Deaf-mutism is generally due to a loss of hearing before the age of 2 - 3 years which hinders learning to speak. Most cases result from acute infectious diseases such as measles, epidemic meningitis, encephalitis, typhoid, otitis media, toxic effects of drugs, etc. Congenital deaf-mutism is also a possible etiology. Endocrine causes like Pendred syndrome involves deafness along with the presence of goitre. The child's intelligence is normal.
For normal speech to develop in a child,the hearing sensation should be intact. The first three years of life is considered to be crucial for the development of speech. Loss of hearing due to any cause during this crucial period of development causes the development of speech to falter.
Congenitally deaf child is also a mute. In congenital deafness there is failure of normal development of cochlea, leading on to deformities i.e. Mondini defect etc. Congenitally deaf and mute child can be identified by the absence of oculo vestibular reflex. This is the reflex that makes the eye deviate to opposite side when the head is bent to one side. In children with acquired deaf mutism this reflex is intact.
Rehabilitation is the only way. In the past these children were taught to communicate using sign language. Now a days the children, if they have residual hearing should be provided with hearing amplification devices (hearing aids). They should also undergo a rigorous course of speech therapy. The recent advances in the field of cochlear implant has added another useful dimension in the management of these patients.