the real Matrix?
Neural implant devices are now a
reality. But misguided federal policies are keeping them from the people who
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By Shy Shoham and Sam Hall (c) 2003
Nov. 11, 2003 |
In the futuristic vision of the Wachowski
brothers' movie trilogy "The Matrix," humans dive into a virtual world by
connecting their brains directly to a computer. Most movie viewers may
consider direct interfaces with the nervous system as much of a fantasy as
the movie's gravity-defying special effects. However, for a small group of
engineers and scientists this very idea is very real -- and is driving
advances in medical technology that could help millions of disabled people
see and hear -- and live normal lives. Unfortunately, bureaucratic hurdles
have slowed the development of this technology, and its potential remains
Real-life human-computer interfaces are called neuroprostheses -- medical
devices that connect directly to the human brain, spinal cord or nerves.
"Matrix" fans might be surprised to learn that neuroprostheses have been
around as long as more "traditional" devices like cardiac pacemakers. In
fact, a number of neuroprosthetic devices were already being developed in
the 1950s, and by the early 1970s the National Institutes of Health
established the Neural Prostheses Program to coordinate research in this
The first neuroprostheses to become commercially available in the United
States were cochlear implants, following their initial FDA approval in 1984.
Sound from a microphone placed near the ear is coverted to weak electrical
currents that activate auditory nerve endings inside the cochlea in the
inner ear. The activity produced in these nerves propagates directly to the
brain, where it produces an auditory perception. By bypassing the normal
hearing apparatus it provides an artificial hearing sensation to deaf
people. To date, more than 55,000 patients worldwide have received cochlear
implants. The technology of cochlear implants has enjoyed remarkable
advances since the early days. Improvements in signal processing now allow
many deaf users to use these devices to perceive speech, talk on the phone,
and even listen to music.
While sensory prostheses like the cochlear implant provide a substitute
sensory percept, motor prostheses are used to move muscles -- allowing the
paralyzed to regain lost function. One example of a motor prosthesis is the
FreeHand system from NeuroControl Corp., which uses implanted muscle
stimulators to restore limited hand movement in individuals paralyzed as a
result of certain forms of spinal cord injury. The user of this system
controls it with a controller-stimulator unit implanted behind his shoulder.
Limb-control systems like the FreeHand system have been implanted in more
than 300 patients.
The most widely used motor neuroprostheses are devices used to stimulate
the bladder in paralyzed individuals who have lost control of bladder
voiding. Thousands of such devices have been implanted worldwide for over
A very different use of neuroprosthetic devices is to disrupt unwanted
brain activity, which can be the result of different neurological diseases.
These devices target the tremors that result from Parkinson's disease,
essential tremor, seizures that result from epilepsy, and chronic,
persistent pain (which has a variety of causes). They are implanted in
patients that are not responding to medication. Anti-tremor devices are
implanted by neurosurgeons in the patient's brain, in a region called the
basal ganglia. More than 15,000 patients have been implanted with such
deep-brain stimulators. Anti-epileptic devices are implanted in the
patient's neck region around the vagus nerve. Over 18,000 patients have been
implanted with vagus-nerve stimulators to date. Devices for chronic pain
have been implanted in a variety of regions, most commonly in the spinal
Many science fiction fans will argue that fully immersive virtual
interfaces are the future of brain-computer interaction. The technology for
such systems does not exist yet, but interestingly, the development of
microelectronic technology over the last four decades, which has enabled
chip manufacturers to squeeze hundreds of millions of transistors onto a
single chip in your PC or cellphone, may also revolutionize the field of
neuroprosthetics, allowing a technical leap in that direction.
Several research labs from universities and companies around the world
are using microelectronic technology to develop devices known as
"microelectrode arrays." These devices can "interact" independently with a
large number of nerve cells: recording their activity or stimulating them.
The development of microelectrode arrays has allowed researchers in the
field to start thinking seriously about a variety of next-generation
neuroprosthetic devices, including new types of neuroprostheses. These
include vision prostheses for the blind and brain-computer interfaces for
the totally paralyzed.
Brain-computer interfaces are arguably the most "futuristic" devices
currently being developed. If successful, they will allow paralyzed
individuals to use their brain instead of their paralyzed muscles to
communicate directly with a computer or control their environment. This may
give patients suffering from the extreme "locked-in" syndrome a way to break
out of their disease-induced solitude, and may provide quality-of-life
benefits to many other individuals whose paralysis is not as complete. As
with most other devices, several possible approaches are pursued in the
development of brain-computer interfaces. Recording electrodes can be placed
noninvasively on the surface of the scalp or implanted surgically into the
brain, where they can be used to tap on the brain's inner communications.
Both approaches have pros and cons, and it is yet unclear which carries the
best long-term potential.
As humans we experience the world through our five senses, and nerves are
used to control the muscles that move our body. Many diseases affect nerves,
muscles and brain. Clearly, being able to bypass or block defective systems
is an important capability -- this is why neuroprosthetics has many possible
applications and holds great promise.
But how have these devices fared in the marketplace? Not well. In the
entire 1990s only eight implantable neuroprosthetic devices received FDA
approval. Moreover, most of those devices were based not on cutting-edge
advances, but on decades-old pacemaker technology.
Why is so little innovation reaching the patient? One basic problem is a
mismatch between the hurdles faced by neuroprosthetic devices in finding a
profitable market, and the dynamics of the marketplace itself. An analysis
of neuroprosthesis commercialization efforts from the last two decades
reveals major barriers posed by FDA regulations and even larger barriers
posed by device-reimbursement policies that fail to account for long-term
The existing regulatory environment is largely adapted for the drug
market, in which large companies and vast markets can shoulder long-term
financial risks. However, the same environment has slowed neuroprosthetic
commercialization and development to a trickle.
Entrepreneurs in this field typically face a decade of regulatory
uncertainty and chronic underpayment for the devices themselves. Many
entrepreneurs are willing to shoulder this uncertainty, but the environment
makes it difficult to raise the capital necessary for clinical trials and
the initial phases of entry into the marketplace. This factor led directly
to the discontinuation of the first cochlear implant introduced the United
States: the 3M/House implant. More recently, distribution of the FreeHand
system described above has been discontinued following disappointing
Most neuroprosthetic devices target a relatively small patient
population, making them ideal candidates for the FDA's Humanitarian Device
Exemption (HDE), which is supposed to waive the costly effort of
demonstrating effectiveness. However, in its present form this exemption
imposes a heavy burden on developers and hospitals as well as tight legal
limits on device prices. In essence, the restrictions have so far prevented
profitable manufacturing of the devices in the United States.
The Vocare system, which restores bladder control to paralyzed
individuals and was marketed in the United States by NeuroControl Corp. of
Cleveland, Ohio, is an illustrative example. Despite years of availability
in Europe, the Vocare system was withdrawn from the U.S. market following
two years of disappointing financial results, leaving tens of thousands of
paralyzed individuals without an equivalent alternative. This withdrawal is
largely attributable to restrictive HDE policies. There are signs that at
least some of the inefficiencies in the FDA review process are slowly being
eliminated: Removing the HDE caveats would probably prove invaluable to
neuroprosthetics as well as to their target users.
The most serious barrier is undoubtedly the reimbursement policy, largely
determined in the United States by Medicare. Medicare's prospective-payment
system does not contain specific reimbursement codes for neuroprosthetic
devices, and they are invariably assigned to nonspecific categories that
cover surgical costs but greatly underpay device costs. In fact, of the more
than 500 reimbursement codes, only four inpatient categories are specific to
implantable devices -- all for cardiac pacemakers.
One may argue that this is a reasonable policy choice for cutting medical
expenses, but a number of studies have shown that the long-term financial
benefits of devices such as cochlear implants for the deaf, vagus-nerve
stimulators for controlling epilepsy, and other neuroprosthetic devices are
much greater than the immediate costs associated with device purchase and
In spite of those studies, Medicare consistently underpays for these
breakthrough technologies. Furthermore, the years spent until the actual
reimbursement decision is made have already led to the withdrawal of several
devices. There is no reason to assume that the fate of future
neuroprostheses will be different. Reimbursement adjustments that will allow
a more predictable, expeditious and unbiased payment for breakthrough
medical devices (possibly by using temporary reimbursement codes) will
almost certainly boost innovation in this field.
In his groundbreaking 1984 novel "Neuromancer," where "The Matrix" was
born, William Gibson describes a future with vast computer networks
accessible through direct human-computer interfaces. Gibson's "cyberspace"
has become an everyday reality in the World Wide Web, but the development of
direct neural interfaces is still a disappointment. Simple policy
adjustments can change this trend, allowing these useful devices, many of
which can already be manufactured, to set the stage for major improvements
in this branch of medical technology.
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Sam Hall is a financial analyst in Citigroup's Investment Banking
Division. During his studies at Princeton University he researched the
commercialization of neuroprosthetic devices.
Dr. Shy Shoham is a Princeton scientist whose
focuses on the development of brain interface technology.