Nothnagel Syndrome Without Extremity Symptoms: A Case Report.

The finding of pupil-sparing third nerve palsy is synonymous with diabetic third nerve palsy in the minds of many clinicians. While this is the most common cause of a third nerve palsy with normal pupillary response, it is not the only cause. We present the case of an elderly diabetic gentleman who presented with pupil-sparing third nerve palsy and gait abnormalities without any weakness or incoordination in the extremities. He was initially diagnosed with a third cranial nerve mononeuropathy due to poorly controlled type 2 diabetes but was later found on MRI to have a small ischemic stroke in the dorsal midbrain. This case highlights the importance of a thorough neurological examination and the findings in such an exam that should prompt clinicians to consider etiologies other than diabetes in patients presenting with a pupil-sparing third nerve palsy. As discussed below, failure to recognize these differential diagnoses can result in poor outcomes for patients.