視神経管骨腫

OSTEOMA OF THE PARANASAL SINUS WITH INVOLVEMENT OF THE OPTIC CANAL:REPORT OF THREE CASES

I．緒言

　骨腫osteomaは頭蓋骨の各所にみられるが，大部分は頭蓋円蓋部に生じ，これは日常しばしば経験されるものである。比較的まれな頭蓋底にできる骨腫としては，前頭洞，篩骨洞，蝶形骨洞などの副鼻腔から生ずるものおよび乳突蜂巣から生ずるものが知られている。

　頭蓋円蓋部の骨腫は頭蓋腔内へ向つて発育することは少なく，従つて神経症状を呈することは少ない。美容的な意味と，軽度の頭痛を除くくらいの目的で手術が行なわれている。これに反して，頭蓋底の骨腫は眼窩内へあるいは頭蓋腔内へ向つて発育し，種々の眼症状ないし神経症状を呈してくる。副鼻腔から発生した骨腫が，硬膜を破つて硬膜内へ侵入し髄液瘻さらに頭蓋内感染などの重篤な合併症を惹起することがある。

Various intracranial complications and orbi-tal involvements of the osteoma of the parana-sal sinus have been recorded by many au-thors.

We have observed three cases which had involvement of the optic canal resulting in optic atrophy. In each case the tumor was removd with unroofing of the thickened optic canal.

Case 1. A girl, 11 years old, was admitted because of failing vision and slight exoph-thalmos of her right eye.There were no other complaints. There was pronounced pallor of the right disc; no other abnormality was found externally. Craniography reveal-ed an osteoma of the sphenoid bone and nar-rowing of the bilateral optic canals, pronounc-ed on the right side.

During the operation, performed through the bilateral frontal craniotomy, the optic ca-nal was found to be involved by the tumor, the walls of the canal being markedly thicken-ed. The osteoma was partially removed and the optic canal was unroofed bilaterally.

Case 2. A boy, 9 years old, noted failing vision of his left eye and occassionally dou-ble vision 6 months prior to his admission to the hospital. There was no other abnor-mality except atrophy of the optic nerve in his left eye. Craniograms showed an ethmoid-orbitals osteoma with narrowing of the optic canals which was more marked on the left side. Removal of the tumor and unroofing of the bilateral optic canals was completed.

Case 3. A man, 58 years old, was admitted because of left ocular proptosis and bilateral blindness.

Further investigations revealed bilateral optic atrophy and marked left ocular prop-tosis with limitation of ocular movements. X-rays showed a huge fronto-orbital osteoma with extreme narrowing of the optic canals. The osteoma was removed subtotally and left optic canal was unroofed.

Intracranial complications and orbital invol-vement of the paranasal sinus osteoma were reviewed, and the authors found that only few cases of involvement of the optic canals had been reported. Optic canals should be carefully studied in cases of the osteoma of the paranasal sinus and early unroofing of the optic canal should be performed for preservation of vision.