正常圧水頭症におけるシャント圧調整とcortical reorganization--fMRIを用いた脳機能評価

Management of Secondary Normal Pressure Hydrocephalus and Assessment of Cortical Reorganization Using fMRI

Ⅰ．はじめに

　正常圧水頭症（normal pressure hydrocephalus，以下NPH）を合併した脳卒中・頭部外傷例において，シャント術を行い適切な圧調整がなされることで機能回復がみられるのは周知の通りである．しかし重症脳卒中・頭部外傷例のNPH合併例では，原疾患による症状とNPH症状がオーバーラップするため両者の鑑別に難渋することが多い．また，シャント術後亜急性期～慢性期にかけても至適な脳圧が変動する場合もあるため，シャント例においては急性期を過ぎたのちも画像や身体機能をこまめに評価し，適正な脳環境を維持する必要がある．

　われわれはNPHを合併した頭部外傷例に対し圧可変式バルブを用いてVPシャント術が行われ，回復期リハ期間中に脳圧調整を行い急激に身体機能が改善した1例を経験した．この症例においては，リハビリテーション経過中の臨床評価に加え圧調整前後での脳室サイズ，およびfunctional magnetic resonance imaging（以下fMRI）を用いて下肢運動タスクにおける大脳皮質での賦活領域を経時的に評価した．

　脳圧調整と大脳皮質の機能的再構築の関連性について究明するため，このたび損傷脳における個人脳のfMRI解析結果を文献的考察を交え報告する．

　We assessed the motor recovery and cortical reorganization associated with intracranial pressure (ICP) control in a secondary normal pressure hydrocephalus (sNPH) patient. A 32-year-old man with sNPH resulting from a head injury presented with left hemiplegia. A ventricular-peritoneum shunt (VP shunt) was surgically inserted for the sNPH using a Codman Hakim Programmable Valve,and his ICP was controlled according to the ventricular size by CT scanning. The motor function of the patient was evaluated by functional MRI (fMRI) during ICP control in our hospital. The fMRI was performed at 3.0T with timed dorsal flexion-extension movement of the foot. After 3 months of shunt valve pressure control,the primary sensorimotor cortex (SM1) was activated during the affected (left) foot movement,an area that had not been able to be activated just after admission. His walking ability also recovered markedly to the point of free independent walking. The motor function of the affected lower extremity appeared to recover to almost the some degree the original motor area after control of the ICP. This finding may reflect functional reorganization of the motor pathway following ICP normalization.