Posts tagged limb amputation
Articles and news from the latest research reports.
The man who needs to paralyse himself
"I have attempted to break my back, but I missed. I need to be paraplegic, paralysed from the waist down."
Sean O’Connor is a very rational man. But he also tried, unsuccessfully, to sever his spine, and still feels a need to be paralysed.
Sean has body integrity identity disorder (BIID), which causes him to feel that his limbs just don’t belong to his body.
Sean’s legs function correctly and he has full sensation in them, but they feel disconnected from him. “I don’t hate my limbs – they just feel wrong,” he says. “I’m aware that they are as nature designed them to be, but there is an intense discomfort at being able to feel my legs and move them.”
The cause of his disorder has yet to be pinpointed, but it almost certainly stems from a problem in the early development of his brain. “My earliest memories of feeling I should be paralysed go back to when I was 4 or 5 years old,” says Sean.
The first case of BIID was reported in the 18th century, when a French surgeon was held at gunpoint by an Englishman who demanded that one of his legs be removed. The surgeon, against his will, performed the operation. Later, he received a handsome payment from the Englishman, with an accompanying letter of thanks for removing “a limb which put an invincible obstacle to my happiness” (Experimental Brain Research).
We now think that there are at least two forms of BIID. In one, people wish that part of their body were paralysed. Another form causes people to want to have a limb removed. BIID doesn’t have to affect limbs either – there have been anecdotal accounts of people wishing they were blind or deaf.
DIY operations
There are many reported cases of people with BIID attempting to break their back, like Sean, or perform a DIY operation to alleviate their discomfort. Some even pay for surgeons to amputate their healthy limbs. Now the first study of this desperate form of treatment, by Peter Brugger at the University of Zurich, Switzerland, and colleagues, suggests that chopping off a healthy limb “cures” people of this form of BIID. Brugger says they interviewed about 20 people with BIID, many of whom have had an illegal amputation. All said they were satisfied with the outcome.
But the findings, so far unpublished, are tentative and do not justify such a treatment, says Brugger. “We don’t have enough scientific evidence to propose amputation or paralysis. Before we have an understanding of something, we can’t think of developing a treatment.”
Brugger disagrees with the suggestion that the disorder is psychological. “The neurological side of the data is too convincing,” he says. “Why would a vague desire to be handicapped show itself as a precise need to be amputated two centimetres above the knee, for example? I certainly think it’s more a representational deficit in the brain in all cases, than a psychological need for attention.”
The parietal lobe, situated at the top of the brain, is almost certainly involved. It is here that a complex set of brain networks enable us to attach a sense of self to our limbs. In 2011, V. S. Ramachandran, at the University of California, San Diego, and his colleagues examined the brain activity of four people with BIID.
Confusion in the brain
They found significantly reduced activation in the right superior parietal lobe when researchers touched the part of the leg that people wanted amputated, compared with when they touched the part people wanted to keep. The researchers say that this area of the brain is key to creating a “coherent sense of having a body” (Journal of Neurological Neurosurgery and Psychiatry).
The brain hates to be confused, says Ramachandran. So when people with BIID feel the sensation of touch, they can’t incorporate this message into the regions of the brain that identify the limb as being part of themselves. In an attempt to remove the confusion, it seems the brain rejects the limb altogether.
Brugger hypothesises that some people are born with a relative weakness in brain networks which enable us to accept all our limbs as our own. This is usually naturally corrected as they grow up, he says, but in some people, the sight of an amputee at a very young age may have reinforce the alterations in the brain. About half of people with BIID – itself a condition so rare there aren’t proper estimates of its prevalence – recall having a fascination or close relationship with an amputee while they were a child.
Would Sean contemplate having his limbs amputated? “I would, if it was available,” he says, “but there are no surgeons currently offering the treatment openly.”
"But I am who and what I am in part because of having BIID and my lived experiences. Take away BIID, and I will be a different person. Not necessarily better, nor worse, but different. But the idea of making all my pain go away? It’s definitely appealing."
Wireless, implanted sensor broadens range of brain research
A compact, self-contained sensor recorded and transmitted brain activity data wirelessly for more than a year in early stage animal tests, according to a study funded by the National Institutes of Health. In addition to allowing for more natural studies of brain activity in moving subjects, this implantable device represents a potential major step toward cord-free control of advanced prosthetics that move with the power of thought. The report is in the April 2013 issue of the Journal of Neural Engineering.
“For people who have sustained paralysis or limb amputation, rehabilitation can be slow and frustrating because they have to learn a new way of doing things that the rest of us do without actively thinking about it,” said Grace Peng, Ph.D., who oversees the Rehabilitation Engineering Program of the National Institute of Biomedical Imaging and Bioengineering (NIBIB), part of NIH. “Brain-computer interfaces harness existing brain circuitry, which may offer a more intuitive rehab experience, and ultimately, a better quality of life for people who have already faced serious challenges.”
Recent advances in brain-computer interfaces (BCI) have shown that it is possible for a person to control a robotic arm through implanted brain sensors linked to powerful external computers. However, such devices have relied on wired connections, which pose infection risks and restrict movement, or were wireless but had very limited computing power.
Building on this line of research, David Borton, Ph.D., and Ming Yin, Ph.D., of Brown University, Providence, R.I., and colleagues surmounted several major barriers in developing their sensor. To be fully implantable within the brain, the device needed to be very small and completely sealed off to protect the delicate machinery inside the device and the even more delicate tissue surrounding it. At the same time, it had to be powerful enough to convert the brain’s subtle electrical activity into digital signals that could be used by a computer, and then boost those signals to a level that could be detected by a wireless receiver located some distance outside the body. Like all cordless machines, the device had to be rechargeable, but in the case of an implanted brain sensor, recharging must also be done wirelessly.
The researchers consulted with brain surgeons on the shape and size of the sensor, which they built out of titanium, commonly used in joint replacements and other medical implants. They also fitted the device with a window made of sapphire, which electromagnetic signals pass through more easily than other materials, to assist with wireless transmission and inductive charging, a method of recharging also used in electronic toothbrushes. Inside, the device was densely packed with the electronics specifically designed to function on low power to reduce the amount of heat generated by the device and to extend the time it could work on battery power.
Testing the device in animal models — two pigs and two rhesus macaques — the researchers were able to receive and record data from the implanted sensors in real time over a broadband wireless connection. The sensors could transmit signals more than three feet and have continued to perform for over a year with little degradation in quality or performance.
The ability to remotely record brain activity data as an animal interacts naturally with its environment may help inform studies on muscle control and the movement-related brain circuits, the researchers say. While testing of the current devices continues, the researchers plan to refine the sensor for better heat management and data transmission, with use in human medical care as the goal.
“Clinical applications may include thought-controlled prostheses for severely neurologically impaired patients, wireless access to motorized wheelchairs or other assistive technologies, and diagnostic monitoring such as in epilepsy, where patients currently are tethered to the bedside during assessment,” said Borton.