A 35-year-old woman with a history of migraines is evaluated due to a recent increase in headache frequency and severity. She has had no focal weakness, sensory loss, vision changes, or seizures. The patient has no other medical conditions and takes sumatriptan as needed. She does not use tobacco, alcohol, or illicit drugs. Physical examination shows no focal neurological deficits. Neuroimaging reveals a small aneurysm arising from the segment of right internal carotid artery within the cavernous sinus. If this patient's aneurysm continues to expand, which of the following findings is most likely to be observed?

Question

A 35-year-old woman with a history of migraines is evaluated due to a recent increase in headache frequency and severity.  She has had no focal weakness, sensory loss, vision changes, or seizures.  The patient has no other medical conditions and takes sumatriptan as needed.  She does not use tobacco, alcohol, or illicit drugs.  Physical examination shows no focal neurological deficits.  Neuroimaging reveals a small aneurysm arising from the segment of right internal carotid artery within the cavernous sinus.  If this patient's aneurysm continues to expand, which of the following findings is most likely to be observed?

Quizplus · Accepted Answer

11ec160b_3592_d7ce_9249_4755ed0e1db2_MD0001_00 This patient has a cavernous carotid aneurysm, which was discovered during an evaluation for a change in headache frequency and severity from past migraines. Small aneurysms of the cavernous segment of the internal carotid artery are typically asymptomatic; however, as they enlarge, they can compress nearby structures and cause a unilateral, throbbing headache and/or cranial nerve deficits. The abducens nerve (CN VI), which passes through the cavernous sinus next to the internal carotid artery, is the most likely structure to be damaged by an expanding aneurysm. Compression or stretching of the nerve results in ipsilateral lateral rectus weakness, which can cause esotropia (inward eye deviation) and horizontal diplopia (double vision) that is worse when looking toward the side of the lesion. Other nerves that can be damaged by a cavernous carotid aneurysm include the oculomotor nerve (CN III), trochlear nerve (CN IV), and V1 and V2 branches of the trigeminal nerve (CN V), all of which run on the lateral wall of the cavernous sinus. (Choice A) The hypoglossal nerves (CN XII) innervate the genioglossus muscles, which are responsible for tongue protrusion. Injury to the right hypoglossal nerve (most commonly during carotid endarterectomy) would cause ipsilateral genioglossus weakness with deviation of the tongue to the right during protrusion. (Choice B) Muscles of facial expression, including the orbicularis oculi, are innervated by the facial nerve (CN VII). Damage to the lower motor neurons of the facial nerve (eg, parotid gland tumor, trauma) often results in complete paralysis of ipsilateral facial muscles. (Choice C) General sensation from the anterior two-thirds of the tongue is carried by the lingual nerve (mandibular division of the trigeminal nerve), which, unlike the other 2 divisions of the trigeminal nerve, does not course through the cavernous sinus. (Choice D) Homonymous hemianopia is a defect in half of the visual field due to a contralateral lesion in the visual pathways posterior to the optic chiasm (eg, optic tract, optic radiations). Cavernous carotid aneurysms can occasionally compress the optic nerve or chiasm, usually resulting in ipsilateral monocular vision loss or a nonspecific decrease in visual acuity rather than homonymous hemianopia. Educational objective: An expanding aneurysm in the cavernous portion of the internal carotid artery (ICA) is most likely to initially cause headache and diplopia (ipsilateral lateral rectus weakness) due to compressing or stretching of the abducens nerve (CN VI) as it runs next to the ICA in the cavernous sinus. Other commonly affected nerves include the oculomotor nerve (CN III), trochlear nerve (CN IV), and the V1 and V2 branches of the trigeminal nerve (CN V).

A 35-Year-Old Woman with a History of Migraines Is Evaluated