Traumatic Abducens Nerve Palsy Due to Avulsion in its Cisternal Segment: Illustrative Cases

BACKGROUND Traumatic abducens nerve palsy can be caused by fractures around the Dorello's canal, direct injury at the dura entry point or within the Dorello's canal, or ischemia due to posterior meningeal artery damage. Recent imaging studies have also identified avulsion of the abducens nerve at its cisternal segment as a significant cause. CASE REPORT We present 2 cases of traumatic abducens nerve palsy due to avulsion at the cisternal segment. Preoperative thin-slice T2 magnetic resonance imaging indicated unclear visualization of the nerve at the cisternal segment in both cases. Surgical exploration revealed a partially avulsed nerve at the root exit zone in Case 1. In Case 2, only the distal stump was visible, compressed by an enlarged tortuous vertebral artery. No surgical intervention was performed in Case 1, while in Case 2, a partial anastomosis was performed between motor branches of the trigeminal nerve and the abducens nerve at the cisternal segment. CONCLUSIONS Avulsion of the abducens nerve at the cisternal segment should be considered an important cause of traumatic abducens nerve palsy. Additionally, vessels located in the cistern of the brain may also contribute to nerve disruption. End-to-end anastomosis, nerve grafting, and nerve transfer are the alternative procedures to treat the avulsion.