Audiology Lesson 6 - Pediatric Hearing Conditions

Question 1

Classify the levels of hearing loss

Answer 1

• mild: between 20/40 db
• moderate: 40/60 db
• severe: 60/90 db
• profound 90/120 db
• complete: >120 db

Question 2

Classify hearing loss according to the development of speech capability

Answer 2

• pre-lingual: before 18 months
• peri-lingual: 18-26 months
• after-lingual: after 36 months

If deafness occurs in the pre-lingual period there is also an important severe implication in the
development of the speech capability. This occurs if deafness is severe or profound.

Question 3

Discuss hereditary and acquired hearing loss

Answer 3

Moreover, hearing loss can be:

• hereditary
• acquired

It can be congenital - already present at birth, but also congenital with a late onset. Do not forget this concept: late onset is not expression of acquired form, it may be also hereditary. Acquired are classified in pre-natal, natal, postnatal
according to the time of presentation.

Question 4

Describe the role of hearing in the development of verbal communication and what occurs in its absence

Answer 4

Hearing is crucial for the development of verbal communication.
The CNS of the newborn/infant appears to include structures whose maturation is triggered by stimuli, and it takes place only during some critical periods.

After 12 months of auditory deprivation we can observe specific changes in the patient’s brain.
- reduction of ganglion spiral cells and cochlear nuclear cells
- reduction of cortical synapses and pyramidal neruons
- The deprived cortical hearing areas are colonized by visual and somatosensory areas
This means that if we implant a cochlear implant - the first sensation the pt will feel is a tactile sensation

An early diagnosis allows speech rehabilitation to be performed from the 6th month. If we do this, the development of speech ability becomes similar to a normal-hearing person only at the age of 4.

Question 5

Discuss Bilateral pre-lingual sensorineural hearing loss

Answer 5

Occurs in 1: 1000 newborns. Most frequently it is a severe impairment.

• 60% of cases are hereditary and 40% are acquired
• usually an expression of an autosomal recessive mutation (70%)
• in 30% of cases, hearing loss is part of a syndromic clinical picture

When evaluating a patient affected by hearing loss, it is mandatory to look for other problems (syndromic)

VERY IMPORTANT
The most frequent non-syndromic hearing loss is related to a mutation in connexin 26 [remember]

Question 6

Name and fully describe the 8 syndromes associated with hearing loss

Answer 6

1. Alport syndrome (Autosomal Recessive/X-Linked).
   Also known as hereditary nephritis -
   characterized by hematuria. When evaluating an infant with hearing loss, it is important to look for blood in their urine.
   • associated with subcapsular cataracts
   • has a later onset of hearing loss
2. Branchio-oto-renal syndrome (Autosomal Dominant)
   Characterized by the presence of branchial cysts or fistulae in the neck
   - bilateral kidney hypoplasia
   - malformation of the inner ear - enlarged vestibular aqueduct. The vestibular aqueduct links the endolymphatic sac (for reabsorption of the endolymph) with the utricle and the saccule. Its enlargement can cause different clinical pictures:
   - sudden hearing loss
   - fluctuating sensorineural hearing loss
   - progressive hearing loss or with vestibular symptoms (Menière disease type).
3. Jervell-Lange-Nielsen (Autosomal recessive).
   It’s associated with prolonged QT interval - increases risk of sudden cardiac death. Perform ECG
4. Pendred Syndrome (Autosomal Recessive).
   This is the most common hereditary hearing loss syndrome. It’s related to thyroid dysfunction Presents with enlargement of the vestibular aqueduct
5. Stickler Syndrome (Autosomal Dominant).
   It’s characterized by a mixed hearing loss. Mixed because the malformation of the inner hear is also associated with the malformation of the middle ear. Other features:
   - Cleft palate
   - Glossoptosis
   - Micrognathia (aka Bird Face)
6. Treacher-Collins-Franceschetti syndrome (Autosomal Dominant).
   The inner ear is malformed.
   - Face is characterised by downward slanting eyes
   - Microtia/anotia
   - cleft palate
   - underdeveloped zygomia
   - micrognathia

Often pts undergo tracheostomy due to a problem of the upper airways

7. Usher syndrome (Autosomal Recessive)
   Presents together with retinitis pigmentosa, meaning patients are both deaf and experience vision problems. Pts also have bilateral vestiular areflexia.

8. Waardenburg Syndrome (AD) 
Is characterized by face alteration with: white forelock, dystopia canthorum (lateral displacement of the inner canthi of the eyes) and
heterochromia iridis (eyes are 2 different colours)

Others worth a mention

Trisomy 21
Mixed HL due to a malfunction of the tensor and levator veli palatini muscles

Charge syndrome, many organs are involved ( also hearing).

Question 7

List and describe the causes of PRE-NATAL acquired hearing loss

Answer 7

1. Infections (TORCH)
   - Rubella: cochlear hearing loss, pulmonary stenosis, mental retardation and microphthalmia (Rubella syndrome)
   - Toxoplasmosis: inflammatory damage in the inner ear
   - Congenital syphilis: progressive degeneration of the inner ear and peripheral neurons associated with interstitial keratitis and dental defects
   - Cytomegalovirus
   - Herpes simplex

2. Drug toxicity
 Quinine
 Aminoglycosides
 Thalidomide
 Alcohol

Question 8

List and describe the causes of PERI-NATAL acquired hearing loss

Answer 8

1. Metabolic
   - Kernicterus (perinatal hyper-bilirubinemia syndrome): athetoid cerebral palsy and sensorineural hearing loss (Rh incompatibility, massive deposits of bilirubin in the cochlear centers and occasionally in the cochlea itself with corresponding cochleoneural deafness

• Perinatal hypoxia: injury to the cochlea and its centers in the brainstem

2. Obstetric trauma
    Forceps
    Intracerebral haemorrhage
    Intracochlear haemorrhage

Question 9

List and describe the causes of POST-NATAL acquired hearing loss

Answer 9

1. Infections
   - Meningitis and meningo-encephalitis: labyrinthitis and cochleo vestibular neuritis with damage to the sensory cells and peripheral neurons; central lesions
   - Mumps: cochlear and neural lesions
   - Measles: degeneration of the cochlea and its peripheral neurons due to infective damage, serous labytinthitis
   - Otitis media
2. Drug toxicity
3. Trauma

Question 10

Detail the diagnostic work-up of a patient with pediatric hearing loss

Answer 10

MEDICAL HISTORY
 Acquired causes vs hereditary causes (familiarity: at least 3 generations!)
 Visual disorders; deambulatory problems (Usher syndrome)
 Haematuria (Alport); renal disorders (BOR)
 White forelock; heterochromia iridis (Waardenburg)
 Goiter (pendred)

PHYSICAL EXAMINATION
external ear, neck (branchial cyst or fistulae; goiter), skin, hair, eyes, hands

INSTRUMENTAL EXAMINATION
 Urine tests (Alport; BOR) + Blood tests(Pendred)
 Ophthalmic evaluation (Alport; Stickler; Usher)
 EKG (Jervell-Lange-Nielsen)
 US (BOR)
 MRI and CT scan (bone inner ear anomalies): not strictly required before 3-4 years of age

CT and MRI are also required if you think that the patient needs a cochlear implantation because before implanting it you need to know if the auditory cranial nerve is there or not and if there is fibro-ossification of the cochlea.

Question 11

Fully describe what a cochlear implant is and how it works

Answer 11

The Cochlear Implant is an implanted device that transforms sound waves into electrical impulses with direct stimulation of the cochlear nerve.

It is not implanted with a very invasive surgery procedure, surgery is only 2-4 hours long. Insure is about 3 cm, auricular so external.

With surgery you create a direct contact between the nerve and the implant. The duration of the implant is still not
known but usually they last around 10-15 years. The second time surgery is easier, you only need to remove it and replace it.

The most important complications are facial nerve injury and extrusion of the device.
To prevent this it is implanted under the skin, but sometimes there are some reject-event

Question 12

In which scenario can the cochlear implant NOT be given?

Answer 12

When there is ossification of the inner ear.