Anterior callosal angle correlates with gait impairment and fall risk in iNPH patients

Background: In idiopathic normal pressure hydrocephalus (iNPH), gait and balance impairment is the most frequent symptom, and it is often associated with a higher fall risk. In a prior study, the anterior callosal angle (ACA) was validated as a reliable marker to discriminate iNPH from Alzheimer’s disease and healthy controls. However, the potential correlation between the ACA with clinical symptoms and functional outcomes has not been assessed. The objective of this study is to determine the utility of the ACA in predicting gait improvement after ventriculoperitoneal (VP) shunting. Methods: Patients with probable iNPH who underwent shunt placement at a single institution were prospectively enrolled from May 2015 to May 2019. Patients were assessed preoperatively and at 6 months postoperatively following a standard clinical and MRI protocol. Callosal angle (CA) and ACA were calculated from 3 T MRI preoperatively and at 6 months postoperatively. CA and ACA were tested for correlation with clinical scores. Results: Forty-seven patients with probable INPH who completed 6-month postoperative follow-up were enrolled in the study. Baseline ACA was significantly correlated with preoperative fall risk, gait, and balance impairment assessed with Tinetti POMA scale. Additionally, baseline ACA differentiated patients who experienced improvement at Tinetti POMA scale after surgery. Conclusions: The baseline ACA is a useful neuroradiological marker to differentiate patients by fall risk and has significant correlation with the improvement in gait and balance impairment following surgery. This study demonstrated that the ACA may be a complementary tool to the CA in predicting shunt responsiveness in iNPH.