• Illustration by Christine Gralapp.
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    Neuro-Ophthalmology/Orbit

    Distribution and topical diagnosis of CN VII lesions. 1. Supranuclear facial palsy: contralateral weakness of lower two-thirds of the face with accompanying weakness of the orbicularis oculi muscle; retained expression 2. Nuclear facial palsy: facial monoplegia (congenital) plus CN VI nucleus involvement (ipsilateral gaze palsy) and frequent ataxia; occasional Horner syndrome Peripheral lesions result in facial monoplegia, including the orbicularis oculi and frontalis muscles, as well as the following: 3. Cerebellopontine angle: decreased tearing, dysgeusia, loss of salivary secretion, loss of taste from anterior two-thirds of tongue, hearing impairment, nystagmus, vertigo, ataxia, and adjacent CN (V, VI) findings 4. Geniculate ganglionitis (Ramsay Hunt syndrome, herpes zoster oticus): findings are the same as in cerebellopontine angle, but the brainstem and other CNs are not involved 5. Isolated ipsilateral tear deficiency due to involvement of vidian nerve (vidian n.) or sphenopalatine ganglion (accompanying CN VI palsy with cavernous sinus involvement) 6. Fallopian canal: involvement of nerve to stapedius muscle, dysacusis, involvement of chorda tympani, loss of taste to anterior two-thirds of tongue, impaired salivary secretion 7. Distal to chorda tympani: isolated paralysis of facial muscles 8. Distal to branching of CN VII after it leaves stylomastoid foramen: only certain branches of CN VII are affected (localized facial; bilateral CN VII palsy may result from weakness) In addition, bilateral CN VII palsy may result from congenital conditions (Möbius syndrome), sarcoidosis, basilar meningitis, Guillain-Barré syndrome, or neurofibromatosis type 2 (bilateral acoustic neuromas). GSPN = greater superficial petrosal nerve; IAC = internal auditory canal.