Muscle Atrophy: Is It ALS or Another Condition?

Amyotrophic lateral sclerosis (ALS), muscle atrophy?

Hello doctor, I am a 40-year-old male.
About six years ago, I suddenly felt unusual soreness in my left arm, and later the small thenar muscle in my left hand began to twitch.
A few days later, I noticed slight atrophy.
I consulted a neurologist who found some mild weakness.
After a few days, I also noticed atrophy in the large thenar muscle of my right hand, but it was not complete; just a small portion was missing.
I underwent nerve conduction studies and electromyography (EMG), as well as an MRI of my neck.
The nerve conduction study showed slight abnormalities, and the EMG indicated some unusual signals that seemed concerning.
The doctor advised me to monitor the situation.
The MRI results were normal.
Later, I visited Cheng Kung University Hospital, where the doctor said my muscles were still present, just slightly atrophied, and I still had strength, so I didn’t need to pursue further investigations.
I stopped regular check-ups after that.
Over the past six years, I have experienced a general sense of fatigue, but my daily life has been normal, and I have not noticed further atrophy or weakness.
I almost forgot about my condition.
The past three to four years have been relatively normal, and I feel much better compared to the year before the onset of my symptoms.
However, in the past few months, my arms have suddenly started to tremble, and my muscles are twitching continuously.
I also experience unexplained spasms throughout my body, and I have noticed some atrophy in my thighs.
I am beginning to wonder if I might have this disease, but how could it not have worsened over the past six years? Isn’t the progression of amyotrophic lateral sclerosis (ALS) typically rapid? How could I have remained stable for six years? Is it possible that I have another type of muscular dystrophy?

Aze, 40~49 year old female. Ask Date: 2023/01/03

Dr. Jiang Junyi reply Neurology

Dear Mr.
Aze,
You mentioned that "my arms suddenly tremble continuously, my muscles twitch, and I experience inexplicable spasms throughout my body.
I also noticed that my thighs seem to be atrophying, and I wonder if I might have this disease." The muscle atrophy you described may suggest damage to the motor neurons that innervate the muscles.
This is typically indicative of peripheral motor neuron damage, which corresponds to lower motor neuron signs (muscle atrophy, weakness, and fasciculations).

Motor neuron disease, commonly known as amyotrophic lateral sclerosis (ALS), may present with upper motor neuron signs such as hyperreflexia, the Hoffmann sign, and the Babinski reflex.
Clinical diagnosis often requires electromyography (EMG) and muscle biopsy, among other methods.

For peripheral nerve issues, electrodiagnostic studies can assist in diagnosis.
Nerve conduction studies assess the conduction velocity and waveform of large fiber nerves, while electromyography evaluates the muscle response in the innervated areas.
I recommend consulting a neurologist specializing in peripheral nerve disorders, as they typically have more experience with EMG diagnostics.
Thank you for your inquiry.
If you have further questions, feel free to discuss them! Wishing you good health and peace.
Sincerely,
Dr.
Jiang Junyi
Taipei Medical University

Reply Date: 2023/01/03

More Info

Understanding muscle atrophy and its potential causes, including conditions like Amyotrophic Lateral Sclerosis (ALS), is crucial for accurate diagnosis and management. In your case, the history of muscle twitching, atrophy, and weakness in your hands raises important questions about the underlying pathology.

Firstly, ALS is a progressive neurodegenerative disease that primarily affects motor neurons in the brain and spinal cord. The hallmark symptoms include muscle weakness, atrophy, and fasciculations (muscle twitching). However, the progression of ALS can vary significantly among individuals. While some may experience rapid deterioration, others may have a slower progression, which seems to align with your experience of having stable symptoms for several years.

The fact that you have experienced muscle atrophy and twitching in both hands, along with a sensation of fatigue, suggests that there may be an underlying neuromuscular condition. However, the absence of significant weakness or functional impairment over the years is atypical for classic ALS. This raises the possibility of other conditions that can cause similar symptoms, such as multifocal motor neuropathy, spinal muscular atrophy, or even benign fasciculation syndrome.

Your previous evaluations, including nerve conduction studies and electromyography (EMG), are essential diagnostic tools. Nerve conduction studies assess the electrical activity of nerves, while EMG evaluates the electrical activity of muscles. Slight abnormalities in these tests can indicate nerve or muscle dysfunction, but they do not definitively diagnose ALS. The presence of "unusual signals" in your EMG could suggest a neuromuscular disorder, but without clear evidence of widespread motor neuron degeneration, a diagnosis of ALS remains uncertain.

The MRI of your cervical spine being normal is also a positive sign, as it rules out structural causes of your symptoms, such as herniated discs or spinal stenosis, which could compress nerves and lead to muscle weakness or atrophy.

Given your symptoms of muscle twitching and the recent onset of tremors, it is advisable to follow up with a neurologist for further evaluation. A comprehensive assessment may include repeat EMG studies, additional imaging if necessary, and possibly blood tests to rule out other conditions, such as autoimmune disorders or metabolic issues that could contribute to muscle symptoms.

In summary, while your symptoms warrant careful consideration of ALS, the relatively stable course over six years and the specific nature of your symptoms suggest that there may be alternative explanations. Conditions like benign fasciculation syndrome or other forms of muscle atrophy could be responsible for your symptoms. It is essential to maintain regular follow-ups with your healthcare provider to monitor your condition and adjust your management plan as needed. Early intervention and accurate diagnosis are key to optimizing your quality of life and addressing any potential complications.

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