T2 L18:Lower Limb Nerve Injuries and Compartment Syndrome Flashcards
what is the difference between a Cauda equina vs conus lesion
1)The conus medullaris is the terminal end of the spinal cord, which typically occurs at the L1 vertebral level in the average adult.[1] Conus medullaris syndrome (CMS) results when there is compressive damage to the spinal cord from T12-L2
The cauda equina is a group of nerves and nerve roots stemming from the distal end of the spinal cord, typically levels L1-L5 and contains axons of nerves that give both motor and sensory innervation to the legs, bladder, anus, and perineum.[2] Cauda equina syndrome (CES) results from compression and disruption of the function of these nerves and can be inclusive of the conus medullaris or distal to it, and most often occurs when damage occurs to the L3-L5 nerve roots
where is lumbar puncture performed
it is performed between L3 and L4
name some differences between cauda equina lesions and conus medullaris
Pain severity in cauda equina is radicular and more severe
location of pain in cauda equina is unilateral/asymmetric in the perineum, thighs and legs but in the Conus medullaris it is bilateral in the perineum and thighs
sensory disturbance in the cauda equina is saddle and unilateral but in Conus medullaris its bilateral saddle distribution
reflexes in the cauda equina that are affected are ankle and knee but in Conus medullaris ankle only is reduced
bowel/bladder in cauda equina is late but in Conus medullaris its early
sexual function in the cauda equina is impaired ad less severe but in Conus medullaris it’s impaired and more severe
what are causes of lesions in the cauda equina
Disc herniation, spinal fracture and tumours
in the Conus medullaris : -disc herniation, tumour and inflammatory conditions- ie- Chronic Inflammatory Demyelinating Polyradiculopathy • Sarcoidosis
also infection- CMV, HSV, EBV, Lyme, TB
give a common area of herniation casing compression of cauda equina
L5/S1 herniation
describe nerve entrapment Sciatica
Compression- Disc- posterior central, lateral Bone- osteophyte Ligaments Small canal- stenosis
Sciatica – usually L5, S1 n. root impingement
L5 n. root – exits between L5/ S1 vertebral bodies S1 n. root exits between S1 / S2 vertebral bodies
Pain may be felt in dermatome (sharp/ superficial) or myotome (deep ache)
describe the lower limb dermatomes
L1 inguinal area L2 front of thigh (front pocket) L3 front of knee L4 front- 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 (back pocket) S3-S5 concentric rings round anus/ genitalia
describe the dermatomic reflexes
Knee jerk L4 Ankle jerk S1
describe where the lower limb root lesions occur and their corresponding weaknesses
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
go over lumbar and sacral plexus
how was it
describe the aetiology of Lumbosacral Plexus Lesions
Childbirth (large head, prolonged labour)- esp obturator n., numbness inner thigh, pudendal n.
Structural – Haematoma (on Warfarin) – Abscess – Malignancy – infiltration – Trauma
Non structural – Inflammatory, – Diabetes – Vasculitis – Radiotherapy
describe ow lesions affect femoral nerve organisation
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
describe femoral/lateral cutaneous nerve damage and pic
Femoral N. Weakness Hip flexion (iliacus) Knee Extension Loss of Knee Jerk Can’t do stairs
Sensory loss Lat Cut. N. Thigh (relief if seated)
Sensory loss Femoral N.
Difficulty standing from seated Up stairs, knee buckling
Saphenous (sensory branch of femoral n.)
describe the surgical procedures that lead to Femoral nerve injury
Gynae procedures, esp hysterectomy, femoral a. bypass/ puncture)
describe the aetiology of sciatica
Pain in sciatic n. distrib
Nerve root entrapment (usually L5 / S1)
Differential diagnosis: Hip – pain may radiate not below knee Sacroiliac joints
Causes: Trauma, Haematoma Rarely sciatic nerve compression per se (Piriformis synd) Or misplaced IM injections
what is piriformis syndrome
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
what occurs in sciatic nerve injury
Apart from Hip flexion Knee extension Hip adduction
Sciatic nerve or its branches, are motor to virtually all other muscle groups in the leg
Isolated Hip fracture – sciatic n. Pelvic/ sacral fracture – sacral plexus)
2 compartments of sciatic nerves
Beware Partial sciatic n. damage can look like Common peroneal or Tibial n. damage
look over major divisions of sciatic nerves
how was it
describe the tibial nerve -behind knee lesions
Can’t stand on tiptoes Weak foot inversion Painful numb sole
Causes: Trauma: Haemorrhage Bakers cyst Nerve tumour Entrapment by the tendinous arch at the soleus muscle.
what muscles are effected by tibial nerve injury
- tibialis posterior
- Flexor digitorum longus
- Flexor hallucis longus
Intrinsic foot muscles
Sole pain worse standing/ walking Not heel pain Differential Morton’s neuroma
describe sural nerve location
how was it
describe the effects of lesions to the common peroneal nerve
May also be damaged by tight plaster casts, leg crossing, Weight loss- slimmers palsy
Sensory loss -dorsum of foot and outer aspect lower leg
Weakness of -dorsiflexion and eversion of foot
describe the neurogenic foot drop
Upper motor neuron
(brain/ spinal cord)
Conus
L4/L5
Cauda equina Sacral plexus Sciatic n.
Common peroneal n.
describe Polyneuropathy
– generalised relatively homogeneous process affecting many peripheral nerves with the distal nerves affected most prominently.
describe peripheral neuropathy
refers to any disorder of the peripheral nervous system including radiculopathies and mononeuropathies
describe length dependent polyneuropathy
Common causes (Toxic/metabolic) – Diabetes – Alcohol – B12 def – Chemotherapy – Idiopathic
Clinical symptoms – Numbness, paraesthesia, weakness
– Pain
describe the non-length dependent polyneuropathy
Guillain Barre syndrome :
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
describe neuronopathy
Form of polyneuropathy
Disorders that affect specifically population of neurons.
Motor neuronopathy
– Site of damage: Anterior horn cell
– Causes: ALS, Polio
Sensory neuronopathy
– Site of damage : Doral root ganglion
– Causes: Sjogrens syndrome, Paraneoplastic
describe neuronopathy
Site of damage to cause sensory neuronopathy - dorsal root ganglion
Site of damage to cause motor neuronopathy -motor neuron in spine
describe polyradiculopathy
Affects multiple nerve roots. Causes:
– Spinal stenosis: Cervical, lumbar
– Cancer: Leptomeningeal metastases
– Infection: Lyme, HIV,
Types of peripheral neuropathies
neuronopathy
polyneuropathy
poly(radiculopathy)
describe shin splints
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)
describe compartment syndrome
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
where does compartment syndrome (CS) occur
Any limb compartment Commonest Lower leg Forearm
Also Hand Foot
leg in particular
what causes CS
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
what are the consequences of CS-physiology
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
Consequence of CS - pathology
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
what is injured in Acute anterior CS leg
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
where does acute posterior CS occur in the leg
Superficial posterior :
Plantar flexors of foot
- Gastrocnemius -Plantaris
- Soleus
Sural nerve -Sensation to lateral aspect of the foot and distal calf
what are the signs of acute posterior CS leg
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
what investigations can be done for CS
Clinical suspicion is all important
Measuring of intra-compartmental pressures can be useful
Creatine kinase (CK) of 1000-5000 U/mL
Myoglobinuria
management of acute CS
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
how does Treatment of compartment synd
fasciotomy procedure- incision in skin and fascia to release pressure
vessels are no longer compressed; capillaries are functional
what are the Complications of mismanagement of CS
If fasciotomy is performed within 25-30 hours following onset of acute CS, the prognosis is good Little or no return of function can be expected when diagnosis and treatment are delayed
Rhabdomyolysis - Renal Failure
Limb Loss
