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Health condition · Clinically reviewed

Enlarged vestibular aqueduct, imaging, genetics and a hearing plan that grows with your child.

The most common inner-ear malformation seen on scans in children with sensorineural hearing loss - protected, monitored and treated by a specialist team.

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A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a UK-registered clinician with paediatric otology experience before publication.

  • 02

    Sourced from guidance

    Checked against BSA, BCIG, ENT UK, Great Ormond Street and specialist commissioned service standards you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK practice including SLC26A4 genetic testing, MRI protocols and bilateral cochlear implantation pathways.

Key facts

EVA at a glance.

The essentials, in plain English - what an enlarged vestibular aqueduct is, how it is measured and what it means for hearing.

  • What it is

    A congenital enlargement of the bony canal that houses the endolymphatic duct and sac - the most common inner-ear malformation seen on imaging in children with sensorineural hearing loss.

  • How it is measured

    Cvitkovic criteria - the vestibular aqueduct measures more than 1.5 mm at its midpoint on CT. The older Valvassori threshold is more than 2 mm.

  • Sides affected

    Bilateral involvement is common - both ears are often abnormal even when one side seems clinically dominant.

  • Genetics

    Frequently linked to SLC26A4 mutations - biallelic (Pendred syndrome, with goitre) or monoallelic (DFNB4 spectrum, non-syndromic).

  • Hearing pattern

    Sensorineural hearing loss - typically progressive, fluctuating and often stepwise after minor head trauma or barotrauma.

  • Managed where

    Specialist paediatric ENT, audiology, clinical genetics and endocrinology teams - usually within a commissioned tertiary or quaternary UK centre.

Why this guide matters

Early answers, and a plan that grows with your child.

EVA is not just an imaging finding - it changes how hearing is monitored, how sports are chosen and how the whole family is supported.

  • Imaging gives you the diagnosis

    A CT temporal bone (Cvitkovic and Valvassori criteria) and an MRI of the internal auditory meatus together confirm EVA and check the rest of the inner ear.

  • Genetics changes the follow-up

    SLC26A4 mutations - biallelic (Pendred) or monoallelic (DFNB4 spectrum) - guide thyroid monitoring and cascade testing across the family.

  • Hearing plans have to be dynamic

    Loss can be progressive and fluctuating - aids first, cochlear implants where indicated, and a written plan for head-trauma and barotrauma avoidance.

How the diagnosis is made

From audiogram to a clear plan.

The steps a UK paediatric ENT and audiology team will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    Detailed history and audiology

    A structured history covering birth, hearing milestones, head injuries and family history, alongside age-appropriate pure-tone or paediatric audiometry.

  2. 02

    Assessing

    Tympanometry and OAEs

    Tympanometry is typically normal (Type A) - EVA is a sensorineural rather than conductive problem. Otoacoustic emissions clarify the cochlear picture.

  3. 03

    Assessing

    Vestibular screen

    Selective vestibular testing where the child has vertigo, imbalance or Tullio phenomenon - sound-induced dizziness.

  4. 04

    Confirming

    High-resolution CT temporal bone

    The gold-standard imaging investigation - the vestibular aqueduct is measured at its midpoint and compared against Cvitkovic and Valvassori thresholds.

  5. 05

    Confirming

    MRI internal auditory meatus

    MRI shows the enlarged endolymphatic duct and sac, and screens the cochlea, vestibule and cochlear nerve before any implant planning.

  6. 06

    Confirming

    Genetic testing

    Specialist-commissioned SLC26A4 and hearing-loss gene panels - arranged through paediatric ENT and clinical genetics.

  7. 07

    Preparing

    Thyroid and endocrine review

    Thyroid function tests and thyroid ultrasound when Pendred syndrome is suspected - a goitre may only appear around adolescence.

Typical pathway: from first abnormal audiogram to a full MDT plan within weeks at a specialist centre.

Symptoms

What EVA looks and feels like.

The classic pattern of progressive, fluctuating sensorineural loss - with vestibular features in around a third of children and, in Pendred, a later goitre.

  • Sensorineural hearing loss

    Often congenital, sometimes emerging in childhood or adolescence - high frequencies tend to drop first.

  • Progressive and fluctuating loss

    Hearing thresholds shift over months or years, sometimes with sudden step-downs then partial recovery.

  • Trauma-triggered drops

    Minor head knocks, contact sports or a heavy fall can precipitate a sudden worsening of hearing.

  • Barotrauma sensitivity

    Pressure changes with SCUBA diving, flying or high-altitude travel can trigger hearing or balance symptoms.

  • Vertigo and imbalance

    Around a third of children have vestibular symptoms - episodic vertigo, motion sensitivity or unsteadiness.

  • Tullio phenomenon

    Loud sounds provoke vertigo, oscillopsia or a brief loss of balance - a classic third-window feature.

  • Goitre in Pendred syndrome

    A neck swelling from thyroid enlargement, usually appearing in later childhood or adolescence - often euthyroid initially.

  • Red flag - sudden hearing loss

    An abrupt drop in hearing, particularly after head trauma, needs same-day specialist ENT and audiology review.

Treatment

How EVA is managed in the UK.

Hearing aids first, cochlear implants where indicated - all wrapped around trauma avoidance, genetics and family support.

  • Hearing aids

    Conventional digital hearing aids under specialist paediatric audiology - the first-line intervention for most children with EVA.

  • Cochlear implantation

    For severe-to-profound or rapidly progressive loss - delivered through specialist commissioned centres. Bilateral implantation is increasingly the norm. See /treatments/cochlear-implant-clinic/.

  • Head-trauma avoidance

    Contact-sport counselling, protective headgear and a written activity plan - agreed with paediatric ENT and school.

  • Barotrauma precautions

    Specific advice against SCUBA diving and caution around high-altitude travel or extreme pressure exposure.

  • Steroids for acute drops

    Systemic or intratympanic steroids may be tried for sudden hearing loss - specialist ENT-led with limited evidence but occasional benefit.

  • Genetic counselling

    For the child, siblings and parents - clarifies inheritance, cascade testing options and reproductive planning.

  • Educational and deaf support

    Teacher of the Deaf input, EHCP where needed, BSL access and Hearing Impaired Service liaison - with reasonable adjustments in class.

  • Endocrine follow-up (Pendred)

    Paediatric endocrinology review for thyroid monitoring and, where indicated, thyroid ultrasound and biochemistry across adolescence.

What this guide is based on

The sources behind every claim on this page.

UK specialist society standards and specialist commissioned service specifications, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your paediatric ENT team, audiologist and geneticist know your child and can tell you which parts apply to them. If in doubt, get seen.

  • British Cochlear Implant Group (BCIG). Standards for paediatric cochlear implantation.

  • British Society of Audiology (BSA). Paediatric audiological assessment recommended procedures.

  • ENT UK / British Association of Otorhinolaryngologists. Paediatric hearing loss guidance.

  • Great Ormond Street Hospital and Manchester Centre for Genomic Medicine. SLC26A4 and hearing-loss panel information.

  • NHS England. Specialist commissioning specifications for cochlear implantation and complex paediatric hearing services.

Red flags

When EVA needs urgent attention.

Most of the year-to-year work happens in outpatients. These are the situations that do not - and where a specialist opinion is needed quickly.

  • Sudden sensorineural hearing loss

    An abrupt drop in hearing, particularly after minor head trauma, needs urgent ENT review within 24 hours - not a routine outpatient wait.

  • Head injury with hearing change

    Any head injury followed by new hearing loss, vertigo or persistent imbalance needs same-day ENT and audiology assessment.

  • Rapidly progressive loss

    Serial audiograms showing month-on-month decline should trigger urgent cochlear implant discussion at a specialist centre.

  • Meningitis or febrile illness

    EVA co-exists with other inner-ear anomalies in some children - meningitis with hearing change is an emergency.

  • Goitre or thyroid symptoms

    A new neck swelling or thyroid symptoms in a child with EVA raises Pendred syndrome - refer for endocrine and imaging review.

  • Speech and language regression

    Loss of previously acquired words or slowing of language milestones needs urgent audiology and speech-and-language therapy review.

  • New balance failure or falls

    Persistent unsteadiness, unexplained falls or oscillopsia deserve vestibular assessment - not a wait-and-see approach.

  • Family with Pendred features

    A relative with combined hearing loss and goitre should prompt earlier genetic counselling and cascade testing.

  • Barotrauma exposure

    A child with EVA who has been diving or flying with a heavy cold needs a low threshold for review after new symptoms.

Living with it

A condition that shapes childhood, not one that defines it.

Four things that make the biggest difference day to day - trauma protection, planning for fluctuations, leaning on the MDT and using the charities.

A quiet reminder

Small steady habits, kept up for years.

Consistent audiology follow-up, protective headgear, a good school plan and a clear pathway for sudden drops in hearing - these carry the day.

  1. 01 Protect

    Guard against head trauma

    Agree a written activity plan with paediatric ENT - swap high-impact contact sports for lower-risk alternatives, and use protective headgear where appropriate.

  2. 02 Anticipate

    Plan for fluctuations

    Hearing can dip and partly recover - keep audiology appointments close together, and know who to call for a sudden drop.

  3. 03 Team

    Lean on the whole MDT

    Paediatric ENT, audiology, genetics, endocrinology, speech-and-language therapy and Teacher of the Deaf all play a part - it is not one clinician alone.

  4. 04 Support

    Use the charities

    RNID, the National Deaf Children’s Society (NDCS) and cochlear implant user groups offer practical, emotional and educational help.

Frequently asked

Everything families ask about EVA.

Quick answers on imaging, Pendred syndrome, hearing aids, cochlear implants and where UK care happens.

  • What is an enlarged vestibular aqueduct?

    The vestibular aqueduct is a narrow bony canal running from the inner ear towards the back of the skull, carrying the endolymphatic duct and sac. When it is wider than normal (Cvitkovic criteria - more than 1.5 mm at the midpoint on CT, Valvassori - more than 2 mm), it is called an enlarged vestibular aqueduct (EVA) or large vestibular aqueduct syndrome (LVAS). It is the most common inner-ear malformation detectable on imaging in children with sensorineural hearing loss.

  • How is EVA linked to Pendred syndrome?

    Pendred syndrome is an autosomal recessive condition caused by biallelic mutations in SLC26A4. It combines EVA, sensorineural hearing loss and a thyroid goitre that usually develops around adolescence. Monoallelic SLC26A4 changes can also cause non-syndromic EVA and hearing loss (part of the DFNB4 spectrum). Genetic testing is arranged through specialist paediatric ENT and clinical genetics services.

  • How is EVA diagnosed?

    Diagnosis combines paediatric audiology (progressive or fluctuating sensorineural hearing loss with normal tympanometry) and imaging. High-resolution CT of the temporal bone measures the vestibular aqueduct at its midpoint and is the gold standard. MRI of the internal auditory meatus shows the enlarged endolymphatic duct and sac and screens the cochlea and cochlear nerve. Genetic testing, thyroid function and thyroid ultrasound follow where Pendred is suspected.

  • Why does hearing sometimes drop after a bump on the head?

    The exact mechanism is not fully understood, but the enlarged endolymphatic sac and altered inner-ear pressure dynamics make the cochlea vulnerable. Even minor head trauma, contact sports or barotrauma (diving, flying with a heavy cold) can trigger a step-down in hearing. That is why children with EVA are counselled to avoid high-impact contact sports and to use protective headgear where appropriate.

  • Will my child need a cochlear implant?

    Many children manage well with digital hearing aids under specialist paediatric audiology. If hearing loss progresses to severe or profound levels, or if aids no longer give useful benefit, cochlear implantation is offered through specialist commissioned centres. Bilateral implantation is increasingly standard. See /treatments/cochlear-implant-clinic/ for how this pathway works.

  • Which UK teams look after children with EVA?

    Care is delivered through specialist paediatric ENT, audiology, clinical genetics and endocrinology teams - often in commissioned tertiary or quaternary centres such as Great Ormond Street or Birmingham Children’s Hospital. Cochlear implantation is provided by BCIG-recognised specialist services. Local audiology and Teacher of the Deaf teams provide day-to-day support alongside the specialist centre.

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