便秘によりシャント機能不全を来した1例

A Case of Ventriculoperitoneal Shunt Dysfunction in an Adult Secondary to Constipation

Ⅰ．はじめに

　水頭症に対して行われる脳室-腹腔シャント（ventriculoperitoneal［VP］シャント）は，頭蓋内圧と腹腔内圧の差を利用して過剰な脳脊髄液を腹腔に流す治療法である．腹腔内圧は通常ほぼ0mmHgであり⁵⁾，髄液腔との圧差2〜25mmHgにより，脳脊髄液は脳室から腹腔内へと流れる．

　VPシャントの機能不全の原因として，シャント閉塞，シャント損傷などのほかに妊娠や，小児においては便秘による腹腔内圧の上昇などの機能的原因が挙げられる⁶⁾．便秘が原因とされるシャント機能不全は小児での報告はいくつかあるが，成人例では報告例は稀である⁸⁾．今回，われわれは成人で便秘によりシャント機能不全を来し，さらに慢性便秘の解除によりoverdrainage気味になった1例を経験したので，報告する．

　INTRODUCTION:Ventriculoperitoneal（VP）shunts function because of the pressure differential between the intracranial space and the peritoneal cavity. Although chronic constipation is often a cause of VP shunt dysfunction in children, it is not well recognized in adults. We present a case of shunt dysfunction that not only resolved after resolution of constipation but also resulted in overdrainage.

　CASE REPORT:A 28-year-old woman who had a VP shunt placed 11 years prior for hydrocephalus was referred to our department because of an enlarged ventricle diagnosed with computed tomography（CT). She had a previous history of pineal germinoma and a VP shunt was placed to treat the associated hydrocephalus. At presentation, she complained of headache and somnolence. Shunt dysfunction was suspected, but no problem was detected in the shunt system, including pressure settings. As constipation was detected, we treated this condition. Soon after, her symptoms resolved and ventricle size normalized. She was discharged without any deficit, but overdrainage was detected with CT obtained 1 month later.

　CONCLUSION:Although constipation is not a common cause of shunt dysfunction in adult patients, it is important to consider to avoid unnecessary shunt revision. In the present case, resolution of chronic constipation resulted in resolution of shunt dysfunction. This suggests the importance of resolution of constipation in case of shunt adjustment, even in adult cases.