Cerebral cortical dysfunction in chronic obstructive pulmonary disease: role of transcranial magnetic stimulation

SETTING: Chest and Neurology Departments, Assiut and Al-Azhar University Hospitals, Egypt.

OBJECTIVES: To study a large population with respect to previous preliminary data, using transcranial magnetic stimulation (TMS) as a prognostic method for evaluation of cerebral cortical functions during acute exacerbation of chronic obstructive pulmonary disease (AE-COPD).

DESIGN: In a case-control study, 41 patients with AE-COPD and 30 healthy controls were included. For all, TMS was used to assess corticospinal pathway function and cortical excitability.

RESULTS: Patients demonstrated increased motor threshold (resting and active), central motor conduction time and increased cortical silent period. Significant correlation was identified between TMS parameters and pulmonary function tests (forced vital capacity, forced expiratory volume 1%, forced expiratory volume in one second) and arterial blood gases (pH, paO₂ and HCO₃), serum chloride and potassium.

CONCLUSION: These results indicate that the motor cortex is less excitable during AE-COPD. This is attributed to reduction of cortical excitability due to chronic hypoxaemia. Therefore, early detection of cerebral changes might be in accordance with the importance of early O₂ therapy in reducing morbidity and mechanical ventilation dependency in COPD. This opens discussion for future early therapeutic use of GABAergic and glutaminergic modulating drugs with oxygen to protect the brains of COPD patients.