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Bilateral trochlear nerve palsy in a patient with neuromyelitis optica
Multiple Sclerosis and Related Disorders, 2, 3, pages 273 - 275
We present a unique case of isolated bilateral simultaneous cranial nerve (CN) IV palsy in a patient with neuromyelitis optica (NMO). Although some CN IV abnormalities have been described in multiple sclerosis (MS), no case of isolated bilateral simultaneous CN IV has been reported, to our knowledge, in either NMO or MS.
Keywords: Trochlear nerve, Multiple sclerosis, NMO, MRI, Clinical-imagingcorrelations, Extra-ocular movements.
1. Case report
A 25 year-old right-handed woman with antibody-positive NMO diagnosed two years prior presents with binocular vertical diplopia improved with tilting her head down. She had remained symptom-free since her initial presentation of transverse myelitis ( Fig. 1 ) and had been off immunosuppressive therapy for the past year during pregnancy and while breast-feeding.
On examination, she had a chin down position. On cross-cover testing, she had a right hypertropia on left gaze and a left hypertropia on right gaze. In primary position, there was no significant extraocular muscle imbalance. There was no nystagmus, internuclear ophthalmoplegia, ptosis or pupil asymmetry. The remainder of the neuro-ophthalmic examination was normal. Cranial MRI demonstrated a new T2/Flair hyperintensity in the periaqueductal gray abutting the right inferior colliculus ( Fig. 2 ). She continued to breast feed and did not wish to be placed on immunomodulatory medication. Her diplopia resolved spontaneously after six weeks.
NMO is an autoimmune disease of the central nervous system, with antibodies against aquaporin-4, the principal water channel of astrocytes, leading to inflammatory demyelinating lesions primarily in spinal cord and optic nerve. Brain lesions have been reported, but are not specific and occasionally resemble those of MS. Aquaporin-4 channels are highly concentrated around the hypothalamus and periventricular areas, and thus, brainstem lesions have been documented (Pittock et al, 2006, Bizzoco et al, 2009, and Wang et al, 2011). Bilateral CN IV palsy, however, has not been described in NMO or in MS.
Although six cases of isolated trochlear nerve palsy have been reported in multiple sclerosis, none were bilateral and no lesions were identified on MRI involving the trochlear nerve or nucleus (Jacobson et al, 1999 and Thomke et al, 1997). To our knowledge, this is the first case reported of isolated bilateral simultaneous CN IV palsy in a patient with neuromyelitis optica (NMO), along with neuroimaging correlate.
Drs. Rizek, Nicolle and Kremenchutzky: study design and concept.
Dr. Rizek: drafting the manuscript.
Dr. Tay: selection and review of neuroimages and figure legends.
Dr. Kremenchutzky: revising the manuscript.
Conflict of interest statement
The authors report no conflicts of interest relevant to the manuscript.
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- Thomke et al., 1997 F. Thomke, E. Lensch, K. Ringel, HC. Hopf. Isolated cranial nerve palsies in multiple sclerosis. Journal of Neurology, Neurosurgery, and Psychiatry. 1997;63:682-685 Crossref
- Wang et al., 2011 K.C. Wang, C.L. Lee, S.Y. Chen, K.H. Lin, C.P. Tsai. Prominent brainstem symptoms/signs in patients with neuromyelitis optica in a Taiwanese population. Journal of Clinical Neuroscience. 2011;18:1197-1200 Crossref
a Department of Clinical Neurological Sciences, University of Western Ontario, London, Ontario, Canada
b Department of Ophthalmology, University of Western Ontario, London, Ontario, Canada
c Department of Medical Imaging, University of Western Ontario, London, Ontario, Canada
Correspondence to: Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, University Hospital, Room B7-005, 339 Windermere Road, London, Ontario, Canada N6A 5A5. Tel.: +1 519 663 3121; fax: +1 519 663 3982.
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