A STEADY hand is vital for surgeons performing intricate operations on
fragile tissues. To minimise tremors, many microsurgeons steer clear of alcohol
the night before and avoid coffee on the day of surgery. Some even use
beta-blockers to steady themselves. But scientists in Pittsburgh think they have
a better solution.
Hand tremors are normal and most of us don鈥檛 notice them. But they can hamper
surgeons operating on tiny, delicate tissues, such as blood vessels on the
retina. 鈥淛ust sometimes you find yourself with a bit of a tremor and if you
start focusing on it, it makes it worse,鈥� says Mark Benson, a vitreo-retinal
surgeon at the Birmingham and Midlands Eye Centre. 鈥淵ou really don鈥檛 want a
tremor if you鈥檙e using a sharp instrument along a blood vessel.鈥�
Cameron Riviere and his colleagues at Carnegie Mellon University in
Pittsburgh adapted a scalpel-like tool to measure the extent of the tremors.
Three tiny devices called accelerometers detected the scalpel鈥檚 movement in the
surgeon鈥檚 hand. In tests at the Wilmer Eye Institute at Johns Hopkins Hospital
in Baltimore, they found that tremors at the tip of the instrument could reach
half a millimetre and followed regular cyclic patterns. So Riviere thought the
tremors ought to be predictable鈥攁t least over the next fraction of a
second.
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To test the idea, he wrote a computer program that recorded the trembling of
the tip in someone鈥檚 hand. This was converted into three wave signals, one for
each dimension. Having worked out how these waves changed over time, Riviere
constructed three other waves to cancel out the tremors.
This month, Riviere plans to feed these 鈥渁nti-tremor鈥� signals to
piezoelectric actuators on the tip of the tool, in the hope that they will
counteract the surgeon鈥檚 tremor.
鈥淚t would be interesting if someone had a device that could counter it,鈥� saysBenson. It wouldn鈥檛 just be useful for surgeons. 鈥淥ne tantalising application is
the idea of a tremor-cancelling pen to enable smooth handwriting,鈥� says Riviere.
Such a device would be invaluable for people who have suffered strokes or have
Parkinson鈥檚 disease, but it won鈥檛 be ready for a while. 鈥淭his is a very
long-term goal.鈥�