Abstract Details

Title Multiple Measures of Nerve Excitability in Chronic Progressive External Ophthalmoplegia

Topic Clinical Neurophysiology

Presentation(s) S59 - (-)

Poster/Presentation
Number 002

Objective

Background CPEO is among the common presentations of mitochondrial disease, but the pathophysiology is poorly understood and the prognosis remains challenging for clinicians.

Design/Methods Twenty patients with histological confirmation of CPEO were genetically explored and tested for muscle strength. Nerve excitability properties of median motor axons were assessed with the TROND protocol and compared with 10 matching normal controls.

Results Within the CPEO patients there was a strong correlation between muscle strength and responses to hyperpolarizing current (e.g MRC sum-score v. TEh[40-60ms], Spearman's rho = 0.86, P < 0.0001), with more 'fanning-out' of threshold electrotonus in the weaker patients. When the patients were split into two groups, 6 with skeletal weakness and 14 with normal strength, abnormalities in nerve excitability were restricted to the weak group. Modelling of the nerve excitability properties in the weak patients suggested that the abnormalities were most likely caused by an increase in the 'Barrett and Barrett' conductance, related to insulation or paranodal sealing of the myelin sheath.

Conclusions These results confirm a previous finding that the mitochondrial disease does not result in axonal membrane depolarization, and instead suggest that it is the energy failure in Schwann cells that first affects axonal function, consistent with morphological studies.

Authors/Disclosures
PRESENTER	No disclosure on file
	No disclosure on file
	No disclosure on file
Davorka Tomic	Davorka Tomic has stock in Meck KGaA.
Francoise Gray, PhD (Anatomie Pathologique)	No disclosure on file
	No disclosure on file
Olivier F. Gout, MD (Hôpital Fondation A de Rothschild)	Dr. Gout has nothing to disclose.
	No disclosure on file

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