Transcranial Doppler and Cerebrospinal Fluid Flow Study in Normal Pressure Hydrocephalus

ABSTRACT

OBJECTIVE: The authors analyze prospectively the result of transcranial doppler(TCD) in normal pressure hydrocephalus and compared its cerebral blood flow parameters to radionuclide cerebrospinal fluid(CSF) flow study, postoperative brain computed tomography(CT) findings and clinical outcome, and studied the relationship betweeen cerebral hemodynamics and clinical performance. METHODS: Twenty five patients with hydrocephalus undertook pre- and post-operative TCD but only preoperative CSF flow study was performed. Mean flow velocity(Vm), pulsatility index(PI) and resistance index(RI) were assessed through TCD and changes in ventricle size and cortical gyral atrophy were checked through brain CT. RESULTS: Postoperative hydrocephalus showed an increase in Vm(ACA P=0.037, MCA P=0.034), decrease in PI(ACA P=0.019, MCA P=0.017) and decrease in RI (ACA P=0.017, MCA P=0.021) compared to preoperative TCD parameters in the postoperative improvement group. In the postoperative improvement group, postoperative TCD parameters correlated with CSF flow study grade (Vm R2=-0.75, PI R2=0.86, RI R2=0.78) and ventriculocranial ratio change correlated with PI change (R2=0.73). The convexity gyral atrophy and initial TCD parameters showed close relationship to outcome. CONCLUSION: PI and RI can be used as an indicator of post operative prognosis, and with the addition of CSF flow study values, can also be used as a tool to predict pre-op and post-op patient status and successful shunt surgery.