脳神経外科領域におけるステロイド使用と特発性大腿骨頭壊死

Avascular Necrosis of the Femoral Head Caused by Steroid Treatment in Neurosurgery

Ⅰ．はじめに

　特発性大腿骨頭壊死はステロイド使用が原因となることは良く知られている．脳神経外科領域では1960年代にdexamethasoneが脳浮腫の治療に有効であることが報告されて以来^8,17），比較的大量のステロイドが使用されてきた．最近になって頭部外傷，脳虚血に対するステロイドの有効性が疑問視され^3,4,13,14），以前と比較しその使用頻度は減少してきたと考えられる．

　ステロイドの副作用は重篤で，耐糖能異常・消化管潰瘍・循環器系合併症・慢性感染症など様々であり，特に高齢者では骨粗鬆症やステロイド性高血圧などが大きな問題となる^18），しかし，脳神経外科疾患とステロイド依存性大腿骨頭壊死との関係については数例の報告があるのみで，今まで注目されてこなかった^2,7,15）．当院整形外科では1985-1997年迄の間に特発性大腿骨頭壊死症例250例を経験しているが，内11例が脳神経外科治療で投与されたステロイドが原因と考えられる症例であった．さらに，11例中6例は下垂体近傍腫瘍の症例であり，下垂体機能低下に対してのステロイド補償療法が行われていた．今回われわれが検討した大腿骨頭壊死症例は，従来考えられていた頻度よりも高いものと考えられる．脳神経外科領域で経験されるステロイド依存性大腿骨頭壊死，特に下垂体近傍腫瘍に対するステロイド補償療法の合併症としての大腿骨頭壊死について，治験例を踏まえて検討してみた．

Steroid induced avascular necrosis of the femoral head is a well known disease, but, there are few re-ports about the disease in neurosurgical patients. In the neurosurgical field, the use of steroids has become prevalent since the 1960's. Recently, the adverse effect of steroids and the limitation of its effect have been highlighted, but its use against neurosurgical diseases is still a common treatment to prevent cerebral edema or to counteract hypo-pituitarism caused by hypophyseal lesions. We reviewed 250 patients of avascular necrosis treated between 1985 and 1997 in our institute. Within these patients, 11 (4.4%) were tre-ated with steroid during neurosurgical treatment. Six patients were treated for brain tumors near hypophyseal lesions, and 5 patients were treated for head injury or cerebro-vascular disease. It is con-cluded that total steroid dose over 5000mg such as hydrocortisone may become a high risk for causing avascular necrosis of the femoral head in neurosurgical disease, and it may occur even with the sup-plemental steroid treatment against hypo-pituitarism. The onset is usually 2 or 3 years after the neurosur-gical treatment, when neurosurgical care is no longer needed. Therefore, it tends to be ignored in the neurosurgical field. The treatments against avascular necrosis of the femoral head were femoral head osteotomy or conservative management, and good results were obtained. Early diagnosis and early treat-ment is essential. Further consideration concerning steroid treatment in neurosurgical patients may be re-quired.