Definition

Noun: A rare autoimmune disorder, also known as Lambert-Eaton myasthenic syndrome (LEMS), characterized by muscle weakness, particularly in the proximal muscles of the hips and thighs, fatigue, and often autonomic dysfunction. It is frequently associated with an underlying malignancy, most commonly small-cell lung cancer, and is caused by antibodies that attack the voltage-gated calcium channels at the neuromuscular junction, impairing the release of acetylcholine and thus muscle contraction.

Usage Examples

• The patient's persistent weakness and aching back led to a diagnosis of myasthenic syndrome.
• Myasthenic syndrome is a paraneoplastic disorder often discovered during the workup for lung cancer.
• The neurologist explained that the fatigue in his legs was due to myasthenic syndrome.

Advanced Usage

• The term is often used in its full form, Lambert-Eaton myasthenic syndrome (LEMS), to distinguish it from the more common .
• In medical literature, it is described as a presynaptic disorder of neuromuscular transmission, contrasting with the postsynaptic pathology of myasthenia gravis.

Variants and Related Words

• Lambert-Eaton myasthenic syndrome (LEMS): The full clinical name for the condition.
• Paraneoplastic syndrome: A broader category of disorders, of which myasthenic syndrome is an example, where a cancer causes symptoms in other parts of the body via immune mechanisms.

Synonyms

• Lambert-Eaton syndrome
• LEMS (acronym)

Related Phrases and Concepts

• Proximal muscle weakness: A key symptom, referring to weakness in muscles closest to the body's core (hips, shoulders).
• Neuromuscular junction: The specific site of the physiological defect in this syndrome.
• Voltage-gated calcium channels: The target of the pathogenic autoantibodies.

Noun

1. a disease seen in patients with lung cancer and characterized by weakness and fatigue of hip and thigh muscles and an aching back; caused by antibodies directed against the neuromuscular junctions