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Improving brain surgery outcomes with TMS



Professor Sandro Krieg specialises in the diagnosis and treatment of challenging brain tumours.

These tumours are located in parts of the brain responsible for critical processes such as language and motor functioning.

The German neurosurgeon has conducted extensive research into the use of navigated transcranial magnetic stimulation (nTMS), both as a mapping tool and a novel treatment for brain injury.

Using nTMS data to guide surgery

When a brain tumour puts pressure on surrounding healthy cells, normal processes are disrupted, sometimes leading to changes in behaviour.

For example, the frontal lobe controls personality and emotions, playing a vital role in long term memory and problem-solving.

A tumour in this area upsets these functions and can lead an individual to act aggressively or impulsively.

The brain can also reorganise in response to a tumour. This unpredictable change adds another layer of complexity and risk to the extraction process.

If the tumour is located in an area now responsible for language, removal could present a huge risk to the patient.

With nTMS, developed by Nexstim, neurosurgeons like Professor Krieg can create a 3D map of the brain and use this data to guide surgery.

The technique enables neurosurgeons to extract more of the tumour, leading to better outcomes for the patient.

Professor Krieg said:

“You no longer have to say to the patient ‘this might be motor function and here might be receptive language, here might be conceptive language, but I’ll find out during surgery.’

                        Professor Sandro Krieg

“Today, we can create a map of the brain that shows us exactly where these processes are.

“With this information, we can make a plan with the patient.

“We can show them, ‘here is your English and Swedish language and here is where some of the tumour might be left behind.’”

Stroke Research

A 2021 year study by Professor Krieg investigated the use of TMS in glioma patients.

The patients had suffered an ischemic stroke during tumour surgery, resulting in loss of motor function in the upper extremity (hand and arm).

Professor Krieg said:

“We focused on paresis of the upper extremity because we wanted to have measurements for a range of motor skills and we wanted to be sensitive.

“We also know that the upper extremity is more reachable by TMS.”

Two-thirds of the patients received 15 minutes of low-frequency TMS of the unaffected hemisphere for seven consecutive days.

The patients were also given 30 minutes of physical therapy within one hour of receiving the TMS.

A third of the patients only received the physical therapy, making up the sham group.

The patients were then invited to attend follow-up assessments after seven days and three months.

These included the NIH Stroke Scale (NIHSS), Fugl-Meyer, which measures motor functioning and balance, and the Nine Hole Peg Test which measures finger dexterity.

The two groups performed to a similar standard at day one and day seven. But by three months, the TMS patients were significantly further ahead.

Professor Krieg said:

“The TMS group developed more power and improved fine motor skills.

“Many patients normally don’t recover at all. Their hand doesn’t function anymore and becomes spastic.

“It’s not only the hand. The whole upper extremity becomes spastic.

“It is really astonishing to be able to modify the motor system in such a way in these older patients.

“I imagine the process would be even more effective in paediatric patients.”

Dr Krieg is confident in the safety and efficacy of the technology.

The paresis treatment requires just one hertz of TMS while the mapping requires five hertz, minimising side-effects.

While some patients report experiencing a mild headache, studies have shown a less than one percent risk of seizure as a result of TMS, even among patients with symptomatic epilepsy.

Prof. Krieg said

“If you have such a short time to live, every day you have more function is extremely valuable for the patient.

“If you have patients who can take care of themselves and leave the hospital, it’s worth doing it. Even just faster recovery would be great.

“But we’re not just talking recovery. The effect is permanent.”

Find out more about Nexstim at Nexstim.com

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