보툴리눔 독소의 근주가 외안근 Palisade Nerve Endings의 미세구조에 미치는 영향
The Effect of Botulinum Toxin Injection into the Extraocular Muscle on Ultrastructural Changes of Palisade Nerve Endings
- 주제(키워드) Botulinum toxin , Extraocular muscle , Palisade nerve endings
- 발행기관 고려대학교 대학원
- 지도교수 조윤애
- 발행년도 2009
- 제출일 2009-01-08
- 학위수여년월 2009. 2
- 학위명 박사
- 학과 일반대학원 의학과
- 세부전공 안과학
- 원문페이지 29 p
- 실제URI http://www.dcollection.net/handler/korea/000000008207
- 본문언어 한국어
- 제출원본 000045530864
초록/요약
Proprioception is defined as a reflex system for the maintenance of body position and coordication of movement. The palisade nerve endings (palisade endings) located in the myotendinous junction are considered as proprioceptors in the extraocular muscles. (EOM) Botulinum toxin (botox) is widely used for the treatment of strabismus by injecting the toxin into the EOM. Botox binds to motor end-plate and inhibits the release of acetylcholine form nerve terminals, causing transitory period of muscle paralysis. The proprioception of extraocular muscles can be altered if botox damages palisade endings. The purpose of this study was to investigate the ultrastructural changes of palisade endings after the injection of botox into the EOM. Under the general anesthesia, the medial and superior rectus muscles of 12 cats (24 eyes) were exposed. A dose of 5 IU of botox (0.1 mL) was injected into the EOM of one eye and 0.1 ml of normal saline was injected into the muscles of the other eye. The injection site was about 10 mm proximal to the myotendinous junction to minimize mechanical trauma of palisade endings. The myotendinous junctional area was harvested at 1, 4 and 12 weeks after the injection, 4 cats at each time period. The samples were examined under electron microscope. The myotendinous junction of 4 normal cats were also examined as a normal control. There was no morphological difference between normal control group and saline injection group. The proximal portion of palisade endings in control group was encapsulated structure containing collagen, myelinated and unmyelinated nerve fiber. At distal palisade endings, myelinated fibers were absent, and encapsulated nerve endings contained unmyelinated fiber and collagen. At pre-terminal region, the capsular structure became incomplete. However, axons of unmyelinated fiber were completely covered with Schwann cell. In botox injection group, separation of myelin sheath, increase of neurofilament in axons of myelinated and unmyelinated nerve fiber were observed 1 week after injection, which persisted to 12 weeks. Around terminal nerve endings, incomplete Schwann cell with axonal exposure were found, and fibroblast-like change of Schwann cells were also occurred. At 12 weeks, palisade endings which was not related to the muscle fiber due to botox induced muscle atrophy were also found. Botulinum toxin injected into the EOM induced ultrastructural changes of palisade endings. Those alteration can influence proprioception of the EOM. The possibility that those changes can diminish proprioception of the EOM should be considered when botulinum toxin is used for the treatment of strabismus.
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