Diseases That Can Mimic ALS

There are a number of conditions that can mimic the symptoms associated with amyotrophic lateral sclerosis (ALS) and as a result, misdiagnosis can sometimes occur.

The ALS diagnostic process typically involves the exclusion of the potential for other diseases. This is normally done through a formal approach using the El Escorial criteria, which has been in use for some 20 years.

Diagnosing ALS and other motor neuron diseases is a complicated process and goes far beyond considering visible symptoms that are being exhibited by the patient. A range of diagnostic tools are used to test individuals and achieve an accurate outcome. However, errors are still made.

What Can Mimic ALS?

There are a number of diseases which can initially be mistaken for ALS, with multiple sclerosis and Parkinson’s among the most well-known. Symptoms exhibited by Patients will vary, especially in the early stages of a disease that affects the nerves and this often leads to misdiagnosis for conditions that have similar presentations.

Here we take a look at the diseases which are commonly mistaken for ALS and how they compare, particularly in the initial stages.

Multiple Sclerosis

Multiple Sclerosis (MS) is one of the most common conditions that can mimic ALS and affects about 400,000 people in the US. In about 15% of MS cases, however, symptoms can mimic primary lateral sclerosis. This occurs most often in men over 50. Individuals with either disease may exhibit muscle stiffness, spasms and difficulty walking in the early stages. Once the diseases progress, however, the differences become more readily apparent.

• MS generally presents with upper and lower motor neuron damage, whereas ALS will often start off in a highly localized part of the body.
• MS is an autoimmune disease whereas ALS is a motor neuron disease.

Parkinson’s Disease 

Parkinson’s and ALS share some similarities. In the early stages, symptoms such as postural instability can lead to confusion between the two diseases. The presence of Lewy bodies in Parkinson’s and Bunina bodies in ALS can appear similar and affect how we move, speak and even think.

However, Parkinson’s affects a particular part of the brain rather than all the neurons in the body, as ALS does. ALS progressively leads to loss of muscle strength, eventual paralysis and fatality because the neurons serving areas like that the heart and lungs are compromised.

Benign Fasciculation Syndrome

A fasciculation is a muscle twitch and a symptoms commonly associated with ALS. Benign forms of fasciculation can be caused by too much caffeine, over exercise and alcohol.

The location in which the twitches occur can provide in insight into whether or not they are a result of serious condition. For example, if they are occurring in the abdomen, it is viewed as more serious than if they are occurring in the calf muscles.

Closer diagnostic inspection usually reveals a big difference – ALS fasciculations have a shorter wavelength and a higher firing rate than benign ones.

Spinobulbar Muscular Atrophy

This condition affects males in their forties and fifties and is usually characterized by weakness in the muscles controlling speech, the neck and the limbs.

There may be additional sensory problems with spinobulbar muscular atrophy and it is often associated with conditions such as diabetes and testicular atrophy.

Inclusion Body Myositis

This can lead to a misdiagnosis of ALS as it involves weakness and wasting in areas like the wrists, fingers and quadriceps on one side of the body. About 13% of patients with this condition are routinely misdiagnosed with a motor neuron disease.

Dysphagia or trouble swallowing occurs in about 65% of cases which can further confuse diagnosis. Muscle biopsy and electromyographic analysis are used in indicating motor neuron disease, especially for those where the progression is relatively slow.

Myasthenia Gravis

Myasthenia Gravis (MG) is one of the most common neurodegenerative conditions and is characterized in the early stages by difficulties in swallowing. MG can be challenging to diagnose and may initially be confused with ALS.

There are certain differences, however. Difficulty swallowing in myasthenia gravis is usually accompanied by fatigue. In ALS the progression is more uniform and progressive and individuals will likely exhibit tongue atrophy, more so than in MG. Clearing the throat is a symptom that is associated with ALS while with MG there is often regurgitation through the nose. MG is better understood than ALS and there are certain biomarkers that can aid with diagnosis. The primary one is the binding of autoantibodies to parts of the neuromuscular junction which eventually cause fatigue and weakness. ALS, on the other hand, affects the nerve cells themselves rather than the junctions between individual cells.