Motor Neurone Diseases

What is motor neurone disease?

Motor neurone disease (MND) refers to a group of neurodegenerative diseases that deteriorate your body’s motor neurons, causing the nerves in your spine and brain to gradually lose function over time. Motor neurones are nerve cells that transmit electrical signals, also known as nerve impulses, from your spinal cord to your muscles, enabling you to move. 

MND can be hereditary, whereby it is passed down genetically from parent to child, or sporadic, meaning that it occurs randomly within a population. It is one of the most common neurodegenerative diseases, and is seen most often in adults aged 40 and above, especially when they are in their 70s. Unfortunately, MND is a rapidly fatal condition, and death usually occurs in most patients within two to five years after diagnosis [1]. 

There are two sets of motor neurones in your body – upper motor neurones (UMNs) and lower motor neurons (LMNs). The UMNs are located in your brain and spinal cord, and are in charge of sending nerve impulses to the LMNs. The LMNs will then transmit nerve impulses to the muscles in the body. MND may affect either one or both of these sets of motor neurones. You may experience different symptoms depending on which sets of motor neurones in your body are affected. 

Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig disease is the most common form of MND, affecting both the UMNs and LMNs. People with ALS often experience progressive muscle weakness that affects the mouth, arms, legs and respiratory system. ALS is fatal as it often ends with respiratory paralysis, whereby an individual will have extreme difficulty or will no longer be able to breathe on his/ her own. Most ALS cases are sporadic, with only 5 to 10 percent of cases being hereditary [2]. 

Other examples of MNDs include: 

Primary lateral sclerosis (PLS) 

  • PLS is rare and unlike ALS, usually affects only the UMNs. Individuals with PLS often experience weakness and stiffness in both legs. 

Progressive Bulbar Palsy (PBP)

  • PBP affects both the UMNs and LMNs. Individuals with PBP often experience difficulties with speech and swallowing, though they may experience weakness in the arms and legs as the disease progresses. 

X-linked spinobulbar muscular atrophy (Kennedy disease)

  • Kennedy disease is rare and affects the LMNs. Individuals with Kennedy disease may experience twitching, often in the tongue and hands, followed by having speech and breathing difficulties.

How will having MND affect me?

In the initial stages, MND may bring you a slight discomfort and inconvenience as you begin to find it hard to move around easily. Daily activities such as eating, dressing and sleeping may become difficult and extremely tiring. As the disease progresses, these symptoms worsen and you may begin to develop locked-in syndrome, whereby despite being conscious and aware, you are unable to move or speak, as if you are being locked inside your own body. 

Besides facing these physical challenges, MND may also negatively affect your mental health as it has been associated with depression and anxiety disorders. In addition, the inability to communicate with others frequently entails low levels of social interaction for patients, and thus may result in feelings of loneliness and isolation, and thus psychological distress [3]. 

What does having MND feel like?

Muscle weakness and fatigue. The main tell-tale sign of MND is muscle weakness. Approximately two thirds of ALS first complain of muscle weakness in the upper or lower limbs, and approximately one fourth of patients with dysarthria, a motor speech disorder whereby your muscles controlling speech are weak or difficult to control [2]. You may find yourself stumbling over and dropping things more often than usual, or getting unusually tired despite moving around only for a short period of time. 

Muscle aches, cramps and twitching. Besides muscle weakness, you may also experience muscle aches, cramps and twitches. For example, you may find yourself having difficulties with tying your shoelaces due to stiff fingers, or your legs jerking out of the blue while you rest. 

Problems with speech and swallowing. With MND, you may also have trouble speaking clearly, and find yourself not being able to sing or shout. Swallowing and chewing may be difficult as well.

What are the causes and risk factors of MND?

As of now, the causes of MND are unknown. Most cases of MND occur randomly and most are not linked to family history. However, MND is considered to be a disease that arises due to a complex interaction between genetics and environmental conditions. 

The biggest risk factor of MND is age. Those between the ages of 50 and 75 have the highest risk of developing MND. In addition, studies have shown that smoking may increase your risk of MND as well [4]. 

How is MND diagnosed?

There is no single test to diagnose MND, but diagnosis is often obvious based on your symptoms. 

Medical examination. To diagnose MND, your doctor will conduct a thorough medical examination and will likely ask you about your medical and family history. 

EMG. In addition, your doctor may conduct an electromyography (EMG) which measures the electrical activity of your nerves and muscles. There are two parts to an EMG. 

The first part comprises of nerve conduction studies (NCS), which measures the rate at which electrical impulses move through your nerves. During this test, small patches which deliver electrical pulses will be attached to your skin. This process may cause you some discomfort depending on the strength of the electrical pulse but is generally painless. 

The second part is known as a needle electrode examination, which measures the electrical activities in your muscles. During this test, five or more thin needles will be inserted into your muscle. You may experience a slight pain during the insertion of the needles. However, this test is otherwise painless as well.

Nerve conduction studies. Your doctor may conduct a nerve conduction study. During a nerve conduction study, your doctor will attach electrode patches onto your body. These patches will then produce electrical impulses, allowing your doctor to measure how fast impulses travel through your nerves. This will help your doctor to differentiate spinal stenosis from other potential neuropathic conditions that may be mimicking your symptoms. 

Neuroimaging. Lastly, your doctor may make use of MRI scans to have a detailed look at your brain, spine and surrounding nerve. This will allow your doctor to look for evidence of other conditions which may be causing your symptoms instead of MND. 

Some conditions which are known to mimic the symptoms of MND include [4]: 

Benign fasciculations 

  • Causes muscle twitching, tingling, or numbness

Neuralgic amyotrophy 

  • Causes severe pain and stiffness or paralysis in the shoulder and arm region

Multiple sclerosis 

  • Causes muscle weakness in extremities (arms and legs) and difficulty with coordination and balance
  • May also cause double or blurred vision

How is MND treated?

Unfortunately, there are currently no cures for MND. Medications may be provided to relieve symptoms such as muscle twitching and excess saliva. However, these are mainly used to improve quality of life and usually will not do much to stop or delay the progression of the disease. 

Having MND can be very debilitating and challenging for both you and those around you. For many, support groups such as the Motor Neuron Disease Support Group can offer valuable help and support in many different ways. 

If you think that you may have MND or are struggling to cope with it, visit a doctor and seek medical attention immediately.

  1. S, S. (2010). Motor neurone disease: clinical features, diagnosis, diagnostic pitfalls and prognostic markers Sathasivam S. Singapore Med J, 51(5), 367–373.
  2. Takei, H. (2019, December 22). Pathology of Motor Neuron Disorders: Definition, Etiology, Epidemiology. Medscape. 
  3. Gibbons, C. J., Thornton, E. W., Ealing, J., Shaw, P. J., Talbot, K., Tennant, A., & Young, C. A. (2013). Assessing social isolation in motor neurone disease: A Rasch analysis of the MND Social Withdrawal Scale. Journal of the Neurological Sciences, 334(1–2), 112–118.
  4. Doyle, P., Brown, A., Beral, V., Reeves, G., & Green, J. (2012). Incidence of and risk factors for Motor Neurone Disease in UK women: a prospective study. BMC Neurology, 12(1).