Accuracy of freehand external ventricular drain placement in patients after a large decompressive hemicraniectomy

Our study aim is to evaluate the accuracy of freehand external ventricular drain (EVD) placement, without the use of adjuncts to placement, immediately following a large decompressive hemicraniectomy (DC). We performed a retrospective cohort analysis comparing patients who underwent freehand EVD placement immediately after a DC, to those who underwent freehand EVD placement without DC. Computed tomography (CT) studies were used to assess accuracy based on catheter tip location. Intracranial catheter length, pre- and post-operative Evan's Index, and midline shift pre- and post-operatively were analysed as separate variables in each group. A previously described grading system was used to assess the accuracy of free hand EVD placement. There were a total 110 patients overall; DC group, n = 50; non-DC group, n = 60. There was a significant reduction from pre-operative midline shift to post-operative midline shift in the DC group (9.13 vs 6.02 mm; p = 0.0064). There was no significant difference in accuracy between the two groups (p = 0.8917), and similar rates of Grade 1 - i.e. optimal - catheter tip location (DC = 78% vs non-DC = 81%) were found. All analysed variables comparing both Grade 1 subgroups (pre- and postoperative Evan's Index, and midline shift) showed significant differences between them. Mean catheter length in Grade 1 EVD placement showed a statistically significant difference between the DC and non-DC groups (63.78 vs 59.96 mm, respectively; p = 0.009). An EVD, after DC for traumatic and non-traumatic intracranial pathologies, can be accurately placed by freehand.