Four roots of abducent nerve at its exit from the pontomedullary sulcus: endoscopic case study

According to the classical description in the textbooks of anatomy, the abducent nerve emerges from the brainstem at the pontomedullary junction as a single trunk, traverses the cranial cavity and enters the orbit through the superior orbital fissure to supply the lateral rectus muscle [1]. Multiple roots of the nerve have been reported at the exit or the nerve may split into branches after its exit somewhere along its course [2–5]. Duplication of the nerve at its exit has been reported by many workers [2–6]. Nathan et al. reported a case in which the abducent nerve had split into three branches in the petro-clival region [4]. In the present study, four roots of the abducent nerve were observed at its exit from the brainstem. There is no such report available in literature and this prompted us to report this case. Recent advances in imaging techniques, cranial base surgery, endovascular interventions etc., have allowed neurosurgeons to attempt intervention in lesions involving the cavernous sinus. The knowledge of variations in the intracranial course of the abducent nerve is, therefore, important for both anatomical knowledge and for neurosurgical procedures. Most of the descriptions of the abducent nerve in literature are based on microanatomic dissection. The nerve has also been examined by endonasal endoscopic approach [6]. Aaijaz Ahmed KHAN [1] Pal Hillol KANTI [2] Muzammil ULLAH [1] Asma Haji HASSAN [1]