Motor Neuron Disease
Case Analysis for Motor Neuron Disease
The motor neuron diseases (MNDs) are a group of progressive neurological disorders that destroy motor neurons, the cells that control essential voluntary muscle activity such as speaking, walking, breathing, and swallowing. Normally, messages from nerve cells in the brain (called upper motor neurons) are transmitted to nerve cells in the brain stem and spinal cord (called lower motor neurons) and from them to particular muscles. Upper motor neurons direct the lower motor neurons to produce movements such as walking or chewing. Lower motor neurons control movement in the arms, legs, chest, face, throat, and tongue. Spinal motor neurons are also called anterior horn cells. Upper motor neurons are also called corticospinal neurons.
When there are disruptions in the signals between the lowest motor neurons and the muscle, the muscles do not work properly; the muscles gradually weaken and may begin wasting away and develop uncontrollable twitching. When there are disruptions in the signals between the upper motor neurons and the lower motor neurons, the limb muscles develop stiffness, movements become slow and effortful, and tendon reflexes such as knee and ankle jerks become overactive. Over time, the ability to control voluntary movement can be lost.
Although there are now gene test for some MNDs there are no specific tests to diagnose most MNDs. Symptoms may vary among individuals and, in the early stages of the disease. MNDs may be similar to those of other diseases, making diagnosis difficult. A physical exam is followed by a thorough neurological exam. The neurological exam is to assess motor and sensory skills, nerve function, hearing and speech, vision, coordination and balance, mental status, and changes in mood or behavior.