Lambert-Eaton myasthenic syndrome

23,356views

00:00 / 00:00

High Yield Notes

5 pages

Flashcards

Lambert-Eaton myasthenic syndrome

of complete

Questions

USMLE® Step 1 style questions USMLE

of complete

A 65-year-old man comes to his outpatient provider because of a chronic cough for the past 3 months. It is occasionally accompanied by flecks of blood-tinged sputum. Review of systems is significant for weakness in the hips and thighs bilaterally and 15 lbs (6.8 kg) weight loss. Past medical history is notable for hypertension. He only takes hydrochlorothiazide. Social history is notable for a 50-pack-year smoking history. In the office, his temperature is 37.0°C (98.6°F), pulse is 76/min and blood pressure is 157/85 mmHg. Pulmonary examination reveals expiratory wheezing on the left side in 5th intercostal space. A chest radiograph is ordered and reveals the following:


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?  

External References

First Aid

2024

2023

2022

2021

Calcium channels

Lambert-Eaton myasthenic syndrome p. 219

Dry mouth

Lambert-Eaton myasthenic syndrome p. 480

Erectile dysfunction p. 584

Lambert-Eaton myasthenic syndrome p. 479

Lambert-Eaton myasthenic syndrome p. 480

autoantibody p. 113

as paraneoplastic syndrome p. 219

small cell lung cancer p. 703

Sexual dysfunction p. 584

Lambert-Eaton myasthenic syndrome p. 479

Small cell lung cancer p. 735

Lambert-Eaton myasthenic syndrome p. 480

External Links

Transcript

Watch video only

In Lambert-Eaton myasthenic syndrome, myasthenia refers to muscle weakness, and Lambert-Eaton refers to Edward Lambert and Lealdes Eaton, the two physicians who first described the condition.

Lambert-Eaton myasthenic syndrome is a rare autoimmune disease that attacks the peripheral nervous system, causing muscle weakness, and actually improves temporarily after repeated use of the muscle.

The nervous system is divided into the central nervous system, which is the brain and spinal cord, and the peripheral nervous system, which includes all the nerves that connect the central nervous system to the muscles and organs.

The peripheral nervous system can then further be divided into the somatic nervous system, which controls voluntary movement of our skeletal muscles, and the autonomic nervous system, which is even further divided into the sympathetic and the parasympathetic, and controls the involuntary movement of the smooth muscles and glands of our organs.

Now, to better understand Lambert-Eaton myasthenic syndrome, let’s review normal skeletal muscle contraction at the cellular level.

First you’ve got your motor neurons, which have voltage-gated calcium channels in their membranes.

Whenever a motor neuron receives an electrical impulse from the brain, these channels open up and let calcium inside.

The increased intracellular calcium concentration triggers the release of small vesicles that contain the neurotransmitter acetylcholine into the neuromuscular junction.

Acetylcholine goes from the neuron over to the nicotinic receptors on muscle cell membranes.

When acetylcholine binds the nicotinic receptors it leads to muscle contraction.

Sources

  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "Available treatment options for the management of Lambert-Eaton myasthenic syndrome" Expert Opinion on Pharmacotherapy (2006)
  6. "Available treatment options for the management of Lambert-Eaton myasthenic syndrome" Expert Opinion on Pharmacotherapy (2006)
  7. "Lambert-Eaton Myasthenic Syndrome" Seminars in Neurology (2004)
Elsevier

Copyright © 2024 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.

RELX