TMS and the Neurology of COPD
Basic findings
Chronic obstructive pulmonary disease (COPD) is characterised by a long, slow decline in lung function. Diagnosis relies on a detailed history and measurement of airflow, while therapy typically involves management of the condition, rather than cure, and attempts to improve the quality of life for the patients. TMS can be used to assess the subclinical central motor, corticospinal pathways, cortical excitability and inhibitory functions in COPD (Mohamed-Hussein et al. 2007).
Ongoing research
Monitoring The Disease
Patients with COPD face an increased respiratory load and in consequence have an elevated respiratory drive. Porcher et al. used TMS to investigate associated changes in corticospinal excitability both at rest and during voluntary facilitation at different levels of inspiratory effort. Diaphragm and abdominal motor thresholds were significantly lower in COPD than healthy controls, but the quadriceps response was the same. The cortical silent period was significantly shorter in COPD. Their results suggest that there is a ceiling effect in motor control output to the respiratory muscles of patients with COPD (Porcher at al. 2004). In general, TMS changes are proportionate to the severity of the illness and the degree of hypoxaemia (Mohamed-Hussein et al. 2007).
Modulating The Disease
Mohamed-Hussein et al (2007) also found that determining the subclinical brain involvement in COPD patients using TMS can provide information about the neurophysiological mechanisms responsible for ventilator dependency with failure of weaning in mechanically ventilated patients and the importance of early oxygen therapy during acute exacerbation of COPD. This information may help in improving quality of life and reduce morbidity and mortality among COPD patients. Early detection of cerebral changes in patients with COPD through assessment of cortical MEP may be as important as early oxygen therapy in reducing morbidity or mechanical ventilator dependency during acute exacerbation of COPD.
Links
References
- Mohamed-Hussein et al., The International Journal of Tuberculosis and Lung Disease, 2007.
- Oliviero et al., Journal of Neurology, 2002.
- Porcher et al., Respiratory Physiology & Neurobiology, 2004.
