Classification of Nerve Injury

According to Seddon, which classification corresponds to Sunderland grade 1 degree?

neuropraxia

Which Seddon classification encompasses Sunderland grades 2 degree and 3 degree?

axonotmesis

Which Seddon classification encompasses Sunderland grades 3 degree, 4 degree, and 5 degree?

neurotmesis

What is the primary physiological definition of neuropraxia?

segmental demyelination

In neuropraxia, how is the action potential affected at the point of demyelination?

it is slowed or blocked

In neuropraxia, how does the action potential perform above and below the point of compression?

it remains normal

What are the common causes of the mild ischemia that results in neuropraxia?

nerve compression or traction

What is the typically muscle wasting presentation in neuropraxia?

no or minimal muscle wasting

Which sensory symptom is specifically noted as being affected in neuropraxia besides numbness and pain?

proprioception

What is the expected recovery time for a neuropraxia injury?

minutes to days

What is the primary physiological definition of axonotmesis?

loss of axonal continuity

In axonotmesis, what happens to the connective tissue coverings of the nerve?

they remain intact

Where does Wallerian degeneration occur in relation to an axonotmesis lesion?

distal to the lesion

Axonotmesis is typically the result of prolonged compression or stretch causing what two pathological states?

infarction and necrosis

What is the muscle wasting status in an axonotmesis injury?

muscle wasting is evident

Which three functional categories are completely lost in axonotmesis and neurotmesis?

motor, sensory, and sympathetic functions

In the recovery of axonotmesis, which function is typically restored first?

sensation

What is the metric rate of axon regeneration during recovery from axonotmesis?

1 mm/day

What is the imperial rate of axon regeneration during recovery from axonotmesis?

1 inch/month

What is the primary physiological definition of neurotmesis?

complete severance of nerve fiber with disruption of connective tissue coverings

Which classification of nerve injury is caused by gunshot wounds, stab wounds, or avulsions?

neurotmesis

What is the characteristic pain symptom (or lack thereof) in neurotmesis?

no pain (anesthesia)

What is the recovery timeframe and primary requirement for neurotmesis?

months and only with surgery

Which Sunderland grade involves only the myelin/segmental demyelination?

grade one degree

Which Sunderland grade is characterized by the loss of the axon while the endoneurium remains intact?

grade two degree

Which Sunderland grade involves the disruption of the axon and the endoneurium?

grade three degree

Which Sunderland grade involves the disruption of the axon, endoneurium, and perineurium?

grade four degree

Which Sunderland grade represents a complete severance of the entire nerve trunk, including the epineurium?

grade five degree

Name the outermost connective tissue covering of a peripheral nerve

epineurium

Name the connective tissue layer that surrounds a fascicle of nerve fibers

perineurium

Name the connective tissue layer that immediately surrounds an individual axon.

endoneurium

What structure is located between the axon and the endoneurium in the nerve hierarchy?

basal lamina

Neuropraxia is characterized by ___ demyelination

segmental

In axonotmesis, the recovery of ____ function occurs after the restoration of sensation

motor

The absence of pain in a complete nerve severance is known as ____

anesthesia

Wallerian degeneration occurs in both axonotmesis and _____

neurotmesis

Sunderland grade one degree is synonymous with the seddon term _____

neuropraxia

Axonotmesis involves the loss of axonal _____

continuity

Which injury classification is specifically associated with the result of mild ischemia

neuropraxia

How does the recovery time for axonotmesis compare to neuropraxia?

axonotmesis takes months while neuropraxia takes minutes to days

Which Sunderland grade is the first to involve damage to the perineurium?

grade four degree

Does muscle wasting occur in neuropraxia?

no

it is absent or minimal

What is the status of sympathetic function in a neurotmesis injury?

it is completely lost

What nerve injury classification involves intact connective tissue but severed axons?

axonotmesis

Which anatomical layer is the final barrier to be breached in a Sunderland grade five degree injury?

epineurium

Is pain present in an axonotmesis injury?

yes

Which classification is described as the result of infarction and necrosis due to prolonged stretch?

axonotmesis

In neuropraxia, is the nerve fiber physically severed?

no

Which classification has a recovery time of months and only with surgery?

neurotmesis

A patient with numbness and affected proprioception but no muscle wasting likely has which seddon grade?

neuropraxia

What is the primary cause listed for a sunderland grade five degree injury?

gunshot or stab wounds, avulsion, or rupture

True or False: Wallerian degeneration occurs in neuropraxia

false

Which sunderland grade marks the transition where both the axon and endoneurium are lost but the perineurium remains?

grade three degree

What is the status of motor function in a patient with axonotmesis?

it is completely lost

In which nerve injury grade is the action potential conduction purely a localized issue at the site of demyelination?

neuropraxia (sunderland one degree)

The process of decay and disappearance of the axon part that is distal to a nerve lesion is defined as?

Wallerian degeneration