Abstract
Purpose :
The aim of the present study was, first to analyze whether patients that had blepharospasm and a poor response or have stopped responding to reasonable therapeutic doses of BoNT/A had developed antibodies to the toxin, and secondly, to perform a morphological study of the Orbicularis oculi muscle and innervation from these blepharospasm patients treated with BoNT/A.
Methods :
Nine patients, treated with BoNT/A, the clinical responses to BoNT/A became very poor, and therefore it was needed to perform a myectomy of the upper Orbicularis oculi muscle.
We send serum to Pasteur Institute (Paris), to determine if the patient had developed antibodies to the toxin.
Patient underwent surgical myectomy of the upper orbicularis oculi, in its pre-tarsal ans pre-septal portion. The morphological study was performed with a Zeiss confocal laser scanning microscope. Immunolabbelling was realised with β-III tubulin (TUJ1), nicotinic acetylcholine receptors (nAChR) and staining with fluorescent a-bungarotoxin.
Results :
The results show that blepharospasm patients that had poor or no clinical response to BoNT/A did not develop neutralizing antibodies to the toxin, as determined by analyzing their serum samples in the Pasteur Institute (Paris). The morphological study performed with a Zeiss confocal laser scanning microscope revealed an important sprouting of motor nerve axons and nerve terminals with abundant growth cones, as revealed by the immunostaining with β-III tubulin (TUJ1). Sometimes the outgrowth of axons and terminals was not accompanied by the presence of nicotinic acetylcholine receptors (nAChR), while in other junctions small clusters of nAChRs abutting the growth cones were present, as revealed by the staining with fluorescent a-bungarotoxin.
Conclusions :
Blepharospasm patient with poor response to Botulinum toxin A did not present neutralizing antibodies, although a long lasting time of BoNT/A injection. The important remodeling of the neuromuscular junctions raises questions concerning the origin of the neuromuscular changes observed after BoNT/A injection.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.