21 - Entrapment Neuropathy Flashcards
(53 cards)
Describe the anatomy of peripheral nerves
- Epineurium-outer connective tissue layer that supports the nerve from compression injury.
- Fascicle-group of nerve fibers supported by perineurium.
- Perineurium-named connective tissue utilized to support and protect the fascicles.
- Endoneurium-covers and protects the individual axon.
Axon-each individual nerve fiber (cell)
Describe the classification of nerve injury
- Neurapraxia
- Axonotmesis
- Neurotmesis
Describe Neurapraxia
Neurapraxia-compression injury, resulting in myelin sheath degeneration. There is conduction deficit without axonal destruction
Describe axontmesis
Axonotmesis-axonal and myelin sheath disruption without disruption of endoneurial tube.
Describe neurotmesis
Neurotmesis-gross nerve disruption.
Describe the sunderland classification of nerve injury
- 1st degree-conduction deficit without axonal damage
- 2nd degree-axon severed without breaching endoneurium
- 3rd degree-disorganization of internal fascicles
- 4th degree-axonal rupture with perineurial disruption
- 5th degree-complete loss of continuity
Look at the chart on slide 82
PRINT THIS
He said to look at the overlap and the involvement
Know what is possible for recuvery if someone has a sunderland grade 3, etc.
Describe the classificaiton of peripheral neuropathy by mechanism
- Demyelination-Guillain-Barre syndrome
- Axonal-metabolic etiologies (arsenic)
- Segmental Demyelination-Diabetes
- Wallerian Degeneration-Nerve transection
- Infarction-Polyarteritis nodosa
- Inflammation-leprosy, CMV
- COMPRESSION-Entrapment (Tarsal Tunnel)
Describe the exogenous etiologies
- Direct trauma
- Repeated microtrauma
- Neuroma-in-continuity
- Space occupying lesions
- Cast pressure-common peroneal nerve as it courses around fibular head, inappropriate cast application.
- Improper tourniquet use-inadequate padding or positioning or prolongation of tourniquet time.
- Biomechanical (pronation with excessive pressure on the nerve compartment with respect to tarsal tunnel.)
Describe the type of space occupying lesions
- Lipoma
- Ganglion cyst
- Varix (an enlarged tortuous vein, artery, or lymphatic)
- Metastatic infiltration
- Neurolemmoma (schwannoma)
Describe the type of endogenous etiologies
Compartment syndrome-edema of the fascial compartments of the leg or foot leading to nerve compression that will cause nerve infarction*** if the fascial compartments are not decompressed.
Intraneural hematoma-direct nerve contusion or from injection that causes intraneural bleeding and compression***
Describe the types of localized neuropathies
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Describe localized neuropathies of the lower extremity
- Saphenous
- Lateral cutaneous
- Common peroneal
- Superficial peroneal
- Deep peroneal
- Sural nerve
- Tipial nerve
What do we see with lateral cutaneous localized neuroapthy?
Lateral cutaneous nerve of the thigh-known as Meralgia Paraesthetica, nerve compressed under the inguinal ligament, causes burning sensation over anterolateral thigh.
What do we see with common peroneal localized neuropathy?
Common Peroneal nerve-compression of the nerve at fibular neck. The nerve courses around fibular neck piercing the two heads of Peroneus Longus. Injury leads to weakness of Tibialis Anterior and resultant foot drop. Altered sensation over lateral leg and dorsum foot may also be experienced.
Drop foot - need an AFO
What do we see with superficial peroneal localized neuropathy
Superficial Peroneal nerve-easily damaged by compression or repeated micro-compression that causes intra and perineural fibrosis that can entrap the axonal tissue. Can become scarified post surgery or from tight fitting shoes.
What do we see with deep peroneal localized neuropathy
Deep Peroneal nerve- (also referred to as Anterior Tarsal Tunnel) usually entrapped in the anterior ankle and dorsum of foot. Most common is in its course as it passes under the muscle and tendon of the Extensor Hallucis Brevis.
What do we see with sural nerve localized neuropathy
Sural nerve-commonly entrapped in scar tissue following Achilles or lateral ankle surgery. Can also be entrapped as its branches pierce the lateral fascia of the leg.
What do we see with tibial nerve localized neuropathy
- Tarsal Tunnel-deep to the laciniate ligament
- Abductor canal-(Medial Plantar Nerve Entrapment) between Abductor Hallucis muscle and spring ligament
- Plantar vault-(Lateral Plantar Nerve Entrapment) between Abductor Hallucis muscle and Quadratus Plantae
What is intermetatarsal neuroma?
Commonly in the third intermetatarsal space
Typically occurs here because medial and lateral plantar nerve contribute branches to this space
Describe the clinical tests for entrapment neuropathy
- Tinel’s sign
- Villioux sign
- Epicritic sensation
- Tourniquet test
Describe Tinel’s test
Tinel’s sign-tapping directly over the nerve that causes numbness and tingling at the site.
Describe Villioux sign
Villioux sign-tapping directly over the nerve that causes radiating sensations either, or both proximal & distal.
Describe epicritic sensation
Epicritic sensations-vibratory, sharp-dull, crude touch, light touch, DTR’s, Plantar Response (Babinski), Kinesthetic sense (joint position or proprioception)