Behavioral recovery from tetraparesis in a captive chimpanzee

林美里・櫻庭陽子・渡邉祥平・兼子明久・松沢哲郎

京都大学霊長類研究所で、群れ飼育されていたチンパンジー・レオ（オス、2006年当時24歳）が四肢麻痺を発症し、寝たきりの状態になった。Miyabe-Nishiwakiら（2010）は獣医学的な視点からレオの介護と治療について報告した。本論文では、発症から41か月間のレオの行動の回復について、体を起こしている割合の縦断的な変化を報告する。第0期（0-13か月）では、ヒトが不在の状態では寝たきりだった。第1期（14-17か月）では体を起こしている割合が増え、第2期（18-29か月）ではその割合が50-70%程度で安定していた。この時期は生活空間がせまく、腕の力だけをつかって、環境エンリッチメントとしてケージ内に取り付けられた物を支えに体を起こすことが主だった。第3期（30-41か月）では、大きなリハビリ部屋に移動し、足首のけがで活動性が落ちた40か月をのぞき、体を起こしている割合がつねに80%をこえていた。生活空間が広がることで、脚をつかった歩行などの運動の種類が増加し、行動の回復が促進された。また、対面場面でリハビリをおこなうことで、ヒトのリハビリ方法を応用することも可能になった。本論文で報告したチンパンジーの行動回復過程は、将来的なリハビリ計画をたてる際の基礎データとして用いることができるほか、障害を持つヒト以外の霊長類のケースにも応用できるだろう。

Primates, online first, DOI 10.1007/s10329-013-0358-2

An adult male chimpanzee living in a captive social group at the Primate Research Institute of Kyoto University developed acute tetraparesis. He was paralyzed and received intensive care and veterinary treatment as previously reported in Miyabe-Nishiwaki et al. (J Med Primatol 39:336–346, 2010). The behavioral recovery of the chimpanzee was longitudinally monitored using an index of upright posture between 0 and 41 months after the onset of tetraparesis. Four phases were identified during the course of behavioral recovery. During Phase 0 (0–13 months), the chimpanzee remained lying on his back during the absence of human caretakers. An increase in upright posture occurred in Phase I (14–17 months), then remained at a stable level of around 50–70 % in Phase II (18–29 months). During Phases I and II, the subject’s small treatment cage represented a spatial limitation. Thus, behavioral recovery was mainly mediated by arm muscle strengthening caused by raising the body trunk with the aid of materials attached to the cage walls as environmental enrichment. When the chimpanzee was moved to a larger rehabilitation room in Phase III (30–41 months), the percentage of upright posture constantly exceeded 80 %, except in the 40th month when he injured his ankle and was inactive for several days. The enlargement of the living space had a positive effect on behavioral recovery by increasing the types of locomotion exhibited by the subject, including the use of legs during walking. Rehabilitation works were applied in face-to-face situations which enabled the use of rehabilitation methods used in humans. The process of behavioral recovery reported in this study provides a basic data set for planning future rehabilitation programs and for comparisons with further cases of physical disability in non-human primates.

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