Peripheral nerve conduction abnormalities precede morphological alterations in an experimental rat model of sepsis

Area of Science:

• Neuroscience
• Pathophysiology
• Critical Care Medicine

Background:

• Critical illness polyneuropathy (CIP) is an acute neuromuscular disorder with unknown pathological mechanisms.
• Understanding early electrophysiological abnormalities in CIP is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the nerve and vascular properties contributing to electrophysiological abnormalities in the early phase of CIP.
• To elucidate the underlying mechanisms of reduced nerve conduction amplitude in CIP.

Main Methods:

• Rats were administered lipopolysaccharide (LPS) or saline for 48 hours.
• Sciatic nerve function, including nerve conduction velocity (NCV), nerve blood flow (NBF), and evoked amplitudes, were measured.
• Histological and electron microscopy analyses were performed to examine nerve morphology and inflammatory infiltration.

Main Results:

• LPS administration significantly reduced NBF and evoked amplitudes, while mean arterial pressure (MAP) remained similar between groups.
• Electrophysiological abnormalities were characterized by increased rheobase and decreased chronaxie, indicating altered nerve excitability.
• No primary axonal degeneration or significant neutrophil infiltration was observed in the sciatic nerves.

Conclusions:

• Early-phase CIP induced by LPS is primarily associated with electrophysiological deterioration due to altered nerve excitability (threshold changes).
• Morphological alterations were not the primary cause of electrophysiological abnormalities in this early stage of CIP.
• These findings highlight the importance of nerve excitability in the pathophysiology of CIP.