Postcranioplasty Quantitative Assessment of Intracranial Fluid Dynamics and Its Impact on Neurocognition Cranioplasty Effect: A Pilot Study.

Abstract

This study was done to evaluate the effects of cranioplasty on cerebrohemodynamics (cerebral blood flow [CBF] and mean transient time [MTT]) and cerebrospinal fluid (CSF) hydrodynamics (flow velocities) by using computed tomography perfusion and cardiac-gated cine phase magnetic resonance imaging (MRI) (phase contrast [PC] MRI), respectively. It also aims to determine the co-relation between changes in CBF, MTT, and CSF flow dynamics with neurocognitive outcome. The mean values of ipsilateral CBF were 27.58 and 41.66 mL/min/100 g in pre- and postcranioplasty patients, respectively (P = 0.04). Contralateral CBF also showed improvement from 38.76 to 60.44 mL/min/100 g (P = 0.03). Mean values of MTT were found to be decreased in the bilateral hemisphere after cranioplasty. On evaluation of CSF flow velocities by PC MRI, the means of the maximum velocity and peak velocity at the aqueduct of Sylvius were increased from pre- to postcranioplasty as 2.36 to 3.84 cm/s (P = 0.048) and 1.21 to 3.50 cm/s (P < 0.001), respectively. Cognitive evaluation showed a significant improvement at 1 (P = 0.035) and 6 months (P = 0.002) postcranioplasty. All cases were subjected to precranioplasty cine phase cardiac gated contrast MRI for CSF dynamics and computed tomography perfusion for cerebrovascular hemodynamic parameters. CBF and related indices were calculated at different regions of interest with the help of the manufacturer's software package of computed tomography perfusion in the ipsilateral hemisphere and simultaneously on the contralateral side. Cine cardiac gated phase contrast MRI was also done for CSF flow velocity at the aqueduct of Sylvius and median aperture (foramen of Magendie). Both studies were again performed on postcranioplasty day 5-7. Cranioplasty can remarkably improve cortical perfusion for both the ipsilateral and contralateral hemispheres. Postoperative increased CSF velocities suggest improved rapid turnover of CSF in a circuit and possibly play a role in good neurologic outcome. Our study shows there is improvement in CSF flow at the aqueduct of Sylvius after cranioplasty. We propose that improvement in CSF circulation along with changes in CBF co-relate well with cognitive outcome (Montreal Cognitive Assessment score).