Amyotrophic Lateral Sclerosis (ALS)

ALS Coronal[1]

Amyotrophic lateral sclerosis (ALS) is one of the most common forms of motor neuron diseases. It is also known as “Lou Gehrig's disease”, after a well-known baseball player in New York.


Presentation

The hallmark of the disease is a mixed upper and lower motor neuropathy that is progressive over time. The upper motor signs include spasticity, hyperreflexia and weakness. The lower motor signs include amyotrophy, weakness and fasciculations. The diagnosis is suspected when there is insidious loss of function in more than one parts of the body. The lower motor neuron signs tend to appear first usually in the tongue and limbs. 80% of patients present with predominately limb symptoms with the rest presenting with bulbar symptoms.

The limb disease may present with altered gate such a foot drag while upper limb involvement usually begins with loss of dexterity and wasting of muscles over time. Eventually the function deteriorates and mobility reduces with spasticity and subsequent contractures.

Patients who present with bulbar symptoms usually present with speech abnormalities and dysphagia. Most patient will tend to preserve ocular movements and bladder control [9].

Workup

Due to it slow progression it may take a neurologist a few months to come to a diagnosis, unless there is a strong family history of the illness. Needle electromyography and nerve conduction studies and will aid in diagnosis and exclude any other conditions that may mimic the disease. Genetic testing is only performed if there is a suspicion that there may be a genetic or familial cause. If there is uncertainty a muscle biopsy may have to be done to exclude other courses.

Treatment

The treatment for this condition is totally supportive and includes, speech, physical and occupational therapy. It is very important that the patient and relatives are educated well on the condition and prognosis. There are also a number of support groups that help families and suffers deal with the condition. The only drug available currently is riluzole that has been shown to delay the time to tracheostomy by about 2 months [10].

Prognosis

As mentioned before, amyotrophic lateral sclerosis is a fatal disease with the median time to death from diagnosis being 3 years. The patients who survive long tend to get the disease at a younger age, with primary limb involvement. Most individuals succumb to secondary infections such a pneumonia [8].

Etiology

The underlying etiology is unknown. Most cases are sporadic with approximately 10% of the cases being familial or genetic. The genes in familial causes are numerous and no single gene has been identified that can explain the pathology. Many of the genes identified have been associated with other neurological diseases such as dementia and Alzheimer disease. In the families which have identified genes the mode of transmission is usually autosomal dominant. There is no clinical difference between the familial variant compared to the sporadic cases.

The only establish risk factor that has been identified is smoking. Studies have shown that smokers are at twice the risk of suffering from this disease as compared to non-smokers [2] [3].

Epidemiology

The annual incidence is approximately 2 per 100,000 population. Finland has the highest incidence in the world with rates almost twice that of other countries. It tends to affect whites more than other races and is higher in men as compared to women.
Amyotrophic lateral sclerosis may occur between teenager years to as high as the 80s. There is increasing risk with age [4] [5] [6].

Sex distribution
Age distribution

Pathophysiology

The pathophysiology of amyotrophic lateral sclerosis is unknown, but a number of theories exist. The disease is named after the pathology is causes - amyotrophy - muscular atrophy, and lateral sclerosis refers to the changes seen in the lateral tracts.

It is thought that there are multiple mechanisms involved, few which have been noted include derangements in free radical scavenging, and derangements in cellular cytoskeletons. The most upcoming theory that has a lot of research focused on it is the theory that aggregation in mRNA processing may be a significant contributor, leading to neuronal dysfunction and death [7].

Prevention

The only risk factor identified is smoking so cessation or avoidance would assume to be beneficial. Suspected family cases should have testing and counselling when appropriate.

Summary

Amyotrophic lateral sclerosis (ALS) is overall a fatal disease with no active treatments. With good support, suffers may lead meaningful, but restricted lives. It is one of many motor neuron diseases, but what makes it stand out is that it presents with both upper and lower motor neuron signs [1].

Patient Information

  • Definition: Amyotrophic lateral sclerosis (ALS) is a disease that affects the nerves that control muscle movement. This causes the muscles to weaken and become shrunken. This makes it difficult for the person to do daily activates and eventually they may be unable to walk, talk or eat as the disease progresses. 
  • Cause: The cause of this disease is unknown, but there are some families that are known to pass it down generations. In these families a few genes have been affected. Most of the cases have no family links. There has been some information that smoking may contribute to its onset.
  • Symptoms: The will be weakness of the affected region of the body, with either rigid limbs or floppy limbs. Speech and swallowing may be the first to be affected in some individuals. 
  • Diagnosis: Most of the diagnosis is made by history and examination, with few tests being done to see if the nerves are functioning well.
  • Treatment: Treatment is very limited with only one drug available called riluzole that slows down the disease, briefly. Most of the other treatment is supportive to help the patient not to get stiffness in the joints and bedsores. They may require speech therapy and devices to aid in movement such as wheel chairs. As speech is also affected communication devices may be required to aid. They may also require breathing support and feeding tubes. 
  • Overall the disease has a poor outcome and family support is very important. There are groups that aid the families psychologically, helping them understand and process all the information.

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References

  1. Mitsumoto H, Chad DA, Pioro EP. Amyotrophic lateral sclerosis. In: Contemporary Neurology Series, 49, F.A. Davis Company, Philadelphia 1998.
  2. l-Chalabi A, Lewis CM. Modelling the effects of penetrance and family size on rates of sporadic and familial disease. Hum Hered. 2011;71(4):281-8. 
  3. Hanby MF, Scott KM, Scotton W, Wijesekera L, Mole T, Ellis CE, et al. The risk to relatives of patients with sporadic amyotrophic lateral sclerosis. Brain. Dec 2011;134:3454-7. 
  4. Chiò A, Mora G, Calvo A, Mazzini L, Bottacchi E, Mutani R. Epidemiology of ALS in Italy: a 10-year prospective population-based study. Neurology. Feb 24 2009;72(8):725-31. 
  5. Alonso A, Logroscino G, Jick SS, Hernán MA. Incidence and lifetime risk of motor neuron disease in the United Kingdom: a population-based study. Eur J Neurol. Jun 2009;16(6):745-51.
  6. Johnston CA, Stanton BR, Turner MR, Gray R, Blunt AH, Butt D, et al. Amyotrophic lateral sclerosis in an urban setting: a population based study of inner city London. J Neurol. Dec 2006;253(12):1642-3.
  7. Barber SC, Shaw PJ. Oxidative stress in ALS: key role in motor neuron injury and therapeutic target. Free Radic Biol Med. Mar 1 2010;48(5):629-41
  8. Visser J, van den Berg-Vos RM, Franssen H, et al. Disease course and prognostic factors of progressive muscular atrophy. Arch Neurol 2007; 64:522.
  9. Hirano A. Neuropathology of ALS: an overview. Neurology 1996; 47:S63.
  10. Miller RG, Jackson CE, Kasarskis EJ et al. Practice Parameter update: The care of the patient with amyotrophic lateral sclerosis: Drug, nutritional, and respiratory therapies (an evidence-based review). Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2009;73:1218-1226

Media References

  1. ALS Coronal, CC BY-SA 3.0

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