Sandbox:ivbalaraman

INTRODUCTION

Lambert Eaton Myasthenic syndrome is a rare disorder causing muscle weakness targeting the Neuromuscular junction.This disorder is usually seen with Small cell Lung cancer, which may be an indication to investigate for SCLC.

Pathophysiology

Understanding the concept of Neuromuscular junction,Presynaptic Acetylecholine (ACh) concentration,end plate potential, post-synpatic ACh receptors, role of Calcium and Voltage gated Calcium channel(VGCC) and role of potassium is essential to understand the pathophysiology of Lambert Eaton syndrome.

• Potassium channels and the concentration of potassium ions does not contribute to the ACh release.

The mechanism by which the ACh is released is by increasing the concentration of calcium ions.

Voltage Gated Calcium Channel

VGCC is a transmembrane protein with many subunits that is the main target in LEMS.

The commonly associated subtypes are L-type,N-type,P/Q-Type of alpha-1 subunit of VGCC, of which the P/Q subtype is the most important target in the disorder.

Paraneolastic LEMS

The Small cell lung cancer expresses the VGCC on the sufrace of the tumor cells