Chapter 45 - Neurologic complications Flashcards
Blood supply to the nerve
1) vasa nervorum
2) diffusion
Time threshold for irreversible nerve injury
6-10 hours (in animals)
Ischemic monomelic neuropathy
No axonal degeneration and demyelination
Altered flow through vasa nervorum cause acute conduction block
persistence –> distal axonal infarction
Chronic ischemic neuropathy vs acute pathology
pathogenesis appears to be the same
Neurapraxia definition
transient nerve dysfunction
Common causes of unilateral neuropathy
1) entrapment
2) trauma
3) ischemia
4) vasculitis
Common causes of bilateral neuropathy
1) metabolic (diabetes, uremia)
2) toxic (alcohol, drugs, metal)
3) connective tissue disease, vasculitis
4) deficiency (vitamin)
5) inflammatory
6) monoclonal gammopathies
7) HIV infection
Ischemic neuropathy in lower extremity presentation
1) unilateral sensory loss - stocking distribution; especially vibration
2) ankle weakness
3) depressed ankle reflex
Distal latency and velocity of conduction in ischemic neuropathy vs diabetic and uremic neuropathy
well preserved in ischemic neuropathy
reduced in a symmetrical bilateral way in diabetic/uremic neuropathy
Sensory nerve in ischemic neuropathy
Absent sensory potential amplitude but velocity is normal
First line treatment for pain control - ischemic neuropathy
1) TCA
2) SSRI
3) Calcium channel alpha-2 delta (Gabapentin, pregabalin)
Peripheral nerves matched to nerve roots
Axillary - C5, C6 Musculocutaneous nerve - C5, C6 Median nerve C5-T1 Radial C5-C8 Ulnar C8, T1
Nerve injury during axillary artery exposure
Cords of the brachial plexus
Nerve injury during brachial artery exposure
Median nerve
Ulnar nerve
Nerve injury from positioning
Ulnar nerve
Nerve injury during basilic vein exposure
ulnar nerve
rate of Nerve injury during brachial artery catheterization
0.2-1.4%
HD access causing IMN most likely with what type of AVF
Brachial artery use
Consequence of axillary nerve injury
weakness of shoulder abduction
sensory deficit over deltoid
Median nerve injury consequences
sensory deficit in D1-3 and radial aspect of D4
weakness in thenar muscle
weakness on flexor of digit and wrist
Consequences of ulnar nerve injury
numbness in D5 and ulnar aspect of D4
weakness of hypothenar muscle
weakness in abduction and adduction of all digits and flexion of D4, D5
Consequences of injury to radial nerve
weakness of wrist and finger extension
Lumbosacral nerves and correlated nerve roots
Lateral femoral cutaneous nerve L2-L3 Femoral nerve L2-L4 Obturator nerve L2-L4 Posterior femoral cutaneous nerve S1-S3 Sciatic nerve L4-S3 Common peroneal L4-S2 Tibial nerve L4-S3
Blood supply to lumbosacral plexus
5 sets of paired lumbar arteries from abdominal aorta, deep circumflex iliac and iliolumbar and gluteal branches of IIA
Rate of lumbosacral plexus injury after open aortic work
0.3%
Course of the femoral nerve
Femoral nerve –> saphenous nerve
Blood supply of the femoral nerve
iliolumbar artery
deep circumflex iliac
lateral circumflex femoral
Symptoms of femoral nerve injury
1) paresis/paralysis of quadriceps
2) diminished/absent extension of knee
3) reduced/absent patellar reflex
4) loss of sensation along saphenous nerve
Origin of the thigh cutaneous nerves
Medial - femoral
anterior - femoral
lateral - lumbosacral plexus
Course of the saphenous nerve
1) subfascial plane along SFA
2) proximal popliteal fossa: more superficial and penetrates fascia to accompany GSV
3) course with GSV to ankle
Course of the sural nerve
1) from tibial nerve in popliteal fossa below fascia
2) descends laterally to SSV in groove between medial and lateral heads of gastrocnemius
3) communicating branch from peroneal nerve joins in mid calf
4) exists fascia down towards lateral malleolus
Rate of saphenous nerve sensory loss with GSV harvest below knee
60%
12.5% for endoscopic harvest
Rate of sural nerve injury in SSV endoablation thermo
4%
Symptoms of saphenous nerve injury
1) decreased sensation to anteromedial calf and ankle
2) parethesia
3) dysesthesia
Symptoms of sural nerve injury
dysesthesia in posterior calf/lateral ankle
Course of the sciatic nerve
1) posterior portion of midthigh into common peroneal and tibial nerve
2) Tibial nerve accompanies popliteal artery through pop fossa
3) continues distally with posterior tibial neurovascular bundle
4) terminates in medial and lateral plantar nerves (parallel to PT artery)
2) common peroneal nerve takes a lateral course from posterior aspect of midthigh
3) crosses knee joint posterior to fibular head
4) wraps proximal fibula
5) divides into superficial and deep peroneal nerve
6) superficial peroneal runs deep to fascia in lateral compartment
7) extends to foot alone
6) deep peroneal nerve enters anterior compartment
7) descends along intermuscular septum accompanies anterior tibial artery
Rate of peroneal nerve injury in SSV harvest
4.7%
Consequence of PT nerve injury
1) weak plantar flex of ankle and toes
2) absent ankle jerk
3) sensory loss sole and lateral aspect of foot
Consequence of peroneal nerve injury
1) weak dorsiflex, invert and evert ankle
2) weak dorsiflex of toes
3) sensory loss in dorsal foot and toes extend to lateral calf
