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Toxins in Neuro-Ophthalmology
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Clinical features of methanol intoxication include nausea, vomiting and abdominal pain. The CNS effects of methanol result from accumulation of formic acid within the optic nerve and leads to flashes of light. It progresses further to scotomas and scintillations. Vision loss is probably caused by interruption of mitochondrial function in the optic nerve which results in hyperemia, edema and optic nerve atrophy. Pupillary response to light is compromised and subsequently lost. Confirmation of diagnosis is by serum methanol level with gas chromatography (>20 mg/dL). Serum levels peak after 60–90 min of ingestion, but these do not correlate with the level of toxicity. Accumulation of formate leads to decrease in pH (<7.2 is a severe intoxication). Imaging findings may be suggestive with bilateral enhancing optic nerves and putaminal necrosis.
Neurological Disease
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
Each nerve carries with it its own blood vessels or vasa nervorum, and occlusion of the arterial supply to a nerve causes it to cease to function. In most cases, function returns, usually over 4–8 weeks. The oculomotor (IIIrd) and abducens (VIth) nerves are most often affected, and causes include diabetes, hypertension, arteriosclerosis and, less commonly, vasculitides including temporal arteritis. Such ‘medical’ causes of IIIrd nerve palsies may be painful, but the pupillary response to light is almost always normal. However, this clinical distinction is often difficult to make with certainty, and so it is reasonable to exclude a posterior communicating artery aneurysm in all patients presenting with a IIIrd nerve palsy.
Patient Assessment
Published in Ian Greaves, Keith Porter, Jeff Garner, Trauma Care Manual, 2021
Ian Greaves, Keith Porter, Jeff Garner
Inspection of the eyes must be carried out before significant orbital swelling makes examination too difficult. It is important to check for haemorrhages, both inside and outside the globe, for foreign bodies under the lids (including contact lenses) and for the presence of penetrating injuries which can be remarkably subtle. If the patient is conscious, the visual acuity can be tested by asking them to read a name badge or fluid label. Even if the patient is unconscious, the pupillary response and corneal reflexes must be determined and recorded.
Evaluation of the GCS-Pupils Score for PrOgnosis in trauMatic brAin injury- The COMA Study
Published in Brain Injury, 2023
Charu Mahajan, Deep Sengupta, Indu Kapoor, Hemanshu Prabhakar, Vijay Kumar, Shobha Purohit, Vansh Priya, Shashi Srivastava, Deepali Thakur, Hemangi Karnik, Hem Chandra Sati, Mani Kalaivani
All patients admitted to the neuro-intensive care unit (NICU), within 12 hours of injury, operated or non-operated, were screened for eligibility. Adult patients (>18 years) admitted to NICU within 12 hours of injury, following acute traumatic brain injury, penetrating or non-penetrating, were included in this study. Each center enrolled the patients for six months and collected data at the time of admission to the hospital. Age <18 years, non-traumatic acute brain injury such as stroke and subarachnoid hemorrhage, patients having eye/orbital injury in whom pupillary response could not be assessed or received medications that could affect pupillary assessment, severe extracranial injuries, patients not admitted to NICU and those who refused consent were excluded from the study.
Dual phenotype: co-occurring Leber congenital amaurosis and familial exudative vitreoretinopathy: a case report
Published in Ophthalmic Genetics, 2023
Virginia Miraldi Utz, Jared J. Ebert, Diana S. Brightman, Brittany N. Simpson, Stefanie Benoit, Robert A. Sisk
A 6-month-old, full-term Caucasian male presented with nyctalopia, nystagmus, and poor visual behavior. The patient had normal growth and development without significant family history. On examination, the patient had no dysmorphic facial features. He responded to light and high contrast, large “Hiding Heidi” face at 2 inches. Pupils were slowly reactive, without paradoxical pupillary response. Posterior segment examination in both eyes was significant for a blunted foveal reflex with pigment mottling, normal vasculature, and fundus periphery. His cycloplegic refraction was +5.50 sphere in each eye. A normal MRI brain and orbits with contrast excluded structural brain abnormalities. During the COVID-19 pandemic, only urgent procedures were performed, so we were unable to evaluate with full-field electroretinograms (ffERG) at that time.
Reversible Bitemporal Hemihypokinetic Pupil Without Hemianopia: A New Chiasmal Sign
Published in Neuro-Ophthalmology, 2022
Jorge Alberto Martins Pentiado Junior, Eduardo Yukio Nakamura, Lucas Ravagnani da Silva, Patricia Approbato Marques, Natalia Oliveira da Silva, Ricardo Santos de Oliveira, Maria Lucia Habib Simao
Notably, hemihypokinesia and pupillary hemiakinesia have always been described in classical studies with pupillometry with the obligatory presence of a visual field defect proportional to the pupillary motor defect.3,4 However, several cases have been reported since the 1920s of hemihypokinesia and/or an RAPD without a corresponding visual field defect. These patients presented with structural damage exclusively affecting the brachium of the superior colliculus or its synapses in the pretectal nucleus/pretectal region (pretectal afferent pupillary pathway). Such dissociation is expected, as the afferent pupillomotor fibres are anatomically separate from the visual fibres at these locations.7,16 It is currently accepted that both an RAPD and hemihypokinesia can also occur with retrogeniculate lesions and without involving the classical pupillary reflex arc, as the pupillary light reaction is controlled by two systems: subcortical (pregeniculate) and cortical (suprageniculate neurons and visual cortex).7,16,17 Thus, the pupillary response encompasses the subcortical and cortical visual pathways with functions and interactions that are still not fully understood.