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Neuro rehab research

A new ice age in rehab?



Offshore oil and gas explorers have inspired a journey into unchartered waters for neuroscience.

For the energy industry’s precise understanding of fluid and heat ow
has been used to investigate how blood transfers heat around the brain.

And the results could bring about new ways of treating head trauma and stroke in their immediate aftermath.

Dr Prashant Valluri, of Edinburgh University, is an expert on “mathematical modelling of flows”.
Usually this sees him working with industry, analysing the flow of substances or heat around complex systems like oil rigs or computer circuitry.
 Blood in the brain is his latest area of focus, however.

“As chemical engineers, when we design cooling systems, we know the most efficient way is to have ow. If there is no ow, it will take a lot longer to cool down.

“It was therefore quite shocking to see that ow in the brain had never really been seriously considered – perhaps because computing technology used in brain modelling was not fast enough in the past. This took us by surprise, but gave us an opportunity to change things.

“We decided to see if ow is necessary
or plays an important role and found
that it plays a dramatic role in terms
of heat transfer.”

The study, based around sophisticated
 3D simulations, has provided new insight on how the brain responds to medically induced cooling, which is routinely used
to limit head injury damage. The ongoing research brings together the university’s medical and engineering faculties.

Its overall aim is to pave the way for new
and improved ways of brain cooling following stroke or head injury.

Current methods include cooling the entire body temperature, particularly in new born babies with brain injury caused by oxygen shortage during birth.

In this procedure, the baby’s body is usually cooled using a special mattress filled with cooling fluid. Sometimes just the head is cooled using a custom-made cap.

As the temperature is lowered from the normal 37°C to between 33 and 35 °C, the processes that cause brain damage have been shown to slow down.

Similar methods are also used among adults after stroke and brain injury. Other approaches include cooling via nasal gas flow, head fanning and liquid-based head and neck cooling devices.

Induced hypothermia in adults sees patients given ice cold intravenous drips within 10 days of their accident and kept cool with cold water blankets or cooling pads for at least 48 hours.

While the practice is widely used in European and North American intensive care units to reduce head pressure linked to brain damage – recent research has questioned its value in supporting long term recovery.

A 2015 study, also by the University of Edinburgh, tracked 400 traumatic brain injury (TBI) cases from 18 countries. Around half of the patients were treated with standard procedures.

The other half were treated with induced hypothermia
to try to protect the brain from further damage caused by swelling.

The team found that induced hypothermia was successful at reducing the build-up
of pressure in the skull after head injury.

Six months later, however, patients who had received the therapy were more likely to fare worse than those treated with standard care Favourable outcomes, ranging from moderate disability to good recovery, occurred in only 
a quarter of the patients in the hypothermia group compared to more than a third of patients in the control group.

Doctors ended the trial early because of fears that the therapy may cause harm to some patients.

Valluri says: “The issue with methods such as scalp cooling is that they are empirical. They are not really informed by the physics of what’s going on in the brain.

“There’s no device that can tell you how long cooling should be carried out for, for optimal results. It’s more a case of ‘see what happens’. It isn’t always clear what the exact routine should be, especially in the event of complications.”

The latest study out of Edinburgh promises to re ne the brain cooling process. It shows that the potentially dangerous process of cooling the entire body may not be necessary to achieve the reduction in core brain temperature needed to minimise damage.

Valluri and colleagues – including experts from both medicine and engineering academic fields – have developed a detailed “bio-heat” model of the brain, showing the impact of cooling.

The model is the first to take into account simultaneous flow, heat transfer and metabolism between arteries, veins and brain tissue in three dimensions throughout the organ.

The “vascular porous (VaPor) model” factors in cerebral blood ow, energy equations, including heat generated by metabolism (based on MRI data) and clever “tree generation” algorithms.T

he result is a more detailed picture of how
the brain responds to medically induced cooling than has ever before been available.

Using computer simulations, researchers found that cooling the heads of new-born babies to 10°C would enable their core brain temperature to fall from a normal level of 37°C to below 36°C – which is recognised as low enough to aid recovery.

This could dramatically help babies at risk of long-term damage from birth complications, without having to cool their entire body, researchers say.

When applied to adult brains, the model predicted that head cooling was able to precipitate a potentially beneficial 0.5°C drop, in line with clinical observations.

Going forward, the model will be modified to test the impact of stroke and administered drugs on the brain.

Upon publishing the results, Ian Marshall, of the University of Edinburgh’s College of Medicine, who co-led the research, said: “Getting vital patient information such as core brain temperature is a challenge and is only currently possible through expensive MRI scans. A robust model which can predict temperature and blood ow is therefore the need of the hour.”

Marrying the expertise of engineers and doctors was crucial to the study’s success, believes Valluri.

It could also support the next stage – new techniques or devices which better target core brain temperature reduction for better outcomes after brain injury, he says.

“The most important thing to come out of this study would be to develop a cooling device. Once we have an idea of what the brain temperature will be if someone has a complication, what treatment will avoid further damage?

“Ideally any new device should not be expensive. It should be accessible to everyone, and quick to administer. Perhaps it could be wearable and flexible.

“It should also be small; in the event of a complication, there is already a lot of medical equipment involved so we don’t want to load the ambulance up with more. The device should also cater for people of any age.

“Of course, it might be that a new routine, rather than device, is what’s required.” Valluri summarises the achievements of
the researchers so far as merely “mimicking reality to the extent that it is possible to act”.

What actions follow the findings could have major implications for neuro-rehab.



Lowering temperature raises survival rates

A 2015 study by the University of Edinburgh found inconclusive evidence that inducing hypothermia in post-brain injury patients supports long term recovery.

A more recent study, however, suggests that it does save lives after trauma.
Therapeutic hypothermia (TH) involves reducing the body temperature of a person to protect neurons from being killed o or damaged.

Researchers from Royal Holloway, Ashford and St Peters Hospital and Imperial College London evaluated the value of TH in 2016.

They found that adults subjected to TH were significantly less likely to die or suffer serious cognitive impairment due to damaged neurons.

“Lowering the body temperature to treat people with TBI is a controversial treatment, but one that our latest research has shown to reduce deaths and long-term injury,” said Professor Pankaj Sharma, director of the Institute of Cardiovascular Research at Royal Holloway.

“We have undertaken the largest such analysis of data on the use of therapeutic hypothermia and have found that patients have an 18 per cent better chance of surviving and a 35 per cent improvement in neurological outcome if they are given this treatment.”

Researchers looked at around 3,100 cases of TBI in adults and around 450 cases in children.

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