After studying Li's symptoms, Tian suggested that Jin bring her mother to Beijing for a more detailed examination.

"Doctor Tian diagnosed my mom with essential tremor and suggested the deep brain stimulation procedure and the electrode implants," says Jin.

Surgery always carries risk and none more so than brain surgery. Tian was careful to lay the dangers out for Li and Jin.

"Unlike a routine surgery, such as removing a tumor, DBS is a functional surgery which carries the risk that the patient may lose some essential functions after surgery. It's more of an exploratory procedure," says Tian.

According to Tian, unlike surgery that save people's lives, DBS surgery simply aims to improve the patient's quality of life, noting that, "because movement disorders are not fatal, the patient has to decide whether they want to take the risk or not."

Tian says that, because most of the movement disorder patients he treats have suffered with their respective conditions for years, many have developed mental disorders as a result. Equally, family members who've witnessed the deterioration of their loved ones, and have to care for them, often manifest mental and emotional complaints as well.

"Sometimes neurologists also have to act as psychiatrists, especially before surgery," says Tian.

After weighing up the pros and cons, the chance of having her normal life back was too great a reward, so Li opted for surgery.

"My confidence in the surgery came from Tian. He is passionate and professional, and he is gentle and kind to all of his patients. We are lucky to have met him," says Jin.

Preparation for surgery is key, as Tian needs to locate the nidus of the condition. It goes without saying that the brain is a complicated organ, with a network of millions of cells and neurons. Locating the root of the problem, therefore, is not always that easy. Tian needs to use a combination of experience and technology to detect it.

"The nidus is like an enemy that has disguised itself and infiltrated an army unit," says Tian. "What's more, it has made itself so integral to the working of the unit, that if you take it down, you need to have a good one to take its place."

The electrode is that replacement and the success of the surgery relies on finding the exact position to place the electrode-in this case, nuclei around 5 mm in diameter.