Lower limb nerve injuries and compression syndromes Flashcards

1
Q

Where is the conus medularis?

A

L1/L2

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2
Q

What is found below the conus medularis?

A

Cauda equina

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3
Q

Where are lumbar punctures taken?

A

Below L3

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4
Q

Describe the severity of cauda equina pain

A

Radicular

More severe

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5
Q

Describe the severity of conus medularis pain

A

Less severe

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6
Q

Give the location of the cauda equine pain

A

Unilateral/asymmetric Perineum, thighs, and legs.

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7
Q

Give the location of conus medularis

A

Bilateral Perineum, thighs

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8
Q

Describe the sensory disturbance of the cauda equina

A

Saddle Unilateral/asymmetric

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9
Q

Describe the sensory disturbance of the conus medularis

A

Bilateral saddle distribution

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10
Q

Describe the motor loss of cauda equina

A

Asymmetric and atrophy

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11
Q

Describe the reflexes of cauda equina

A

Ankle and knee reduced

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12
Q

Describe the reflexes of conus medularis

A

Ankle only reduced

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13
Q

Describe the bowel and bladder in cauda equina

A

Late

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14
Q

Describe the bowel and bladder in conus medularis

A

Early

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15
Q

Describe sexual function in cauda equina

A

Impaired - less severe

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16
Q

Describe sexual function in conus medularis

A

Impaired - more severe

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17
Q

List some causes of cauda equina

A

Disc herniation

Spinal fracture

Tumour

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18
Q

List some causes of conus medularis

A

Disc herniation

Tumour

Inflammatory conditions

Infections

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19
Q

List some inflammatory conditions which may cause conus medularis

A

Chronic inflammatory demyelinating
Polyradiculopathy
Sarcoidosis

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20
Q

List some infections which may cause conus medularis

A
CMV
HSV
EBV
Lyme 
TB
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21
Q

Describe sciatica

A

Compression- Disc- posterior central, lateral Bone- osteophyte Ligaments Small canal- stenosis

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22
Q

Which nerve roots is sciatica usually?

A

L5,S1

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23
Q

Where is the L5 nerve root?

A

Between L5 and S1 vertebral bodies

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24
Q

Where is the S1 nerve root?

A

Between S1 and S2 vertebral bodies

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25
Q

Where may pain be felt in sciatica?

A

Dermatome (sharp/superficial)

Myotome (deep ache)

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26
Q

What is the L1 dermatome?

A

Inguinal area

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27
Q

What is the L2 dermatome?

A

Front of thigh (front pocket)

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28
Q

What is the L3 dermatome?

A

Front of knee

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29
Q

What is the L4 dermatome?

A

Front-inner/medial leg

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30
Q

What is the L5 dermatome?

A

Outer leg, dorsum of the foot, inner sole

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31
Q

What is the S1 dermatome?

A

Little toe, rest of sole, back of leg

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32
Q

What is the S2 dermatome?

A

Thigh to top of buttock (back pocket)

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33
Q

Where are the S3-S5 dermatomes?

A

Rings around anus and genitalia

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34
Q

Which spinal level is the knee jerk reflex?

A

L4

35
Q

Which spinal nerve is the ankle jerk reflex?

A

S1

36
Q

Which action does L1/2 do?

A

Hip flexion

37
Q

Which action does L3/4 do?

A

Knee extension

38
Q

Which action does L4 do?

A

Foot inversion

39
Q

What action does L5 do?

A

Knee flexion
Ankle dorsiflexion
Toe extension
Foot inversion and eversion

40
Q

What action does S1 do?

A

Knee flexion
Ankle plantar flexion
Toe flexion
Foot eversion

41
Q

List the causes of lumbosacral plexus lesions

A

Childbirth
Structural
Non structural

42
Q

List some structural causes of lumbosacral plexus lesions

A

Haematoma (on Warfarin
Abscess
Malignancy – infiltration
Trauma

43
Q

List some non-structural causes of lumbosacral plexus lesions

A

– Inflammatory
– Diabetes
– Vasculitis
– Radiotherapy

44
Q

What would be affected in proximal femoral nerve damage?

A

Hip flexors, Iliopsoas

45
Q

What would be affected of a lesion in the femoral nerve below the inguinal ligament

A

knee extension

46
Q

How can the femoral nerve be damaged?

A

Surgery Gynae procedures, esp hysterectomy, femoral a. bypass/ puncture

47
Q

What may be the cause of sciatica

A

Trauma
Haematoma Rarely sciatic nerve compression per se (Piriformis synd)
misplaced IM injection

48
Q

Describe piriformis syndrome

A

Controversial as to whether muscle compression per se can cause tingling in buttock and down leg (eg after exercise or straining, or prolonged sitting)

Probably may rarely occur in those with anatomical predisposition.

No consensus on criteria Diagnosis of exclusion

49
Q

What can partial sciatic nerve damage look like?

A

Common peronal or Tibial nerve damage

50
Q

Where is the tibial nerve located?

A

Behind the knee

51
Q

What actions cant be performed after tibial nerve damage?

A

Can’t stand on tiptoes
Weak foot inversion
Painful numb sole

52
Q

List some causes of tibial nerve damage

A

Trauma: Haemorrhage
Bakers cyst
Nerve tumour
Entrapment by the tendinous arch at the soleus muscle.

53
Q

Where does the tibial nerve branch?

A

Popliteal fossa

54
Q

Name the branches of the tibial nerve

A

gastrocnemius, popliteus, soleus and plantaris, and the sural nerve.

55
Q

What passes through the tarsal tunnel?

A

tibialis posterior, flexor digitorum longus, flexor hallucis longus

Intrinsic foot muscles

56
Q

Give some symptoms of tarsal tunnel syndrome

A

Sole pain worse standing/ walking

Not heel pain

57
Q

What would be a differential for tarsal tunnel?

A

Differential Morton’s neuroma

58
Q

How may the common peronal nerve be damaged?

A

May also be damaged by tight plaster casts, leg crossing, Weight loss- slimmers palsy

59
Q

Give the sensory loss of damage to the common peronal nerve

A

dorsum of foot and outer aspect lower leg

60
Q

What weakness would result from damage to the common peronal nerve?

A

dorsiflexion and eversion of foot

61
Q

List the nerves which could be affected in neurogenic foot dropo

A
Upper motor neuron (brain/ spinal cord) 
Conus  
L4/L5  
Cauda equina  
Sacral plexus  
Sciatic n.  
Common peroneal n.
62
Q

What is polyneuropathy?

A

generalised relatively homogeneous process affecting many peripheral nerves with the distal nerves affected most prominently.

63
Q

What is peripheral neuropathy?

A

Refers to any disorder of the peripheral nervous system including radiculopathies and mononeuropathies

64
Q

List some common causes of length dependent polyneuropathy

A
– Diabetes 
– Alcohol 
– B12 def 
– Chemotherapy 
– Idiopathic
65
Q

List the symptoms of length dependent polyneuropathy

A

– Numbness, paraesthesia, weakness

– Pain

66
Q

Describe Guillian barre syndrome

A

Also known as Acute inflammatory demyelinating polyneuropathy 

Immune response to a preceding infection 

Rapidly progressive (days to weeks) weakness
including limbs, facial, respiratory and bulbar muscles 
Absent reflexes

67
Q

Give the site of damage for motor neuropathy

A

Anterior horn cell

68
Q

Give the causes of motor neuropathy

A

ALS, Polio

69
Q

Give the site of damage for sensory neuropathy

A

Doral root ganglion

70
Q

Give the causes of sensory neuropathy

A

Sjogrens syndrome, Paraneoplastic

71
Q

What does polyradiculopathy affect?

A

Affects multiple nerve roots

72
Q

What are the causes of polyradiculopathy?

A

– Spinal stenosis: Cervical, lumbar
– Cancer: Leptomeningeal metastases
– Infection: Lyme, HIV

73
Q

Describe shin splints

A

Muscle bulk increases 20% during exercise and contributes to the transient increase in intracompartmental pressure

Anterior and lateral compartments of the lower leg are commonly affected Generally causes pain on and post exercise- AKA Shin Splints

Manage with RICE (rest / cooling – ice

74
Q

What is compartment syndrome?

A

Increase in pressure within a myofascial compartment which has limited ability to expand
May be acute or chronic
Acute compartment syndrome is a surgical emergency

75
Q

Where does compartment syndrome occur?

A

Any limb compartment Commonest Lower leg Forearm

Also Hand Foot

76
Q

What causes compartment syndrome?

A
Fractures (1-6% Tibial Fractures) 
Crush Injuries 
Burns 
Electric Shock 
Fluid Injection
 Drugs • Warfarin/other anticoagulants • Anabolic Steroid use • Iv drug use 
Disease • Haemophilia 
External Causes • Tight splints/casts • Tourniquet
77
Q

What are the consequences of compartment syndrome?

A

Tissue perfusion is proportional to the difference between the capillary perfusion pressure and the interstitial fluid pressure

elevated compartment pressure causes muscle and nerve ischemia

Untreated, within 6-10 hours, the final result is muscle infarction, tissue necrosis, and nerve injury

Certain tissues are more sensitive than others and this can be a clue to diagnosis Sensory nerves

78
Q

Describe acute anterior compartment syndrome

A

Dorsiflexion muscles of ankle and foot Tibialis anterior, Extensor digitorum longus Extensor hallucis longus, Peroneus tertius Anterior tibial artery Commonly injured in lateral tibial plateau fractures Deep peroneal nerve Sensation to the first dorsal web space

79
Q

Describe aute posterior compartment syndrome

A

uperficial posterior Plantar flexors of foot Gastrocnemius Plantaris Soleus Sural nerve Sensation to lateral aspect of the foot and distal calf

80
Q

What are the signs of compartment syndrome?

A

Pain! (out of proportion to the original injury)  Pain +++ on passive stretching  Tense limb  Decreased function of the compartment muscles  Distal neurologic compromise  Reduced distal pulses

81
Q

What investigations are carried out in compartment syndrome?

A

Clinical suspicion is all important

Measuring of intra-compartmental pressures can be useful

Creatine kinase (CK) of 1000-5000 U/mL Myoglobinuria

82
Q

Describe the management of acute compartment syndrome

A

Genuine confirmed CS is an emergency

Often surgery is required Aim is to lay open the myofascial compartment and diminish intra-compartmental pressure

However don’t forget to look for external causes Tight casts/ splints Dressings

83
Q

What can be some complications of mismanagement of compartment syndrome?

A

Little or no return of function can be expected
when diagnosis and treatment are delayed
Rhabdomyolysis - Renal Failure
Limb Loss

84
Q

When must the fasciotomy be performed for a good prognosis?

A

If fasciotomy is performed within 25-30 hours
following onset of acute CS, the prognosis is
good