46: Entrapment Neuropathies - Drown

Question 1

peripheral n. anatomy

Answer 1

Question 2

review LE dermatomes

Answer 2

Question 3

review LE dermatomes

Answer 3

Question 4

seddon’s classification

Answer 4

neurotmesis (nerve division)

axonotmesis (lesion in continuity)

neuropraxia (transient block)

Question 5

describe neurotmesis

Answer 5

• most devastating n injury
• complete disruption of n as well as associated connectie tissue
• budding neurites unable to bridge defect
• requires surgical intervention

Question 6

describe axonotmesis

Answer 6

• axonal disruption
• supportive connective tissue maintained
• can be due to: prolonged compression, traction, ischemia, toxins
• distal: wallerian degeneration/distal axon degradation
• proximal: axon and n cell body convert from NT production to axonal regeneration
• as distance from site of lesion to end organ increases, functional recovery diminishes

Question 7

describe neuropraxia

Answer 7

• disruption of myelin sheath
• short lived paralysis develops
• repair in days to months (full recovery)

Question 8

sunderland’s classification

Answer 8

1st degree: conduction deficit w/o axonal interruption (neuropraxia)

2nd degree: axon severed w/o breaching endoneurium (axonotmesis)

3rd degree: lesion in endoneurium, epineurieum and perineuriem remain intact

4th degree: only epineurium remains intact

5th degree: complete transection of n

Question 9

entrapment neuropathy involving the tibial n

Answer 9

tarsal tunnel syndrome

• involves entrapment of tibial n or one of its terminal branches

Question 10

anatomy of tarsal tunnel

Answer 10

• fibro-osseous canal
• posterior to medial malleolus

borders

• anterior: tibia
• lateral: posterior process talus and calcaneus
• medial: flexor retinaculum (lacinate ligament)

Question 11

3 terminal branches of tibial n

Answer 11

medial plantar n

lateral plantar n

medial calcaneal n

Question 12

s/s tarsal tunnel syndrome

Answer 12

• cc diffuse plantar pain or medial ankle pain
• pain aggravated by standing and relieved with rest
• pain may radiate proximally to the calf

Question 13

common causes tarsal tunnel syndrome

Answer 13

• space occupying lesion (ganglion, lipoma, varicosities, neurilemoma)
• exostosis or fracture fragments
• hindfoot varus or valgus (decreases volume w/i tarsal tunnel –> increase pressure on tibial n)
• talo-calcaneal coalition
• accessory m w/i canal (accessory soleus or FDL)

Question 14

tinel vs. villeix sign

Answer 14

tinel = pain radiating distal (shooting pain alon gthe course of MPN and LPN)

villeix = pain radiating proximal

ask “what do you feel”

Question 15

diagnostic criteria tarsal tunnel syndrome

_***********_

Answer 15

1. history of neurtic symptoms
2. positive tinel sign
3. supporting NCV studies

• If none of above criteria is met then diagnosis should be excluded
• If one of above criteria is met then other diagnosis should be considered
• If all three criteria is met and symptoms are reproducible then diagnosis is considered

Question 16

indications for tarsal tunnel syndrome surgery

Answer 16

space occupying lesions or failed conservative treatment

Question 17

entrapment of the common plantar digital n occupying the 3rd interspace

Answer 17

morton’s neuroma

Question 18

causitive factors morton’s neuroma

Answer 18

• Transverse metatarsal ligament
• Narrower innerspace between 3rd and 4th metatarsals
• Increased mobility between 3rd and 4th rays
• Tethering of nerve beneath metatarsal heads during dorsiflexion when ambulating

Question 19

s/s morton’s neuroma

Answer 19

• medial-lateral squeeze
• focal tenderness to deep palpation
• positive mulder’s click
• complaints of anesthesia to neighboring toes