Ear disorders in autistic children

Autism and nutrition: the role of the gut-brain axis

Autism spectrum disorder (ASD) is characterised by deficits in the ability to socialise, communicate and use imagination, and displays of stereotypical behaviour. It is widely accepted that ASD involves a disorder in brain development. However, the real causes of the neurodevelopmental disorders associated with ASD are not clear. In this respect, it has been found that a majority of children with ASD display gastrointestinal symptoms, and an increased intestinal permeability. Moreover, large differences in microbiotic composition between ASD patients and controls have been reported. Therefore, nutrition-related factors have been hypothesised to play a causal role in the aetiology of ASD and its symptoms. Through a review of the literature, it was found that abnormalities in carbohydrate digestion and absorption could explain some of the gastrointestinal problems observed in a subset of ASD patients, although their role in the neurological and behavioural problems remains uncertain. In addition, the relationship between an improved gut health and a reduction of symptoms in some patients was evaluated. Recent trials involving gluten-free diets, casein-free diets, and pre- and probiotic, and multivitamin supplementation show contradictive but promising results. It can be concluded that nutrition and other environmental influences might trigger an unstable base of genetic predisposition, which may lead to the development of autism, at least in a subset of ASD patients. Clear directions for further research to improve diagnosis and treatment for the different subsets of the disorder are provided.

The otological manifestations associated with autistic spectrum disorders

OBJECTIVES

To elucidate the otological manifestations found in this increasingly commonly diagnosed condition. This paper will discuss the diagnosis, aetiology, pathogenesis, management and the outcomes of treatment.

STUDY DESIGN

Systematic literature review.

MATERIALS AND METHODS

The following databases were searched for articles pertaining to the otological manifestations of autistic spectrum disorders: MEDLINE, EMBASE, CURRENT CONTENTS, PSYCHLIT, CINAHL and HEALTHSTAR. Articles from 1965 to June 2012 were extracted. Relevant articles from the literature were selected and reviewed by two independent authors. Each paper was assessed as to its level of evidence and validity. The relevant results are presented and discussed in order to present a practical approach to the management of these patients.

RESULTS

Patients with ASD have an increased incidence of peripheral and central otological pathology. This pathology plays a key role in the behavioural, communication, and social aspects of the disease. ASD patients have a higher incidence of profound sensorineural hearing loss, middle ear infections, and abnormalities of the cochlear nerve and brainstem auditory pathways. There are cortical and brainstem neurodevelopmental abnormalities in the way auditory information is interpreted and processed in the ASD patient.

CONCLUSIONS

The otolaryngologist plays a key role in the multidisciplinary management of individuals with ASD due to the high prevalence of otological pathology amongst these patients. Early diagnosis and expedient treatment focusing on normalisation of auditory input and development can maximise developmental outcomes.

The contribution of muscular and auditory pathologies to the symptomatology of autism

Most research concerning the pathology of autism is focused on the search for central abnormalities that account for the production of symptoms. We, however, instead of looking at muscular and auditory features as merely associated manifestations, propose that they are somatic contributors by which some of the main clinical features of autism might be explained. Evidence suggests that muscles affect emotional experience. We think certain muscular dysfunctioning can impair communication and social interaction, and create stereotypic behavior, giving rise to the diagnostic features of autism. Furthermore, because speech is synchronized with facial movements and voice is controlled mainly through auditory feedback, a distortion of auditory feedback could disrupt voice, which in turn might cause parallel abnormal facial muscle functioning.

Language development in autism

In this short review article, a summary of the behavioural impairments most commonly associated with the spectrum of autism-related disorders is presented, with a slightly amplified account of the defining communication impairment. The patterns of language ability and disability which typically occur in some forms of autism are then outlined, followed by a short section on possible cognitive, or psychological, explanations of these patterns. In particular, the hypothesis that defective socio-affective and socio-cognitive ('theory of mind') causes language impairments, and the hypothesis that temporal processing deficits cause these impairments, are outlined and briefly discussed. An extensive list of references is included, to support and amplify the summary data included in the review.

Autism and Clostridium tetani

Autism is a severe developmental disability believed to have multiple etiologies. This paper outlines the possibility of a subacute, chronic tetanus infection of the intestinal tract as the underlying cause for symptoms of autism observed in some individuals. A significant percentage of individuals with autism have a history of extensive antibiotic use. Oral antibiotics significantly disrupt protective intestinal microbiota, creating a favorable environment for colonization by opportunistic pathogens. Clostridium tetani is an ubiquitous anaerobic bacillus that produces a potent neurotoxin. Intestinal colonization by C. tetani, and subsequent neurotoxin release, have been demonstrated in laboratory animals which were fed vegetative cells. The vagus nerve is capable of transporting tetanus neurotoxin (TeNT) and provides a route of ascent from the intestinal tract to the CNS. This route bypasses TeNT's normal preferential binding sites in the spinal cord, and therefore the symptoms of a typical tetanus infection are not evident. Once in the brain, TeNT disrupts the release of neurotransmitters by the proteolytic cleavage of synaptobrevin, a synaptic vesicle membrane protein. This inhibition of neurotransmitter release would explain a wide variety of behavioral deficits apparent in autism. Lab animals injected in the brain with TeNT have exhibited many of these behaviors. Some children with autism have also shown a significant reduction in stereotyped behaviors when treated with antimicrobials effective against intestinal clostridia. When viewed as sequelae to a subacute, chronic tetanus infection, many of the puzzling abnormalities of autism have a logical basis. A review of atypical tetanus cases, and strategies to test the validity of this paper's hypothesis, are included.

Do musical hallucinations always arise from the inner ear?

It has been known for some time that musical hallucinations occur in deaf patients. This has been ignored, as it has been believed that neurological and psychiatric causes predominate. However, despite specific appeals, no one with musical hallucinations and a lesion in the brain but not in the ear has been produced. The postulated otological basis is a hyperactive state of the ear, a slight endolymphatic hydrops or pre-Meniere's disease. The hallucinations probably develop out of rhythmic tinnitus. A review of all the very disparate states and diseases supposedly causing musical hallucinations shows that peripheral ear symptoms are always present. It therefore seems that they always have the same simple otological trigger.

The UCLA-University of Utah epidemiologic survey of autism: Recurrent infections

Two hundred and forty-one children with autism were ascertained and diagnosed (DSM-III criteria) in an epidemiologic survey of Utah. Pediatric and other pertinent medical records were abstracted for 233 patients and 66 of their siblings without autism for otitis media, upper respiratory, and other infections. A significantly greater number of children with autism had recurrent otitis media, upper respiratory and other infections than their nonautistic siblings. A greater number of children with autisru with recurrent infections had lower IQ scores, seizures, hearing deficits, delayed motor milestones, poorer speech, congenital anomalies, feeding problems, vomiting, diarrhea, and other types of infections than children with autism with mild or no infections. The only significant pre-, peri-, or postnatal risk factors between children with autism with recurrent, mild or no infection was an increase in the maternal-fetal incompatibility (ABO or Rh) in the recurrent infection group. Half the families with more than one child with autism had recurrent infections and 72% of those children with concurrent diseases which effect the CNS had recurrent infections. Methodological limitations are discussed.

Auditory brainstem responses in autism: brainstem dysfunction or peripheral hearing loss?

The advent of electrophysiological techniques for audiologic and neurologic assessment in the late 60s has generated at least 11 auditory brainstem response (ABR) studies in autism designed to test the integrity of the auditory brainstem pathways. The results reported are contradictory, involving prolongation, shortening, and no abnormalities in central transmission latencies. When sample and methodological factors influencing the ABR are taken into consideration in the interpretation of results, the ABR data available at present can be seen as only suggestive, rather than supportive, of brainstem involvement in autism. Paradoxically, these studies revealed the presence of peripheral hearing impairment in a non-negligible number of autistic individuals. Additional evidence of auditory abnormalities as well as the implications for the clinician are considered.