How elec­tric­ity could be the new medicine

Tehran Times - - HEALTH -

In the near fu­ture, your doc­tor might pre­scribe elec­tric­ity for what ails you, says Ben­jamin W Met­calfe

when your only tool is a ham­mer, ev­ery prob­lem looks like a nail. This say­ing is par­tic­u­larly apt in medicine where doc­tors treat nearly ev­ery con­di­tion – from de­pres­sion to hy­per­ten­sion – with a pill. If your doc­tor pre­scribed you any­thing other than a pill (as­sum­ing you don’t need surgery), you might think they were a quack. But this will soon change. Medicine is get­ting rad­i­cal, and one of the rad­i­cal new ap­proaches for treat­ing dis­ease is elec­tric­ity.

Why elec­tric­ity? Well, ev­ery­thing you do, from walk­ing to dream­ing, is con­trolled or reg­u­lated by elec­tri­cal sig­nals. These tiny im­pulses travel through your ner­vous sys­tem, con­vey­ing in­for­ma­tion and al­low­ing com­plex de­ci­sions to be made. The hub of elec­tri­cal ac­tiv­ity is in the brain, and from there the nerves branch out to all cor­ners of the body.

The im­por­tance of these elec­tri­cal sig­nals is demon­strated by the im­pact of in­jury to any part of the ner­vous sys­tem, which of­ten leads to ir­re­versible paral­y­sis. The most com­mon trauma in­volves an in­jury to the spinal cord. World­wide, spinal cord in­jury af­fects about 2.5 mil­lion peo­ple with about 130,000 new cases each year.

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If we could find a way to read and write the elec­tri­cal sig­nals, in other words un­der­stand the lan­guage of the ner­vous sys­tem, we would have a dig­i­tal in­ter­face to the body. An im­planted de­vice would then be able to bridge the gap left by a spinal cord in­jury.

And it’s not just peo­ple with spinal cord in­juries who would ben­e­fit from this kind of tech­nol­ogy. We could in­struct the pan­creas to pro­duce more in­sulin, or we could raise or lower the heart rate with­out need­ing to re­sort to pills. In essence, we could take con­trol of the body.

Danc­ing frogs

Luigi Gal­vani was one of the first sci­en­tists to re­alise that elec­tric­ity might have some in­volve­ment in the nor­mal op­er­a­tion of life. He dis­cov­ered this in 1791 when he con­ducted ex­per­i­ments on frogs, mak­ing their legs twitch with elec­tric­ity. A cen­tury later, the idea of an ar­ti­fi­cial car­diac pacemaker was first mooted.

To­day bio­elec­tron­ics is a highly ac­tive field of re­search, yet in the two cen­turies since Gal­vani first made his frogs dance there are still only a hand­ful of com­mer­cially avail­able de­vices that in­ter­face with the ner­vous sys­tem. The pa­tient out­lived both the sur­geon and the en­gi­neer who in­vented it.

A promis­ing tar­get for new de­vices is the va­gus nerve. This nerve, which runs down both sides of your neck, is con­nected to many or­gans, and de­vices that stim­u­late it may be able to treat dis­eases as far rang­ing as rheuma­toid arthri­tis and al­co­holism.

One of the key suc­cess sto­ries has been a de­vice for treat­ing drug-re­sis­tant epilepsy. This de­vice, made by Li­vaNova, has been used by over 100,000 peo­ple. It helps pre­vent the ab­nor­mal elec­tri­cal ac­tiv­ity that causes seizures within the brain by ap­ply­ing small elec­tri­cal im­pulses at reg­u­lar in­ter­vals 24 hours a day, ev­ery day. These im­pulses travel up the va­gus nerve and into the brain.

More than 40 per cent of pa­tients fit­ted with this de­vice re­duce their num­ber of seizures by half. How­ever, the con­stant stim­u­la­tion can cause un­wanted side ef­fects, in­clud­ing pain, headaches and short­ness of breath.

Ad­vances are be­ing made

While stim­u­lat­ing the va­gus nerve with elec­tric­ity is clearly ben­e­fi­cial, it’s still quite a crude ap­proach. Stim­u­lat­ing the nerve is like shout­ing an in­struc­tion rather than join­ing a con­ver­sa­tion. It would be much more pow­er­ful if we could record the mes­sages al­ready trav­el­ling along the nerves. These mes­sages might alert us to the on­set of an epilep­tic seizure, for ex­am­ple, and en­able on-de­mand stim­u­la­tion that mit­i­gates the un­wanted side ef­fects of the cur­rent sys­tem.

How­ever, record­ing sig­nals in a nerve isn’t easy. The va­gus nerve con­tains tens of thou­sands of neu­rons and each elec­tri­cal sig­nal is in­cred­i­bly weak and hard to de­tect. Cou­pled with this is the fact that in­ter­fer­ing sig­nals from mus­cles are of­ten 100 times larger than the sig­nals within the nerves.

In or­der to de­tect an im­pend­ing seizure, for ex­am­ple, an im­planted de­vice must be able to record and iden­tify one small sig­nal from an­other, at the same time. This is not un­like be­ing at a rock con­cert and try­ing to lis­ten to a con­ver­sa­tion on the other side of the sta­dium.

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