Neuromuscular junction disorders: Pathology review
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Neuromuscular junction disorders: Pathology review
Musculoskeletal system
Pediatric musculoskeletal conditions
Radial head subluxation (Nursemaid elbow)
Developmental dysplasia of the hip
Legg-Calve-Perthes disease
Slipped capital femoral epiphysis
Transient synovitis
Osgood-Schlatter disease (traction apophysitis)
Musculoskeletal injuries and trauma
Rotator cuff tear
Dislocated shoulder
Radial head subluxation (Nursemaid elbow)
Winged scapula
Thoracic outlet syndrome
Carpal tunnel syndrome
Ulnar claw
Erb-Duchenne palsy
Klumpke paralysis
Iliotibial band syndrome
Unhappy triad
Anterior cruciate ligament injury
Patellar tendon rupture
Meniscus tear
Patellofemoral pain syndrome
Sprained ankle
Achilles tendon rupture
Spondylolysis
Spondylolisthesis
Degenerative disc disease
Spinal disc herniation
Sciatica
Compartment syndrome
Rhabdomyolysis
Bone disorders
Osteogenesis imperfecta
Craniosynostosis
Pectus excavatum
Arthrogryposis
Genu valgum
Genu varum
Pigeon toe
Flat feet
Club foot
Cleidocranial dysplasia
Achondroplasia
Osteomyelitis
Bone tumors
Osteochondroma
Chondrosarcoma
Osteoporosis
Osteomalacia and rickets
Osteopetrosis
Paget disease of bone
Osteosclerosis
Lordosis, kyphosis, and scoliosis
Joint disorders
Osteoarthritis
Spondylosis
Spinal stenosis
Rheumatoid arthritis
Juvenile idiopathic arthritis
Gout
Calcium pyrophosphate deposition disease (pseudogout)
Psoriatic arthritis
Ankylosing spondylitis
Reactive arthritis
Spondylitis
Septic arthritis
Bursitis
Baker cyst
Muscular disorders
Muscular dystrophy
Polymyositis
Dermatomyositis
Inclusion body myopathy
Polymyalgia rheumatica
Fibromyalgia
Rhabdomyosarcoma
Neuromuscular junction disorders
Myasthenia gravis
Lambert-Eaton myasthenic syndrome
Other autoimmune disorders
Sjogren syndrome
Systemic lupus erythematosus
Mixed connective tissue disease
Antiphospholipid syndrome
Raynaud phenomenon
Scleroderma
Limited systemic sclerosis (CREST syndrome)
Musculoskeletal system pathology review
Back pain: Pathology review
Rheumatoid arthritis and osteoarthritis: Pathology review
Seronegative and septic arthritis: Pathology review
Gout and pseudogout: Pathology review
Systemic lupus erythematosus (SLE): Pathology review
Scleroderma: Pathology review
Sjogren syndrome: Pathology review
Bone disorders: Pathology review
Bone tumors: Pathology review
Myalgias and myositis: Pathology review
Neuromuscular junction disorders: Pathology review
Muscular dystrophies and mitochondrial myopathies: Pathology review
Assessments
Neuromuscular junction disorders: Pathology review
USMLE® Step 1 questions
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USMLE® Step 1 style questions USMLE
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Reproduced from: Radiopaedia.org
Laboratory testing reveals a creatinine kinase level of 75 U/L. Which of the following additional examination findings will most likely be present in this patient?
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Content Reviewers
Contributors
Daniel Afloarei, MD
Sam Gillespie, BSc
Tanner Marshall, MS
Kaia Chessen, MScBMC
While doing your rounds, you see Kira, a 23-year-old female who presents with a series of recurrent symptoms that get worse as the day progresses. These include slurring of speech, difficulty swallowing, and double vision. She also mentions that her head feels heavy and is hard to hold up. She also complained that her arms are so weak she can’t even brush her hair. Additionally, she reports severe fatigue and shortness of breath. On examination, sensation and reflexes are normal. Next, you see a 62-year-old man named Jonathan, who presents with a history of leg muscle weakness that prevents him from doing simple things like climbing stairs or standing up, which gets better the more he uses his legs. He also reports shortness of breath, fatigue, dry mouth, impotence, and unintentional weight loss. Examination reveals a severely underweight man with dilated pupils. Reflexes are initially absent, although these are obtainable after a brief period of exercise. Blood tests were obtained, detecting anti-acetylcholine receptor antibodies in Kira and anti-voltage-gated calcium channels antibodies in Jonathan.
Now, both seem to have some type of neuromuscular junction disease. But first, a bit of physiology. In normal neuromuscular function, a nerve impulse is carried down the axon from the spinal cord, to the nerve endings, in the neuromuscular junction, where the impulse is transferred to the muscle cell. Here, the nerve impulse leads to the opening of voltage-gated calcium channels, causing an influx of calcium ions into the nerve terminal, which triggers synaptic vesicle fusion with plasma membrane. These synaptic vesicles contain a neurotransmitter called acetylcholine, which is released into the synaptic cleft. The neurotransmitter then binds to nicotinic acetylcholine receptors on muscle cell membranes and activates a chain reaction in the muscles that ultimately results in their contraction.
Sources
- "Robbins Basic Pathology" Elsevier (2017)
- "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
- "Myasthenia Gravis: A Review" Autoimmune Diseases (2012)
- "Recent advances in understanding and managing myasthenia gravis" F1000Res (2018)
- "Clinical features, pathogenesis, and treatment of myasthenia gravis: a supplement to the Guidelines of the German Neurological Society" Journal of Neurology (2016)
- "Lambert-Eaton Myasthenic Syndrome; Pathogenesis, Diagnosis, and Therapy" Autoimmune Diseases (2011)
- "Lambert-Eaton Myasthenic Syndrome" Neurol Clin (2018)
- "Synaptic Pathophysiology and Treatment of Lambert-Eaton Myasthenic Syndrome" Molecular Neurobiology (2014)
- "Lambert-Eaton myasthenic syndrome (LEMS): a rare autoimmune presynaptic disorder often associated with cancer" J Neurol (2017)
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