Introduction: Temporal horn entrapment is a potentially lethal form of hydrocephalus caused by obstruction of the trigone of the lateral ventricle. Emergent decompression can be achieved via the bedside insertion of an external ventricular drain directly into the temporal horn (tEVD). The purpose of this study is to identify and describe the safest, most accurate, and most easily standardized method for the bedside insertion of tEVDs.
Methods: Volumetric imaging of 20 patients with trapped temporal horns were loaded onto an intraoperative imaging guidance workstation. Three trajectories were identified as most likely to be successful (named perpendicular, lateral, and medial approach). Trajectories were evaluated for success in penetrating the temporal horn, distance from vital structures, as well as for target error and accuracy.
Results: Temporal horn penetration was achieved in 100% of perpendicular approaches and 84% of lateral and medial approaches. No significant difference existed between the three approaches in trajectory error. The perpendicular approach had significantly more accuracy than the lateral approach (p=0.012) and the medial approach (p=0.002). When evaluating a subset of patients with critical temporal horn dilation, the perpendicular approach had significantly less error than the medial approach (p=0.020). The perpendicular approach was also significantly more accurate than the medial approach (p=0.019) and trended toward more accuracy than the lateral approach (p=0.057).
Conclusions: The perpendicular approach to bedside tEVD insertion appears to be the easiest, safest, and most reliable. Based on the above results, we recommend bedside tEVD placement in patients with critical temporal horn dilation who are clinically deteriorating at a rate that prohibits placement of an EVD or shunt in the OR under image guidance. Since the development of this standardized approach, three patients at our institution have required emergent bedside placement of a tEVD, and in each case the perpendicular approach was both safe and effective.
Patient Care: There has yet to be described in the literature a safe and effective approach to bedside tEVD insertion. Temporal horn entrapment is a potentially lethal form of obstructive hydrocephalus as progressive dilation of the temporal horn threatens uncal herniation and midbrain compression. It is important, therefore, for the neurosurgeon to be capable of safely decompressing a critically dilated temporal horn at the bedside without the use of imaging guidance. This research describes a standardized method for temporal horn decompression that appears in both radiographic studies and early clinical experience to be safe, effective, and easily standardized.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of having a standardized approach to bedside decompression of a trapped temporal horn, 2) Discuss, in small groups, the various approaches that can be taken to tEVD placement at the bedside, 3) Identify the safest, most effective, and most easily standardized method for bedside tEVD placement.