The Difference Between ALS and Multiple Sclerosis

Lou Gehrig's disease and MS share symptoms, but they are distinct diseases

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Multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, are lifelong neurological diseases associated with muscle weakness and physical disability. Though they have similar sounding names, there are major differences between the two.

MS is not life-threatening, and life expectancy can be the same as that of anyone without the disease. ALS, on the other hand, requires major life-sustaining interventions and is eventually fatal.

While neither is curable, there has been major progress in terms of medical care and treatment for both conditions.

Symptoms

Neurological symptoms are the hallmark of MS and ALS, and while there are a few overlaps in symptoms, there are major differences.

Muscle weakness or trouble speaking (dysarthria) or swallowing (dysphagia) are among the first symptoms of ALS. In contrast, the first symptoms of MS are often paresthesias (numbness or tingling in extremities) or vision changes.

But either of these conditions can begin with mild problems, such as twitching of the hand, or a major event, such as leg weakness and a sudden fall.

ALS is characterized by a steady decline and worsening symptoms. In contrast, some types of MS are characterized by a gradual decline, while others are characterized by periods of remission (improvement) and exacerbations (relapses). 

Symptom ALS MS
Muscle Weakness (Arms and Legs) Yes Yes
Paralysis Yes Rare
Trouble Speaking Yes Yes (less severe)
Cognitive Issues Yes (less common) Yes
Mood Changes Yes (less common) Yes
Swallowing Problems Yes Yes (less severe)
Breathing Problems Yes Rare
Vision Changes No Yes
Sensory Issues Rare Yes
Bladder/Bowel Issues Yes Yes

Muscle Weakness in Arms and Legs

ALS always advances to cause muscle paralysis (complete weakness). The muscles eventually atrophy (shrink and deteriorate). Eventually, everyone who has ALS will need an assistive device, such as a walker, wheelchair, or scooter.

Many people with MS experience mild or moderate muscle weakness, but only rarely experience paralysis. MS can affect your walking, and you may need an assistive device to get around, but most people with MS have more independence than those with ALS.

Trouble Speaking

Dysarthria is common in ALS and MS. Dysarthria does not affect your understanding of words because it is not a language disorder. Your speech may be hard to understand, and you might also drool, especially when speaking.

Generally, dysarthria is more severe with ALS than with MS.

Cognitive Issues

MS can produce cognitive dysfunction, which often manifests with clouded thinking or slowed thinking. This can be intermittent or can progress throughout the disease course.

ALS can also have cognitive and behavioral dysfunction that is worse with advancing disease, but not as common when compared to MS patients.

Mood or Personality Changes

MS may produce mood and personality changes due to its direct effect on the brain.

ALS can also be associated with depression, anxiety, and personality changes, but these tend to be less common in patients with MS.

Swallowing Problems

ALS commonly produces dysphagia. This will often progress to the point that a feeding tube or other means of nutrition is needed.

While MS-related swallowing problems can occur too, they are usually less severe and can typically be managed with swallowing therapy and dietary adjustments.

Breathing Problems

ALS usually causes impaired breathing due to degeneration of the nerves that power the respiratory muscles. Most people with ALS need a device to help with breathing, often starting with noninvasive ventilation (a mask that delivers oxygen), and then progressing to mechanical ventilation, which uses a powered machine to support lung function. 

Breathing problems rarely occur in MS and are usually mild. It is rare for MS-related respiratory problems to require breathing assistance.

Vision Changes

In MS, vision can be affected by optic neuritis or nystagmus. In fact, decreased vision, double vision, and blurred vision are common in MS and often impact driving ability.

ALS does not affect vision, but it can cause altered eye movements late in the course of the disease.

Sensory Symptoms

Sensory changes are common in MS and can manifest with a range of unpleasant sensations, such as numbness and tingling or pain.

Some people with ALS report tingling sensations. However, this is not common and it usually goes away.

Tingling or sensory discomfort in ALS is caused by pressure and prolonged immobility rather than by the disease itself.

Bladder and Bowel Symptoms

It is estimated that over 90 percent of people who have MS experience bladder dysfunction, including the inability to initiate urine and/or incontinence. People who have ALS can lose motor control and may experience bowel and bladder incontinence.

MS and ALS are both commonly associated with constipation.

Causes

Both of these conditions affect the brain and the spine. However, in MS, demyelinating lesions can be seen in the brain and spine by MRI, while in ALS the neuronal damage is not able to be seen on imaging. MS, but not ALS, can also involve the optic nerves (the nerves that control vision). In addition, the disease pathophysiology (biological changes) of the two conditions is completely different.

Cause of MS

MS is a disease caused by demyelination of nerves in the brain, spine, and optic nerves. Myelin is a fatty coating that insulates nerves, allowing them to function efficiently. The nerves don't function as well as they should when they lack adequate myelin, and this results in the symptoms of MS.

Myelin is regularly replaced, and you can recover from a relapse without any residual effects. Sometimes, nerve damage or scarring can occur, and the neurological deficit can be long lasting or permanent.

It is believed that the demyelination of MS is caused by an autoimmune reaction, in which the body attacks its own myelin. There may be hereditary and environmental components to MS, but the cause remains a mystery.

Cause of ALS

With ALS, the nerves in the lateral regions (sides) of the spine that control movement are gradually destroyed. This part of the spine is where motor neurons are located. These neurons send messages to muscles to activate them to move. 

Eventually, the lateral spinal nerves degenerate and their corresponding muscles begin to atrophy (shrink) and weaken. ALS is not believed to have an autoimmune cause, but it isn't clear exactly why the disease occurs.

Diagnosis

Your physical examination can show some overlapping features. For example:

  • Both MS and ALS can cause you to have increased reflexes.
  • You may have decreased motor strength with either condition.
  • They can both affect one or both sides of your body.
  • Your muscle tone can be increased or decreased with either condition.

With MS, you can have altered sensation anywhere on your body (although you might not), but your sensory examination should be normal with ALS.

ALS is often characterized by muscle fasciculations, which look like rapid fluttering of tiny muscles on your tongue, lips, or any other area of the body. With MS, you can have muscle spasms, which are noticeable, involuntary muscle jerks. Spasms may develop late in the course of ALS.

Because of this, testing is needed. You may have some of the same diagnostic tests if you have either of these two conditions, but the results will be completely different.

Tests

Your diagnostic tests can help distinguish these two conditions. MS is characterized by abnormalities that can be seen on a brain or spine magnetic resonance imaging (MRI) test, while these tests are not affected by ALS.

ALS is characterized by alterations in the patterns seen on electromyography (EMG), while MS patients have a normal study.

And, if you have a lumbar puncture (spinal tap), the results can show a characteristic pattern with MS that is not seen with ALS.

Treatment

The treatment of the conditions is quite different, but both diseases are treated with disease-modifying therapy as well as therapy aimed at managing health complications.

Disease-Modifying Therapy

MS disease-modifying therapies (DMTs) are taken on a regular basis to prevent exacerbations and overall neurological decline. There are also treatments used during an MS exacerbation, including corticosteroids.

A new disease-modifying therapy for ALS, Radicava (edaravone), was approved by the U.S. Food and Drug Administration (FDA) in 2017. This medication is believed to prevent neurotoxic damage, preventing disease progression. Because it is relatively new, the impact on people who have ALS is not yet known.

Disease Management

With both of these conditions, support for medical complications and disabilities is a major part of medical care.

For example, you may benefit from physical therapy to optimize your swallowing and motor control. A supportive brace can help you walk or use your hands and arms. Prevention of bed sores, respiratory infections, and malnutrition is important, and strategies related to these issues may be worked into your care over time.

Adapting to bladder and bowel issues may be necessary, and medications used to prevent painful spasms may be helpful.

A Word From Verywell

If you or a loved one are experiencing any neurological symptom, be sure to speak with your doctor. There are many neurological diseases, and while the thought of having one can seem daunting, know that many neurological diseases are quite manageable.

Getting a speedy diagnosis is your best chance of optimizing your recovery in the long term. And even for a serious condition like ALS, recent advances in care have improved the average survival rate.

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