Rationale and Objectives
In this prospective study, we aimed to reveal the efficiency of phase-contrast magnetic resonance imaging (PC-MRI) in the diagnosis of idiopathic normal pressure hydrocephalus (INPH) and prediction of shunt response.
Materials and Methods
The study group consisted of 43 patients with INPH diagnosis and 15 asymptomatic age-matched controls. PC-MRI studies were applied on cerebral aqueduct and superior sagittal sinus (SSS) in all the cases.
Results
The maximum and mean cerebrospinal fluid (CSF) flow velocities were significantly higher in the INPH patients compared with the controls ( P < .05). CSF stroke volume (43.2 ± 63.8 μL) and output/min (3921 ± 5668 μL) were remarkably higher in the NPH group compared with the control group (3.9 ± 3.9 μL, 439 ± 487 μL, respectively) ( P < .05). Maximum and mean venous velocity values of the INPH patients (maximum, 19.2 ± 4.3 cm/s; mean, 16 ± 3.7 cm/s), were lower than those of the control group (maximum, 21.8 ± 4.6 cm/s; mean, 18.9 ± 3.9 cm/s) ( P < .05). Stroke volume and venous output/min values of INPH patients in SSS, were significantly lower than those of the control group ( P < .001, P = .007, respectively). The response of INPH patients against shunt treatment showed no statistical correlation with any of the PC-MRI parameters ( P > .05).
Conclusion
The measurement of CSF venous flow velocities with PC-MRI is a noninvasive test that benefits INPH diagnosis, but remains inadequate in prediction of response against shunt treatment.
Normal pressure hydrocephalus (NPH) demonstrates a normal initial pressure during lumbar puncture and follows a course including hydrocephalus and certain symptoms (dementia, gait disorder, urinary incontinence) . It is a rarer cause of cognitive deficits, responsible for 0%–5% of all dementia, but is probably being underestimated partly because of inconsistent definitions . Imaging reveals ventriculomegaly and flow void sign in the cerebral aqueduct without displaying a marked dilatation (differing from the one in cerebral atrophy) in cortical sulci . Because NPH is the only cause of dementia that benefits from shunt treatment, its differentiation from other dementia causes associated with ventriculomegaly bears importance . NPH may be either idiopathic (INPH) or secondary (SNPH) to subarachnoid hemorrhage, meningitis, cranial trauma, and intracranial surgery . The success rate of shunt treatment in NPH patients varies between 30% and 70%. INPH benefits less from shunt treatment (30%–50%) . Recently, most of the studies have been focused on determination of patients who would benefit from shunt treatment .
Many tests have been employed in the diagnosis of NPH before now. Among the imaging methods, we can mention radionuclide cisternography, computed tomography (CT), magnetic resonance (MRI), computed tomography cisternography, phase-contrast cine MRI (PC-MRI) . There is no test that can establish a definitive diagnosis or predict shunt response . PC-MRI is noted as a method that is helpful in NPH diagnosis and prediction of shunt therapy . In the present study, we aimed to determine the efficiency of PC-MRI in INPH diagnosis and prediction of treatment response.
Materials and methods
Study Group
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MRI Study Protocol and Statistical Evaluation
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Results
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Table 1
CSF Flow Dynamics of NPH and Control Cases
CSF parameters NPH cases (mean ± SD) Controls (mean ± SD) NPH vs. controls Shunt response Mean velocity 1.22 ± 1.54 cm/s 0.57 ± 0.36 cm/s_P_ < .05 NS Maximum velocity 8.53 ± 4.13 cm/s 4.78 ± 2.48 cm/s_P_ < .05 NS Stroke volume 43.2 ± 63.8 μL 3.9 ± 3.9 μlt_P_ < .001 NS Output/min 3921 ± 5668 μL 439 ± 487 μlt_P_ < .001 NS
CSF, cerebrospinal fluid; NS, not significant; SD, standard deviation.
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Table 2
Venous Flow Dynamics of NPH and Control Cases
Venous parameters NPH cases (mean ± SD) Controls (mean ± SD) NPH vs. controls Shunt response Mean velocity 16 ± 3.7 cm/s 18.9 ± 3.9 cm/s_P_ < .05 NS Maximum velocity 19.2 ± 4.3 cm/s 21.8 ± 4.6 cm/s_P_ < .05 NS Stroke volume 1274 ± 741 μL 1828 ± 562 μl_P_ < .001 NS Output/min 141 ± 32 cm 3 195 ± 41 cm 3 P < .007 NS
NPH, normal pressure hydrocephalus; NS, not significant; SD, standard deviation.
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Discussion
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Conclusion
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Acknowledgment
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