Familial Large Vestibular Aqueduct Syndrome:
A Report of Two Siblings
Ailesel Geniş Vestibüler Kanal Sendromu:
İki Kardeşe Ait Olgu Sunumu
*Özmen ÖZTÜRK, MD, **Çağlar BATMAN, MD
* İstanbul Medipol University Medical Faculty, Department of Otorhinolaryngology and Head and Neck Surgery, ** Marmara University Medical Faculty, Department of Otorhinolaryngology and Head and Neck Surgery, İstanbul
ABSTRACT
The large vestibular aqueduct syndrome is a disorder in the spectrum of congenital inner ear malformations with distinct features. The syndrome is asso-ciated with bilateral progressive sensorineural hearing loss marked with decreases in the hearing level following minor head trauma or an event causing increased intracranial pressure. We present two siblings with inherited large vestibular aqueduct syndrome and discuss clinical, audiologic, radiographic and surgical findings. Cochlear implantation was performed to the first patient, while her sister had perilymphatic fistula during the follow-up. This family with unaffected parents provides a better understanding of the pathophysiology of large vestibular aqueduct syndrome.
Keywords
Vestibular aqueduct; inner ear; abnormalities; sensorineural hearing loss
ÖZET
Geniş vestibüler kanal sendromu belirgin özellikleri ile konjenital iç kulak malformasyonları yelpazesinde değerlendirilen bir hastalıktır. Sendrom minör kafa travmaları veya kafa içi basıncını arttıran bir olay sonrası azalan işitme seviyesi ile belirginleşen bilateral ilerleyici sensörinöral işitme kaybı ile iliş-kilidir. Geniş vestibüler kanal sendromu tespit edilen iki kardeşi sunmakta ve klinik, odyolojik, radyolojik ve cerrahi bulguları tartışmaktayız. İlk hastaya koklear implant uygulanırken, kardeşinde takipler esnasında perilenfatik fistül tespit edildi. Hastalıktan etkilenmeyen ebeveynler ile bu aile geniş vestibüler kanal sendromu patofizyolojisinin daha iyi anlaşılmasını sağlamaktadır.
Anahtar Sözcükler
Akueduktus vestibuli; iç kulak, anormallikler; sensörinöral işitme kaybı
Çalıșmanın Dergiye Ulaștığı Tarih: 01.09.2010 Çalıșmanın Basıma Kabul Edildiği Tarih: 20.01.2011
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Correspondence
Özmen ÖZTÜRK, MD
İstanbul Medipol University Medical Faculty, Department of Otorhinolaryngology and Head and Neck Surgery,
Turkiye Klinikleri J Int Med Sci 2008, 4 165 IN TRO DUC TI ON
lar ge ves ti bu lar aqu e duct (LVA) is one of the most com mon con ge ni tal in ner ear mal for ma -ti ons, as so ci a ted with sen so ri ne u ral he a ring loss (SNHL).1-4Alt ho ugh LVA is re por ted in in comp le -te par ti ti on type II mal for ma ti on (Mon di ni de for mity),5 lar ge ves ti bu lar aqu e duct syndro me (LVAS) is con si de -red to exist only when en lar ge ment of the ves ti bu lar aqu e duct (VA) is the so le ano maly of the in ner ear evi -dent on ra di og rap hic stu di es.6-8The pa ti ents typi cally ex pe ri en ce bi la te ral and prog res si ve SNHL, with acu te dec re a ses in the he a ring le vel fol lo wing he ad tra u ma or ac ti vi tes in vol ving a Val sal va ma ne u ver.1,2,7,9Cur rently, the re is no tre at ment to pre vent the prog res si on of SNHL in pa ti ents with LVAS, but avo i dan ce of he ad tra u ma is es sen ti al for pa ti ent ca re.2,6,9
We pre sent two sib lings with LVAS with cli ni cal, au di o lo gic, ra di og rap hic, and sur gi cal analy sis and em-p ha si ze the im em-por tan ce of con si de ring iso la ted LVAS as a se pa ra te en tity in the spec trum of in ner ear di se a ses. CA SE RE PORT
CCAA SSEE 11
The first pa ti ent (Pt.1) was first sus pec ted to ha
-ve he a ring loss at 3 ye ars of age, had the au di o lo gi cal eva lu a ti on el sew he re, and was fit ted with a he a ring aid on the left ear. Her first au di o lo gi cal eva lu a ti on at the age of 9 ye ars de mons tra ted pro fo und SNHL on the right ear, and mo de ra te to se ve re mi xed type he a ring loss on the left ear (Fi gu re 1). Aco us tic im mi tan ce metry in di ca ted type As tympa nog rams bi la te rally, with aco us -tic ref le xes pre sent only on the left ear con tra la te rally at the ma xi mum in ten sity le vels at 500 Hz, 1 kHz and 2 kHz. The pa ti ent was ma na ged with con ven ti o nal he a -ring amp li fi ca ti on.
The birth his tory was nor mal with the pa ti ent de li -ve red at full term by nor mal la bor. The mot her was not ex po sed to any known po ten ti al te ra to gens. The ne o na -tal co ur se inc lu ded physi o lo gic ja un di ce, re qu i ring no tre at ment. Pt.1 had no his tory of oto to xic me di ca ti on ex-po su re, he ad tra u ma or me nin gi tis. De ve lop men tally, she had met ap prop ri a te ne u ro lo gic mi les to nes. The re was no his tory of con san gu i nity or ge ne tic di sor ders in the fa mily.
The otor hi no lary ngo lo gic and ne u ro lo gic exa mi -na ti ons re ve a led no ab nor ma li ti es. The tympa nic
membra nes we re in tact and mo bi le with no evi den ce of os si -cu lar mal for ma ti ons. The cra ni al ner ves we re in tact bi-la te rally. She had no dysmorp hic fe a tu res or go it re. Ro u ti ne blo od che mis try tests we re nor mal. Comp le te me ta bo lic wor kup inc lu ding thyro id func ti on tests and thyro id an ti body scre e ning were wit hin nor mal limits. A tem po ral bo ne com pu ted to mog raphy (CT) scan ning de -mons tra ted bi la te ral LVA (Fi gu re 2). The right and left VAs me a su red 4.2 mm and 4 mm, res pec ti vely, ac cor -ding to the tech ni qu e of Val vas so ri and Cle mis.8The ra-di o lo gic ano maly was con sis tent with iso la ted LVAS.
Her he a ring le vel de te ri o ra ted and even tu ally prog -res sed to pro fo und SNHL over the next six ye ars. The pa-ti ent was eva lu a ted for the coch le ar imp lan ta pa-ti on at the age of 17 ye ars (Fi gu re 3) and fo und to be a go od can di da te. Coch le ar imp lan ta ti on to the right ear was per for -med in the ye ar 2000 wit ho ut pe rilym pha tic gus her du ring coch le os tomy. Full in ser ti on of the elec tro de ar
-Figure 1. The first audiogram of Pt.1 obtained at the age of 9 years (SDT:speech detection test, SRT: speech reception threshold).
Figure 2. Axial computed tomography scan of Pt.1 demonstrating large vestibular aqueduct (arrow) and vestibule (right ear).
ray was ac hi e ved. Elec tri cally evo ked sta pe di us ref le xes we re re cor ded and elec tri cally evo ked com po und ac ti on po ten ti als we re re li ably me a su red in tra o pe ra ti vely. She has open spe ech un ders tan ding with the coch le ar imp lant.
CCAA SSEE 22
The first pa ti ent’s sis ter (Pt.2) was re fer red to our
cli nic for he a ring eva lu a ti on at the age of 11 ye ars. The au di o lo gic eva lu a ti on de mons tra ted bi la te ral mo de ra te SNHL with a flat au di o met ric con fi gu ra ti on (Fi gu re 4). Aco us tic im mi tan ce metry re ve a led type As tympa nog rams bi la te rally with pre sent con tra la te ral aco us tic ref -le xes at the ma xi mum in ten sity -le vels at 500 Hz, 1 kHz and 2 kHz.
She was the pro duct of a nor mal preg nancy, had a ne ga ti ve me di cal his tory and had pro per fin dings at her physi cal exa mi na ti on. She had no dysmorp hic fe a tu res or go it re. Ro u ti ne blo od che mis try tests we re nor mal. Comp le te me ta bo lic wor kup inc lu ding thyro id func ti on tests and thyro id an ti body scre e ning we re wit hin nor-mal limits.
The pa ti ent was fit ted with mo de ra te ga in he a ring aids and was fol lo wed thro ugh ro u ti ne exa mi na ti ons.
The he a ring loss prog res sed gra du ally from mo de ra te to se ve re SNHL in the fol lo wing seven ye ars and the he a ring aids’ fit ting was mo di fi ed ac cor ding to the new he -a ring le vels.
In July 2000, the pa ti ent was re fer red with an at-tack of sud den he a ring loss (SHL) and a comp la int of au ral full ness on the left ear with flat con fi gu ra ti on on au di og ram. Au di o lo gi cal eva lu a ti on in di ca ted pro fo -und SNHL on the left ear and se ve re SNHL on the right ear. Bi la te ral type As tympa nog rams were ob ta i ned. The pu re to ne thres holds and the spe ech tests we -re fo und to be de te ri o ra ted. Tran si ent evo ked oto a co us tic emis si ons we re bi la te rally ab sent. Me di -cal tre at ment with ste ro ids was ad mi nis te red and im-pro ve ment was ob ser ved in the midd le and high fre qu en ci es. Im pro ve ment was al so evi dent on the spe ech re cep ti on thres hold and spe ech dis cri mi na ti on sco -re on the left ear.
One month la ter, SHL re cur red on the right ear. Me di cal tre at ment was re pe a ted with an out co me of im-pro ve ment in both midd le and high fre qu en ci es as well as spe ech dis cri mi na ti on sco res. The pa ti ent ex pe ri en ced uns te a di ness with a left be a ting, first deg re e, di rec ti on fi xed ho ri zon tal nystag mus. The re ma i ning ves ti bu lar exa mi na ti on bat tery con sis ted of a ne ga ti ve fis tu la test and a nor mal Rom berg’s test.
A tem po ral bo ne CT was ob ta i ned, de mons tra ting a LVA with a me a su re ment of 3.5 mm for both VAs (Fi -gu re 5). Mag ne tic re so nan ce ima ging (MRI) scans re-ve a led mas si re-ve en lar ge ment of the en dolym pha tic sac, with an en han ce ment in the mas to id cells and me soty mpa num of the right ear iso in ten se to that of en dolym -pha tic system (Fi gu re 6).
Af ter exp la i ning the pro ce du re and the out co me to the fa mily in de ta il, right exp lo ra ti ve tympa no tomy was per for med with the tho ro ugh un ders tan ding that the re might be no re co very of he a ring. Os si cu lar cha in and sta pes fo otp la te were hyper mo bi le with a pro mi nent mem bra ne o us ro und win dow bul ging. The es ca pe of pe rilymph was ob ser ved from the oval win dow with re-pe a ted Val sal va ma ne u ver. The midd le ear ca vity was ob li te ra ted with fat tis su e and fib rin glu e. Pos to pe ra ti ve au di o lo gi cal exa mi na ti ons re ve a led slight im pro ve -ment in the high fre qu en ci es. Du ring the fol low-up pe ri od of 10 ye ars, she had eight SHL at tacks: fi ve ti -mes in the right ear and thre e ti -mes in the left ear. Sub-Figure 3. The audiogram of Pt.1 before the cochlear implantation at the age
of 17 years (SRT: speech reception threshold, WDS: word discrimination score).
Turkiye Klinikleri J Int Med Sci 2008, 4 167 In or der to ad dress the pos si bi lity of in he ri tan ce of
LVA, a tho ro ugh eva lu a ti on of each pa rent was per for -med. The au di o lo gic exa mi na ti ons we re nor mal. HRCT ima ges we re ob ta i ned from the pa rents with nor mal VAs and no de tec tab le in ner ear ab nor ma li ti es, in di ca ting that they are unaf fec ted.
This re port was ap pro ved by the et hics com mit te e of our de part ment and car ri ed out in ac cor dan ce with the Dec la ra ti on of Hel sin ki. In for med and full con sent has be en re ce i ved from the pa rents for sha ring and pub-lis hing the da ta in this study.
DIS CUS SI ON
The VA is the bony ca nal con ta i ning the en dolym pha tic duct, which is for med by the jo i ning of the ut ri -cu lar and sac -cu lar ducts, and the in tra os se o us por ti on of the en dolym pha tic sac.10,11It is pro po sed that an ar rest in the de ve lop ment in the 5th we ek of ges ta ti on pri or to the leng the ning and nar ro wing of the VA re sults in a lar -ger-ca li ber.1,7,8,12,13LVA is de fi ned as me a su red on a ra-di og raph, at half ra-dis tan ce bet we en the com mon crus and its ex ter nal aper tu re at the pos te ri or fos sa, in the an te -ro pos te ri or di men si on.3,4,8,12The ra di o lo gi cal di ag no sis of LVAS re qu i res that a VA, by a me a su re ment gre a ter than 1.5 mm at the mid po int of the dis tal limb, be the so -le ab nor ma lity.4,6
With iso la ted LVA, SNHL which usu ally be gins in early child ho od is of ten ex pe ri en ced with an acu te on -set, and fluc tu a ting or prog res si ve in co ur se in re la ti on to he ad tra u ma and ac ti vi ti es in vol ving a Val sal va ma-ne u ver.1,2,7,9,14-16The SNHL is bi la te ral in 81% to 94% of ca ses, ran ging from nor mal to pro fo und de af ness with pre do mi nantly down slo ping au di og rams.1,2,4,7,12Ves ti -bu lar symptoms are re por ted by one third of pa ti ents with LVAS.1,6,17
Mul tip le re ports ha ve spe cu la ted on the pat hoph ysi o logy of SNHL in LVAS. LVA may not ha ve be en ab -le to ser ve as a re sis tor to the ref lux of the hype ros mo tic flu id from the sac in to the coch le a af ter acu te pres su re fluc tu a ti ons in ce reb ros pi nal flu id as se en in he ad tra u ma, with da ma ge to the coch le ar ne u ro e pit he li um and ves ti -bu lar struc tu res.8,9Fre qu ent at tacks might gra du ally ca u -se per ma nent da ma ge to in ner ear struc tu res.1,2Anot her pos sib le ca u se of SHL in LVAS is PLF, which is known to be fre qu ently ob ser ved in con ge ni tally mal for med ears.1,18,19Our pa ti ent (Pt.2) had fluc tu a ting and prog res -si ve SNHL with a ves ti bu lar at tack. The sus pec ted PLF was eli ci ted du ring a right exp lo ra ti ve tympa no tomy.
The ge ne tic stu di es map ped the res pon si bi lity of LVA and in comp le te par ti ti on type II mal for ma ti on to PDS (al so known as SLC26A4) ge ne on chro mo so me 7q31, which has be en known to be as so ci a ted with Pen-dred’s syndro me (PS).6,20,21PS is cha rac te ri zed by a pro-fo und SNHL and dif fu se go it re.20 Our pa ti ents had thyro id func ti on tests and thyro id an ti body scre e ning wit hin nor mal ran ges.
Tre at ment of LVAS is pri ma rily sympto ma tic with di sap po in ting re sults. The re exists no be ne fi ci al tre at -ment ot her than amp li fi ca ti on with he a ring aids.1,6,9The Figure 5. Axial computed tomography scan of Pt.2 demonstrating a large
vestibular aqueduct (arrow) (right ear).
Figure 6. MRI image of Pt.2 showing a large endolymphatic sac (star) with an enhancement in the mastoid cells isointense to that of endolymphatic sys-tem (arrow) (right ear).
re si du al he a ring of chil dren with LVAS may al low them to ac qu i re ex cel lent spe ech using the se he a ring aids be-fo re the ad vent of pro be-fo und SNHL.22If no ai dab le he a -ring re ma ins, a coch le ar imp lant may be con si de red.22 Pt.1 with pro fo und SNHL had coch le ar imp lan ta ti on per for med suc ces fully.
Upon di ag no sis of LVAS, the pa ti ent must be edu -ca ted to ref ra in from even mi nor he ad tra u ma and con-tact sports.1,4,6,9Fa mily mem bers sho uld be scre e ned with au di o metry and CT, and dis co u ra ged from con san-gu i ne o us ma tings. The pos si bi lity of LVAS sho uld be
con si de red in chil dren with unexp la i ned prog res si ve SNHL, es pe ci ally tho se who de ve lop de af ness af ter he -ad tra u ma.
A
Acckk nnooww lleedd ggee mmeenntt
The aut hors wish to thank Asist. Prof. Jef frey How lett from “Ka dir Has Uni ver sity, De part ment of Ame ri can Cul tu re and Li te ra tu re ” for lan gu a ge edi ting of the ma -nus cript and Ay ça Çip rut from “Mar ma ra Uni ver sity, De part ment of Otor hi no lary ngo logy, Sub-de part ment of Au di o log y” for au di o lo gic eva lu a ti ons.
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