Paresis of More Than One Cranial Nerve
The framework for managing isolated ocular motor CN palsies presented earlier in this chapter assumes that no other neurologic abnormalities are present. Benign microvascular disease rarely causes simultaneous involvement of more than 1 ocular motor CN. Simultaneous involvement of unilateral CNs III, IV, V, and VI, and sympathetic nerves strongly suggests a lesion of the cavernous sinus (see the following section). Bilateral involvement of the CNs suggests a diffuse process such as infiltrative disease (eg, carcinoma, leukemia, or lymphoma), a midline mass lesion that extends bilaterally (eg, chordoma, chondrosarcoma, or nasopharyngeal carcinoma), a meningeal-based process, an inflammatory polyneuropathy (eg, Guillain-Barré syndrome or its variant, the Miller Fisher syndrome, or sarcoidosis), or myasthenia gravis.
If symptoms or signs indicate that more than 1 CN is involved, a neurologic evaluation should be undertaken. If neuroimaging is normal, a lumbar puncture with cytopathologic examination should be considered. Special testing for cancer-associated protein markers may be helpful in uncovering an elusive diagnosis. In suspected neoplastic meningeal involvement (ie, meningeal carcinomatosis), combined computed tomography–positron emission tomography (CT-PET) scans are often the studies of choice to demonstrate accessible biopsy sites. Repeat studies may be needed to obtain a definitive diagnosis. Idiopathic multiple cranial neuropathy syndrome should be considered only after neuroimaging, cerebrospinal fluid analysis, other tests, and extended observation have excluded neoplastic, inflammatory, or infectious causes.
Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.