True about primary pulmonary hypoventilation is:

Answer is A (Does not respond to chemical stimuli): Ventilatory responses to chemical stimuli are reduced or absent- Harrison 161/1/1570 Primary pulmonary hypoventilation Characterized by: Impaired chemoreception resulting in decreased ventilatory drive. Chronic hypercapnia and hypoxemia in the absence of identifiable neuromuscular disease or mechanical ventilatory impairment. Presentation : Occurs in all age groups but majority of cases have been repoed in males aged 20-50 years. Early: lethargy, fagtigue, daytime somnolence, disturbed sleep and morning headache. Late: Cyanosis polycythemia, pulmonary hypeension, congestive hea failure. Note : Dyspnea is uncommon despite severe aerial blood gas derangements because of impaired chemotherapy. Diagnosis : The key diagnostic feature is respiratory acidosis in the absence of respiratory muscle weaknesses or impaired ventilatory mechanics.