Effects Of Botulinum Toxin Type A On Central Sensory Conduction Pathway Of The Primary Blepharospasm

Background:Blepharospasm (BSP) is a kind of focal dystonia,commonly primary. Researcheshave proved that the primary blepharospasm is caused due to genetic susceptibilityfactors and the dysfunction of eye’s sensorimotor integration in the central nervoussystem.Botulinum toxin type A (BTX-A) is treatment of choice forblepharospasm.Studies have shown that BTX-A improve the symptoms ofblepharospasm, not only by its peripheral effects, but also through its central effects.Atpresent,there is very few research about the BTX-A effects on central sensoryconduction pathways.The trigeminal nerve somatosensory evoked potentials (TSEP) areobtained by electrical stimulation of the trigeminal nerve endings and recording theamplitude of evoked potentials in the trigeminal sensory pathway neurons.To someextent,TSEP reflect the changes in the perioral sensory pathway function.Supplementary motor cortex(SAM) accept the projection of the sensory-motor neuronand thus represent a part of the of sensorimotor integration process.The TSEP recordedthough C5/C6sensory areas and the F5/F6sites of the SAM represent the changes in thesensory pathway and the part of sensorimotor integration process,respectively.Objective:Before and after BTX-A injection to the BSP patients,Analyze the cortexmulti-point record of TSEP characteristics to compare the change in the excitability ofthe trigeminal nerve pathway of the BSP patients and normal subjects.To observe thatwhether the improvement in the motor symptoms and the changes in the excitabilityof seneory pathway and sensorimotor integration process occurs at the same time or not.Methods:Cortex multi-point record of the TSEP research:14cases of normal control (I),14 diagnosed patients of primary blepharospasm before BTX-A injection (II) and a monthafter the injection of BTX-A (III), perform Cortex multi-point record of the TSEP testrespectively, the interpeak latency of C(5,6)N13-P19, P19-N30F (5,6)N13’-P19’,P19’-N30’and the interpeak amplitude of C(5,6)N13-P19,P19-N30F(5,6)N13’-P19’,P19’-N30’are compared between the three groups. Analyze the index mentioned aboveamong the three groups.Results:After BTX-A injection, the patients of BSP with JRS scale score is significantlylower than before the injection of BTX-A, the difference was statistically significant (P<0.05).The average BIDS score of14patients is0.73±0.02.Cortical multi-point record of the trigeminal nerve somatosensory evokedpotentials:Among the three groups of C(5,6) sites,the records of the interpeak latency ofN13-P19,P19-N30shows no significant difference in statistics(P>0.05).The interpeakamplitudes of group II N13-P19,P19-N30were higher than group I, the difference wasstatistically significant(P<0.05).The interpeak amplitudes of group II N13-P19,P19-N30were higher than group III,the difference was statistically significant(P<0.01).The interpeak amplitude of N13-P19, P19-N30are compared between thegroup I and III,there was no significant difference in statistics(P>0.05);Among the three groups of F(5,6) sites,the records of the interpeak latency ofN13’-P19’,P19’-N30’ are not statistically significant difference (P>0.05). The interpeakamplitudes of group II N13’-P19’,P19’-N30’ are higher than group I, the difference isstatistically significant (P<0.05).The interpeak amplitudes of group IIN13’-P19’,P19’-N30’are higher than group III, the difference is significant in statistics(P<0.01). the interpeak amplitudes N13’-P19’,P19’-N30’are compared between thegroup I and III shows no significant difference in statistics (P>0.05).Conclusion:1.The botulinum toxin type A injection treatment can significantly improve theclinical symptoms of primary blepharospasm.2.In the patients of primary blepharospasm after injection of botulinum toxin typeA, trigeminal sensory pathway excitation is reduced.3.After injection of botulinum toxin type A,the excitation of the sub-cortexneurous to the supplementary motor cortex pathways is decreased.