Autism, Asperger's disorder (AD), and pervasive developmental disorder not otherwise specified (PDDNOS) are commonly referred to as ‘autistic spectrum disorders’ (ASD) and are classified as pervasive developmental disorders (PDD) in the fourth edition of the Diagnostic and Statistical Manual on Mental Disorders (DSM-IV). Deviant and delayed development in social and communication skills and the presence of restricted routines and interests, and stereotypic behaviours are variously present in ASD. The majority of children with autism have an intellectual disability (ID) while those with AD do not.

Ataxia is the cardinal sign of cerebellar dysfunction and when it occurs, it indicates the possibility of cerebellar lesions. However, this may not always be the correct explanation. Appenzeller and Hanson reviewed studies, published between 1916 and 1953, of patients with cerebellar signs attributed to parietal lesions. Extensive lesions within the parietal lobes and sensory changes were common in these patients. They also reported on an adult who presented with pain and weakness of the left arm, lasting for 2 hours. When examined 2 weeks later, the limb was severely ataxic, but with no detectable weakness or sensory deficit. In addition, the patient had a dressing apraxia. At autopsy a small infarct in the arm area of the right postcentral gyrus was observed. The cerebellum and brainstem were normal.

Down syndrome (DS) is an autosomal chromosomal anomaly resulting from trisomy of all or a critical part of chromosome 21. It affects approximately 1 in 700 to 800 live births. Despite the development of prenatal diagnosis, the incidence of DS births is predicted to remain static or even to increase over the next decade, partly due to increased maternal age in Western societies. Many of the medical and physiological characteristics of DS have direct consequences for the oral health of subjects affected and indirect consequences for the quality of life of persons with DS and their carers. This article aims to give an overview of the current literature concerning the orofacial problems confronting patients with DS, and to explain the different treatment modalities available.