A 53-year-old man comes to the office due to double vision. The patient lives in a two-story house and has had difficulty walking down stairs because he sees duplicates of every step and doesn't "know which ones are real." He does not have significant problems walking up stairs. The patient is also frustrated because he has trouble reading certain things, such as the morning newspaper and work-related documents. He has had no eye trauma, headache, focal weakness, or numbness. The patient has a history of hypertension and type 2 diabetes mellitus. He exercises regularly and does not use tobacco, alcohol, or illicit drugs. A lesion affecting which of the following structures is most likely responsible for this patient's visual symptoms?

Question

A 53-year-old man comes to the office due to double vision.  The patient lives in a two-story house and has had difficulty walking down stairs because he sees duplicates of every step and doesn't "know which ones are real."  He does not have significant problems walking up stairs.  The patient is also frustrated because he has trouble reading certain things, such as the morning newspaper and work-related documents.  He has had no eye trauma, headache, focal weakness, or numbness.  The patient has a history of hypertension and type 2 diabetes mellitus.  He exercises regularly and does not use tobacco, alcohol, or illicit drugs.  A lesion affecting which of the following structures is most likely responsible for this patient's visual symptoms?

Quizplus · Accepted Answer

11ec160b_35a6_5ff5_9249_15390732e73b_MD0001_00 This patient likely has trochlear nerve (CN IV) palsy. The trochlear nerve innervates the superior oblique muscle, which causes the eye to intort (internally rotate) and depress while adducted. The nerve is particularly susceptible to injury due to its long course and small caliber. Most cases of neuropathy are traumatic or idiopathic in origin, although a proportion of idiopathic cases may actually be due to microvascular nerve ischemia in the setting of diabetes mellitus. Patients with trochlear nerve palsy typically present with vertical diplopia, which is most noticeable when the affected eye looks down and toward the nose (eg, up-close reading, walking down stairs). Examination may show impairment of downgaze with the eye in the adducted position. In severe cases, the affected eye can appear vertically deviated (hypertropia). Symptoms often improve when the chin is tucked and the head is tilted away from the affected eye as this compensates for hypertropia and extorsion. (Choice A) The abducens nerve (cranial nerve [CN] VI) innervates the lateral rectus, which is responsible for abduction of the eye. Palsies of this nerve can cause horizontal diplopia and inward deviation (esotropia). (Choice B) Lesions of the medial longitudinal fasciculus are associated with internuclear ophthalmoplegia. This typically presents with impaired horizontal eye movement and weak adduction of the affected eye with simultaneous abduction nystagmus of the contralateral eye. (Choice C) The oculomotor nerve (CN III) innervates the superior rectus, medial rectus, inferior rectus, and inferior oblique. These muscles collectively perform most eye movements. Palsies of this nerve can cause vertical and horizontal diplopia, ptosis, and an enlarged and nonreactive pupil. (Choice D) The optic nerve (CN II) transmits visual information to the brain. Damage to this nerve causes loss of vision. Educational objective: The trochlear nerve innervates the superior oblique muscle, which causes the eye to intort (internally rotate) and depress while adducted. Trochlear nerve palsy is typically traumatic or idiopathic and presents with vertical diplopia that worsens when the affected eye looks down and toward the nose (eg, walking downstairs, up-close reading). Patients may compensate by tucking the chin and tilting the head away from the affected eye. __________ References: Adult hypertropia: a guide to diagnostic evaluation based on review of 300 patients. (http://www.ncbi.nlm.nih.gov/pubmed/21057518)

A 53-Year-Old Man Comes to the Office Due to Double