From the Guidelines
Wallerian degeneration can be seen in Guillain-Barré syndrome, a rare, but potentially fatal, immune-mediated disease of the peripheral nerves and nerve roots. This process occurs when there is damage to the axon of a peripheral nerve, leading to degeneration of the distal segment separated from the cell body. Common conditions where Wallerian degeneration is observed include peripheral nerve trauma (such as lacerations, crush injuries, or stretch injuries), entrapment neuropathies (like carpal tunnel syndrome or cubital tunnel syndrome), diabetic neuropathy, chronic inflammatory demyelinating polyneuropathy (CIDP), and vasculitic neuropathies. The degeneration process begins within 24-48 hours after injury and involves fragmentation of the axon and myelin sheath, followed by macrophage infiltration to clear the debris, as noted in a study on the diagnosis and management of Guillain-Barré syndrome 1. Some key points to consider:
- Guillain-Barré syndrome is an inflammatory disease of the PNS and is the most common cause of acute flaccid paralysis, with an annual global incidence of approximately 1–2 per 100,000 person-years 1.
- The clinical presentation of Guillain-Barré syndrome is heterogeneous, and several distinct clinical variants exist, including acute inflammatory demyelinating polyradiculoneuropathy (AIDP), acute motor axonal neuropathy (AMAN), and acute motor sensory axonal neuropathy (AMSAN) 1.
- Electrophysiological studies provide evidence of PNS dysfunction and can distinguish between the subtypes of Guillain-Barré syndrome, which is essential for diagnosis and management 1.
- Imaging techniques such as MRI can detect Wallerian degeneration as increased T2 signal intensity along the affected nerve pathway, which can help in diagnosis and monitoring of these peripheral nerve conditions. In terms of prognosis, about 20% of patients with Guillain-Barré syndrome develop respiratory failure and require mechanical ventilation, and cardiac arrhythmias and blood pressure instability can occur owing to involvement of the autonomic nervous system 1. However, with proper management, 60–80% of patients with Guillain-Barré syndrome are able to walk independently 6 months after disease onset, with or without treatment 1.
From the Research
Peripheral Diseases Associated with Wallerian Degeneration
- Diabetic peripheral neuropathy (DPN) is a condition that can lead to Wallerian degeneration, as it affects the peripheral nerves and can cause damage to the nerve fibers 2.
- Other peripheral nerve diseases, such as degenerative, metabolic, heritable, toxic, inflammatory, and ischemic disorders, can also undergo Wallerian-like degeneration 3.
- Wallerian degeneration can occur after an axon is cut or crushed, and it entails the disintegration and clearance of the severed axon distal to the injury site 4.
Characteristics of Wallerian Degeneration
- Wallerian degeneration is a cascade of stereotypical events in reaction to injury of nerve fibers, including cellular and molecular alterations, such as macrophage invasion, activation of Schwann cells, and neurotrophin and cytokine upregulation 5.
- The process of Wallerian degeneration is associated with an inflammatory response, including the rapid upregulation of immune signal molecules like cytokines, chemokines, and transcription factors 5.
- The discovery of genetic mutations that delay Wallerian degeneration has provided insight into mechanisms underlying axon degeneration in disease 6.
Relationship between Wallerian Degeneration and Axon Regeneration
- Wallerian degeneration can set the stage for the success or failure of subsequent regeneration, and manipulations of Wallerian degeneration are being investigated as a potential means of altering the outcome of nerve regeneration 3.
- The process of Wallerian degeneration can also contribute to axonal regeneration, as it provides a environment that can support the growth of new axons 5.