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Auditory Brainstem Implant (ABI)

  1. This implant is designed to stimulate the cochlear nuclear complex in the brainstem directly by placing the implant in the lateral recess of fourth ventricle. Such an implant is needed when CN VIII has been severed in surgery of vesti­bular schwannoma.
  2. In these cases, cochlear implants are obviously of no use. In unilateral acoustic neuroma, ABI is not necessary as hearing is possible from the contralateral side but in bilateral acoustic neuromas as NF2, rehabili­tation is required by ABI.
  3. Brainstem implant is similar to “Nucleus” multichannel cochlear implant except that the multielectrode array is attached to a Dacron mesh which is placed on the brain­stem.
  4. Receiver/stimulator has a removable magnet so that MRI can be safely performed in such cases if need arises.
Table: Syndromes associated with hearing loss

 

Sl.

Sydrome

Features

Type of hearing

loss

Onset

(Congenital/

Delayed)

Type of

Inheritance

1.

Waardenbur’g

syndrome

White forelock

Heterochromia iridis

Vitiligo

Dystopia conthorum

Unilateral or

bilateral SNHL

Congenital

AD

2.

Usher

Syndrome

Retinitis pigmentosa

Night blindness

SNHL

Delayed

AR

3.

Jervell and

Lange

Nielson’s

syndrome

Repeated syncopal attacks

Prolonged QT interval in ECG

SNHL

Congenital

AR

4.

Pendred

syndrome

Goitre (non-toxic) usually evident

before puberty

Perchlorate discharge test shows

Defect in organic binding of iodine

 

 

 

5.

Alport

syndrome

Hereditary progressive

glomerulonephritis

Corneal dystrophy

Progressive

SNHL

Delayed

AD or X-linked

6.

Treacher-

Collins

syndrome

(mondibulofac

ial dysostosis)

Antimongoloid palpebral fissures

Coloboma of lower lid

Hypoplasia of mandible and malar

bones

Malformed pinna and meatal atresia

Malformed malleus and incus (stapes normal)

Conductive

Congenital

AD

7.

Crouzon’s

syndrome

(craniofacial

dysostosis)

Frog eyes (exophtholmos with

divergent squint)

Hypertelorism

Parrot-beak nose

Mandibular prognathism

Premature closure of cranial sutures

with mental retardation

Conductive or

mixed

Congenital

AD

8.

 

Apert’s

syndrome

Syndactyly

All other feature of Crouzon’s

syndrome

Conductive

(Stapes fixation)

 

AD

9.

Klippel-Feil

syndrome

Short Neck

Fused cervical vertebrae

Spina bifida

Atresia of ear canal

SNHL or mixed

Congenital

AR

10.

Wildervanch

syndrome

Klippel Feil syndrome

SNHL

CN VI Paralysis

SNHL

Congenital

X-linked

11.

Branchio-

otondrome-

renal sy

Branchial fistulas/cysts

Malformed pinnae with preauricular

pits or sinuses

Renal abnormalities

Conductive or

mixed

Congenital

AD

12.

Sticker’s

syndrome

Small jaw

Cleft palate (Pierre Robin sequence)

Myopia≥retinal detachment

Cataract

Juvenile onset orthritis

Conduct-ive

Or

SNHL

Delayed

AD

13.

Van der

Hoeve’s

syndrome

Osteogenesis imperfect a with history

of fractures

Blue sclera

otosclerosis

Hearing loss (delayed onset)

Conductive,

SNHL or Mixed

Delayed

AD

14.

Pierre-Robin

sequence

Micrognathia

Glossoptosis

Cleft palate

Often part of stickler’s syndrome

SNHL

Conduc-tive loss

 

AD

15.

Golenhar’s syndrome (Facio-auriculo-vertebral dysplasia) or (aculo-auriculo-vertebral [OAV] syndrome)

Facial asymmetry

Low set ears, atresia of earcanal

Cardiac abnormalities

Preauricular tags/pits

Hemivertebrae in cervical region

Epibular dermoid

Coloboma of upper lid

Mixed or

Conduc-tive

Congenital

AD or sporadic

extra

chromosome

 

Multifactorial

(genetic and

environm

ental)

16.

Dow’n

syndrome

(Trisomy 21)

Microcephaly

Mental retardation/deloyed development

Short stature

Epicanthal folds

Stenosis of ear canal

High incidence of serous otifis media

Atlanto-axial instability

Conduc-tive

Congenital

Extra chromosome


SNHL = Sensorinevral hearing loss, AD= Autosomal dominant, AR= Autosomal recessive

*it is called a sequence, not a syndrome, because multiple anormalies result in sequence from a single primary abnormality., ie micrognathia which leads to glossoplosis which in turn causes cleft palate.





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