正常圧水頭症が疑われた症例における経頭蓋超音波ドプラ法による炭酸ガス反応性の測定

―特にシャント手術の適応決定上の有用性について―

抄録

To investigate end-tidal carbon dioxide partial pressure (P_ET CO₂) response in suspected cases of normal pressure hydrocephalus (NPH), velocity in middle cerebral artery (MCA) was measured by transcranial Doppler sonography (TCD) .
A total of 23 patients of suspected NPH, 8 men and 15 women, whose ages ranged from 30 to 82, were included in this study. They underwent shunt surgery for ventriculomegaly the control group consisted of 30 healthy volunteers and 4 patients of asymptomatic hydrocephalus. CO₂ reactivity (CO₂R) was evaluated by the change of MCA velocity in response to P_ETCO₂ elevation (30-60 mmHg) . The shunt was effective in thirteen patients, but 10 patients did not respond to the surgery. In most of the shunt-effective group (90%), CO₂R was more than 0.20, whereas in all of the shunt-ineffective group, CO₂R was less than 0.20.
We conclude that CO₂R is a good indicator of reversibility from NPH and that it is useful to differentiate shunt-effective patients from ineffective patients.