Asthenia is a term used to describe a lack of energy, strength or a general feeling of weakness. It can also refer to feeling tired all the time and muscle fatigue. Several conditions may contribute to the disorder, including cancer, chronic fatigue syndrome and anemia. Some forms of the condition are linked to immune system disorders that prevent muscles from operating normally.
Myasthenia gravis is a form of asthenia that disrupts the signal sent by nerves that control muscle contraction. In this form of asthenia, the immune system produces too many antibodies that block nerve impulses from reaching the muscles. Weakness can occur in the face, limbs, neck or in the muscles that control breathing.
The first sign of this disease is commonly seen in the eye muscles and may affect the eyelid or muscles that control vision. In some patients, slurred speech or trouble swallowing might be a sign of the disorder. For others, weakness in the legs that causes an uneven gait might appear. The symptoms commonly vary from one person to another in how they appear and in their severity.
Diagnoses of the various forms of asthenia often take years, especially if the symptoms are mild, because the signs may mimic other diseases. A blood test can detect high levels of certain antibodies that spark the disorder when the eye is affected. In other tests, a substance can be injected into the patient that causes muscle weakness to temporarily resolve. Some doctors use a device in the diagnosis process to stimulate nerves and muscles to measure if they react normally. Asthenia can afflict both genders at any age, but is more common in children.
Pregnant women with the condition can pass it on to an unborn child. The mother’s antibodies might attack the fetus, which then becomes paralyzed and unable to move in the womb. After birth, the baby may suffer limited motion of the joints, often in several joints. There is no cure for this kind of asthenia but it can be prevented if the mother is treated with medication that limits the production of antibodies while she is pregnant.
Asthenia due to autoimmune system disorders can be controlled with immunosuppressive medications that block the overproduction of antibodies and improve muscle strength. In some patients, a disorder of the thymus gland contributes to weakness, and its removal might help. Sometimes, donor blood is used to flush abnormal antibodies from the blood as well.