Abstract
For many reasons an accurate and straightforward identification of congenital deafblindness can be difficult. This article reports on the assessment procedures and experience in Denmark where medical examinations were combined with functional assessments performed through direct observation. The study evaluated the assessment procedure of 190 children and adults found to be congenitally deafblind. Among the 190 individuals 76 percent were determined using functional assessment in addition to medical examination. A case example involving a 12-year-old child is also presented to illustrate the complexity in identifying congenital deafblindness. It is concluded that determining deafblindness should not be limited to medical procedures (vision and hearing tests) alone, but may also involve a lengthy process to assess the level of sense functioning the individual possesses.
Introduction
An accurate and straightforward identification of congenital deafblindness is often difficult. This is attributable to: 1) inconsistent definitions of deafblindness, 2) a huge heterogeneity within the group of individuals with congenital deafblindness, and 3) difficulties in assessing sensory functioning in persons with severe cognitive and behavioural deficits, since testing requires cooperation of the person in question. This article reports and evaluates the assessment procedures and experience in Denmark where medical examinations were combined with functional assessments performed through direct observation.
People afflicted with congenital deafblindness are both deaf and blind from birth. Pre-lingual deafblindness refers to people who become deaf and blind early in life before the development of language and subsequently post-lingual deafblindness refers to people who become deaf and blind after the development of language (acquired deafblindness).
The prevalence of congenital deafblindness has been reported to be extremely rare. Approximately one in 27,000 newborn babies is affected (Dammeyer, 2010). The prevalence of congenital deafblindness is around 1/5 of the total population of individuals with deafblindness (congenital and acquired), or 2:10,000 (Rødbroe & Janssen, 2006). There are a number of causes for congenital deafblindness in the population. The most common causes is CHARGE syndrome, prematurity, meningitis, cytomegalovirus and, in countries without inoculation programs, the Rubella Syndrome (Dammeyer, 2010). Similarly there are many causes for acquired deafblindness and if we exclude the elderly population (who are the majority of people with acquired deafblindness), the most common cause is found to be Usher Syndrome which accounts for approximately half of the people with acquired deafblindness (Møller, 2003). For the purpose of this study this article will only focus on the identification of congenital deafblindness and not acquired deafblindness.
Although the term deafblind implies a complete absence of hearing and sight, it also refers to individuals with varying degrees of vision and hearing loss. Even a slight impairment of both vision and hearing may affect the daily life and the cognitive, social and communicative development of an individual with deafblindness (Janssen & Rødbroe, 2007). The combination of vision and hearing loss experienced in deafblindness is far more debilitating than losing a single sense, as one cannot compensate the one sense with another.
An accurate identification of congenital deafblindness is often difficult and complicated. Standard measurements of hearing and vision impairment (determining Snellen fraction and dB hearing loss) often do not give sufficient information. The assessment of vision and hearing requires the cooperation of the person being examined. This can become difficult where congenital deafblindness is involved since most children and adults may not have any verbal (or signed) language and many have additional disabilities such as severe motor, cognitive, and behavioural difficulties. Individuals with congenital deafblindness may also exhibit unusual behaviours (e.g., self-stimulating behaviour such as rocking, looking into light, and so forth, (Hoevenaars-van den Boom, Antonissen, Knoors, & Vervloed, 2009) and as such it is often difficult to assess whether the behaviour is a direct result of deafblindnes.
To account for the limitations of medical assessments of individuals with deafblindness, a functional assessment approach has been developed in Scandinavian countries. Here deafblindness is defined as a functional condition where:
Deafblindness is a distinct disability. Deafblindness is a combined vision and hearing disability. It limits activities of a person and restricts full participation in society to a degree which requires that society compensates by means of specific services, environmental alterations and/or technology. (Nordisk Lederforum, 2007)
Along with this functional definition, a functional assessment, that is, an identification “toolbox” was developed by Andersen and Rødbroe (2000) to determine whether a person was deafblind or not. This “toolbox” was developed as part of a national survey study conducted by The Danish Resource Centre for Congenital Deafblindness in Denmark on the population of people with congenital deafblindness (The Danish Resource Centre for Congenital Deafblindness, 2004; Dammeyer, 2010). The “toolbox” consists of two levels: 1) Medical screening and tests, 2a) Functional evaluation of vision, hearing and tactile modality, and 2b) Evaluation of functional use of the senses in social interaction and communication. (See the method section for elaboration.) (The complete toolbox is translated into English and is available at: http://www.servicestyrelsen.dk/dovblindfodt/in-english/publications/identification-of-congenital-deafblindness-1.)
The lack of accurate identification may be a reason why only a small portion of research has been reported regarding people with deafblindness compared to people with either vision or hearing impairment alone. This article will contribute to the research on this issue. The aim of this study therefore, is to report and evaluate the assessment procedures of congenital deafblindness in Denmark.
Method
The Danish Centre for Deafblindness offers a service to all individuals with congenital deafblindness living in Denmark. All individuals known to be congenitally deafblind and had been referred to The Danish Centre for Deafblindness from hospitals and institutions nationwide were included in this study. This amounted to 190 children and adults, the same population as reported on in a former survey study (Dammeyer, 2010). This population of 190 accounts for all the individuals with congenital deafblindness known by The Danish Resource Centre for Congenital Deafblindness.
The “toolbox” was used to determine whether the person in question was congenitally deafblind. A screening questionnaire (part 1 in the toolbox, pp. 127–144) was completed by parents, teachers etc. and if an individual was suspected to be congenitally deafblind a medical and, if needed, functional assessments were also completed.
To explain the complexity of identifying congenital deafblindness, a case of a 12-year-old child from the updated survey study, is presented. The child was enrolled for assessment at The Danish Centre for Deafblindness. One ophthalmologist and one otolaryngologist completed the medical assessment of vision and hearing, respectively. Two pedagogical experts on congenital deafblindness conducted the functional assessment. The case was made anonymous.
Method of assessment of congenital deafblindness
The assessment process of congenital deafblindness was divided into two parts:
1) Medical screening and tests of hearing and vision (see description below).
2a) Functional evaluation of vision, hearing and tactile modality, and
2b) evaluation of the functional use of the senses in social interaction and communication.
Part 1
Medical screening and tests: If a three frequency average hearing level (500, 1000, 2000 Hz) was found to be >79 dB HL and vision <6/60, deafblindness was concluded without further assessment. Individuals with a hearing loss at 60–79 dB or visual impairment at 6/18–6/60 did undergo further assessment (part 2). Hearing and vision loss must have been congenital or had degenerated before three years of age (pre-lingual deafblindness). In most cases, existing reliable medical tests of hearing and vision were available. If not, new tests were administered.
Part 2a
Functional assessment of hearing and vision, was administered if: a) the person had a hearing loss at 60–79 dB or visual impairment at 6/18–6/60, b) the medical tests of hearing and vision were impossible to conduct with the person with deafblindness or c) test results were indistinct and difficult to interpret. The functional assessment was conducted through direct observation in natural contexts. Interviews with the parents were also taken. The functional evaluation of vision and hearing is described in detail in Andersen and Rødbroe (2000) and is only presented here in brief.
Some examples relating to vision:
Is the person able to recognize people using vision?
Is it possible to guide the visual attention of the person?
Is the person able to recognize objects or places/rooms?
Some examples relating to hearing:
Does the person react to familiar voices?
At what distance does the person react to sounds?
Does the person use his/her voice?
Is it possible to wake up the person using sound?
Part 2b
Evaluation of the functional use of the senses in social interaction and communication: The identification of congenital deafblindness may often include an analysis of the social interaction and communication. The nature of congenital deafblindness manifests itself in social interaction and communication, showing the tactile senses are often employed in more sophisticated ways than with typical individuals without hearing and vision impairment (Andersen & Rødbroe, 2000). Responding to tactile communication and employing tactile strategies may be indicators of deafblindness. Recognizing these activities is also a part of the assessment described in the “toolbox”. The functional evaluation of vision and hearing and social interaction and communication were carried out by experts on congenital deafblindness. All functional evaluations of deafblindness were made by at least two experts, and if needed, in cooperation with a psychologist, and physiotherapist.
Results
Among the 190 children and adults with congenital deafblindness 45 percent had hearing loss at >79 dB HL and 55 percent at 60–79 dB HL, 59 percent vision impairment at <6/60 and 41 percent at 6/18–6/60.
Deafblindness was determined using functional assessment (Part 2) in 76 percent of the cases. Only 24 percent were identified by medical tests of hearing and vision alone (Part 1).
A Case illustration
The 12-year-old boy, represented in the case, arrived in Denmark at the age of 10, together with his parents, as refugees from a country in the Middle East. He had spastic hemiplegia (left side) and was unable to walk without assistance. He displayed no language ability (oral or signed) and had severe mental retardation. No medical etiology was known, but perinatal asphyxia was suspected to be the cause of his disabilities.
Vision: An ophthalmologist did not find any organic abnormalities in his eyes. The Teller Test was used but it was not possible to make any conclusions because of indistinct responses. However, by using the functional assessment through direct observation, it was found that he attended to some visual stimuli but not to others, e.g., he attended to moving objects more than inanimate objects. Because of the left side spastic hemiplegia, he was more attentive to visual stimuli from the right side. Consequently, it was concluded the child had cortical visual impairment (CVI) with an estimated visual impairment at 6/30.
Hearing: An otolaryngologist used Oto Acoustic Emissions (OAE) and an audiometer several times, but only occasional responses were observed. No medical conclusions could be made of his auditory abilities. Therefore a functional assessment was conducted. By observing responses to voices, different music instruments etc., it was discovered that the boy could hear sounds. He favoured toys with sounds, but it also became clear that there were many sounds that he often did not respond to. It was concluded that his hearing difficulties were associated to cerebral damage. In addition, the visual impairment made it difficult for him to identify the location of a sound, which made it difficult for him to understand and use sound. A moderate functional hearing impairment about 60–70 dB HL was concluded. Hearing aids were introduced to observe potential improvements.
Social interaction and communication: An evaluation of the functional use of the senses in social interactions and communication (part 2b) was also carried out. Observations were made of the boy’s social interaction with his teachers. It was observed that if his teacher waited for a response and guided the boy’s visual and auditory attention, it improved turn-taking in communication considerably. Together, the teacher and the boy explored sounds around him, closing the door, opening the water tap etc., and paying attention to and listening to sounds. If the boy responded to a sound in the environment the teachers supported him in exploring that sound. The teachers were also instructed by a specialist in deafblindness on how to improve the social interaction and communication with the boy. Tactile cues were used to guide attention and some tactile sign language signs were introduced with focus on turn-taking and dialogue. It became evident that working with social interaction and communication provided him with a better understanding of what he could hear and see.
As a result of these assessments, it was concluded that the boy suffered from deafblindness and recommended that a reassessment of his functional hearing and vision abilities should be completed within two years.
Discussion
The large percentage of the population being assessed by functional assessment indicates the value of this approach in identifying individuals with congenital deafblindness. The results reflect that the majority of people determined to be congenitally deafblind are not entirely deaf and blind, but experience varying degrees of vision and hearing loss. It is the combined hearing and vision impairment that result in deafblindness. The large percentage of individuals being assessed using functional assessment also reflects medical assessments of vision and hearing alone is often not possible due to the additional disabilities of the person involved.
As illustrated in the case example, a functional assessment of vision and hearing is needed to differentiate between behaviours related to developmental disabilities and behaviours related to sensory deprivation. Without a functional assessment many individuals with congenital deafblindness may go incorrectly identified and therefore not receive appropriate intervention.
The use of functional assessment procedures adheres to a general habilitation approach with people with congenital deafblindness in the Scandinavian countries, focusing on social interaction and communication (Janssen & Rødbroe, 2007; Rødbroe & Souriau, 1999). This approach emphasizes creating and expanding social interaction which is fundamental for the development of communication and a possible precursor to signed or oral language development over time. During play activities and in natural settings the teacher/parent responds to and expands upon the child’s expressions by regulation of contact, joint attention, turn-taking, and rhythm and tempo utilizing the tactile senses (Bjerkan, 1996; Janssen & Rødbroe, 2007; Nafstad & Rødbroe, 1996). The theory involved is linked to research concerning infant intersubjectivity (Trevarthen, 1993; Trevarthen & Aitken, 2001).
The functional assessment process of vision and hearing disabilities used in this study, reflect the social interaction and communication approach (Andersen & Rødbroe, 2000). The person’s use of his/her vision and hearing is evaluated by observing social interaction and communication abilities: Does the person respond to his/her mother’s voice? Is the person visually able to switch between two different people in a play situation? Is the person able to hear and follow a communication among two other people? It is during social interaction that the function of hearing and vision develops and therefore relevant to be evaluated.
While working with individuals with dual sensory loss it is important to continuously monitor and analyse the communicative competencies of the person in context. Observing vision and hearing in relation to the person’s social interaction and communication gives important information to how caretakers can best support the development of the person in need. Continuous functional assessment of the person’s vision, hearing, and social interaction is often needed. Video observation and analysis are useful tools for this purpose. It can be advantageous to use video analysis as it adds specific value to some of the key parameters in the functional assessments. Nafstad and Rødbroe (1999), Andersen and Rødbroe (2000) and Dammeyer (2009) describe approaches of video analysis which can be used in relation to assessment. Video analysis methods typically focus on different aspects of communication and functional use of hearing and vision, such as attention and emotional response.
In Denmark, the functional assessment of congenital deafblindness is often carried out through an observation stay, during which the person’s socially interactive and communicative competencies are tested under favourable light and sound conditions in a specially designed room. The caretakers are present and take part in the assessment. It may be helpful to triangulate with different methods during the functional assessment as described in the case example. The assessment of a person with deafblindness is often a cross-disciplinary task of clinical ophthalmologists, otolaryngologists, speech and hearing therapists, psychologists, physiotherapists etc. It is of vital importance for all of them to have knowledge and experience working with individuals with deafblindness.
The van Dijk Framework for Assessment of Children and Youth with Multiple Disabilities and Deafblindness provide a supplementary approach to the functional assessment procedures outlined in this article (Nelson, van Dijk, McDonnell, & Thompson, 2002; Nelson, van Dijk, Oster, & McDonnald, 2009). The van Dijk Assessment is a child-guided developmental assessment approach that examines the processes children use as they learn and internalize information.
Future research on the identification of congenital deafblindness may focus on the development of the functional assessment approach as outlined in this study. Evaluation of its reliability and validity is one important issue of concern.
Conclusion
Congenital deafblindness is not only determined by objective vision and hearing tests but often include functional assessments. Among the 190 individuals, 76 percent were determined using functional assessments in addition to medical examinations. The functional assessments included observing the use of tactile sense and the use of hearing and vision in social interaction and communication. Accurate assessment of congenital deafblindness is important in order to make an appropriate habilitation plan of the person in need. In many cases clinical experience is needed, as well as cross-disciplinary cooperation and specialized observation methods in order to be able to determine congenital deafblindness.
Footnotes
Acknowledgements
The author thanks The Danish Resource Centre on Congenital Deafblindness and The Centre for Deafblindness, Aalborg, Denmark. No potential conflicts of interest.
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.