurosurgeons eager to find new and more effective ways to manage AVMs. In September (2009] Dr Davidson spoke about his early findings at two major conferences: The World Congress of Neurological Surgery in Boston and the Neurosurgical Society of Australasia Annual Scientific Meeting held in Alice Springs.

Dr Davidson was a Surgeon Lieutenant-Commander in the Royal Australian Navy before specializing in neurosurgery.  He undertook his neurosurgery training in New South Wales, and was admitted as a Fellow of the Royal Australasian College of Surgeons in 2008. Dr Davidson was awarded the John Loewenthal Medal for his research on dural arteriovenous malformations in 2005, and graduated with the degree of Master of Surgery from University of Sydney in 2006.  His interests include microsurgery for aneurysms, arteriovenous malformations, cavernomas and skull base surgery. He will be a founding member of the Department of Neurosurgery at the new Macquarie University Hospital, due to open early in 2010.