Progressive muscular atrophy

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at October 3, 2016
StartDiseasesProgressive muscular atrophy

Progressive muscular atrophy (PMA) is a rare type of motor neuron disease (MND) that typically affects individuals who are under the age of 50. This disease only affects five to seven percent of the individuals who suffer from a motor neuron disease, and the majority of those who suffer from PMA are males. There currently is no cure for PMA, but those with the disease typically only have a lifespan of five to ten years after they are diagnosed.


Definition & Facts

PMA is a condition that affects the lower motor neurons of an individual’s body. These neurons are a group of nerve cells in the body that control the muscles. These control centers are located in either the brainstem or the spinal cord.

Over time this disease causes the muscles to become weaker, muscle control to decline, and the muscles to shrink and deteriorate. Those diagnosed with PMA typically do not have a family history of the disease; the symptoms just seem to appear.

Symptoms & Complaints

The first symptoms that individuals who are diagnosed with PMA notice are a weakness in one of their hands or feet. Sometimes the weakness can occur in the leg or the arm as well. From there, the weakness will spread to other muscles in the body.

A common complaint from patients at the beginning of the diagnosis is that walking is difficult. A patient may stumble frequently. He or she may also find it difficult to pick up items and hold them properly. Painful muscle cramps and twitching limbs can also be seen in the early stages of this disease.

A loss of reflexes will follow the onset symptoms as well as muscle contractions and fatigue. Eventually, swallowing food may become difficult (dysphagia) and communicating with others may be difficult due to speech problems and language problems. Because PMA only affects the lower motor neurons, the patient will still have control over their emotional state. 


Currently, the actual cause of PMA is unknown, but the medical community has recently conducted a study that links PMA to amyotrophic lateral sclerosis (ALS). ALS is known to be a more severe version of MND because it affects not only the lower motor neurons, but the upper motor neurons as well. Since both diseases do affect the lower motor neurons, there may be a possible link to that causes the two diseases to form.

There are a few hypotheses in the works to identify what causes PMA. It could be the result of abnormal clumps of protein that have found their way into the motor neurons. This would stop the pathways from functioning properly and cause stress on that area of the body.

Another theory is that the body lacking the antioxidants that it needs to properly transport toxins from the body, which causes the motor neurons to be disrupted from the way they normally function. 

Diagnosis & Tests

PMA can be fairly difficult to detect, especially if other lower neuron disorders are being treated. The best way that a doctor can diagnose this disease is to observe the patient. By observing and performing a few tests such as a neurological examination and a physical examination to rule out other medical issues, the doctor will be able to narrow it down and pinpoint the diagnosis of PMA. Some of the tests that will be performed on the patient include:

  • A magnetic resonance imaging (MRI) scan– A magnetic resonance imaging (MRI) is often performed to rule out brain abnormalities or irregularities involving the spinal cord. When this test is being conducted, the patient must remain as still as possible to ensure that the test results are accurate.
  • An electromyography (EMG) – This test can be done to see if there is any muscle dysfunction in the lower abdomen or in the brain. This test involves small needles being inserted into the muscles of the individual.
  • Blood tests– Blood tests are a common method that is used to rule out other diseases that could be causing the symptoms that the patient is experiencing.
  • Nerve conduction studies – This test involves a series of small shocks that are designed to measure the response between the nerve conduction and the muscles of the patient.

Treatment & Therapy

The treatment for PMA is mostly about managing the symptoms of the disease. When walking becomes difficult, a walker or even a wheelchair may be required to accommodate the weakness that is progressing. The patient will most likely need help to communicate with others because they will lose muscle control to form the words.

There is no real treatment to improve the status of PMA patients, but the best thing that can be done is to make the time that the patient has left as comfortable as possible. Eventually a breathing machine will be needed as the muscles continue to deteriorate and a feeding tube may be required when eating with a fork and knife is no longer a viable option, which will ensure that the patient is getting all of the nutrients that they need each day.

Prevention & Prophylaxis

Since the cause of PMA is not known as of yet, it is hard to pinpoint a prevention method that will work to stop this type of motor neuron disease. Due to the 2014 ice bucket challenge, the NEK1 gene has been discovered as a potential cause and there has also been links to traumatic brain injury, which was noted when several football players with head injuries were diagnosed with ALS. If the two diseases are truly linked, then the cure to PMA may not be as far away as it may have been a few years ago.