Nerve excitability changes related to muscle weakness in chronic progressive external ophthalmoplegia

作者：Gueguen Antoine; Jardel Claude; Polivka Marc; Tan S Veronica; Gray Francoise; Vignal Catherine; Lombes Anne; Gout Olivier; Bostock Hugh^*

来源：Clinical Neurophysiology, 2017, 128(7): 1258-1263.

DOI：10.1016/j.clinph.2017.04.013

• CPEO
• Mitochondrial disease
• Nerve excitability
• Myelin sheath
• Barrett-Barrett conductance

Objective: To explore potential spreading to peripheral nerves of the mitochondrial dysfunction in chronic progressive external ophthalmoplegia (CPEO) by assessing axonal excitability.
Methods: CPEO patients (n = 13) with large size deletion of mitochondrial DNA and matching healthy controls (n = 22) were included in a case-control study. Muscle strength was quantified using MRC sum-score and used to define two groups of patients: CPEO-weak and CPEO-normal (normal strength). Nerve excitability properties of median motor axons were assessed with the TROND protocol and changes interpreted with the aid of a model.
Results: Alterations of nerve excitability strongly correlated with scores of muscle strength. CPEO-weak displayed abnormal nerve excitability compared to CPEO-normal and healthy controls, with increased superexcitability and responses to hyperpolarizing current. Modeling indicated that the CPEO-weak recordings were best explained by an increase in the 'Barrett-Barrett' conductance across the myelin sheath.
Conclusion: CPEO patients with skeletal weakness presented sub-clinical nerve excitability changes, which were not consistent with axonal membrane depolarization, but suggested Schwann cell involvement.
Significance: This study provides new insights into the spreading of large size deletion of mitochondrial DNA to Schwann cells in CPEO patients.

• 出版日期2017-7