BACKGROUND: A trapped temporal horn can be emergently decompressed by inserting a bedside temporal horn external ventricular drain (tEVD). However, no standardized method for this procedure has been described. OBJECTIVE: To identify methods for bedside tEVD insertion, and determine the safest, most accurate, and most easily standardized approach. METHODS: Volumetric images of 20 patients with trapped temporal horns were analyzed. Three tEVD approaches (perpendicular, lateral, and medial) were defined, along with standardized insertion points and external landmarks for trajectory guidance. Predicted success in penetrating the temporal horn, skin-to-temporal horn entrance distance, temporal horn distance traversed, and trajectory target error and accuracy were evaluated; data were compared with independent sample t tests. RESULTS: Nineteen of 20 cases were analyzed; 13 had critical temporal horn entrapment. Penetration was achieved in 100% of perpendicular and 84% (16/19) of lateral and medial approaches (92% [12/13] of critical entrapments). In 19 patients, trajectory error was not significantly different among approaches. The perpendicular approach had significantly more accuracy than the lateral (P = .01) and medial (P = .002) approaches. The lateral approach afforded significantly more traversable distance than the perpendicular approach (P = .009). In cases with critical entrapment, the perpendicular approach had significantly less error (P = .02) and significantly better accuracy (P = .02) than the medial approach. The perpendicular approach trended toward more accuracy than the lateral approach (P = .06). CONCLUSION: The perpendicular approach appears to be the easiest, safest, and most reliable approach tested. We recommend conducting bedside tEVD placement only in patients with a critically dilated temporal horn who are clinically deteriorating at a rate that prohibits other procedures
