Phrenic Nerve and Diaphragm Electrophysiology in Pompe Disease

Inclusion Criteria: Age ≥ 18 years. For the prospective cohort: * Genetically confirmed diagnosis of Pompe disease. * Ability to undergo routine neurophysiological and respiratory assessments. * Written informed consent provided. For the retrospective cohort: * History of restrictive respiratory failure or unexplained hypoventilation. * Availability of previous phrenic nerve conduction studies and/or diaphragm electromyography performed as part of routine clinical evaluation. Exclusion Criteria: \- Age \< 18 years. For the prospective cohort: * Conditions preventing completion of neurophysiological assessments (e.g., inability to maintain required positioning or relevant clinical contraindications). * Known primary phrenic nerve injury (e.g., postsurgical phrenic palsy or documented traumatic phrenic neuropathy). * Presence of other neuromuscular disorders potentially confounding data interpretation. * Refusal or inability to provide informed consent. For the retrospective cohort: * Incomplete or technically non-interpretable neurophysiological examinations. * Previously established respiratory or neuromuscular diagnoses fully explaining respiratory impairment. * Cases requiring additional clinical information for study purposes when patient consent for contact or data completion cannot be obtained.