脳深部刺激用バーホールキャップの脳内迷入により前頭葉症状を呈した1例

Frontal Lobe Signs Caused by Migration of a Burr Hole Cap into the Brain after Deep Brain Stimulation Surgery:A Case Report

Ⅰ．はじめに

　脳深部刺激療法（deep brain stimulation：DBS）は，wearing-off現象や薬剤誘発性ジスキネジアなどの運動合併症が出現している進行期パーキンソン病に対する標準的な治療として広く普及している¹⁾．DBSは機能の回復を目的にした治療であるが，DBSに用いられるデバイスを埋設する手術手技に起因した合併症として，頭蓋内出血や創部感染などのリスクがある³⁾．デバイスに起因した合併症には機器の感染が最も多く（1.5〜22.2%）⁶⁾，他に，ハードウェアのトラブルとしてDBSリードおよび延長ケーブルの移動（ずれ），断線，接続不良などが報告されている^2,4)．

　DBS手術では，リードの移動を防止する目的で，穿頭部位に固定用のバーホールリングとカバー（バーホールキャップ）が用いられる．しかし，DBS手術やデバイスに関連した合併症として，これらの固定具が頭蓋内や脳実質内へ迷入した報告はこれまでにない．今回われわれは，DBSリード固定に用いられるバーホールキャップが脳実質内へ迷入したことにより前頭葉症状を呈した1例を経験したので報告する．

　We report a rare complication in a patient with Parkinson's disease who underwent deep brain stimulation（DBS）surgery. The patient was a 60-year-old woman who presented with frontal lobe signs, including ataxic gait and memory disturbance, that were caused by the unexpected migration of a burr hole cap into the brain three to four months after surgery. The patient had no incidence of a head injury prior to development of symptoms. The patient underwent surgery to extract the migrated cap from the frontal lobe, and her symptoms improved several months after the operation. The cap serves to fix the DBS lead to the skull using an adjunctive burr hole ring. It was intraoperatively confirmed that only the cap detached from the ring, and no cap or ring defects were detected in a postoperative quality check by the manufacturer.

　We have previously utilized a burr hole ring and cap, which are packaged along with the DBS electrode, when employing the product made by Medtronic Inc. No previous report has described the cap packed in the official DBS kit to have migrated into the intracranial space. It seems unlikely that the cap migration into the intracranial space would occur without the cap and/or ring breaking through either traumatic injury or from manufacturing defects. It is important to consider the migration of a burr hole cap into the intracranial space in the absence of head injury as a possible device complication after DBS surgery.