(BMJ)—A 50-yo man w/ poorly controlled DM presented w/ a droopy L eyelid and double vision. He denied headache. Exam: L pupil 4 mm, sluggish reaction to light; R pupil 3 mm, normal reaction to light. L eye: impaired extraocular movements. Visual acuity: 20/30 R and L. Posterior segment exam grossly normal. Head CT normal. Labs: blood glucose, 330 mg/dL to 350 mg/dL; HbA1c, 12.2%. What’s the dx?
Diabetic cranial neuropathy
Acute ischemic stroke
Myasthenia gravis
Cerebral venous sinus thrombosis
Intracerebral aneurysm
You are correct. The pt had a 3rd-nerve palsy related to his long-standing hyperglycemia. Negative head CT and gadolinium-enhanced MRI scans, as well as magnetic resonance angiography of the head and neck, ruled out intracerebral and vascular causes, and his palsy resolved when glycemic control was achieved. Cranial nerve neuropathies are rare long-term complications of type 2 DM, and the prevalence depends on the severity and duration of hyperglycemia. Among pts w/ mononeuropathies, oculomotor nerve palsy secondary to DM occurs in 11% of pts. Typically, the palsy occurs as a result of microvasculopathy from uncontrolled hyperglycemia.

BMJ Case Reports CP 2019;12:e231485
By switaschek, 7 July, 2020

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