Flashcards in 21 - Entrapment Neuropathy Deck (53):
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-compression injury, resulting in myelin sheath degeneration. There is conduction deficit without axonal destruction
Axonotmesis-axonal and myelin sheath disruption without disruption of endoneurial tube.
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
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
- 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
- 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
Describe localized neuropathies of the lower extremity
- 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)
Describe tourniquet test
Tourniquet test- If Vena Comitans is suspected etiology.
What are ancillary studies?
- Nerve Conduction Studies-tests the latency between stimulation of the nerve to contraction of the muscle. Normal muscle latency runs between 45-80 m/s depending on age of patient and nerve involved.
- Magnetic Resonance Imaging-can evaluate for nerve edema or enlargement.
What is saphenous nerve entrapment?
Spinal Level L3, L4 (don't need to know spinal levels, FYI)
Areas of injury
- Pierces the Sartorius muscle and fascia at the lower medial thigh
- Crosses the ankle at the level of the medial malleolus
- At the base of the first metatarsal
What is common peroneal nerve entrapment?
Spinal Level L4, L5, S1
Area of injury
- Nerve pierces the two heads of the Peroneus Longus muscle branches into Three basic trunks: recurrent articular, deep peroneal, superficial peroneal. The topographical location is approximately two fingers widths distal to head of the fibula.
What are the causes of common peroneal entrapment?
- Cast pressure from improper application
- Bedridden patient (nursing home)
- High fibular fractures
- Crossing legs for extended period of time
What are the symptoms of a common peroneal entrapment?
Symptoms-pain and paresthesias over lateral leg and dorsum of foot with weakness in dorsiflexion of foot
What is superficial peroneal nerve entrapment?
Spinal level-L4, L5, S1
Common nerve that pierces the deep fascia in the lateral side of leg approx. 8-10 cm proximal to the ankle joint. Splits into medial and intermediate dorsal cutaneous nerve. Branches are very superficial on the dorsum of the foot.
What are the areas of injruy for superficial peroneal nerve entrapment
- Trunk injury
- Medial dorsal cutaneous nerve
- Intermediate dorsal cutaneous nerve
Describe deep peroneal nerve entrapment (anterior tarsal tunnel)
Spinal level-L4, L5, S1
Can be referred to as anterior tibial nerve) Nerve crosses the ankle joint between Extensor Hallucis Longus and Extensor Digitorum Longus, also lies in close proximity to Extensor Digitorum Brevis muscle. Nerve lies deep to the extensor retinaculum.
Two terminal branches: Medial and Lateral
- Medial ends at the first intermetatarsal space
- Lateral ends on the lesser tarsus
What can cause deep peroneal nerve entrapment?
Sight of injruy is just distal to the ankle joint
Compression for tight shoes ***
Cavus foot exposes the nerve to compression
Compression for overactive Extensor Digitorum Brevis
Describe sural nerve entrapment
Spinal level-L5, S1, S2
Courses parallel to the Achilles tendon in the lateral leg, its continuation in the foot becomes the Lateral Dorsal Cutaneous nerve.
What are the sites of injury in sural nerve entrapment?
- Sural-lateral posterior leg occurs from chronic tendonitis of the Achilles that can compress the nerve or from scarification following Achilles or Peroneal tendon surgery.
- Lateral Dorsal Cutaneous Nerve-in the foot can be entrapped following 5th metatarsal fracture, can be scarified after lateral ankle surgery.
What is tibial nerve (tarsal tunnel) entrapment?
Spinal levels- L4, L5, S1, S2, S3
Areas of injury
- Deep to the laciniate ligament (flexor retinaculum), four basic structures traverse this area: Tom, Dick and very nervous Harry (Tibialis Anterior, Flexor Digitorum Longus, Tibial Nerve and vessels, and flexor Hallucis Longus)
- Injuries to any of the structures in this compartment can put pressure on the nerve causing compression entrapment.
What are the symptoms of tibial nerve (tarsal tunnel) entrapment?
Symptoms include: pain and paresthesias at the ankle. Tapping on the nerve may cause tingling at the site of tapping. (Tinel’s sign) Tingling may also be felt proximal and distal to the site of tapping (Villioux sign).
How do you treat space occupying lesions?
Space occupying lesions should be excised
How do you treat ganglionic cysts?
Ganglionic cysts can be aspirated or excised
How do you treat inflammation?
Reduce inflammation through non-steroidal anti-inflammatory medicine and steroid injections.
How do you treat scar tissue?
- Mobilization with physical therapy
- Intralesional steroid injection
- Surgical scar revision with lysis of adhesions
How do you treat vena comitans
- Compression stockings
- Surgical ligation
How do you treat a biomechanical problem?
- Functional orthosis
- Surgical release of offending compartment (tarsal tunnel-laciniate ligament)
Describe the treatment of tibial nerve entrapment
- Do not use sclerosis therapy
- Motor components in the nerve, so you would have major issues (atrophy, contraction, less functional)
Sclerosis would NOT be appropriate
What is Morton's neuroma?
Most common entrapment neuropathy experienced in the foot
What are the types of causes of Morton's neuroma?
Describe biomechanical causes of Morton's neuroma
Pronated foot placing stretch on plantar nerves.
Describe anatomical causes of Morton's neuroma
*** Medial and Lateral plantar nerves extend communicating branches that contribute to the third interspace that naturally enlarges the branch to the third interspace.
Describe systemic causes of Morton's neuroma
Inflammatory disorders of the lesser metatarsal joints that place compression on the interdigital nerves.
What are the signs of a Morton's neuroma?
- Numbness tingling to third and fourth toes with pinching pain under the ball of the foot.
- Positive Mulder’s click to the third interspace. (compressing the nerve between the 3rd and 4th metatarsal that produces a “click”
What is the treatment for Morton's neuroma?
- Metatarsal pad placed behind the metatarsal to “lift and separate”
- Therapeutic cortisone injections
- Sclerosing injections
- Surgical Excision