Central auditory impairment in children with nonsyndromic cleft lip and/or palate

Abstract

Auditory impairment in patients with craniofacial clefts has been well studied for

decades. However, most previous research has only focused on middle ear disorders

and related auditory consequences in this group. Studies of higher level auditory

status and central auditory processing abilities of this group—particularly in

children—have been unsystematic and have significant limitations, while the

potentially negative impact of central auditory impairment on children should not be

ignored. One important area which needs further research is the status of the central

auditory nervous system (CANS) in children with non-syndromic cleft lip and/or palate (NSCLP). In order to objectively investigate possible central auditory

impairment in children with NSCLP, the present research programme was initiated.

Firstly, two major studies aimed to provide anatomical structural analysis and

functional evaluation of the auditory structures of CANS in a group of infants with

NSCLP, and compare the results to those of normal controls (Studies 1 and 2).

Secondly, a pilot study (Study 3) was conducted to provide preliminary data and

suggest methodology to support a major, future research programme to

comprehensively investigate central auditory processing abilities in children with

NSCLP.

A multi-disciplinary approach that included brain magnetic resonance image

(MRI) scanning, auditory evoked potentials (AEP) recording, and a central

behavioural auditory test battery assessment protocol, was applied in the present

research programme. Based on the results of the studies and data analysis, it was

concluded that: (1) Structural abnormalities of CANS in infants with NSCLP may be

primarily located in the left cerebral hemisphere and cortical abnormalities were more

marked compared with those in other subcortical locations. The development and

maturation of the auditory cortex in infants with NSCLP may be abnormal, compared

with that in normal children; (2) Infants with NSCLP might have normal auditory

sensory function at brain stem and subcortical levels, yet this group may have

significant impaired auditory discriminatory function at cortical level; (3) Children with NSCLP may show normal auditory processing abilities in a quiet listening

environment. However, they may be more vulnerable to background noise and have

impaired auditory processing abilities in areas such as monaural low redundancy and

temporal resolution ability.

In summary, combining the results of MRI, AEP and behavioural measurements

in the present research programme, it is suggested that children with NSCLP are at

potential risk of both structural abnormalities and functional disorders of the CANS,

particularly at auditory cortical level. In addition, this group might also be at risk of

auditory processing impairments to some degree, particularly in noisy environments.

The present research programme has made a contribution to our understanding of the

central auditory status of children with NSCLP, which was not systematically

investigated in previous studies, and provided information on which to base further

research. The research findings should draw the attention of researchers and clinicians

to improving auditory assessment and intervention for patients with craniofacial cleft

disorders. Further efforts in this field in the long-term may help to develop a more

sophisticated audiological evaluation and intervention approach for this population.