いわゆるFar-out syndrome（腰仙椎移行部の椎間孔外狭窄）の臨床所見

Clinical Features of Extraforaminal Stenosis at Lumbosacral Junction

　一般的にFar-out syndromeと呼称される腰仙椎移行部の椎間孔外狭窄の臨床所見について調査した．対象は椎弓根外縁から外側の領域に主たる狭窄病変を有する第5腰神経根症に対し後方除圧のみを行った結果，症状の寛解が得られた19例である．他覚的には神経麻痺が軽微なものが多く，従来報告されてきたような安静時の下肢痛や異常知覚が著しく強い傾向はみられなかった．高度な下肢痛など特異的な臨床徴候を呈することが多いと考えられてきた椎間孔部狭窄の概念は，本疾患には必ずしも該当しないことが判明した．

　The authors investigated the clinical features of extraforaminal stenosis at lumbosacral junction in 19 cases with L5 radiculopathy due to this lesion alone diagnosed by 3D-MRI.　The neurological deficit was relatively mild in almost all cases, and severe leg pain and neurogenic intermittent claudication were not always present.　It is well known that unique clinical manifestations, such as spontaneous pain and dysesthesia due to mechanical irritation of dorsal root ganglia, are often observed in cases of foraminal stenosis.　The key to success in diagnosing foraminal stenosis is thought to be recognition of these specific symptoms.　However, that was not always true for the diagnosis of extraforaminal stenosis at lumbosacral junction in our series, because there were differences between the anatomical structure of the damaged nerves, and spinal nerves are mainly involved in the extraforaminal area, not dorsal root ganglia.