Researcher Profile: Professor Todd Hardy

A career shaped by curiosity – and one unforgettable patient

Prof Hardy did not initially set out to become a neurologist. He began with a science degree, then a PhD exploring the mechanisms that control neurotransmitter release from nerve terminals – the intricate chemical signalling that underpins everything the brain does. Medicine came later.

“I always thought I might want to specialise in neurology after starting Medicine,” he says, “but I tried to keep an open my mind to other possibilities during training.” Nonetheless, as he progressed through medicine, the neurology cases kept drawing him back – complex, fascinating, and at the time, on the cusp of a revolution.

“There was a real shift happening in multiple sclerosis (MS) and neuroimmunology,” he recalls. “We were able to make new diagnoses and start new treatments that were quite revolutionary. It was stimulating to go into that field because things were moving rapidly and it was becoming possible to make a real difference to patients.”

But it was a single patient that would set the course of a significant part of his career.

She was young and deteriorating quickly. The diagnosis wasn’t clear, and the clock was ticking. Prof Hardy spent hours combing through the medical literature before finally reaching a breakthrough. 

“I had a Eureka moment that she had Susac’s syndrome,” he recalls. “Once confirmed, we were able to treat her and see her recover to have a normal life.”

It is the kind of outcome that stays with a doctor. 

From that moment, Prof Hardy’s commitment to Susac’s syndrome only deepened. He went on to establish Australia’s first Susac’s syndrome database (known as SuSAD) and today is effectively the national reference point for the disease, with Susac’s patients referred to him from neurologists right across the country. 

He now serves on the International Susac’s Syndrome Steering Committee, helping coordinate global research efforts into the disease, with a major international registry now underwaybeing planned.

A disease hiding in plain sight

So what exactly is Susac’s syndrome? In simple terms, it is an autoimmune condition in which the body’s immune system turns on itself – mistakenly attacking the tiny blood vessels of the brain, inner ear and retina. 

The consequences are wide-ranging and often devastating. In the brain, patients can experience cognitive deficits, confusion, delirium, and even psychiatric symptoms. Damage to the inner ear can cause hearing loss, tinnitus and balance problems. In the eyes, patients develop areas of visual loss. 

Because the symptoms span neurology, audiology, and ophthalmology, it is a disease that can slip through the cracks – misdiagnosed as MS, migraine, Meniere’s disease, or stroke.

“It’s so rare it hasn’t really been studied properly,” Prof Hardy says. 

Estimates put its prevalence at around 0.15 per 100,000 people – so uncommon that most clinicians may go their entire career without seeing a case. And yet, the Sydney-based neurologist suspects the true number may be higher than that.

 “Over time there’s been a greater recognition of Susac’s syndrome and a better understanding of what the MRI findings look like,” he says. “We’re slowly getting better at diagnosing it.”

One of the most telling MRI features – “snowball” lesions in the corpus callosum, the structure that connects the two hemispheres of the brain – has become an important diagnostic marker. But even with improved awareness, misdiagnosis remains common. The disease is a master of disguise.

With support from the Brain Foundation, Prof Hardy and his team undertook a study designed to better understand how Susac’s syndrome damages the brain — and how that damage progresses over time.

Using serial MRI scans alongside advanced imaging software and AI-assisted imaging analysis tools developed in collaboration with the Sydney Neurological Neuroimaging Analysis Centre, the researchers examined two key factors: the number and distribution of brain lesions, and changes in brain volume over time.

The findings were striking.

“We found that Susac’s syndrome causes widespread and progressive damage to the brain that can be measured clearly on MRI,” Prof Hardy explains. 

Lesions were detectable even in the early stages of the disease, particularly in the corpus callosum – reinforcing its importance as a diagnostic marker. But it was the brain volume findings that really underscored the seriousness of the condition.

The research revealed that people with Susac’s syndrome lose brain tissue at a significantly faster rate than healthy individuals. While some degree of brain shrinkage occurs naturally with ageing, the level observed in Susac’s patients went far beyond what could be attributed to age alone. 

“That reflects real, ongoing injury to brain cells and connections,” he says. “Not just temporary inflammation.”

Hit it hard – and early

For Prof Hardy, the clinical implications are clear. The research reinforces what he has long suspected: that Susac’s syndrome must be treated aggressively, and early.

“We definitely need to be aggressive in our treatment. Not undertreat at the start – clinical experience and the available evidence converge to say hit it hard,” he says. 

Corticosteroids remain the frontline treatment, suppressing the immune system and limiting damage. In many almost all cases, higher-powered immunotherapies are added, though not without risk, given the potential side effects, including serious infection.

What this research now helps clarify is which patients may need that more intensive approach from the outset, and how long ongoing immune treatment may need to continue in order to minimise lesion formation, prevent further brain shrinkage, and protect long-term function.

“The findings reinforce the importance of early diagnosis, careful monitoring with MRI, and prompt, effective treatment to limit long-term disability and protect brain function,” he says.

The reality of researching a rare disease

Ask Prof Hardy about the challenges of this work, and he doesn’t hesitate.

“There are lots of challenges in research generally, especially being a clinician as well.” 

The administrative burden alone is immense. Ethics approvals, patient consent forms, grant applications – years of work before a single blood sample can be taken. And unlike research into more common conditions, there are no large, well-resourced teams research teams to share the load.

“You’re essentially battling away, doing it in your spare time,” he says. “There’s always a struggle for help and resources. And then once the study is up and running, you need to be able to pay people – for analysis, for working on study endpoints, for consumables.”

This is where philanthropic funding becomes not just helpful, but essential.

“Rare diseases are often neglected,” Prof Hardy says. “They don’t have the loud voice that more common conditions do. Charitable organisations like the Brain Foundation play a critical role in making sure these patients are not forgotten and that the research can actually happen. Without it, this work simply doesn’t get done.”

Reasons for hope

Beyond Susac’s syndrome, Prof Hardy is also involved in MS research, working with colleagues Prof Laura Piccio and Prof Anthony Don from the University of Sydney on a biobank of blood samples from MS patients. Using tandem mass spectrometry, the team is investigating whether certain molecules could serve as biomarkers for diagnosing MS, distinguishing it from other relapsing neurological conditions, and measuring how well patients respond to treatment. 

It is, in many ways, characteristic of the way Prof Hardy approaches his work – methodical, collaborative, and always with the patient in mind.

When asked what gives him hope for the future of Susac’s syndrome, he points to the growing momentum of the international research community.

“At the moment, people are interested. There are researchers mobilising around the world, trying to collaborate on an international level around diagnosis and treatment. That’s really encouraging.”

And for patients and families living with Susac’s syndrome, many of whom have spent years searching for answers, he has a simple but powerful message.

For the patients who first inspired his career, and for those still waiting for better answers, Clinical Professor Todd Hardy is making sure it does.