A rare presentation of isolated sixth nerve palsy as dolichoectasia of vertebral artery

Vertebrobasilar dolichoectasia is a condition where the vertebral arteries are dilated, elongated and distorted, causing significant deterioration of tunica intima. The most common causes of sixth nerve palsy include infection, stroke, brain tumour and injury. We reported a case of a 56-year-old man with underlying of diabetes mellitus and hypertension who presented with diplopia over his left gaze. There are no other associated neurology signs. Computed tomography (CT) brain showed well-defined hypodensities at right lentiform nucleus and brain magnetic resonance angiography (MRA) showed impingement of V4 vertebral artery to anterior lower pons near midline which is the exit of the left abducens nerve from the pons. This case illustrated the importance to investigate thoroughly the causes of sixth cranial nerve palsy.