1. Peripheral nerve (Lower extremity)
Yohei Harada, PGY2
Neurology
09/12/2017

2. Objectives
To understand the anatomy of peripheral nerve in lower extremity
To understand the function of each peripheral nerve in lower extremity
To understand the exam/test of peripheral nerve disorder in lower extremity

3. Lumbosacral plexus
Lumbar plexus nerves
Lower lumbosacral plexus

4. Lumbar plexus nerves Formed from L1-4 roots
Has several important nerves

5. Femoral nerve Root: L2-4 Plexus: lumbar plexus
Muscle: Hip flexion (Psoas, iliopsoas), Knee extension (sartorius, pectineus, quadriceps femoris muscles)
Branch: saphenous nerve

6. Femoral nerve
Sensory distribution of femoral nerve
Saphenous nerve

7. Clinical signs of femoral neuropathy
Buckling of the knee
Difficulty lifting up the thigh
Sensory disturbance may be seen over the medial and anterior thigh and the medial calf
1 Where in the thigh sensory is spared?

8. Clinical signs of femoral neuropathy
Buckling of the knee
Difficulty lifting up the thigh
Sensory disturbance may be seen over the medial and anterior thigh and the medial calf
1 Where in the thigh sensory is spared?
Lateral thigh (lateral femoral cutaneous nerve)
Proximal medial thigh (obturator nerve)
Posterior thigh (posterior cutaneous nerve of thigh)

9. Clinical signs of femoral neuropathy
Buckling of the knee
Difficulty lifting up the thigh
Sensory disturbance may be seen over the medial and anterior thigh and the medial calf
2 How about reflex?

10. Clinical signs of femoral neuropathy
Buckling of the knee
Difficulty lifting up the thigh
Sensory disturbance may be seen over the medial and anterior thigh and the medial calf
2 How about reflex?
Reduced/Absent knee reflex

11. Causes of femoral neuropathy
Surgical complications
Retraction during surgery
THA (sciatic neuropathy is the most common)
Lithotomy position

12. Causes of femoral neuropathy
Surgical complications
Retraction during surgery
THA (sciatic neuropathy is the most common)
Lithotomy position

13. Causes of femoral neuropathy
Surgical complications
Retraction during surgery
THA (sciatic neuropathy is the most common)
Lithotomy position

14. Less commonly….

15. How do we test?
NCS; technically feasible, but not common. Difficult to cancel noise
EMG; which muscle?

16. How do we test?
NCS; technically feasible, but not common. Difficult to cancel noise
EMG; which muscle?
Vastus lateralis or medialis
Iliopsoas

17. Obturator nerve

18. Obturator nerve Root; L3 Plexus; Lumbar plexus
Muscle; Hip adduction (Adductor longus, magnus, gracillis)
Sensory; medial proximal thigh

19. Lateral femoral cutaneous nerve
What is the name of neuropathy?

20. Meralgia paresthetica
Symptoms - burning pain, numbness, decreased sensation over the anterolateral thigh

21. Meralgia paresthetica
Symptoms - burning pain, numbness, decreased sensation over the anterolateral thigh
Causes – entrapment/compression due to obesity, pregnancy, tight belt, bicycling

22. Meralgia paresthetica
Symptoms - burning pain, numbness, decreased sensation over the anterolateral thigh
Causes – entrapment/compression due to obesity, pregnancy, tight belt, cycling

23. Meralgia paresthetica
Also, diabetes is the important cause. Doubles the risk.

24. Meralgia paresthetica
Diagnosis – clinical diagnosis (sensory distribution, Tinel’s sign)
How to differentiate from L3-4 radiculopathy?

25. Meralgia paresthetica
Diagnosis – clinical diagnosis (sensory distribution, Tinel’s sign)
How to differentiate from L3-4 radiculopathy?
Doesn’t affect below knee!

26. Meralgia paresthetica
Diagnosis – NCS

27. Meralgia paresthetica
Treatment
Neuropathic pain meds (gabapentin, lyrica, etc)
Ultrasound guided nerve block

28. Lower lumbosacral plexus
Sciatic nerve
Superior gluteal nerve
Inferior gluteal nerve

29. Sciatic nerve Root: L4-S3 Plexus: lower lumbosacral plexus
Reflex: ankle jerks
Muscle: knee flexion (medial and lateral hamstrings)
Becomes common peroneal and tibial nerves at mid-thigh

30. Sciatic nerve Sensory distribution of sciatic nerve
Both peroneal and tibial distribution (including sural nerve)
Spares saphenous nerve distribution

31. Sciatic nerve Peroneal nerve Tibial nerve Both
Which nerve is affected by sciatic neuropathy?
Peroneal nerve
Tibial nerve
Both

32. Sciatic nerve Peroneal nerve Tibial nerve Both
Which nerve is affected by sciatic neuropathy?
Peroneal nerve
Tibial nerve
Both
3. However…
Initially, peroneal nerves are preferentially affected in sciatic nerve lesion.

33. Causes of sciatic neuropathy
Common causes
Hip or Femur fracture
THA
Gun shot wounds
Tumor (neurofibroma, schwannoma, neurofibrosarcoma, lipoma, lymphoma…etc)

34. Let’s create a case This is a sciatic neuropathy case.
A 52 yo woman was referred for evaluation of 6 months history of left foot drop. She initially felt numbness over ( where? ). This was shortly followed by left foot dropping. Most recently, she noted a sensation of tightness and pain from ( where? ) to ( where? ).

35. Clinical presentation of sciatic neuropathy
This is a sciatic neuropathy case.
On exam, left ankle dorsiflexion was 1/5 on MRC scale, (weak or strong? ) on ankle eversion. Ankle inversion was (weak or strong?). Toe extension was (weak or strong?). Hip abduction was (weak or strong?). Knee flexion was (weak or strong?). Reflexes were normal except for ( which? ). There was sensory disturbance to light touch on ( where? ).
Of note, there was a well healed surgical scar over the left lateral thigh.

36. Might be a bit too complicated until understanding peroneal and tibial.

37. Common peroneal Root: L4-S1 Plexus: Lower lumbosacral plexus
Divides into superficial peroneal and deep peroneal

38. Deep peroneal Branches out from common peroneal and goes medially.
Muscles: dorsiflexion of ankle and toes (TA, EHL, EDB)
Sensory: web space between 1st and 2nd toes

39. Superficial peroneal
Muscle: Ankle eversion (peroneus longus, peroneus brevis)
Sensation: mid and lower lateral calf

40. Tibial nerve Root: L5-S1 Plexus: lower lumbosacral plexus
Motor: Plantar flexion (AHB, gastrocnemius), Inversion (tibialis posterior), Toe spreading (Abductor digiti quinti pedis)
Mnemonic; TIP= Tibial Inverts and Plantarflexes, if injured, cannot stand on TIP toes

41. Tibial nerve Sensory distribution of tibial nerve
Tarsal tunnel syndrome
Sural nerve

42. Sural nerve
Sensory nerve to the lateral calf, ankle, foot and heel (pink area)
Root; S1-2
Emerges from the junction of the medial sural cutaneous with lateral sural cutaneous nerve

43. Sural nerve biopsy

44. Superior/Inferior gluteal nerve
Superior gluteal nerve – Hip abduction (gluteus medius, tensor fasciae latae)
Inferior gluteal nerve – Hip extension (gluteus maximus)

45. Let’s create a case This is a sciatic neuropathy case.
A 52 yo woman was referred for evaluation of 6 months history of left foot drop. She initially felt numbness over ( where? ). This was shortly followed by left foot dropping. Most recently, she noted a sensation of tightness and pain from ( where? ) to ( where? ).
the top of the foot and the lateral calf, from her hip down to her knee and into her calf

46. Clinical presentation of sciatic neuropathy
This is a sciatic neuropathy case.
On exam, left ankle dorsiflexion was 1/5 on MRC scale, (weak or strong? ) on ankle eversion. Ankle inversion was (weak or strong?). Toe extension was (weak or strong?). Hip abduction was (weak or strong?). Knee flexion was (weak or strong?). Reflexes were normal except for ( which? ). There was sensory disturbance to light touch on ( where? ).
Of note, there was a well healed surgical scar over the left lateral thigh.
Weak, weak, weak, strong, weak, left ankle, the top of the foot, lateral foot and calf, lateral knee, and posterior calf on the left side

47. thanks