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Open this photo in gallery:Juhn Wada (March 28, 1924 – April 22, 2023), a Japanese–Canadian neurologist known for research into epilepsy and human brain asymmetry, including his description of the Wada test for cerebral hemispheric dominance of language function. On the day he received his honorary degree from UBC in 2015, taken in the back yard. Courtesy of the Family

Juhn Wada, on the day he received his honorary degree from UBC in 2015, was known for his research into epilepsy and human brain asymmetry, including his description of the Wada test for cerebral hemispheric dominance of language function.Courtesy of the Family

Sitting high in the steeply raked amphitheatre of the Montreal Neurological Institute, with a view of the imposing bald pate of its director Wilder Penfield, a young Japanese scientist named Juhn Wada dared to raise his hand.

It was 1955, and Dr. Penfield – probably the world’s most famous neurosurgeon – was presenting two patients with severe epilepsy at the institute’s weekly conference. He wanted to know which side of their brains were responsible for the faculty of speech, because it varied from person to person, and because he would soon be cutting into their grey matter, hoping to remove the source of their seizures.

It was always risky to open the skull without knowing if the area responsible for verbal ability lay beneath. There were few greater disasters in the OR than cutting in the wrong place and leaving someone with aphasia – unable to speak, or understand speech, or make sense when they did talk – and yet it continued to happen in the absence of a good pre-operative test.

Fortunately, this newcomer with an unfamiliar accent had an idea. “I stood up and said, ‘I’m Wada from Japan, and I have a technique for finding your speech area,’” he recalled.

A stunned silence filled the theatre. Who was this man, blithely claiming to have a solution for one of neurosurgery’s most bedeviling problems? Dr. Penfield whipped off his glasses, a sure sign he was annoyed, and muttered, “Nonsense.”

It wasn’t. The brilliantly simple procedure consisted of injecting a short-acting barbiturate into the patient’s carotid artery to put half their brain to sleep, before a psychologist tested their speech and memory. If those faculties were affected, the doctors knew they had found the “dominant” hemisphere – and to tread more carefully there. The Wada Test, as it came to be known, revolutionized epilepsy surgery and helped colour in our map of the human brain. It even made an appearance on Grey’s Anatomy.

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Dr. Wada's created the Wada test, which revolutionized epilepsy surgery and helped fill in the map of the human brain.Courtesy of the Family

Dr. Wada died on April 23 after a short illness, at the age of 99. After his history-making stint at The Neuro (as it came to be known) in Montreal, he went on to a long, successful career as a neurologist at the University of British Columbia in Vancouver. Raised in prewar Japan by a family that belonged to the country’s Imperial-era elite, he became a proud Canadian who picked up maple leaves as he walked home from work, pressed them in telephone books and included them in virtually every letter he sent.

Although his name will always be associated with his famous test, patients, friends and family also remember Dr. Wada as a caring physician, loving dad and husband, and a passionate lover of art, music, and philosophy.

He was a “Renaissance man,” said his daughter, Eileen Wada Willett.

Juhn Atsushi Wada was born in Tokyo on March 28, 1924 to prosperous parents in what was then a confident, booming empire. His father was a law professor and diplomat from a business clan who had obtained degrees from Berkeley and Stanford before teaching at the University of Chicago during a stint in the U.S. His mother came from a long line of scholars and studied at the country’s most prestigious girls’ school.

Like many Japanese boys at the time, young Juhn harboured dreams of attending the country’s storied Imperial Naval College. But it was the late 1930s, war was breaking out around the world, and his mother had other ideas. She secretly refused to submit his application and finally disclosed to her son through sobs that she couldn’t bring herself to see him go down on some sinking ship.

“It was the first of many blessings in my life,” Dr. Wada later wrote in a memoir.

Medical school was a safer bet – it exempted him from military service – if slightly improbable for a sensitive soul who spent his free time gazing at a book of van Gogh paintings in a local bookstore and once, as a student, had fainted at the sight of a man’s infected nail bed. In any case, he was soon hardened by the conditions in Japanese health care during and after the Second World War. Amidst the poverty that followed Japan’s surrender to U.S. forces, patients slated for surgery had to bring their own supply of scarce bandages; one hallway in Dr. Wada’s hospital was known as the “Siberian Corridor,” because snow poured through its broken windows.

The troubled times also provided plenty of interesting “clinical material” – as patients were then often called – for a young neurologist. One day a Japanese cook came in with a gunshot wound to the left side of his head from a drunk American GI who had claimed that he could shoot the man’s hat clean off, William Tell-style. When the cook developed seizures originating in his right leg, Dr. Wada realized he could try out a pet idea: he would temporarily shut down the patient’s damaged left hemisphere with an injection of the sedative sodium amytal to freeze the onset of attacks. When the drug also produced complete speech loss for several minutes, Dr. Wada knew it was a “profound experience.”

Although he published his findings in Japan in 1949, the country’s scientific establishment was sufficiently isolated from the West that his breakthrough went largely unnoticed until he arrived in Montreal in the mid-1950s. He chose the city’s Neurological Institute because it was probably the world’s greatest centre for brain research, and its best known. Wilder Penfield would be profiled in Time and The Saturday Evening Post for his groundbreaking “Montreal procedure,” which used an electrode to find the source of a waking patient’s seizures, while stimulating other spontaneous responses, including vivid cinematic memories.

The Neuro was also a strikingly cosmopolitan place, where some of the first Chinese, Indian, Arab and African-American neurosurgeons were trained, and where brilliant scientists from all over war-scarred Europe had found refuge. It was one of the places in Canada – then just a decade removed from the mass internment of Japanese-Canadians – where Dr. Wada’s national origins were least likely to matter.

Sure enough, after Dr. Penfield’s chilly initial response in the amphitheatre, the institute’s staff jumped at the chance to explore the sodium amytal test. Most immediately, it gave them a way to avoid repeating a haunting mistake: a series of patients left severely amnesiac after Dr. Penfield removed their hippocampus, when the other half of the seahorse-shaped brain structure – crucial for forming new memories – was already damaged. The Wada test could now identify patients whose memory was concentrated in one hemisphere.

Even as computerized brain imaging technology became widespread, the more analog Wada drug injection remained the gold standard for determining the language-dominant hemisphere before surgery, saving the speech faculty of untold hundreds of patients. His procedure became a household name – never mind that some doctors thought “Wada” was an acronym.

Established as a neurologist at UBC with a focus on treating epilepsy, Dr. Wada saw his profile grow. He was featured on an episode of The Nature of Things with David Suzuki, performing his namesake test. Although he cringed at the way Hollywood botched the details in Grey’s Anatomy (Season 5, Episode 23, by the way), he was proud of his brainchild’s renown. And he was rewarded with a growing list of honours: the Order of Canada, the Queen Elizabeth II Diamond Jubilee Medal, the Wilder Penfield Gold Medal Award.

Despite facing overt racism in Vancouver – one neighbour got up a petition to have him removed from the street when he first moved to the city in the late 1950s – he was also proud to make his career in Canada, and soon renounced his Japanese citizenship. Again, medical colleagues embraced him: his partnership with the neurosurgeon Dr. Gordon Thompson, who also trained at the Montreal Neurological Institute, was a decades-long success, clinically and socially. The Thompson children were grateful, among many other things, that their mother became adept at making Mary Wada’s tempura recipe.

Along with Mary and his children Kent and Eileen, Bach and Aristotle counted among Dr. Wada’s great loves. His book shelves literally sagged with the weight of art books. Gardening provided another creative outlet. Dr. Wada was in charge of the backyard, and Mary the front yard – each dominant in their own area, like two hemispheres of the same brain.

He leaves children Eileen and Kent, and grandchildren Matthew and Jamie Willett, and is predeceased by wife Mary Wada (1924-2019) and grandson Georgie Willett (1998-2011).

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