Amyotropic Lateral Sclerosis (ALS)

6 mins read

Introduction
Amyotropic lateral sclerosis (ALS) is a progressive neurodegenerative disease which affects the nerve cells (motor neurons) in brain and spinal cord. It is also known as ‘Lou Gehrig Disease’.

Motor neuron connects the brain with muscles as they carry the information from brain to muscles which lead to response to any stimulus.

Motor neurons first reach from brain to spinal cord and from spinal cord to muscles throughout the body. In ALS, motor neuron progressive degeneration leads to their death. Because of death of motor neurons, the ability of brain to initiate and control the movement of muscles is lost. Since, the person with ALS has dead motor neurons so the muscles cannot move and this finally results in paralysis and atrophy of muscles.

Types
Classical ALS- This form of ALS includes upper and lower motor neurons. This from of disease starts with weakness in one part of body and it gradually increases within the part and then to the rest of the body. The rate of progression of this type of ALS varies widely, with some patients dying within few months of their first symptom of disease and others can move even after many years.

Familial ALS- As per records, this type makes about 5 percent of the total cases. Familial ALS is inherited mainly in form of dominant autosomal trait having reduced penetrance while some cases with X-linked and autosomal recessive inheritance are also seen.

Cause
The actual cause of ALS is still not known. Major successes in this front came when scientist discovered that mutation in gene which produce SOD1 enzyme is linked with some of the familial ALS. However, it is still not clear how the mutation in SOD1 gene can affect the degeneration of motor neurons. There are some evidences showing that the mutant SOD1 protein can become toxic.

After this number of other gene mutations have been identified which are believed to play some role in ALS. Studies has revealed that defect in the C9orf72 gene also plays important role in  cause of ALS.

Researchers also studying the role of environmental factors, physical trauma, behavioral and occupational factors in cause of ALS.

Epidemiology
Classical type ALS makes 90-95 percent of total cases with no clearly associated risk factors while 5-10 percent of cases are inherited or familial.

Prevalence On Basis Of Race
ALS affects whites more as compared to non-whites with a ratio of 1.6:1.

Prevalence On Basis Of Sex And Age
The occurrence of ALS in more in males as compared to females with overall ratio of 1.5-2:1. This tends to equalize in later stages of life. ALS may occur from teenage to late 80s with an increased rate as the age increases.

Symptoms
The initial symptoms of ALS are different in different people. Some may experience trouble in lifting, some may have slurred speech while some may experience tripping over carpet edges. However, with progression of disease following symptoms can be seen-

  1. Muscle twitch or cramping of muscles, mainly hands and feet.
  2. Difficulty to speak and thick speech.
  3. Weakness in muscles of hand, legs, muscles of speech etc.
  4. Inability to move hands and legs.
  5. In advanced stages, shortness of breathing, difficulty in swallowing etc.

Diagnosis

  1. Neurological examination
  2. X-rays and Magnetic resonance imaging
  3. Nerve or muscle biopsy
  4. Myelogram of cervical spine
  5. Blood test & urine test including test for thyroid and parathyroid hormone level, test for heavy metal in urine and high resolution serum protein electrophoresis
  6. Electromyography and nerve conduction velocity test.

Treatment
For ALS, no cure has been found till yet. However, the first drug to cure this disease, approved by FDA in 1995 was Riluzole.

Riluzole decrease the release of glutamate and thus reduces the damage to motor neurons. Damage which is already done by ALS cannot be reversed by this drug and also the patient has to be monitored for liver damage and other side effects of the drug. However, this drug gives the hope to stop the progression of ALS with new medication and combination of other drugs.

A variety of medication may be useful in reducing the symptoms of ALS.

  1. Muscle relaxants to reduce cramps and spasticity of muscles.
  2. Antianxiety drugs such as lorazepam
  3. Pseudobulbar effect can be decreased by the combination of drug dextromethorphan and quinidine.
  4. Mucolytic drugs for thick secretions.
  5. Non-steroidal anti-inflammatory drugs.
  6. Fentanyl for pain.

Complications

  1. Inability to perform the activities of daily routine.
  2. Insufficiency in respiration
  3. Aspiration pneumonia
  4. Ambulation deterioration
  5. Ulcers and skin infection due to inability to move.
  6. Deep vein thrombosis and pulmonary emboli, rare but encountered in some cases.

Alternate Treatment

Physical Therapy- Physical therapist can recommend exercise which can help patients in being mobile without overworking of muscles.

Accupuncture- Nervous system functioning is improved by acupuncture.

Speech Therapy- It helps to retain the ability to talk.

Nutritional Therapy- Vitamin B complex, Vitamin C and Vitamin E, are believed to improve nervous system functioning as well as muscles.

 

References
1. Brooks BR, Miller RG, Swash M, Munsat TL. El Escorial revisited: revised criteria for the diagnosis of amyotrophic lateral sclerosis.Amyotroph Lateral Scler Other Motor Neuron Disord. Dec 2000;1(5):293-9.

2. 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.

3. Phukan J, Hardiman O. The management of amyotrophic lateral sclerosis.J Neurol. Feb 2009;256(2):176-86.

4. Brooks BR. Managing amyotrophic lateral sclerosis: slowing disease progression and improving patient quality of life.Ann Neurol. Jan 2009;65 Suppl 1:S17-23.

5. Hudson AJ. Clinical Neurology. In:The motor neuron diseases and related disorders. Vol. 4. 1996:11-14.

6. Bensimon G, Lacomblez L, Meininger V. A controlled trial of riluzole in amyotrophic lateral sclerosis. ALS/Riluzole Study Group.N Engl J Med. Mar 3 1994;330(9):585-91.

7. Cronin S, Hardiman O, Traynor BJ. Ethnic variation in the incidence of ALS: a systematic review.Neurology. Mar 27 2007;68(13):1002-7.

8. de Carvalho M, Dengler R, Eisen A, et al. Electrodiagnostic criteria for diagnosis of ALS.Clin Neurophysiol. Mar 2008;119(3):497-503.

9. Valdmanis PN, Rouleau GA. Genetics of familial amyotrophic lateral sclerosis.Neurology. Jan 8 2008;70(2):144-52

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