Abducens Nerve Palsy as the First Manifestation of Type Two Diabetes Mellitus

Abstract

Abstract Introduction: Diabetes mellitus has varied presentations at different times from onset. One of the uncommon presentations is cranial nerve palsy secondary to microvascular ischemia. Approximately 20% of isolated abducens nerve palsies are secondary to vascular microangiopathy. Clinical Case: A 53-year-old female with no significant past medical history presented to the emergency department with concerns of double vision. The patient first noticed her symptoms five days prior to presentation. The patient endorsed blurry vision and stated that she has double vision in certain gazes that resolves with shutting either eye. Furthermore, she has also developed headaches during that period, described as a pressure-like sensation in her forehead and behind her eyes. She otherwise denied any tearing, redness, or pain. On review of systems, she denied numbness, tingling, changes in hearing, changes in speech, or extremity weakness. Due to the persistence of symptoms the patient presented to the emergency department. On exam, the patient’s vitals were normal. Pupils were equal and briskly reactive to light with no relative afferent pupillary defect. External examination was unremarkable without scalp tenderness, proptosis, or ptosis. Color vision was intact. Ocular motility testing revealed limited abduction of the left eye causing double vision on lateral gaze. Confrontation visual fields were full in each eye. Bilateral lower extremity exam revealed decreased sensation in the sole of the foot. The rest of the physical exam was unremarkable. Laboratory work revealed blood glucose level of 305 mg/dl (Reference range 70–99 mg/dl). HBA1C was 12.3% (Reference range 3.8–5.6%). CT head and CTA of the neck was performed and were unremarkable. Given the normal imaging and findings on examinations, her ocular motor findings were attributed to diabetes mellitus. The patient was started on insulin, aspirin, and received diabetic education for lifestyle modification, and was scheduled for outpatient follow up. The patient’s acute isolated left sixth cranial nerve palsy was most likely owing to microvascular ischemia from previously undiagnosed diabetes mellitus. A study of 59 patients with an isolated sixth cranial nerve palsy showed a 6-fold increase in the odds of having diabetes compared with controls.(1) Conclusion: Given the infrequent presentation of Diabetes with Abducens nerve palsy, diagnosis is usually delayed with the expense of ordering costly investigations that put a financial and psychological burden on patients. Thus, we urge clinicians’ awareness when encountering cases of isolated cranial nerve palsies.