In a typical person the signals received from all the senses are processed by the brain and a response is made based on these signals as well as prior experience, knowledge and memories that are stored in the brain. The processing of sensory integration happens in the mid-brain and brain stem regions of the central nervous system. The sensory signals pass through these regions first and then are routed to the brain regions responsible for emotions, memories and the higher cognitive functions.
Sensory processing disorder occurs when the brain has trouble receiving, processing and responding to information that comes in through the senses and turning them to appropriate motor and behavioural responses.
Sensory processing disorder may affect someone in only one sense e.g. only sound or taste or just movement, or it could also affect in multiple senses. A person with this disorder may be oversensitive to stimuli and find the sensory inputs to be unbearable. They may not be able to stand physical contact, light, sound or some tastes. Others, may under-respond or show no reaction to even strong stimulus e.g. extreme hot or cold.
In case sensory processing of messages from the muscles and joints (vestibular system) is impaired in a child, posture and motor skills can be affected. This kind of impairment leads to clumsiness and such children have uncoordinated movements with poor posture and equilibrium.
Sensory processing disorder is generally diagnosed in children, but may also be present in adults. If these have not been treated in childhood they may become severe enough to adversely affect performing routines and activities involved in work, relationships and other day to day activities.
The causes of sensory processing disorders are still being studied. According to researchers at Sensory Processing Disorder Foundation and their collaborators elsewhere, preliminary research suggests that these disorders are often inherited. This would mean that the genetic disorders are coded into the genetic material of the baby. Prenatal and birth complications as well as environmental factors may also be involved.
Children with sensory processing disorders often have problems with motor skills, and other abilities needed for academic success in schools. They have difficulty in making friends and may become socially isolated and suffer from low self-esteem.
Effective treatment for sensory processing disorder is available, but far too many children with sensory symptoms are misdiagnosed and not properly treated leading to adults who have difficulty in coping with work, relationships and society at large.