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A 74-year-old man was hospitalised in January 2021 because he developed in few days a severe muscle weakness associated with ascending numbness in the four limbs. His medical history only included a pulmonary embolism in 2016 and myelodysplastic syndrome (MDS) with multilineage dysplasia diagnosed in 2019, with low risk score according to the Revised International Prognostic Scoring System classification.
Initial neurological examination showed a symmetrical proximal and distal quadriparesis associated with distal hypoesthesia in all four limbs and diffuse areflexia. Motor testing revealed a deltoid and biceps brachii deficit of MRC grade 3/5 and a first dorsal interosseous deficit of 2/5. In the lower limbs, psoas and quadriceps muscle testing were graded 3/5.
Nerve conduction studies (NCS) revealed prolonged distal motor latencies and increased duration of the compound motor action potential (CMAP) in bilateral ulnar, median, tibial and common peroneal nerves. Conduction blocks were present in the forearm on both ulnar nerves (Martin-Gruber anastomosis was excluded). F wave latencies were prolonged and motor conduction velocities were reduced in all four limbs. Needle electromyography showed fibrillatory potentials in several muscles in favour of acute diffuse and sustained muscle denervation.
Cerebrospinal fluid (CSF) revealed a leucocyte count of 2/mm3 (normal values <5/mm3) and a protein level of 0.81 g/L (0.15–0.45 g/L). Laboratory tests revealed a bicytopenia: haemoglobin was 8 g/dL (13–16 g/dL) with macrocytosis and platelets were 56 G/L (150–400 G/L). C reactive protein was increased at 34 mg/L (normal value <5 mg/L). Virological and immunological screenings were …
Contributors CB-M: collected clinical data and wrote the original manuscript. AB: co-author of the manuscript. BF: co-author of the manuscript, follow the patient. GC: performed initial electrophysiological examination. ME: supervised the project. SA: contributed to the final manuscrit and supervised the project. ED: performed nerve biopsy and contributed to the final manuscrit. EF: co-author the manuscript, created the figure and supervised the project.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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