Editing Motor neuron diseases (section)

=== Tests ===
* [[Cerebrospinal fluid]] (CSF) tests: Analysis of the fluid from around the brain and spinal cord could reveal signs of an infection or inflammation.<ref name=":12">{{cite journal | vauthors = Foster LA, Salajegheh MK | title = Motor Neuron Disease: Pathophysiology, Diagnosis, and Management | journal = The American Journal of Medicine | volume = 132 | issue = 1 | pages = 32–37 | date = January 2019 | pmid = 30075105 | doi = 10.1016/j.amjmed.2018.07.012 | s2cid = 51910723 }}</ref>
* [[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).<ref name=":12" />
* [[Electromyography|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.<ref name=":12" />
* 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 neuron]]s should remain unaffected.<ref>{{cite journal | vauthors = Duleep A, Shefner J | title = Electrodiagnosis of motor neuron disease | journal = Physical Medicine and Rehabilitation Clinics of North America | volume = 24 | issue = 1 | pages = 139–151 | date = February 2013 | pmid = 23177036 | doi = 10.1016/j.pmr.2012.08.022 }}</ref>
* [[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.