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Amyotrophic lateral sclerosis

Synonyms: ALS, Lou Gehrig’s Disease
German: Amyotrophe Lateralsklerose

1 Definition

Amyotrophic lateral sclerosis (ALS) is a chronic neurodegenerative disease of the central nervous system (CNS). It affects the motoric system leading to atrophy of skeletal muscles and abnormal modulation of peripherous reflexes.

2 Pathophysiology and clinical presentation

The exact mechanisms underlying amyotrophic lateral sclerosis are not yet fully understood. However, different theories such as genetic diposition (e.g. gene mutations in genes for TDP-43 or SOD1) and other possible reasons such as viral infection, traumatic brain injury or autoimmune processes are discussed.

The underlying cause for the multiple symptoms caused by ALS is the death of motor neurons in the myelon. This closely correlates with degeneration processes in certain brain areas. Ganglia cells in the areas of motoric cranial nerve nuclei can be observed.

As a consequence, the neuronal degeneration results in atrophy in the corresponding muscles, often starting in the extremities (limb-onset). In cranial nerves, common symptoms are atrophy of facial muscles and progressive bulbar palsy (PBP).

Early symptoms, which are often overlooked, can be muscle weakness – presenting as cramps, stiffness etc.

Later, symptoms develop into palsy, dysphagia, dysarthria. A frequent complication is aspiration pneumonia due to insufficient swallowing and breathing. If upper motor neurons are also damaged, spasticity and hyperreflexia and pathologic reflexes, such as Babinski’s sign, can also be observed.

Inevitably, ALS progresses over time. Most patients die after respiratory failure, the time between onset of symptoms and death is an average of three to five years, with big variations and exceptions such as Stephen Hawking who has survived with ALS for more than 50 years now.

3 Epidemiology

ALS typically presents with the onset of symptoms in patients >50 years of age, with the peak age decade being around 70 years. Men are more often affected than women.

Incidence (for Europe): around 2/100.000 Prevalence: 5/100.000

4 Diagnosis

The main diagnostic option is assessing a detailed medical history and conducting a full neurological examination. Several tests can be suggestive of ALS. For example, evidence for both peripheral (palsy) and central (e.g. spasticity) motorical dysfunction in one muscular group can be a hint. Another probable sign is the occurrence of fasciculations after mechanical or thermal stimulation of a muscle.

Instrumental diagnostic methods include EMG, CT/MRT or muscle biopsies.

5 Therapy

To the date (2016), no curative therapy for ALS has been found. Physiotherapy as well as symptomatic therapy in the best possible extend are the only options so far. Glutamate antagonist Riluzol may lead to a slow-down of progression of ALS.

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