Amytrophic Lateral Sclerosis

Amytrophic lateral sclerosis (ALS) is a progressive, fatal motor neuron disease that causes degeneration of both the upper and lower motor neurons of the brain and spinal cord. Approximately 22,000 Americans suffer from ALS; 5,000 new cases are reported annually. Men develop ALS at a rate of 1.5 times that of women.

The degeneration of motor neurons causes the muscles under their control to weaken and waste away, eventually resulting in total paralysis. Degeneration usually begins with the hands and feet, moves to the arms and legs, and eventually progresses to the trunk where respiratory and swallowing/chewing functions are impaired. In end-stage disease, mechanical ventilatory support is usually required. Death generally results within five years of diagnosis; respiratory failure is the main cause of mortality in ALS patients.

Airway clearance indications that may be present in ALS include:

  • Forced immobility prevents the use of exercise to maintain aerobic capacity, bellows function, and lung volume, resulting in restrictive lung disease. The consequent inability to generate a large inspiratory or expiratory force or to cough effectively compromises mucociliary clearance and exposes patients to recurrent respiratory infection.
  • Impaired bulbar function and dysphagia can cause dyscoordinated swallowing, leading to aspiration. Aspiration of salivary or gastric contents introduces bacteria into normally sterile airways resulting in pulmonary infection.
  • Ineffective secretion clearance associated with mechanical ventilator dependency results in impaired gas exchange and significant risk of bacterial colonization within the respiratory tract. Recurrent infection and progressive pulmonary damage frequently end in respiratory failure.

Aggressive bronchial hygiene, including daily Airway Clearance Therapy, is essential to prevent or manage the pulmonary complications that contribute most significantly to morbidity and mortality among patients with ALS.

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Sources

Jackson CE, Bryan WW. Amyotrophic lateral sclerosis. Seminars in Neurology 1998; 18: 27-39. Polkey MI, Lyall RA, Green M, Leigh PN, Moxham J. Expiratory muscle function in amyotrophic lateral sclerosis. Am J Respir Crit Care Med 1998; 158: 734-741.

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