Pathological changes in levator palpebrae superioris muscle treated with botulinum toxin in a case of carotico-cavernous fistula. We describe the case of a patient with carotico-cavernous fistula who had botulinum toxin A to induce a protective ptosis 4.5 days before death. The levator palpebrae superioris muscle from both sides and the superior rectus muscle from the injected side were obtained for examination. The preserved samples were stained with haematoxylin and eosin, Martius scarlet blue, Glees, S100, dehydrogenase, ATPase, and toluidine blue as well as being examined by electron microscopy. Inflammation and oedema were found that were probably due to the carotico-cavernous fistula. Axonal and some myelin sheath damage were also seen. 