Relationship between Burr Hole Placement and Postoperative Sensory Impairment over Parietal Scalp in Chronic Subdural Hematoma Cases

Abstract

  The lateral branch of supraorbital nerve (LSON) which supplies the frontoparietal scalp courses parallel and medial to the superior temporal line (STL), and changes the direction to the inside anterior to the coronal suture (CS) and gives off tiny branches. We examined the relationship between sites of burr hole and postoperative sensory impairment in 28 cases who had been operated for chronic subdural hematoma. Postoperatively, sensation over parietal scalp was altered in 3 cases. We postulate that LSON was injured during skin incision, because the burr hole in these cases were located medial to the STL and adjacent to the CS. There was no postoperative sensory impairment in cases where burr holes were located over 10 mm posterior to the CS. The mean distance between the anterior end of STL and CS was 64.1 mm (±5.7). So, we estimate that the risk of postoperative sensory impairment over parietal scalp would be greatly reduced if the burr hole is placed at least 80 mm posterior to the anterior end of STL.