Deafness can be classified according to the degree of loss, the location of the injury, the age of onset.
Depending on the degree of hearing loss, the following are distinguished: mild deafness (20-40 dB), average deafness (40-70 dB), severe deafness (70-90 dB), deep deafness (over 90 dB) and total deafness (no auditory residue).
This classification, compared with the intensity of the word (65 dB average one meter away), makes it possible to understand the difficulties that the hearing impaired encounters in listening to the voice of conversation and, consequently, what effect it has in linguistic acquisition if it arises before three years of life.
Considering the place of injury, transmissive deafness (by dysfunction of the outer and/or middle ear) is distinguished from perceptual or neurosensory deafness (by lesions of the inner ear and/or acoustic pathways): the latter are distinguished into cochlear, retrococlear and central.
Transmissive deafness is susceptible to medical and/or surgical therapy often decisive on impairment, while perceptual deafness is not yet treatable with this type of therapy and the intervention is prosthetic-rehabilitative in order to reduce and also solve the disability and communication handicap related to deafness,but not impairment.
Finally, with regard to the moment of onset, it is customary to propose two subclassifications,the first concerning the period of onset in relation to the acquisition of verbal language which, asyou know, is learned through the auditory way, and the second in relation to the chronological age and the event of insevery.
In relation to the acquisition of language are distinguished: preverbal deafness (within the 12th month), periverbal deafness (1-3 years) and verbal deafness (insurgent after three years) and this classification acquires an important practical value sincethe organization of a possible rehabilitation activity will have to be mainly auditory in verbal deafness, while in hearing loss that arose before language acquisition it must also be cognitive-linguistic.
As for the moment of onset, prenatal deafness is distinguished, from neonatal and postnatal; the former are also called congenital and the remaining acquired deafness; finally, it is remembered that the age of hearing loss can be stable, fluctuating or evolutionary.
With regard to the causes of deafness, it is well known that transmissive hearing loss sees as more frequent causes: earwax caps, catarrhal otitis, acute middle otitis and external and/or middle ear dysmorphism; perceptual deafness is 60% genetic, sindromic and non-syndromeic, 20-30% toxic-infectious and in the remaining idiopathic cases.
With regard to epidemiological aspects, the data in the literature indicate that disabling deafness (over 70 dB) has a prevalence of 1.6 per thousand, with an incidence for newborns of 1 per thousand. Less important hearing loss, on the other hand, is very frequent and affects a third of the paediatric population at preschool age when the peak prevalence of Essudative Medium Otitis (OME) is higher.
Since hearing is the main channel for learningin general and language in particular, prevention, early diagnosis and timely treatment of hearing loss are key activities for the future cognitive growth of the small patient.
Also in the audiological field there are three types of prevention: primary, secondary and tertiary.
Thanks to primary prevention it is possible to avoid the onset of deafness and this is not possible today for all forms of hearing loss, but only for those caused by neonatal jaundice due to Rh incompatibility, ototoxicity from drugs and some infectious diseases.
a) Neonatal jaundice deafness
Primary prevention is achieved by methods aimed at reducing the level of serical bilirubin. The type of resource to be used (phototherapy, immunoglobulins e.v., exanguinotransfusion) is decided on the basis of the level of bilirubinemia, the age of the child and the pathology possibly associated with it.
(b) Ototoxicy from drugs
Taking ototoxic drugs is an audiological risk factor for deafness. Among the substances of which ototoxicy has been established are aminoglycosis antibiotics (gentamicin, streptomycin, kanamicin),salicylates, quinine, chemotherapy (cisplatin), diuretics of the loop as well as certain substances such as alcohol and carbon monoxide.
Ototoxicy can vary appreciably not only depending on the dosage, route of administration and the rate (duration and number of daily administrations) of treatment, but also for individual sensitity.
Taking into account the above it is useful to emphasize that, in case of absolute need for treatment with ototoxic drugs, continuous monitoring of the auditory function is necessary to identify initial damage, before they become disabling. On the other hand, sensory damage can occur some time after causal drug treatment, so that only with appropriate follow-up can such cases be identified.
(c) Deafness from infectious diseases
Many infectious diseases causing deafness can be prevented with an intelligent vaccination program, predicting that the main causes of congenital perceptual deafness on an infectious basis are rubella, cytomegalovirus, toxoplasmosis. While the most frequent causes of deafness are secondary to mumps (cause of generally monolateral deafness) and bacterial meningitis.
In the context of congenital infections transmitted in utero, specific serological investigations play a
diagnostic confirmation of clinical suspicion, but as far as rubella is concerned, these tests are significant in the pre-conceptional period in order to identify unprotected women to be vaccinated.
In addition to vaccination for rubella, vaccinations are also recommended for mumps,
measles and pathogens of bacterial meningitis, in particular for haemophilus and pneumococcal.
Carrying out vaccinations against these pathogens can therefore prevent most of the acquired deafness.
Secondary prevention avoids aggravation of hearing impairment especially in middle otitis and meningitis deafness.
For medium otitis, the hygiene and health of the rhinopharynx is a fundamental condition. Important is the use of cortisone in bacterial meningitis (especially those from Hemophilus)to reduce the consequences of endococlear ossification that must be immediately identified before it affects the results of a possible cochlear implant.
Tertiary prevention aims to prevent deafness from becoming a cause of disability and communication disabilities, especially chronic ones such as the lack of learning verbal language, realizing the condition of deafmutism.
The means to prevent deafness from complicateing are early diagnosis and treatment that can only be real if preceded by early identification carried out through mass screening in congenital deafness and with immediate diagnosis in those acquired, especially if from meningitis.
The most important audiological screening in paediatric age is neonatal screening because it allowsto identify early severely disabling deafness at an optimal age for rehabilitation treatment.
Neonatal screening may be limited to those at audiological risk, but today it is preferable to test the entire population of newborns.
AUDIOLOGICAL RISK FACTORS
• Familiarity with congenital neurosensory deafness;
• Congenital infections (Cytomegalovirus,toxoplasmosis, rubella, herpes etc);
• Craniofacial malformations;
• Birth weight less than 1500 g;
• Jaundice with bilirubinemia of at least 20 mg/dl or which required exanguinotransfusion;
• Ototoxic drugs;
• Bacterial meningitis;
• Mechanical ventilation with a duration of more than 4 days;
• Apgar score 0-4 in the 1st minute and 0-6 in the 5th minute;
• Syndromes/chromosomopathies associated with auditory impairment;
Before activating any screening activity it is necessary to keep in mind some concepts that prevent a “deistage” from revealinging,costly and harmful.
It is important to stress that screening is not a diagnostic procedure since it aims toindicate whether or not an individual is normal, while the diagnostic survey allows a quantitative and qualitative evaluation of anyhearing impairment.
Before implementing a screening programme, it is essential to bear in mind that it is not enough to have a valid screening test, but that we must have an effective organization and a link with a diagnostic center of pediatric audiology since’the objective is not only the identification, but the diagnosis and early treatment of deafness’.
Neonatal screening may be limited to those at audiological risk (2-4%bilateral significant hearing loss), but, in view ofthe fact that 30-40 % of subjects with significant hearing loss do not have risk factors, it is preferable to test the entire infant population, according to the following recommendations:
Otoemissions (OAE) and/or acoustic evoked potentials of the automatic trunk (AABR) whose positivity must be confirmed by conventional acoustic evoked potentials with the determination of the auditory threshold carried out at the center itself or at a paediatric audiology service.
In the event that the conditions for effective neonatal screening are not met by the methods indicated, an information booklet may be used to be delivered to new mothers to ensure that they watch over the hearingof the child.
Early detection of deafness does not end with neonatal screening as preverbal deafness can arise even in later times; audiological surveillance can be carried out through the same information booklet delivered to all new mothers on discharge from birth centres, public and/or private.
Neonatal audiological screening, because it is effective, must affect at least 95% ofthe population surveyed with a REFER(positive tests for deafness)not exceeding4% and must be able to identify a person with disabling deafness for every thousand births.
The audiological diagnosis is clinical-instrumental and involves several moments of investigation, grouped into two batteries: one for transmissive deafness and the other for perceptual deafness, emphasizing that the collection of anamnestic data should not be conducted only to identify the etiopathogenesis of auditory impairment, but above all to highlight the symptomatic characteristics of the various types of hearing loss in terms of communication skills.
In the presence of transmissive deafness, it will be possible to limit ourselves to the audio/impedenzometric study which, in most cases, is sufficient to propose the appropriate therapeutic treatment.
For perceptual deafness, on the other hand, it is necessary to know:
• the level of hearing impairment;
• the effects of the deficit on disability and disability;
• the place of injury both in terms of functional and morphological topodiagnosis,
• the etiopathogenesis of deafness,
• the presence of associated pathologies.
All information should be collected in a single diagnostic document so as not to disperse useful information for preventive, therapeutic and rehabilitation purposes.
THE STATE OF THE DEFICIT
Hearing impairment must be precisely defined for all frequencies normally evaluated in tonal audiometry. In this regard, it should be emphasized that all trusted objective tests(ECoGh, ABR) do not allow the reconstruction of a tonal audiogram and do not allow to identify auditory thresholds greater than 100 dB HL, therefore these are confirmation tests and not the main evaluation.
The audiometry tests to be used will vary according to the age of the patient, distinguishing:
• B.O.A (Behavioral Observation Audiometry)
• V.R.A. (Visual Reinforced Audiometry)
• C.O.R. (Conditionated Orientation Audiometry)
• PLAY AUDIOMETRY;
and the clinician will implement his own strategy to improve awareness and specificity (repetition of the test by different personnel with a blind procedure, training of a team of expert examiners, etc.).
It should be remembered that deafness is distinguished in: mild hearing loss (20-40 dB), medium (40-70 dB), severe (70-90 dB), deep (90-120 dB), cophosis if total bilateral deafness, anacusia se monolateral.
DISABLING EFFECTS OF THE DEFICIT
All deafness over 70 dB does not allow you to hear the voice of conversation and therefore cause an obvious disabling effect with social repercussions.
Mild or medium deafness, on the other hand, is not always the cause of disability or disability that must be investigated both by evaluating the communicative behavior of the patient (in the small child can be used the Video Analysis of Communicative Behavior) and the judgment produced by parents and teachers, pre-vilifying the questionnaires that allow the quantification of the judgment itself.
The importance of this investigation arises from the fact that in some cases of mild or medium perceptual deafness, with a cochlear location, recruitment compensates for hearing impairment for superliminal stimuli such as the voice of conversation and for these subjects no prosthetic/rehabilitative treatment is advisable, other than a periodic follow-up. The principle described above is valid especially in the first months of life sincethe communicative situations in which the infant is found are rarely multiple listening where mild or medium hearing loss acquires a disabling value.
PLACE OF INJURY
Audiological topodiagnosis is achieved by impedenzometry, otoemissions and the study of evoked potentials.
The morphological diagnosis, in turn, mainly concerns the dysmorphisms of the oxycularchain, the innerear and the acoustic nerve, using CT when the object of investigation is bone tissue and MRI when instead you want to study soft tissues.
ETIOPATHOGENESIS OF DEAFNESS
In the first diagnosis the clinician can be faced with two consequences: deafness from known causes and unknown causes. In all deafness from unknown causes it is useful to carry out the search for a possible infection with Cytomegalovirus or a genetic transmission of the deficit.
Cytomegalovirus deafness is today the most frequent cause of hearing impairment for congenital infection even if it causes often evolutionary hearing loss even after the first months of life.
More than 60% of deafness is of genetic origin, of which 30% are part of a syndromeic condition (i.e. they are associated with other alterations), mendelian hereditaryity, such as: Alportsyndrome, Norie syndrome, Usher syndrome, Pendred syndrome, Waardenburg syndrome,etc.
70% are non-syndrome forms with Mendelian or mitochondrial hereditaryity divided as follows:
Recessive (about 80% of cases)
Dominant (about 18% of cases)
X-linked (about 1% of cases)
Mitochondrial (about 1% of cases).
Each mode of transmission corresponds to a specific genetic risk of recurrence of deafness.
It is the task and responsibility of the geneticist to frame the patient after the diagnosis of deafness by identifying or excluding associated pathologies (syndrome forms). The definition of genetic etiology of deafness should not only be pursued for diagnostic completeness, but also becausecertain morbid conditions maybe susceptible to therapy, or may limit therapeutic outcomes.
In practical terms, there are three main situations:
1. Subject with hearing loss within an obvious polymalformativeframework:
it will perform for the first time a dismorfological evaluation in an outpatient context, to adequately set the most suitable procedure for the general diagnostic framework, and then, depending on the final diagnosis placed, it will be reevaluated for the monitoring of possible complications through Day-Hospital and /or admissions at the Reference Center.
It will perform genetic (cytogenetic and/or molecular) tests specific to each pathology.
2. Subject with malformative syndrome and potential risk of hearing loss as a known complication of the sindromic picture:
an accurate assessment of the auditory function will be set up and, if it is abnormal, appropriately addressed for treatment.
3. Subject with isolated deafness:
it will be subjected to the genetic test of connessin 26 and possibly connessin 30 and mitochondrial, after having gathered consent in the context of a genetic consultation explaining the characteristics and limits of the genetic test.
At the end of the genetic consultation, the risk of transmission of deafness in the family will be formulated on a case-by-case basis and a written report containing the results of molecular investigations will be delivered.
Geneticists therefore contribute to the identification of etiology and to the definition of the genetic risk of patients suffering from genetic hearing loss and their families, facilitating the realization of an integrated path with other specialists.
Medical therapy mainly concerns the treatment of otitis divided into OME (Otitis Media Effusiva), OMA (Acute Otitis Media), WTO (Chronic Otitis Media).
The dimorphisms of the chain provide for reconstructive surgical treatment whose effectiveness must be carefully evaluated by the operator sinceacoustic prosthesis allows to achieve immediate and effective functional results.
Chronic otitis mucous serum(Glue-ear):
Surgical treatment with transtimpanic drainage is indicated in cases of glue ear characterized by hearing loss, typical otoscopic signs and pervia tuba.
Purulent chronic otitis (with tympanic perforation):
The surgical treatment includes three options: miringoplasty, open tympanoplasty, closed tympanoplasty, as the case may be, but favoring conservative treatments when the type and extent of the pathology does not require demolition interventions to definitively resolve the infection.
REHABILITATION PROSTHETIC TREATMENT
The strategy to be followed concerns above all perceptual deafness and transmissives that cannot be treated with medical or surgical therapy. There are two decisive moments, that is, prosthesis and speech therapy rehabilitation that will be guaranteed by a team of specialists coordinated by the manager of the structure that takes care of the patient and of which the family is an active part.
Leaving aside the transmissive hearing loss for which it may be necessary to use prostheses by bone, prosthesis isinitially, alwaysacoustic, binaural and associated, when necessary, with the use of a vibrator.
Prosthetic prescribing follows the rules laid down in current national and regional legislation and must be carried out immediately after diagnosis. The first times of use of the prosthesis will also be used by the clinician as an ex iuvantibus test to confirm the diagnosis.
From a general point of view, the rule applies that in shallow hearing loss it is appropriate to prescribe digital prostheses to ensure a good reproduction quality. In case of deep deafness, on the other hand, the main interest concerns the amount of amplification that is not always enough with digital prostheses to compensate for important hearing losses. In this case, the clinician will consider programmable prostheses that will allow to achieve the necessary levels of amplification.
Finally, it should not be forgotten that the prosthetic choice depends on the rehabilitation methods that the patient will followsince the oralistic methods “dependent expression” require less amplifications than those that accompany the rehabilitation methods of an acupedic type.
As soon as the small patient enters multiple listening situations (kindergarten, kindergarten…) it is necessary to associate the use of an FM system, also binaural, with the acoustic prosthesis.
The deep deaf will subsequently be candidates for cochlear implant to be performed after twelve months of life when there is no risk of ossification as can happen in postmeningitic deafness. In this case the cochlear implant is indicated even before twelve months of life.
The indication to the cochlear implant will have to be confirmed if the hearing aids and vibrators do not allow sufficient rehabilitation results to be achieved. The application of the cochlear implant is generally monoaural, except in cases of recent bacterial meningitis for which the risks of fibrosis and/or ossification require intervention for both ears and in the deaf-blind where hearing orientation makes it possible to reduce the mobilityhandicap.
Speech therapy rehabilitation will be mainly oral, limiting itself to auditory aspects in mild and medium deafness and also dealing with linguistic cognitive ones in the most important hearing deficits.
In any case, sign language teaching will be guaranteed in suitable places if the child’s parents prefer this type of treatment or where the prosthetic-oralchoice does not allow sufficient communication results to be achieved.
LIMITATION OF BENEFITS AND BENEFITS
The competent doctor and/or prescriber will also have to provide the necessary documentation to obtain the provisions to which the patient is entitled. The most important are the communication and attendance allowance and the choice between the two will have to be made by the parent according to the provisions of the legislation in force. It should be remembered that you can benefit from the communication allowance after the first year of life, but with the attendance allowance it is possible to cover the expenses for this first rehabilitation moment, then allowing the patient’s parents to transform the allowance of frequency itself into communication if considered more favorable.
In addition to the allowance, it is necessary to make a declaration of the state of disability and to inform parents about the facilities provided for the stamp duty and purchase of the car as wellas on local facilities and that concern above alltransport.
ASSIGNMENT OF SUPPORT TEACHER
At the beginning of each calendar year it is necessary that the team that follows the patient fill in the request of the possible support teacher to be supported by the child. The report will be attached to the functional communication diagnosis in which the hours at which the support teacher is to be present during the school week will be suggested, but bearing in mind that the final decision on the allocation of resources rests with the school director.
ASSIGNMENT OF THE HOME ASSISTANT
The Provincial Department of Care, either directly or through the municipalities, generally provide for the possibility of assigning a communication assistant whose activities take place at the patient’s home. These are staff prepared ad hoc and whose activities will have to be organized by the audiological center to which the child refers.
Controls vary depending on the type of hearing loss.
For all surgically treated ear pathologies, the healing of the disease and the solution or stabilization of impairment at least two years later must be verified.
Diseases that have benefited from medical therapy alone should be evaluated in accordance with the experience of the curant.
For perceptual deafness, the follow-up will have to be more articulated involving impairment, prosthetic gain, degree of disability and degree of disability.
Monitoring impairment will assess the stability of hearing loss and thus the continuous effectiveness of the prescribed prosthetic devices.
Prosthetic control will refer both to functional gain (tonal and verbal) and to the proper functioning of the instruments in use.
The degree of family and school disabilities will inform about the difficulties encountered by the patient both in a domestic and social environment and will lead to consideration of the opportunity for supplementary rehabilitation interventions such as the assignment of a home assistant or support teacher.
The periodicality in which the follow-up of the perceptual deaf is advisable is six-monthly and on that occasion it is advisable to formalize subsequent rehabilitation plans.