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204: The Musculoskeletal System > Lower limb nerve injuries and compartment syndrome > Flashcards

Lower limb nerve injuries and compartment syndrome Flashcards

1
Q

Pain severity

A

Cauda equina

  • radicular
  • more severe

Conus medullaris
- less severe

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2
Q

Location of pain

A

Cauda equina

  • unilateral/ asymmetric
  • perineum, thighs and legs

Conus medullaris

  • bilateral
  • perineum, thighs
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3
Q

Sensory disturbance

A

Cauda equina

  • saddle
  • unilateral/ asymmetric

Conus medullaris
- bilateral saddle distribution

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4
Q

Motor loss

A

Cauda equina

  • asymmetric
  • atrophy

Conus medullaris
- symmetric

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5
Q

Reflexes

A

Cauda equina
- ankle and knee reduced

Conus medullaris
- ankle only reduced

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6
Q

Bowel/ bladder

A

Cauda equina
- late

Conus medullaris
- early

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7
Q

Sexual function

A

Cauda equina
- impaired- less severe

Conus medullaris
- impaired- more severe

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8
Q

Causes of pain

A

Cauda equina
- disc herniation, spinal fracture, tumours

Conus medullaris

  • disc herniation, tumour
  • inflammatory conditions (chronic inflammatory demyelinating, polyradiculopathy, sarcoidosis)
  • infection (CMV, HSV, EBV, lyme, TB)
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9
Q

Nerve root entrapment- ‘sciatica’

A

Compression

  • disc: posterior central, lateral
  • bone: osteophyte
  • ligaments
  • small canal: stenosis

Sciatica- usually L5, S1 nerve root impingement

Pain may be felt in dermatome (sharp/ superficial) or myotome (deep ache)

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10
Q

Lower limb root lesions- reflex and sensory loss

A

Lower limb dermatome more variable than upper limb

L1 inguinal area
L2 front of thigh
L3 front of knee
L4 from- inner/ medial leg
L5 outer leg, dorsum of foot, inner sole
S1 little toe, rest of sole, back of leg
S2 thigh to top of buttock
S3-5 concentric rings around anus/ genitalia

Knee jerk L4
Ankle jerk S1

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11
Q

Lower limb root lesions- weakness

A

L1/2- hip flexion

L3/4- knee extension

L4- foot inversion

L5- knee flexion, ankle dorsiflexion, toe extension, foot inversion and eversion

S1- knee flexion, ankle plantar flexion, toe flexion, foot eversion

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12
Q

Lumbosacral plexus lesions

A

Childbirth (large head, prolonged labour)- esp obturator, numbness inner thigh, pudendal nerve

Structural

  • haematoma
  • abscess
  • malignancy
  • trauma

Non structural

  • inflammatory
  • diabetes
  • vasculitis
  • radiotherapy
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13
Q

Femoral nerve organisation

A

Hip flexors, iliopsoas affected if proximal damage (above inguinal ligament)

Only knee extension if below inguinal ligament

Distal lesion may produce a pure motor or pure sensory syndrome

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14
Q

Femoral/ lateral cutaneous nerves

A 
Femoral nerve weakness
Hip flexion
Knee extension
Loss of knee jerk
Can't do stairs

Sensory loss- femoral nerve

Saphenous (sensory branch of femoral nerve)

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15
Q

Femoral nerve damage

A

Surgery

Gynae procedures, esp hysterectomy, femoral artery bypass/ puncture

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16
Q

Sciatica

A

Pain in sciatic nerve distribution

Nerve root entrapment (usually L5/S1)

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17
Q

Differential diagnosis of sciatica

A

Hip- pain may radiate, not below knee

Sacroiliac joints

18
Q

Causes of sciatica

A

Trauma

Haematoma

Rarely sciatic nerve compression

Misplaced IM injections

19
Q

Piriformis syndrome

A

Controversial as to whether muscle compression can cause tingling in buttock and down leg

Probably may rarely occur in those with anatomical predisposition

Diagnosis of exclusion

20
Q

Sciatic nerve injury

A

Apart from hip flexion, knee extension, hip adduction

Scaitic nerve or its branches are motor to virtually all other muscle groups in the leg

Isolated hip fracture- sciatic nerve
Pelvic/ sacral fracture- sacral plexus

21
Q

Tibial nerve- behind knee

A

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

Causes

  • trauma: haemorrhage
  • bakers cyst
  • nerve tumour
  • antrapment by the tendinous arch at the soleus muscle
22
Q

Tibial nerve- lower leg/ ankle

A

Sole pain worse standing/ walking

Not heel pain

Differential morton’s neuroma

23
Q

Common peroneal nerve

A

May also be damaged by tight plaster casts, leg crossing, weight loss (slimmers palsy)

Sensory loss- dorsum of foot and outer aspect of lower leg

Weakness of- dorsiflexion and eversion of foot

24
Q

Neurogenic foot drop

A

Upper motor neuron

Conus

L4/L5

Cauda equina

Sacral plexus

Sciatic nerve

Common peroneal nerve

25
Q

Polyneuropathy

A

Generalised relatively homogenous process affecting many peripheral nerves with the distal nerves affected most prominently

26
Q

Length dependent polyneuropathy

A

Common causes

  • diabetes
  • alcohol
  • B12 deficiency
  • chemotherapy
  • idiopathic

Clinical symptoms

  • numbness, paraesthesia, weakness
  • pain
27
Q

Guillain barre syndrome

A

Acute inflammatory demyelinating polyneuropathy

Immune response to a preceding infection

Rapidly progressive weakkness including limbs, facial, respiratory and bulbar muscles

Absent reflexes

28
Q

Neuronopathy

A

Form of polyneuropathy

Disorders that affect specifically population of neurons

Motor neuropathy

  • sites of damage: anterior horn cell
  • causes: ALS, polio

Sensory neuronopathy

  • site of damage: dorsal root ganglion
  • causes: sjogrens syndrome, paraneoplastic
29
Q

Polyradiculopathy

A

Affects multiple nerve roots

Causes

  • spinal stenosis: cervical, lumbar
  • cancer: leptomeningeal metastases
  • infection: lyme, HIV
30
Q

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- shin splints

Manage with RICE

31
Q

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

32
Q

Where does compartment syndrome occur?

A

Any limb compartment

Commonest

  • lower leg
  • forearm
33
Q

What causes compartment syndrome?

A

Fractures (1-6% tibial fractures)

Crush injuries

Burns

Electric shock

Fluid injection

Drugs

Disease

External causes

34
Q

Consequences of compartment syndrome- physiology

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 ischaemia

35
Q

Consequences of compartment syndrome- pathology

A

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

Certain tissues are more sensitive than other and this can be a clue to diagnosis

36
Q

Acute anterior compartment syndrome leg

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

Depp peroneal nerve
- sensation to the first dorsal web space

37
Q

Acute posterior compartment syndrome leg

A

Superficial posterior

Plantar flexors of foot

  • gastrocnemius
  • plantaris
  • soleus

Sural nerve
- sensation to lateral aspect of the foot and distal calf

38
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

39
Q

Investigations for compartment syndrome

A

Measuring of intra-compartmental pressures can be useful

Creatine kinase of 1000-5000 U/ml

Myoglobinuria

40
Q

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

204: The Musculoskeletal System (23 decks)

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