Sci­en­tists seek ways to take a real mea­sure of pain

Lexington Herald-Leader - - News - BY LAURAN NEERGAARD

Is the pain stab­bing or burn­ing? On a scale from 1 to 10, is it a 6 or an 8?

Over and over, 17year-old Sarah Tay­lor strug­gled to make doc­tors un­der­stand her some­times de­bil­i­tat­ing lev­els of pain, first from joint-dam­ag­ing child­hood arthri­tis and then from fi­bromyal­gia.

“It’s re­ally hard when peo­ple can’t see how much pain you’re in, be­cause they have to take your word on it and some­times, they don’t quite be­lieve you,” she said.

Now sci­en­tists are peek­ing into Sarah’s eyes to track how her pupils re­act when she’s hurt­ing and when she’s not – part of a quest to de­velop the first ob­jec­tive way to mea­sure pain.

“If we can’t mea­sure pain, we can’t fix it,” said Dr. Ju­lia Finkel, a pe­di­atric anes­the­si­ol­o­gist at Chil­dren’s Na­tional Med­i­cal Cen­ter in Wash­ing­ton, who in­vented the ex­per­i­men­tal eye-track­ing de­vice.

At just about every doc­tor’s visit you’ll get your tem­per­a­ture, heart rate and blood pres­sure mea­sured. But there’s no stetho­scope for pain. Pa­tients must con­vey how bad it is us­ing that 10-point scale or emo­jistyle charts that show faces turn­ing from smiles to frowns.

That’s prob­lem­atic for lots of rea­sons. Doc­tors and nurses have to guess at ba­bies’ pain by their cries and squirms, for ex­am­ple. The aching that one per­son rates a 7 might be a 4 to some­one who’s more used to se­ri­ous pain or ge­net­i­cally more tol­er­ant. Pa­tientto-pa­tient vari­abil­ity makes it hard to test if po­ten­tial new painkillers re­ally work.

Nor do self-rat­ings de­ter­mine what kind of pain some­one has – one rea­son for trial-and-er­ror treat­ment. Are opi­oids nec­es­sary? Or is the pain, like Sarah’s, bet­ter suited to nerve-tar­get­ing medicines?

“It’s very frus­trat­ing to be in pain and you have to wait like six weeks, two months, to see if the drug’s work­ing,” said Sarah, who uses a com­bi­na­tion of med­i­ca­tions, acupunc­ture and lots of ex­er­cise to counter her pain.

The Na­tional In­sti­tutes of Health is push­ing for de­vel­op­ment of what its di­rec­tor, Dr. Fran­cis Collins, has called a “pain-o-me­ter.” Spurred by the opi­oid cri­sis, the goal isn’t just to sig­nal how much pain some­one’s in. It’s also to de­ter­mine what kind it is and what drug might be the most ef­fec­tive.

“We’re not cre­at­ing a lie de­tec­tor for pain,” stressed David Thomas of NIH’s Na­tional In­sti­tute on Drug Abuse, who over­sees the re­search. “We do not want to lose the pa­tient voice.”

Around the coun­try, NIH-funded sci­en­tists have be­gun stud­ies of brain scans, pupil re­ac­tions and other pos­si­ble mark­ers of pain in hopes of fi­nally “see­ing” the ouch so they can bet­ter treat it. It’s early-stage re­search, and it’s not clear how soon any of the at­tempts might pan out.

“There won’t be a sin­gle sig­na­ture of pain,” Thomas pre­dicted. “My vi­sion is that some­day we’ll pull these dif­fer­ent met­rics to­gether for some­thing of a fin­ger­print of pain.”

NIH es­ti­mates 25 mil­lion peo­ple in the U.S. ex­pe­ri­ence daily pain. Most days Sarah Tay­lor is one of them. Now liv­ing in Po­tomac, Mary­land, she was a tod­dler in her na­tive Aus­tralia when the swollen, aching joints of ju­ve­nile arthri­tis ap­peared. She’s had mi­graines and spinal in­flam­ma­tion. Then two years ago, the body-wide pain of fi­bromyal­gia struck; a flare-up last win­ter hos­pi­tal­ized her for two weeks.

One re­cent morn­ing, Sarah climbed onto an acupunc­ture ta­ble at Chil­dren’s Na­tional, rated that day’s pain a not-too-bad 3, and opened her eyes wide for the ex­per­i­men­tal pain test.

“There’ll be a flash of light for 10 sec­onds. All you have to do is try not to blink,” re­searcher Kevin Jack­son told Sarah as he lined up the pupil­track­ing de­vice, mounted on a smart­phone.

The eyes of­fer a win­dow to pain cen­ters in the brain, said Finkel, who di­rects pain re­search at Chil­dren’s Sheikh Zayed In­sti­tute for Pe­di­atric Sur­gi­cal In­no­va­tion.

How? Some pain-sens­ing nerves trans­mit “ouch” sig­nals to the brain along path­ways that also al­ter mus­cles of the pupils as they re­act to dif­fer­ent stim­uli. Finkel’s de­vice tracks pupil­lary re­ac­tions to light or to non-painful stim­u­la­tion of cer­tain nerve fibers, aim­ing to link dif­fer­ent pat­terns to dif­fer­ent in­ten­si­ties and types of pain.

Cer­tain med­i­ca­tions also can be de­tected by other changes in a rest­ing pupil, she said. Last month the Food and Drug Ad­min­is­tra­tion an­nounced it would help Al­gometRx, a biotech com­pany Finkel founded, speed de­vel­op­ment of the de­vice as a rapid drug screen.

MANUEL BALCE CENETA AP

Clin­i­cal Re­search As­sis­tant Kevin Jack­son uses Al­gometRx Plat­form Tech­nol­ogy on Sarah Tay­lor’s eyes to mea­sure her de­gree of pain at the Chil­dren’s Na­tional Med­i­cal Cen­ter in Wash­ing­ton. Chil­dren’s Na­tional Med­i­cal Cen­ter is test­ing an ex­per­i­men­tal de­vice that aims to mea­sure pain ac­cord­ing to how pupils re­act to cer­tain stim­uli.

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