Introduction

Frontofacionasal dysplasia (FFND) is an inheritable disorder characterised by many abnormalities of the bones, especially in the face. These include brachycephaly (horizontally short head and broad face), midface hypoplasia (underdeveloped upper jaw, cheeks, and nose), incomplete fusion of some structures (cleft palate, cleft lip, and split uvula), and abnormal positioning and development of teeth. In addition to speech and language issues, children living with FFND experience difficulty in many ways. If you have children with FFND, we hope this article can provide a better understanding of how the disease affects their speech and language so you can implement more suitable care. 

Mechanisms of speech and language

How do speech and language work?

Speech is produced by modifying airflows to create various vibrations. The airflow is first generated by the lungs and their surrounding muscles, which compress and push air upwards the windpipe (known as the trachea). Before voicing, the two voice cords in the voicebox (known as the larynx, at the top of the windpipe) meet in the middle and seal the windpipe. When sufficient air accumulates below the voicebox, the two vocal cords are forced apart, and the leaked air forms an airflow that forces the vibration of the vocal cords, which becomes our voice. When the airflow goes through the mouth, it is modulated by our articulators (including the tongue, teeth, lips, and other parts of the oral cavity), forming different consonants and vowels. When grouped together, they form words.

While these form the essential components of speech, other body parts play ancillary roles. For example, the oral cavity (the space within the mouth) and the nasal cavity (the space behind the nostrils) resonate with the vocal cords to amplify the sound and shape it into individual tones.

Equipped with the ability to produce speech, we also need to choose words from our vocabulary and group them into sentences to communicate with verbal language. These are enabled by many complicated neural processes happening inside our brain, like instructing our tongue and mouth muscles how to move to produce the desired articulation.

Why can humans speak? This is a complex question with many answers. The structure of our vocal tracts is a unique human characteristic that allows speech capacity. The lowered voicebox and more flexible tongue movements expand the repertoire of consonants and vowels that can be articulated. This provides a wide range of combinations of sounds to express different meanings.¹ 

How do speech and language develop

Infants typically start talking from one year old. How infants acquire their speech capacity during development is similar to how humans acquire it through evolution. It involves the gradual acquisition of the essential anatomy for speech production, such as the lowering of the larynx and the increase in the angle between the oral cavity and the windpipe.² The development of certain articulations also necessitates teeth growth.

The physical development of relevant structures is insufficient for the use of languages. An effective social environment that provides exposure and interaction of communication via certain languages is mandatory for training children to produce intelligible speech and comprehend others’ expressions.

However, for children suffering from FFND, many parts of the vocal tract are formed incorrectly, compromising their ability to produce certain sounds correctly and subsequently hampering their learning of languages.

Impact on speech development

Articulation issues

FFND affects many parts of the face, as mentioned above. Many of them (the upper lip, teeth, the palate, and the uvula) are key articulators vital to correct pronunciation. Numerous consonants and vowels cannot be pronounced accurately when these parts do not have the right shape. 

In English, consonants can be classified by the places of articulation, or which articulators in the oral cavity modify the airflow into different sounds. As mentioned above, people with FFND may have an incomplete upper lip, palate, and uvula and incorrect teeth positioning. Therefore, it is difficult to pronounce bilabial consonants (using two lips, e.g., /b/ in bat), labiodental consonants (using the lower lip and upper teeth, e.g., /f/ in fat), dental consonants (using the tongue and upper teeth, e.g., /ð/ in that), alveolar, postalveolar, palatal, and velar consonants (using different parts of the upper jaw, e.g., /tʃ/ in chat). These account for 91% of all English consonants. In other major languages like French, uvular consonants (using the uvula, /ʁ/ in rue) are also affected.

Articulators affected by FFND play a less major role, but vowels still require the correct positioning of the tongue relative to other parts of the oral cavity.  As a result,  vowels can also be affected by certain abnormalities observed in FFND, like cleft palate.

 As different consonants and vowels are unable to be articulated correctly, they are less easily distinguished from each other and reduce speech clarity.

Velopharyngeal dysfunction

 In addition to articulation, other ancillary systems of speech may also be affected by some FFND symptoms, especially the cleft palate, a common FFND syndrome. It compromises the partition between the oral cavity and the nasal cavity, which allows more air to leak into the nasal cavity and this is known as velopharyngeal dysfunction (VPD).

A consequence of VPD is hypernasality, i.e., excessive resonance of the nasal cavity during vowel pronunciation. Another effect is nasal air emission, which affects consonants that require the buildup of air pressure within the oral cavity. For example, plosives like /t/, which are pronounced by the sudden release of airflow, are blurred by hissing sounds of the leaking of air from the oral cavity to the nasal cavity. Along with other consonants affected by nasal air emission, they comprise 71% of all English consonants.

Although the effect of VPD on the speech intelligibility of people with FFND is not as significant as that of the articulation issues mentioned above, VPD still compromises the overall quality of speech.

Further impact of low speech intelligibility

It was reported that children experiencing hypernasality were later than other children in terms of saying their first words. This may also lead to delays in other hallmarks of speech development.

More importantly, in early social environments, children experiencing speech disorders are frequently unfavoured and isolated by peers. Not only does it injure their social development and self-esteem, but further speech development is also negatively affected due to potentially reduced verbal interactions with peers. Even without these social factors, children affected by FFND may be less inclined to talk with others. This is because they are not confident in starting a conversation, and others, aware of the reduced efficiency in communicating with them, may tend to avoid verbal interactions. These problems can subsequently hinder other steps of language development.

Impact on language development

Exposure to the language via various media and daily practice is important for the acquisition of the language.^3,4 Reduced verbal interaction of children with FFND unavoidably exacerbates the negative impact on language development by speech problems. Neurobiological research has explained this relationship by the lesser extent of brain circuitry development. Specifically, the reduced exposure is associated with reduced connectivity between different parts of the cerebral cortex involved in speech and language, especially the connections to Broca’s area, a key brain region regulating various language functions such as articulation, semantics, and syntax.⁵ In extreme cases, when children lack exposure to the language within a critical age range,  when neuronal circuitries are highly plastic, they may fail to obtain fundamental language skills.^6,7

The impact of FFND on language development may also be caused by encephalocele, a possible FFND symptom that involves a protrusion of part of the brain out of the skull due to the incomplete fusion of parts of the skull. The protrusion may lead to malformation in that part of the brain and thus compromise relevant functions.⁸ In rare cases, where the protrusion is on the left side of the brain, brain areas involved in language production and comprehension may be affected, resulting in language use failing to develop normally.

Treatment and intervention

Surgical reparations are available for most structural abnormalities affecting speech and language development, including but not limited to cleft palate, misaligned teeth, and encephalocele. Early treatment can allow children with FFND to obtain the physical capacity for normal speech and language development earlier, thus returning to the right development trajectory faster. 

If affected children have already developed incorrect articulation habits, speech therapy may help them improve their speech intelligibility. The earlier this is done, the more effective the therapy will be and the better the outcome. Similar to surgeries, this improvement may also help these children obtain healthier social relationships and further exposure to language use, which can accelerate their speech and language development. During this period, parents should also maximise verbal interaction with their training to facilitate their development.

If both surgeries and speech therapies fail to restore intelligible speech or are not available, augmentative and alternative communication (AAC) methods allow people with FFND to communicate through means other than speech. It is expected that high-tech AAC devices may become more intelligent, portable, and straightforward with the advancement of health technologies.⁹

Nonetheless, FFND can differ from case to case, which means the best treatment options should be decided by your consultants based on the exact symptoms present and other relevant factors.

Summary

For children with FFND, structural deficits make the use of speech and language particularly challenging. Problems including articulation and VPD can impair their speech clarity, which may lead to reduced verbal interaction and thus further hinder the progress of language acquisition. Various treatment options are available to alleviate this impact. Getting professional advice as soon as possible can significantly improve the quality of life for children with FFND.