subject: Central Disorder: Spinal Cord Disorders [print this page] The Spinal cord and the brain are organs of the Central nervous system. The spinal cord is made up of nervous tissues. It is a long and thin in shape. This tubular structure extends from the brain. This delicate and well protected structure is responsible for motor as well as sensory functions. It also takes care of certain reflex co-ordination.
An injury small or big to the spinal column can result in life altering conditions. If during a road accident the backbone of an individual is affected, it can cause the vertebral column to shatter. Thus the underlying spinal cord can be punctured. Such individuals can suffer loss of any feeling in certain parts of the body. In severe cases such injuries can lead to paraplegia or even full body paralysis. While in mild cases it can lead to loss of sensation in hand or foot. The loss is generally sensory and motor, which means both sense and motion control is lost.
Any injury to the upper motor neuron axons of the spinal cord can cause central disorder like hyperreflexia and muscle weakness. Hyperreflexia is the over responsive reflexes like twitching and spastic motions which are also characterized by loss of control. Damage to the lower motor neurons can cause muscle weakness, hyporeflexia and muscle atrophy.
Spinal Muscular Atrophy is a motor neuron central disorder. Motor neurons are nerve cells present in the spinal cord which have nerve fibers in the muscles of the body. Activities such as swallowing, walking, control of head and neck are affected. The motor neurons present in the spinal cord affect the voluntary muscles which are used to carry out these activities. It is a well known but rare disease of the central nervous system. It affects every muscle in the body. According to a study approximately one in sixty thousand babies are affected by this disease. It can lead to respiratory problems and pneumonia. Sensation and ability to feel is not affected and patients are intellectually and socially normal.
Spinal Muscular Atrophy (SMA) is an autosomal recessive genetic central disorder. It means a child can be affected by SMA if both the parents are carriers of the defective gene. And both the parents must pass the abnormal gene to the child. The patient has a missing or mutated gene which is responsible for producing the protein (Survival Motor Neuron- SMN) required by the motor neurons. Without the essential SMN protein the health of the motor neuron is affected. So the motor neurons can tend to shrink and eventually die which results in muscular weakness. And as the individual grows, the stress on the nerve cells and the muscle tissues also increases. This can lead to bone and spinal deformities.
Survival motor Neuron 1, 2 are the two genes which are present in normal individuals. In maximum patients the SMN gene sequence is missing. And sometimes SMN1 gene is mutated in nature. Testing for the presence or absence of the abnormal gene (SMN1) by a blood test can help detect SMA.
