axonotmesis

Seddon's axonotmesis and second-degree are the same.

In order of degree of severity, injury to a nerve can be described as neuropraxia, axonotmesis, or neurotmesis.

The second degree in which the axon is damaged but the surrounding connecting tissue remains intact is called axonotmesis.

Treatment of axonotmesis consists of :

Seddon classified facial nerve injuries into three broad categories: neuropraxia, neurotmesis, and axonotmesis.

In Seddon's Classification, nerve injury is described as either neurapraxia, axonotmesis, or neurotmesis.

According to NCV study, in axonotmesis there is an absence of distal sensory-motor responses.

More severe nerve injury like axonotmesis or neurotmesis warrant the repair of the epineurium because the connective tissue is damaged.

Lastly, axonotmesis consists of damage to the inner nerve fibers while the outer covering remains whole, and also yields a flat line in response to stimulation.

In axonotmesis, EMG changes (2 to 3 weeks after injury) in the denervated muscles include:

Depending on the type of injury (i.e. Seddon classification: neuropraxia, axonotmesis, and neurotmesis) they can be prolonged or permanent.

EMG and NCV findings are as axonotmesis.

The assessment of partial hypoaesthesia (axonotmesis) is based on the concept of the largest cutaneous distribution of the nerve branch.

If axons, and their myelin sheath are damaged, but schwann cells, the endoneurium, perineurium and epineurium remain intact is called axonotmesis.

In axonotmesis, the proximal section is repaired by creating a sprout with its growth cone, but in the distal section occurs axonal degeneration.

Loss in both motor and sensory spines is more complete with axonotmesis than with neurapraxia, and recovery occurs only through regenerations of the axons, a process requiring time.

With Seddon's classification of nerve injuries it is often tough to identify whether a particular nerve injury is neurotmesis, or axonotmesis, which has damage to the nerve fibres but preservation of the nerve trunk.

In electrodiagnostic testing with nerve conduction studies, there is a normal compound motor action potential amplitude distal to the lesion at day 10, and this indicates a diagnosis of mild neuropraxia instead of axonotmesis or neurotmesis.

Axonotmesis: Involves axonal degeneration, with loss of the relative continuity of the axon and its covering of myelin, but preservation of the connective tissue framework of the nerve (the encapsulating tissue, the epineurium and perineurium, are preserved).

In order for the condition to be considered neurapraxia, according to the Seddon classification system of peripheral nerve injury, there must be a complete and relatively rapid recovery of motor and sensory function once nerve conduction has been restored; otherwise, the injury would be classified as axonotmesis or neurotmesis.