MRI pre­dicts de­vel­op­ment de­lay

New tech­niques mean tai­lored treat­ments for pre­ma­ture ba­bies, writes Denise Cullen

The Weekend Australian - Travel - - Health -

AN­DREA Krieger’s son An­gus faced tough odds when he was was born 15 weeks early five years ago. So­phis­ti­cated med­i­cal in­ter­ven­tions over the past two decades have dra­mat­i­cally in­creased sur­vival rates for very pre­ma­ture ba­bies.

But the flip­side of th­ese ad­vances is that ba­bies born pre-term, par­tic­u­larly if, like, An­gus they are born be­fore 26 weeks’ ges­ta­tion, are likely to be dogged by a host of neu­rode­vel­op­men­tal dif­fi­cul­ties, many of which per­sist into adult life.

‘‘ When An­gus was born at 25 weeks, he was given less than a 50 per cent chance of sur­vival,’’ Krieger re­calls. ‘‘ We were told that the ba­bies like him that do sur­vive will have brain in­jury, or de­layed de­vel­op­ment, along with other health is­sues.

‘‘ It was a very dif­fi­cult time, but for me, hav­ing all the cards laid out on the ta­ble, and know­ing all the pos­si­bil­i­ties was im­por­tant, be­cause with knowl­edge, there’s power, and your choices can be more in­formed.’’

While the bal­ance of the risk of health prob­lems had been thought to be still on the baby’s side in the case of a pre-term birth, in pop­u­la­tion terms the dan­gers are rel­a­tively high. One study, pub­lished in the jour­nal Brain (2007;130:667-677), re­vealed that 10-15 per cent of very pre-term in­fants de­vel­oped cere­bral palsy, while up to half had other sig­nif­i­cant prob­lems such as low­ered IQ, at­ten­tion deficit hy­per­ac­tiv­ity dis­or­der (ADHD), anx­i­ety disor­ders and learn­ing dis­abil­i­ties.

To make mat­ters worse, try­ing to pre­dict which pre-term ba­bies will ex­pe­ri­ence th­ese out­comes us­ing stan­dard clin­i­cal indicators — ges­ta­tional age, birth weight, and com­pli­ca­tions dur­ing the neona­tal pe­riod — has proven prob­lem­atic. Some chil­dren con­sid­ered to be at high risk for de­vel­op­men­tal dys­func­tion seem to do just fine; oth­ers who are pre­dicted to do well do not.

But a novel study in Melbourne is us­ing high-tech mag­netic res­o­nance imag­ing (MRI) to un­cover vi­tal clues as to how pre­ma­ture ba­bies will de­velop, by iden­ti­fy­ing spe­cific ab­nor­mal­i­ties in their brains.

Doc­tor Peter An­der­son, a psy­chol­o­gist and se­nior re­search fel­low at the Univer­sity of Melbourne and Mur­doch Chil­drens Re­search In­sti­tute (MCRI), says the long-term study will fol­low 230 chil­dren re­cruited as pre­ma­ture ba­bies from 2001-2003, through­out child­hood and hope­fully into adult­hood.

In do­ing so, it will fo­cus on the con­se­quences of brain ab­nor­mal­i­ties re­vealed in the neona­tal pe­riod on sub­se­quent brain de­vel­op­ment and neu­robe­havioural out­come in this high-risk pop­u­la­tion.

Cra­nial ul­tra­sound is the stan­dard tech­nique for as­sess­ing brain in­jury in pre­ma­ture in­fants, and while this tech­nique is good at pick­ing up sig­nif­i­cant ab­nor­mal­i­ties, it is not as sen­si­tive when it comes to pick­ing up more com­mon and sub­tle brain ab­nor­mal­i­ties,’’ An­der­son says.

We have also demon­strated that brain MRI scans are more pre­dic­tive of early de­vel­op­men­tal de­lay than cra­nial ul­tra­sound.’’

Krieger’s son was re­cruited into the MCRI study and un­der­went an MRI scan on his due date.

‘‘ It showed that his brain was im­ma­ture in gen­eral, but that was al­ways go­ing to be the case be­cause he was a pre­ma­ture baby,’’ his mother says.

‘‘ The re­searchers then linked the in­for­ma­tion in the scan to the types of phys­i­cal, mo­tor and in­tel­lec­tual prob­lems An­gus may be at risk for, and the chal­lenges he could face in the fu­ture.’’

As a re­sult of that in­for­ma­tion, the fam­ily en­gaged in early in­ter­ven­tion ser­vices in­clud­ing speech ther­apy, phys­io­ther­apy and oc­cu­pa­tional ther­apy through Vic­to­ria’s Broad In­sight Group.

‘‘ He reached all his mile­stones, like learn­ing to crawl — he just reached them later,’’ Krieger said.

An­der­son points out that MRI stud­ies, such as the one con­ducted in Melbourne, have re­vealed a far higher in­ci­dence of brain ab­nor­mal­i­ties in pre­ma­ture ba­bies than was be­lieved to ex­ist, with about 70 per cent later hav­ing pathol­ogy rang­ing from mild to se­vere.

For fraught par­ents al­ready strug­gling to deal with the health and other is­sues that typ­i­cally con­front their pre­ma­ture in­fants, such fig­ures sound any­thing but com­fort­ing.

Yet through delv­ing into the rea­sons why par­tic­u­lar pat­terns of dif­fi­culty oc­cur, re­searchers hope to de­vise in­ter­ven­tion and re­me­di­a­tion strate­gies to bridge the ba­bies’ de­vel­op­men­tal gaps.

‘‘ Our abil­ity to iden­tify chil­dren at risk for dif­fer­ent types of de­vel­op­men­tal de­lay is crit­i­cal for se­lect­ing the most ap­pro­pri­ate early in­ter­ven­tion pro­gram for each child,’’ says An­der­son.

While no one can ex­plain ex­actly why early in­ter­ven­tion works, most peo­ple agree it does. It’s gen­er­ally be­lieved young, mal­leable brains can be rewired’’, at least to some de­gree, through speech ther­apy, oc­cu­pa­tional ther­apy, phys­io­ther­apy and other in­ter­ven­tions.

MRI scans have shown that ba­bies born pre­ma­turely not only tend to have smaller brains over­all, but that cer­tain parts of the brain — in par­tic­u­lar the white mat­ter, the ca­bling that fa­cil­i­tates com­mu­ni­ca­tion within the brain — are at risk of in­jury.

Re­search tends to sug­gest that pre­ma­tu­rity has a se­lec­tive ef­fect on spe­cific re­gions of the brain, or that there are re­gions of spe­cific vul­ner­a­bil­ity,’’ says An­der­son.

One of th­ese re­gions is the cor­pus cal­lo­sum, which links the right and left hemi­spheres of the brain, and plays an im­por­tant role in es­tab­lish­ing which sides of the brain be­come spe­cialised for per­form­ing par­tic­u­lar tasks.

Ac­cord­ing to a pre­vi­ous pa­per in Brain (2004;127:2080-2089), re­search con­ducted on ado­les­cents aged 14-15 years re­vealed that thin­ning of the cor­pus cal­lo­sum was of­ten ob­served in those born very pre-term.

This was strongly cor­re­lated with their deficits in ver­bal intelligence and ver­bal flu­ency, and is be­lieved to be the case be­cause the cor­pus cal­lo­sum is in­te­gral to high-or­der cog­ni­tive pro­cesses, such as lan­guage, which

Pic­ture: Michael Pot­ter

Get­ting to know pos­si­bil­i­ties: An­drea Krieger with her son An­gus, who was born 15 weeks pre­ma­ture

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