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The Mediastinum (including pre-and para-spinal lines, neural tumours, and pneumomediastinum).
Published in Fred W Wright, Radiology of the Chest and Related Conditions, 2022
Myasthenia gravis (see Ilus. MYASTHENIA GRAVIS) is an auto-immune condition characterised by muscular weakness and fatiguability (in contrast to the Eaton Lambert syndrome see p. 23.6). It may occur 'early' with a hyperplastic thymus or 'late' with an atrophic thymus. Ocular myasthenia is the most common manifestation, but in most patients other muscle groups become affected. The antibody causes the loss of response of the acetylcholine receptors at the neuro-muscular junctions. In some patients (even those with thymomas) the myasthenia may be a transient phenomenon. Medical control is largely with cholinesterase inhibitors or steroids - the latter probably protecting the acetylcholine receptors from immunological attack. Azathiaprine may also produce a remission and plasma exchange may be used in some severely affected patients.
Examine the eyes
Published in Hani TS Benamer, Neurology for MRCP PACES, 2019
Q: How would you confirm the diagnosis? Edrophonium (Tensilon) test or ice pack test.Check the acetylcholine-receptor antibodies (positive in more than 90% in generalised myasthenia and 50% in ocular myasthenia).EMG and single-fibre EMG.
Clinical Aspects
Published in Marc H. De Baets, Hans J.G.H. Oosterhuis, Myasthenia Gravis, 2019
It is usual that the symptoms and signs spread over other muscle groups, mostly in the first years after onset, but rarely much later. The maximal severity is reached in the first year in about two thirds of the patients, in 70 to 90% in the third to fifth year.3,11 In 10 to 15% of the patients3,3,5,12,13 the signs remain clinically confined to the ocular muscles and the eyelids (“ocular myasthenia”). If other muscles are (also) affected the disease is called generalized, but the degree of clinical involvement may vary widely from patient to patient, and may be obviously asymmetrical. Especially in older people, a rather localized weakness occurs in the muscles innervated by the cranial motor nerves (oculo-bulbar myasthenia).
Ophthalmoplegia associated with anti-GQ1b antibodies: case report and review
Published in Orbit, 2023
Camille Yvon, Dominic Nee, Dennis Chan, Raman Malhotra
Our patient presented with clinical features suggestive of ocular myasthenia given the ‘positive’ ice pack test. In myasthenia gravis, the transient improvement is due to the cold reducing the acetylcholinesterase breakdown of acetylcholine at the neuromuscular junction. The test is cheap, painless, safe and effortless to complete; in addition, it has an acceptable sensitivity and high specificity in the differential diagnosis of myasthenic diplopia.14 Interestingly, case reports of MFS have reported a ‘positive’ ice pack test.15,16 It is thought that the neuromuscular junction is the main pathological site in anti-GQ1b antibody syndrome.17 We postulate that the cold enhances transmission at the neuromuscular junction and inhibits the anti-G1Q antibodies in cases of AO.
Eunos 2022: Birmingham, United Kingdom, 20th – 23rd June 2022
Published in Neuro-Ophthalmology, 2022
Sophie L. P. Mollan, Susan P. Mollan
The last session of the day was a super line-up of case presentations from across the globe. Dr Margaret Dayan (Newcastle, UK), presented a case in her formidable style entitled ’A Straightforward Diagnosis at Last’ which set the bar for the other presenters. Dr Clare Fraser‘s (Sydney, Australia) case ‘The case of the Black Diamond’ didn’t disappoint with a diagnosis of vitamin A deficiency being diagnosed with EDTs. ‘Hang in there’ delivered by Dr Dan Milea (Singapore) and ‘Out Back’ by Dr Aki Kawasaki (Geneva, Switzerland) put the knowledge from the other sessions into working practice. Dr Peter Quiros (Los Angeles, USA) followed a person’s journey with ptosis through investigations and surgical correction. The surgery worsened the symptoms leading to prompt re-investigation and an eventual, unsuspected, diagnosis of ocular myasthenia gravis.
Electrophysiologic evaluation of myasthenia gravis and its mimics: real-world experience with single-fiber electromyography
Published in Hospital Practice, 2022
Anthony Khoo, Hnin Hay Mar, Maria Victoria Borghi, Santiago Catania
Ocular myasthenia accounted for 46% of confirmed cases of MG referred to our center for investigation. In contrast, ocular myasthenia is felt to be the clinical phenotype in only 15–25% of those with MG in population-based studies [28,29]. There are two possible explanations for this discrepancy. First, there may be a referral bias, as ocular MG may be more likely to be referred to tertiary centers due to greater challenges with diagnosis and higher rates of seronegativity (50% seronegative in ocular vs. 15% seronegative in generalized MG) [30]. Our hospital has close links with Moorfields Eye Hospital, which is one of the largest ophthalmic centers in the UK. Secondly, the duration of follow-up was relatively short in our cohort, and it is known that up to half of people with myasthenia initially present with isolated ocular involvement that only later in the course of disease develops more generalized manifestations [28]. It is therefore possible that some people diagnosed with ocular MG may later develop more generalized disease manifestations.