Treacher Collins Syndrome
There is a wealth of information available on Treacher Collins Syndrome (TCS); a topic search on PubMed yields a daunting 1,458 articles. Surprisingly, there is a paucity of large-n studies on speech-language disorders and their treatments. Why would this be?
There is significant heterogeneity within this clinical population. Not all individuals are equally affected, and the manifestations can vary. Those of us who have taken care of larger numbers of individuals with TCS (relatively speaking) in the course of our careers know that there is no specific "TCS Communication Disorder," and in fact, many individuals with TCS never have any problems with speech or language. To consider what sorts of disorders might occur in affected individuals with communication disorder, one must consider the individual risks with which a particular patient presents.
Hearing is of course significant, and those with hearing impairment related to microtia/atresia are at risk for abnormal speech language development. Those who begin audiologic management from birth may be amplified very early, and the prognosis for speech-language development is subsequently better. Those with persistent hearing impairment may manifest disorder according to the particular features of their hearing impairment. The evaluation tools used would be the same that you might use for any child with speech and language disorders related to hearing impairment.
Some individuals with TCS may have cleft palate, and may manifest cleft-related articulation disorder, or velopharyngeal dysfunction, or both. Standard articulation tests are used in these cases, and instrumental assessments including velopharyngeal imaging, pressure-flow studies, or acoustic studies might be performed at a medical center. It is also possible to develop normal speech and language without therapy in the presence of a cleft palate. Cleft palate and conductive hearing impairment combined may produce a complex speech-language disorder with manifestations of both the cleft and the hearing impairment.
Mandibular hypoplasia, one of the key features of TCS, is often associated with glossoptosis, or posterior displacement of the tongue into the airway. Some children with glossoptosis may favor posterior articulations over anterior articulations in their early development, and this tendency may be compounded by cleft palate, velopharyngeal dysfunction, or conductive hearing impairment.
Mandibular lengthening procedures, known as distraction osteogenesis, or more traditional mandibular advancement procedures, such as sagittal split osteotomy, may occur in childhood but are typically not done repeatedly. They may be done more than once in a minority of cases, and not all children with TCS have such procedures. The most common reason for mandibular surgery is to open the airway, so the surgery may be done to avoid tracheotomy, to allow removal of a tracheostomy tube, to treat obstructive sleep apnea or to improve occlusion or facial appearance. The surgery is typically not done to facilitate normal speech development.
If a child has a speech disorder, and also has a mandibular lengthening procedure, what would happen to the speech? It is difficult to predict, since there is likely to be a great deal of variability amongst TCS individuals who might undergo mandibular lengthening, and the nature of their speech disorder might be related to factors other than the mandible itself. Guyette, et al, (2001) studied the speech changes in 7 individuals who underwent unilateral mandibular distraction osteogenesis. Their patients had hemifacial microsomia, a condition in which there is hypoplasia of the mandible on only one side. Like TCS patients, though, some individuals with hemifacial microsomia may have hearing impairment or cleft palate, and some may have airway obstruction problems. Guyette and his colleagues found that 28% of the patients had deterioration of their articulation immediately post operatively, and 42% had changes in their speech resonance. Upon further follow up, all of the patients had resolution of the postoperative deterioration, and returned to their preoperative baseline.
We can wander now into the realm of speculation. We have seen in our experience with children with a variety of structural anomalies that a surgery that alters oral structure often does not spontaneously change an articulation disorder. For example, children with cleft palate and articulation disorder who have surgery to close a fistula or to manage velopharyngeal dysfunction may have success in correcting air leakage into the nose with speech, but it is rare to see spontaneous resolution of the articulation disorder. Speech therapy must continue post operatively to correct the maladaptive articulations. From this we might speculate that, as Guyette and his colleagues found, the TCS child may actually deteriorate at first as the mouth changes shape and the child must adapt, but it is possible that the child will return to their preoperative articulation patterns as they adjust to the change.
Could the procedure cause speech improvement? It is possible, but unfortunately we don't have much in the way of clinical evidence to promise that that would occur. Once again, we can speculate. If the child can open their mouth better, it might be possible for the speech pathologist to use more visual feedback in the therapy. Sometimes, oral resonance seems less "muffled" if the oral cavity is larger. If the child is getting better quality sleep because they are breathing better with sleep, they may respond better to therapy.
Your question illustrates the complexity of the populations of individuals with craniofacial differences. There are trends and patterns, but one must carefully evaluate the syndromic manifestations, and also consider the individual's specific characteristics in relation to those manifestations.
Guyette TW, Polley JW, Figueroa A, Botts J, Smith BE.
Changes in speech following unilateral mandibular distraction osteogenesis in patients with hemifacial microsomia.
Cleft Palate Craniofac J. 2001 Mar; 38(2):179-84.
Peterson-Falzone S, Pruzansky S.
Cleft palate and congenital palatopharyngeal incompetency in mandibulofacial dysostosis: frequency and problems in treatment.
Cleft Palate J. 1976 Oct; 13:354-60
A profile of the features and speech in patients with mandibulofacial dysostosis.
Cleft Palate Craniofac J. 2002 Nov; 39(6):623-34.