Both motor neurons are necessary for the strong contraction of a muscle, but damage to an UMN can be distinguished from damage to a LMN by physical exam. Tests
Cerebrospinal fluid (CSF) tests: Analysis of the fluid from around the brain and spinal cord could reveal signs of an infection or inflammation. Magnetic resonance imaging (MRI): An MRI of the brain and spinal cord is recommended in patients with UMN signs and symptoms to explore other causes, such as a tumor, inflammation, or lack of blood supply (stroke). Electromyogram (EMG) & nerve conduction study (NCS): The EMG, which evaluates muscle function, and NCS, which evaluates nerve function, are performed together in patients with LMN signs. For patients with MND affecting the LMNs, the EMG will show evidence of: (1) acute denervation, which is ongoing as motor neurons degenerate, and (2) chronic denervation and reinnervation of the muscle, as the remaining motor neurons attempt to fill in for lost motor neurons. By contrast, the NCS in these patients is usually normal. It can show a low compound muscle action potential (CMAP), which results from the loss of motor neurons, but the sensory neurons should remain unaffected. Tissue biopsy: Taking a small sample of a muscle or nerve may be necessary if the EMG/NCS is not specific enough to rule out other causes of progressive muscle weakness, but it is rarely used. Treatment
There are no known curative treatments for the majority of motor neuron disorders. Please refer to the articles on individual disorders for more details.
Motor neuron diseases or motor neurone diseases (MNDs) are a group of rare neurodegenerative disorders that selectively affect motor neurons, the cells which control voluntary muscles of the body. They include amyotrophic lateral sclerosis (ALS), progressive bulbar palsy (PBP), pseudobulbar palsy, progressive muscular atrophy (PMA), primary lateral sclerosis (PLS), spinal muscular atrophy (SMA) and monomelic amyotrophy (MMA), as well as some rarer variants resembling ALS. Motor neuron diseases affect both children and adults. While each motor neuron disease affects patients differently, they all cause movement-related symptoms, mainly muscle weakness. Most of these diseases seem to occur randomly without known causes, but some forms are inherited. Studies into these inherited forms have led to discoveries of various genes (e.g. SOD1) that are thought to be important in understanding how the disease occurs.Symptoms of motor neuron diseases can be first seen at birth or can come on slowly later in life. Most of these diseases worsen over time; while some, such as ALS, shorten ones life expectancy, others do not. Currently, there are no approved treatments for the majority of motor neuron disorders, and care is mostly symptomatic. Signs and symptoms
Signs and symptoms depend on the specific disease, but motor neuron diseases typically manifest as a group of movement-related symptoms. They come on slowly, and worsen over the course of more than three months. Various patterns of muscle weakness are seen, and muscle cramps and spasms may occur.