The callosal angle measured on MRI as a predictor of outcome in idiopathic normal-pressure hydrocephalus

Abstract

Object Different neuroimaging biomarkers have been studied to find a tool for prediction of response to CSF shunting in idiopathic normal-pressure hydrocephalus (iNPH). The callosal angle (CA) has been described as useful in discriminating iNPH from ventricular dilation secondary to atrophy. However, the usefulness of the CA as a prognostic tool for the selection of shunt candidates among patients with iNPH is unclear. The aim of this study was to compare the CA in shunt responders with that in nonresponders and clarify whether the CA can serve as a predictor of the outcome. Methods Preoperative MRI brain scans were evaluated in 109 patients who had undergone shunt surgery for iNPH during 2006–2010. Multiplanar reconstruction was performed interactively to obtain a coronal image through the posterior commissure, perpendicular to the anterior-posterior commissure plane. The CA was measured as the angle between the lateral ventricles on the coronal image. The patients were examined clinically before surgery and at 12 months postoperatively. Results Shunt responders had a significantly smaller mean preoperative CA compared with nonresponders: 59° (95% CI 56°–63°) versus 68° (95% CI 61°–75°) (p < 0.05). A CA cutoff value of 63° showed the best prognostic accuracy. Conclusions The preoperative CA is smaller in patients whose condition improves after shunt surgery and may be a useful tool in the selection of shunt candidates among patients with iNPH.

Feasibility of radiological markers in idiopathic normal pressure hydrocephalus

“…For example, our results concerning the width of the temporal horns and disproportion of SA spaces are not completely in line with those of a recent study by Virhammar et al, reporting them to be predictive markers of shunt response [35]. Although we found no significant associations with shunt response, CA was the smallest in the shuntresponsive group, and this tendency is in line with Virhammar et al The predictability of shunt response by radiological markers in previous studies [34,35] could be attributed to utilization of more sensitive measurements of shunt response (e.g., measured gait speed and detailed cognitive evaluation) than the simple clinical evaluation used here. In addition, the negative results could be due to the small number of nonresponders indicating a successful selection of patients for shunt surgery.…”

“…The CA is smaller in iNPH (less than 90°) than in patients with AD or normal controls [18]. Additionally, it has been reported that the CA is smaller in shunt-responsive iNPH patients than in non-responsive patients [34].…”

Preoperative Prognostic Value of MRI Findings in 108 Patients with Idiopathic Normal Pressure Hydrocephalus

“…5 The results in this and a previous study of a smaller callosal angle in patients who responded to shunt surgery further support its prognostic value. 3 The significant OR Ͻ 1 for the callosal angle can be interpreted as showing that patients with a larger angle are less likely to benefit from shunt surgery.…”

Quantitative MRI for Rapid and User-Independent Monitoring of Intracranial CSF Volume in Hydrocephalus

“…2,3 The brain morphology in iNPH is characterized by large ventricles, enlarged Sylvian fissures, tight convexity sulci, and a small callosal angle. [4][5][6] The symptoms can be relieved by removal of CSF in patients with iNPH, either permanently by shunt implantation or temporarily by a lumbar puncture as a prognostic test (CSF tap test). 7 Radiologic evaluation of the size of the ventricles and sulci is also important in patients with other types of hydrocephalus (eg, secondary to a subarachnoid hemorrhage).…”