Imagine feeling pain in a non-existent limb or an itch that cannot be scratched. It is a maddening sensation, always nagging and niggling away, and for some amputees it is very real.

Called Phantom limb pain, the sensation has been described in medical literature as far back as in the 16th century, and even has echoes in fiction. Captain Ahab, the protagonist of the classic Moby Dick, was haunted by the ghost of a lost leg. Closer home, in Vikram Chandra’s Love and Longing in Bombay, Major General Antia’s missing leg ached intolerably, years after the amputation.

So how does a physician treat this ailment?

In the mid-1990s, VS Ramachandran, a clinical neurologist and researcher at the University of California, San Diego, saw a patient who complained that his missing arm had clenched into a fist. The man was in agony as (phantom) fingernails dug into his (phantom) palm.

Ramachandran came up with a novel solution: mirror therapy. When the patient placed his hand inside a mirror-lined box, the reflection of his good hand took the place of his missing hand. Accepting this illusion as truth, the man clenched and unclenched his good fist. The phantom pain subsided and was gone for good after two weeks of treatment – cured by a well-designed optical illusion.

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“Ramachandran had discovered a rudimentary yet revolutionary technique for altering consciousness,” writes Dr Brennan Spiegel in his book VRx: How Virtual Therapeutics Will Revolutionize Medicine, which came out in October this year. Ramachandran’s treatment of phantom limb pain with a $2 mirror box demonstrated that a patient’s perception could be altered briefly – and that altered consciousness could be leveraged for therapy.

That epiphany is a cornerstone of an emerging field of medicine that has the potential to help treat a range of medical conditions – from acute pain to arachnophobia – without the use of invasive surgery or addictive opioids. It is called virtual therapeutics or virtual reality therapy.

There is a breathtaking overview of the field in Spiegel’s book. In it, Spiegel, a physician at the Cedars-Sinai Medical Center in Los Angeles, makes an argument for virtual therapeutics and recounts its somewhat unusual beginnings. Videogames, for instance, inspired some of the early work in virtual therapeutics. Psychologist Albert “Skip” Rizzo of the University of Southern California, a pioneer in virtual therapeutics, recalls his “aha!” moment in 1991 when he watched one of his clients playing a Nintendo Game Boy. He wanted to use the lure of games, combine it with evidence-based principles of talk therapy, and embed the result in a virtual reality headset to use in therapy sessions with patients.

“Nearly thirty years later, Rizzo has built and tested a range of virtual environments designed to manage anxiety. His most famous program called BraveHeart treats soldiers who are mentally scarred by the calamity of war. By plunging veterans into the thick of battle in a highly realistic virtual environment, Rizzo recreates the visceral full body experience of war, complete with the bone-rattling vibration of rolling Humvees, with the thick sent of burning oil, and the sound of concussive blasts. Through Bravemind, Rizzo exposes soldiers to their worst nightmares, but he does it within the controlled safety of VR. His procedure called VR exposure therapy, gradually inoculates the brain against the triggers of post-traumatic stress syndrome.”  

It is the immersiveness of virtual reality – that embodied feeling of “being there” and interacting with a new world – that focuses our attention like no visual medium, writes Spiegel. When you strap on a headset and obscure every physical distraction, you are lost to the real world just like a person deep in meditation or someone tripping on psychedelics, or, why, a teenage gamer. Our brains have no bandwidth left to consider anything beyond the immediate digital experience.

Virtual reality analgesics can alleviate physical pain, reducing the need for addictive pain killers. For instance, in the book, we learn of Snow World, a VR treatment which ushers burn patients into a soothing winter landscape, while bandages come off their seared skin in the real world. Patients reported that wound care felt a lot less agonising, as they threw snowballs at penguins and snowmen in an engaging game.

We are also introduced to the first case of VR therapy for schizophrenia, which is a condition in which the patient may hear, see or smell things that don’t exist. When we meet the patient, Richard Breton, the 54-year-old is wearing a VR headset and staring at a satanic figure, complete with blazing eyes, horns, and tail – a representation of the demon which keeps berating him.

“The patient is seeing a concrete representation of his hallucination,” explains Alexandre Dumais, who has pioneered this new form of VR-assisted talk therapy at the University of Montreal. “He has a direct dialogue with the hallucination.” The voice talking back comes from Dumais, who is sitting in a room wearing a headset. As he speaks, Dumais’ voice is permuted by a computer into devilish tones, piped through the software, and then emerges through the mouth of the virtual avatar… But every so often, Dumais breaks character and offers some coaching. He instructs Breton to stand up to the voice, to talk to it and reason with it… Since the therapy, Breton’s intruding voice has dropped from fifteen times per day to far fewer.  

There are other powerful examples of transformative therapy in Spiegel’s VRx. Through interviews with physicians and patients, he makes a compelling case for virtual reality as a medical treatment, although there are a few caveats.

Spiegel emphasises that virtual reality is not a digital panacea. Even for conditions where VR has proven to be effective, it may not work for every patient. Some people may experience cybersickness, a new term for the sensation of motion sickness triggered by feeling out of sync with the virtual world. For others, the barrier to VR could be mental. “What may seem like a fantastical voyage to the well may seem like an unwelcome intrusion to someone who is unwell with an advanced illness,” Spiegel writes.

Besides, a patient’s psychology needs to be considered before sending them into an immersive experience, which is unlike reading a book or watching a movie. Could VR be addictive? Could a VR experience implant fake memories? The ethics of the therapy have to debated.

Rheumatologist Swamy Venuturupalli, a colleague of Spiegel’s, first used the technology on a patient with multiple sclerosis to alleviate her arthritic pain. He noticed that the intensity of the patient’s pain reduced when she was in VR. Her MS-related tremors also vanished briefly. VR was, by no means, a cure for the MS. Regardless, the physician, who was happy to see the mind gain control momentarily over the body, began offering the technology to other patients as well. “For many, they just don’t even know VR even exists. It’s not that the doctors are afraid; it’s just that they haven’t heard of it…,” says Venuturupalli.

Physicians, virtual reality developers and technophiles may seem to be the obvious audience for a book on virtual therapeutics. But anyone who has to visit a clinic for anything ranging from a dental procedure to treatment for depression could find Spiegel’s book an engaging read.