In total, 14% (141) of the 979 patients had reoperations due to mechanical complications, 6.4% (63) due to infections, 3.7% (36) due to subdural hematomas and 9.1% (89) due to other or not specified causes. These groups are overlapping, as one patient may have had more than one type of complication at different time points. The patients’ first complications leading to reoperation are shown in Fig. 3.Fig. 3Complications causing first-time reoperations in 979 iNPH patients, visualized year by year after primary surgery. For each year, the percentage of patients who needed reoperation because of complications is represented in the bar chart, in four groups based on the type of complication. The corresponding numbers of patients and the total number of available patients for each year are shown in the table