Infantile Neuroaxonal Dystrophy (INAD)
Infantile neuroaxonal dystrophy (INAD) is an extremely rare, inherited degenerative disorder of the nervous system characterized by abnormalities of nerve endings (axons) within the brain and spinal cord (central nervous system) and outside the central nervous system (peripheral nerves). In most cases, infants and children with INAD appear to develop normally until approximately 14 to 18 months of age, when they may begin to experience progressively increased difficulties in walking. In other cases, symptoms may begin at approximately six to eight months of age, at which time infants may experience delays or an arrest in the acquisition of skills requiring the coordination of mental and physical activities (delayed psychomotor development).
The symptoms and physical characteristics associated with infantile neuraxonal dystrophy are the result of swelling and degeneration of nerve endings (dystrophic axonal swellings or "spheroids") within and without areas of the brain and spinal cord (central nervous system). In most cases, INAD is inherited as an autosomal recessive genetic trait.
In some cases, signs and symptoms of infantile neuroaxonal dystrophy first appear later in childhood or during the teenage years and progress more slowly.
Children with infantile neuroaxonal dystrophy experience progressive difficulties with movement. Generally they have muscles that are at first weak and "floppy" (hypotonic), and then gradually become very stiff (spastic). Eventually, affected children lose the ability to move independently. Lack of muscle strength causes difficulty with feeding and breathing problems that can lead to frequent infections, such as pneumonia. Seizures occur in some affected children.
Rapid, involuntary eye movements (nystagmus), eyes that do not look in the same direction (strabismus), and vision loss due to deterioration (atrophy) of the optic nerve are characteristic of infantile neuroaxonal dystrophy. Hearing loss may also develop. Children with this disorder experience progressive deterioration of cognitive functions (dementia), and eventually lose awareness of their surroundings.
Infantile neuroaxonal dystrophy is characterized by the development of swellings called spheroid bodies in the axons, the fibers that extend from nerve cells (neurons) and transmit impulses to muscles and other neurons. A part of the brain called the cerebellum, which helps to control movements, may also be damaged. In some individuals with infantile neuroaxonal dystrophy, abnormal amounts of iron accumulate in a specific region of the brain called the basal ganglia.
There is no cure for INAD and no treatment that can stop the progress of the disease. Treatment is symptomatic and supportive. Doctors can prescribe medications for pain relief and sedation. Physiotherapists and other physical therapists can teach parents and caregivers how to position and seat their child, and to exercise arms and legs to maintain comfort.
INAD is a progressive disease. Once symptoms begin, they will worsen over time. Generally, a baby’s development starts to slow down between the ages of 6 months to 3 years. The first symptoms may be slowing of motor and mental development, followed by loss or regression of previously acquired skills. Rapid, wobbly eye movements and squints may be the first symptoms, followed by floppiness in the body and legs (more than in the arms). For the first few years, a baby with INAD will be alert and responsive, despite being increasingly physically impaired. Eventually, because of deterioration in vision, speech, and mental skills, the child will lose touch with its surroundings. Death usually occurs between the ages of 5 to 10 years.
Researchers continue to search for the defective gene that causes INAD in hopes of developing drugs that can stop the disease. The National Institute of Neurological Disorders and Stroke (NINDS) conducts research related to INAD in its laboratories at the National Institutes of Health (NIH), and also supports additional research through grants to major medical institutions across the country. Much of this research focuses on finding better ways to prevent, treat, and ultimately cure disorders such as INAD.
The information on this page was compiled from information on the websites below. For additional information please see the original websites.
