ABSTRACT
Aims: The aim was to assess the etiology of sixth nerve palsy and on the basis of our data, to formulate a diagnostic algorithm for the management in sixth nerve palsy. Design: Retrospective chart review. Results: Of the 104 neurologically isolated cases, 9 cases were attributable to trauma, and 95 (86.36%) cases were classified as nontraumatic, neurologically isolated cases. Of the 95 nontraumatic, isolated cases of sixth nerve palsy, 52 cases were associated with vasculopathic risk factors, namely diabetes and hypertension and were classified as vasculopathic sixth nerve palsy (54.7%), and those with a history of sixth nerve palsy from birth (6 cases) were classified as congenital sixth nerve palsy (6.3%). Of the rest, neuroimaging alone yielded a cause in 18 of the 37 cases (48.64%). Of the other 19 cases where neuroimaging did not yield a cause, 6 cases were attributed to preceding history of infection (3 upper respiratory tract infection and 3 viral illnesses), 2 cases of sixth nerve palsy were found to be a false localizing sign in idiopathic intracranial hypertension and in 11 cases, the cause was undetermined. In these idiopathic cases of isolated sixth nerve palsy, neuroimaging yielded no positive findings. Conclusions: In the absence of risk factors, a suggestive history, or positive laboratory and clinical findings, neuroimaging can serve as a useful diagnostic tool in identifying the exact cause of sixth nerve palsy. Furthermore, we recommend an algorithm to assess the need for neuroimaging in sixth nerve palsy.
ABSTRACT
Myasthenia gravis (MG) is a disease that affects the neuro‑muscular junction resulting in classical symptoms of variable muscle weakness and fatigability. It is called the great masquerader owing to its varied clinical presentations. Very often, a patient of MG may present to the ophthalmologist given that a large proportion of patients with systemic myasthenia have ocular involvement either at presentation or during the later course of the disease. The treatment of ocular MG involves both the neurologist and ophthalmologist. Thus, the aim of this review was to highlight the current diagnosis, investigations, and treatment of ocular MG.
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Purpose: To investigate the effect of optic neuritis (ON), ischemic optic neuropathy (ION) and compressive optic neuropathy (CON) on multifocal visual evoked potential (mfVEP) amplitudes and latencies, and to compare the parameters among three optic nerve disorders. Materials and Methods: mfVEP was recorded for 71 eyes of controls and 48 eyes of optic nerve disorders with subgroups of optic neuritis (ON, n = 21 eyes), ischemic optic neuropathy (ION, n = 14 eyes), and compressive optic neuropathy (CON, n = 13 eyes). The size of defect in mfVEP amplitude probability plots and relative latency plots were analyzed. The pattern of the defect in amplitude probability plot was classified according to the visual field profile of optic neuritis treatment trail (ONTT). Results: Median of mfVEP amplitude (log SNR) averaged across 60 sectors were reduced in ON (0.17 (0.13‑0.33)), ION (0.14 (0.12‑0.21)) and CON (0.21 (0.14‑0.30)) when compared to controls. The median mfVEP relative latencies compared to controls were significantly prolonged in ON and CON group of 10.53 (2.62‑15.50) ms and 5.73 (2.67‑14.14) ms respectively compared to ION group (2.06 (‑4.09‑13.02)). The common mfVEP amplitude defects observed in probability plots were diffuse pattern in ON, inferior altitudinal defect in ION and temporal hemianopia in CON eyes. Conclusions: Optic nerve disorders cause reduction in mfVEP amplitudes. The extent of delayed latency noted in ischemic optic neuropathy was significantly lesser compared to subjects with optic neuritis and compressive optic neuropathy. mfVEP amplitudes can be used to objectively assess the topography of the visual field defect.
ABSTRACT
Advancements in physics, computers, and imaging science in the last century have seen neuro-imaging evolving from a plain X-ray to computed tomography, magnetic resonance imaging scans, noninvasive angiography, and special sequences such as fat suppression, fluid attenuation recovery and diffusion-weighted imaging. A prompt prescription of an appropriate imaging modality and the most suitable sequence can increase the diagnostic yield, and in many instances, it can be a sight-saving and even a life-saving decision. This article discusses basic principles of neuro-imaging, its common indications, and the appropriate application in an ophthalmology practice.