Changes in Callosal Angle and Evans' Index After Placing a Lumboperitoneal Shunt in Patients with Idiopathic-Normal-Pressure Hydrocephalus

AIM: To evaluate changes in the Evans' index (EI) and callosal angle (CA) in patients who underwent lumboperitoneal (LP) shunting for idiopathic normal pressure hydrocephalus (INPH) and whose symptoms improved post-operatively. MATERIAL and METHODS: We retrospectively analysed patients who were clinically and radiologically diagnosed with INPH and treated with an LP shunt between 2010 and 2020. In all patients, we performed radiological imaging with EI and CA measurements and completed clinical assessments, including Mini-Mental State Examination (MMSE) and cognitive, urinary continence, balance and 10-m walking tests, preoperatively and post-operatively (less than 1 year later). Results were compared by statistical analyses. RESULTS: We evaluated 42 patients who received an LP shunt for INPH and had cranial magnetic resonance imaging (MRI) performed within the first 2 months after surgery. When the pre-operative and post-operative MRIs of the patients were compared, a statistically significant decrease was found in EI and CA measurements (p<.001, for each). A statistically significant improvement was found in clinical tests. Post-op early radiological images predicted recovery of the gait-balance function and urinary incontinence (p<.001) but did not predict recovery of dementia (p=.06). CONCLUSION: Radiological and clinical improvements are expected after the placement of ventriculoperitoneal (VP) or LP shunts in patients with INPH. Radiological measurements after an LP shunt in patients with INPH have not been reported in the literature. In the current study, radiological measurements after LP shunt placement were evaluated for the first time in patients with INPH. Significant changes in EI and CA after LP shunt placement may indicate whether patients will benefit clinically from an LP shunt during follow-up. A significant decrease in CA and EI measurements in the early period may be a marker for whether patients with INPH will show signs of clinical improvement and benefit from an LP shunt.