An Ocular Chameleon.

Patients presenting with transient visual loss is common in emergency departments. Neurologists, ophthalmologists and emergency care physicians may be called upon to evaluate such patients. Monocular visual loss should be differentiated from the binocular involvement as the oetologies, investigations and management of such patients differ considerably. We report a case of monocular visual loss that involved predominantly one eye but affected the other side independently, albeit less frequently. A meticulous history, thorough general, neurological and ophthalmological examinations are necessary in such patients to identify the cause and to treat appropriately. Ocular ischemic syndrome (OIS) is due to chronic hypoperfusion of the structures supplied by ophthalmic artery leading to monocular visual loss. Stenosis of the ipsilateral internal carotid artery from a variety of causes is the main underlying mechanism. The first case of OIS was reported by Hedges in 1963 and the term was coined later by Barry and Magargal. Ocular ischemic syndrome is an important differential diagnosis to consider especially in older people and those with vascular risk factors. An overview of important differential diagnosis, clinical features and treatment of OIC are discussed in this article. A multidisciplinary team is optimal for the management of ocular ischemic syndrome.

Diagnosis, differential diagnosis and misdiagnosis of Susac syndrome.

BACKGROUND AND PURPOSE: Susac syndrome (SuS) is an inflammatory condition of the brain, eye and ear. Diagnosis can be challenging, and misdiagnosis is common. METHODS: This is a retrospective review of the medical records of 32 adult patients from an Australasian cohort of SuS patients. RESULTS: An alternative diagnosis prior to SuS was made in 30 patients (94%) with seven patients receiving two or more diagnoses. The median time to diagnosis of SuS was 3 months (range 0.5-100 months). The commonest misdiagnoses were migraine in 10 patients (31%), cerebral vasculitis in six (19%), multiple sclerosis in five (16%) and stroke in five (16%). Twenty-two patients were treated for alternative diagnoses, 10 of whom had further clinical manifestations prior to SuS diagnosis. At presentation seven patients (22%) met criteria for definite SuS, 19 (59%) for probable SuS and six (19%) for possible SuS. Six patients (19%) presented with brain-eye-ear involvement, 14 with brain-ear (44%), six with brain-eye (19%) and six (19%) with only brain involvement. In patients with the complete triad of symptoms the median delay to diagnosis was 3 months (range 1-9 months) compared to 5.25 months (range 0.5-100 months) for patients with encephalopathy and ocular symptoms at presentation. CONCLUSIONS: Susac syndrome patients are frequently misdiagnosed at initial presentation, despite many having symptoms or radiological features that are red flags for the diagnosis. Delayed diagnosis can lead to patient morbidity. The varied ways in which SuS can present, and clinician failure to consider or recognize SuS, appear to be the main factors leading to misdiagnosis.

The neuro-otology of Susac syndrome.

OBJECTIVE: We characterised the clinical and neuro-otological characteristics of patients with Susac syndrome. METHODS: The medical records of 30 patients with Susac syndrome were reviewed for details of their clinical presentation and course, neuro-otological symptoms, investigation results including audiology and vestibular function tests, treatment and outcomes. RESULTS: Our findings demonstrate that 29 of our 30 patients with Susac syndrome developed neuro-otological symptoms such as hearing loss, disequilibrium, tinnitus or vertigo during their disease course. Hearing loss was the most common neuro-otological symptom occurring in 93% of patients. A rising configuration of low-frequency greater than the high-frequency sensorineural hearing loss was the most characteristic finding on audiological testing (37% of reviewed audiograms). Disproportionately poor speech discrimination was identified in 20% of cases, and one case demonstrated a retrocochlear pattern on electrophysiological testing. Four patients required hearing aids and a further two patients required a cochlear implant due to severe hearing loss. Two out of two treated patients had improvements in hearing after the prompt administration of corticosteroids, indicating the potential for recoverable hearing loss if relapses are treated early. Effects on vestibular function were variable in ten patients who were tested, with most showing preservation of function despite significant hearing loss. CONCLUSIONS: Neuro-otological symptoms in Susac syndrome are almost universal. In the correct clinical context, a rising configuration of low to high-frequency sensorineural hearing loss should prompt consideration of Susac syndrome. Treatment of inner ear symptoms in Susac syndrome requires further research as early immunotherapy may be beneficial.

Topiramate associated non-glaucomatous visual field defects.

We report a 34-years-old woman who presented with bilateral incongruous inferior visual field defects after the commencement of topiramate for management of migraine. Investigations did not reveal any underlying angle closure glaucoma, reported in current literature to be associated commonly with topiramate associated visual field defects. The changes in the peripheral visual fields gradually improved over several months after the medication was withdrawn. There were only minor changes persistent on the left side on a background of pre-existing myopia and keratoconus. Visual field deficits secondary to topiramate are more commonly attributed to angle closure glaucoma due to ciliochoroidal effusion syndrome. In such instance, the visual field defects are associated with considerable pain due to raised intra-ocular pressure. There have also been reports of visual scotomas due to retinal damage and maculopathy in patients taking topiramate. It is worthwhile to obtain a baseline perimetry in patients being considered for topiramate therapy in order to gauge any changes in their peripheral field of vision during the treatment. Changes in visual fields during the course of medication use and after cessation can be easily compared especially if there are other possible confounders such as refractive errors or a history of migraine.

Facial Involuntary Movements and Respiratory Failure in CANOMAD, Responsive to IVIG Therapy.

CANOMAD is a rare chronic neuropathy, characterized by chronic sensory ataxia and intermittent brain stem symptoms due to antidisialosyl antibodies. The disorder results in significant morbidity but is poorly understood and often misdiagnosed. We describe a unique case of CANOMAD, associated with involuntary movements of the face; patient reported exacerbations with citrus and chocolate and respiratory muscle weakness. Our patient was initially misdiagnosed with Miller Fisher Syndrome, highlighting the need for vigilance should neurological symptoms recur in patients initially diagnosed with a Guillain Barre variant. Moreover, the optimal treatment is unknown. This patient responded remarkably to intravenous immunoglobulin and has been maintained on this treatment, without further exacerbations.