The organization of this clinical mind map is based upon whether vision improves after covering one eye or not covering the eye. If the vision improves, it is monocular diplopia and if the vision does not improve, then it should be considered binocular. Although patients may not be able to make this determination on their own, a vision exam may need to be performed to elicit this feature, which is not in line with the general principles of first taking a history and then doing an exam. However, the ability of this feature to help a clinician narrow the differentials between monocular and binocular vision lends itself to being an appropriate high yield question / feature and an efficient way to think about causes of diplopia.
Probable diagnoses range from common to rare diagnoses, such as diabetes and cavernous sinus thrombosis respectively, and mostly affect middle to old age populations. These diagnoses are further classified as those arising directly or indirectly from cranial nerve pathology, such as upper motor neuron lesions (MS, CVA) and lower motor neuron lesions. A helpful mnemonic to remember is C2ADITT – cavernous sinus thrombosis, alcohol, drugs, infection, tumor, trauma) and M2OT – migraines, myasthenia gravis, and thyrotoxicosis.
Urgent and emergent situations include the presence of features which may suggest an acutely evolving neurological event such as stroke, or cavernous sinus thrombosis. Clinical features consistent with these events are based upon the FAST mnemonic, such as facial droop/weakness, arm/limb weakness, speech impairment, and altered mental status. In addition, acute fever, headache and/or neck stiffness may suggest an acute CNS infection or cavernous sinus thrombosis.
Weighing and removing anchor bias involves asking questions about individual diagnoses listed on the clinical mind map, such as past medical history, symptoms of thyroid disease, and symptoms suggestive of multiple sclerosis. Finally, physical exam findings and labs/imaging can help arrive at the final diagnosis.