Amyotrophic Lateral Sclerosis (ALS) shines as the most widely recognized and prevalent form of motor neuron disease (MND), yet it’s important to note that ALS is just one among several types of these conditions. MNDs encompass a family of related diseases, each with its unique characteristics.
But what defines an MND? Motor Neuron Diseases are a group of neurological disorders where motor neurons undergo degeneration over time. These motor neurons play a crucial role in controlling essential skeletal muscle functions such as breathing, walking, speaking, and swallowing. Unfortunately, in the realm of MNDs, these vital neurons suffer destruction.
The hallmark shared by all Motor Neuron Diseases is the progression of muscle weakness, which tends to intensify as time goes on. It’s worth noting that many of these diseases within the MND spectrum pose a significant threat to life.
Difference between ALS and MND
The question isn’t “ALS vs MND.” Admittedly, ALS is the most prevalent motor neuron disease. However, primary lateral sclerosis, progressive muscular atrophy, progressive bulbar palsy, and spinal muscular atrophy are among the disorders that fall under the MND umbrella. Some experts suspect that some of the other MNDs are actually ALS. ALS is degenerative, irreversible, and devastating, just like the other MNDs. It is invariably lethal.
Around 2 out of every 100,000 people develop ALS every year. Over 90% of ALS cases are sporadic (with no obvious family history), and only 5% to 10% of ALS cases are inherited through a mutated gene. ALS is a subtype of Motor Neuron Disease, and the two terms are often used interchangeably. When people refer to MND, they might be talking about ALS or other subtypes of motor neuron diseases that have different clinical presentations and characteristics. ALS is the most well-known and common form of MND, but there are other types as well, such as Primary Lateral Sclerosis (PLS), Progressive Muscular Atrophy (PMA), and others, each with distinct patterns of motor neuron involvement and progression.
Other Motor Neuron Diseases Types
- Progressive bulbar palsy (PBP): It is also known as progressive bulbar atrophy, and is a neurological condition that affects the lower motor neurons. Individuals with progressive bulbar palsy initially experience muscle weakness that limits their ability to chew, swallow and breathe. Since most patients with PBP ultimately acquire more widespread symptoms, many doctors also classify it as part of the ALS spectrum. PBP could signal the start of bulbar-onset ALS.
- Primary Lateral Sclerosis: It affects just the lower motor neurons and is usually misdiagnosed as ALS. It develops more gradually than ALS and is rarely deadly. Many persons with PLS will acquire upper motor neuron disease and their diagnosis changes to ALS. PLS produces voluntary muscular weakness, leading to mobility issues and poor balance.
- Spinal muscular atrophy (SMA): It is the most frequent motor neuron disease. It mostly affects children and newborns, unlike other MNDs. It is the leading genetic cause of newborn death. The earlier symptoms develop, the more serious they are likely to be. The majority of children who acquire SMA before the age of six months (type 1 SMA) die of respiratory failure before reaching the age of two. Adult-onset SMA, or SMA type 4, is relatively rare and causes only mild to moderate muscle atrophy.
- Pseudobulbar Palsy: It has an impact on one’s ability to speak, swallow, and chew food. It can arise in people with neurological disorders including multiple sclerosis and MND and is often defined as a syndrome rather than a disease. It can also occur as a consequence of a stroke or a brain tumour. One of its most distinguishing features is unintentional or unexpected tears and laughter.
- Progressive Muscular Atrophy (PMA): It only affects the lower motor neurons. The majority of PMA patients have a course of illness that is remarkably similar to that of ALS patients. In fact, some research suggests that PMA is a form of ALS. Weakness usually begins in the hands and progresses to the lower body. Muscle wastage, clumsy hand movements, trembling, muscle spasms, and breathing difficulties are all possible symptoms.
- Flail Arm Syndrome (FA): FA is a rare subtype of ALS that primarily impacts the muscles in the arms and shoulders. It causes muscle weakness, atrophy, and cramps in these areas. Unlike typical ALS, where leg muscles are also affected, individuals with FA tend to have relatively preserved leg strength and function.
- Flail Leg Syndrome (FLS): FLS, another rare subtype of ALS, mainly affects the muscles in the legs. It leads to muscle weakness, atrophy, and cramps in the lower limbs. Upper body strength is usually less affected initially, setting it apart from traditional ALS.
ALS vs MND
When discussing neurological disorders that affect motor neurons, Amyotrophic Lateral Sclerosis (ALS) and Motor Neuron Disease (MND) often intertwine in conversation. While ALS is a prominent subtype of MND, understanding their relationship and differences is essential for grasping the complexity of these conditions.
ALS: A Subtype of MND
Amyotrophic Lateral Sclerosis, or ALS, stands as a distinguished member of the Motor Neuron Disease family. It specifically targets both upper and lower motor neurons, causing a progressive breakdown of nerve cells responsible for controlling voluntary muscle movements. This breakdown leads to muscle weakness, atrophy, and eventually paralysis. ALS is renowned for its association with renowned figures like baseball legend Lou Gehrig, which has led to it being colloquially referred to as Lou Gehrig’s disease. It’s vital to recognize that ALS is a subset within the broader spectrum of Motor Neuron Diseases.
MND: A Broader Landscape
Motor Neuron Disease serves as the overarching term encompassing a range of disorders characterized by the degeneration of motor neurons. These disorders include not only ALS but also other subtypes such as Primary Lateral Sclerosis (PLS) and Progressive Muscular Atrophy (PMA), each with distinct patterns of motor neuron involvement and progression. The common thread among MNDs is the impact on motor neurons responsible for transmitting signals between the brain and muscles, ultimately leading to muscle weakness, impaired movement, and in some cases, respiratory failure.
- Scope: ALS is a specific type of MND that affects both upper and lower motor neurons. MND, on the other hand, refers to the broader category encompassing various motor neuron disorders.
- Variety: MNDs come in multiple subtypes, with each presenting unique patterns of motor neuron involvement and progression. ALS is the most common subtype within the MND spectrum.
- Awareness: Due to its prevalence and association with notable individuals, ALS has garnered significant attention. MNDs, as a collective term, may not always receive the same level of recognition despite their equally impactful effects.
Living with MND
A multidisciplinary framework will help patients in dealing with their symptoms. Physiotherapy can help people maintain muscle strength and flexibility in their joints, while certain medications can help alleviate physical problems as well as anxiety and depression. When a disease is fatal, palliative care can help stabilize pain and symptoms while also providing interpersonal support to MND patients.