Diagnosis: Unspecified ptosis of eyelidClinical question: intermittent left ptosis, especially rule out pathology of CN3 tractSigns and Symptoms: intermittent ptosis of the left upper eyelid MRI of the brainNo diffusion weighted abnormalities are appreciated.The CSF spaces are appropriate for the patient's stated age with no midline shift. No abnormal mass lesions are appreciated intracranially. No intracranial hemorrhage is identified. No edema is identified within the brain parenchyma.A small extra-axial fluid collection is present just inferior to the left cerebellar hemisphere measuring 7 x 10 mm in coronal dimensions and most likely represents a small arachnoid cyst. Follows spinal fluid on all pulse sequences. It is not associated with diffusion restriction.Normal vascular flow voids are present in the distal carotid and vertebral arteries, the basilar artery and the proximal anterior, middle and posterior cerebral arteries as well as the internal cerebral veins and superior sagittal sinus.The visualized portions of the paranasal sinuses are clear. The visualized portions of the mastoid air cells are clear. The visualized portions of the orbits are intact.MRA brain:Antegrade flow is present in the distal internal carotid arteries, the distal vertebral arteries, the basilar artery and the proximal anterior, middle and posterior cerebral arteries.There is no evidence for intracranial aneurysm or cerebrovascular occlusion.The anterior communicating artery is identified and is small. The posterior communicating arteries are identified and are small. The posterior communicating arteries are associated with small infundibula. The left vertebral artery is larger than the right vertebral artery.
1.No evidence for cerebrovascular occlusive disease.2.No evidence for intracranial aneurysm.3.No evidence for acute ischemic cerebral infarction.4.Findings are compatible with a small arachnoid cyst adjacent to the left cerebellar hemisphere.