T2 L13. Lower limb nerve injuries and compression syndrome (RC)(2).ppt

Lower Limb Nerve Injuries and Compartment Syndrome Dr Rebecca Cooper Consultant Neurologist Slides adapted from presentation prepared by Dr Romi Saha Learning Objectives • Nerve roots, cauda equina, lumbar and sacral plexus • Common patterns of lower limb nerve injury • Differential diagnosis of f...

Lower Limb Nerve Injuries and Compartment Syndrome Dr Rebecca Cooper Consultant Neurologist Slides adapted from presentation prepared by Dr Romi Saha Learning Objectives • Nerve roots, cauda equina, lumbar and sacral plexus • Common patterns of lower limb nerve injury • Differential diagnosis of foot drop • Common causes of peripheral neuropathy • Diagnosis and management of compartment syndrome Organisation of Lower Limb nerves Cauda equina vs conus lesions Upper motor neuron L1/2 Lower motor neuron Landmarks for lumbar puncture Cauda equina vs conus medullaris Symptom Cauda equina Conus medullaris Pain severity Radicular More severe Less severe Location of pain Unilateral/ asymmetric Perineum, thighs, and legs. Bilateral Perineum, thighs Sensory disturbance Saddle Unilateral/ asymmetric Bilateral saddle distribution Motor loss Asymmetric, Atrophy Symmetric Reflexes Ankle and knee reduced Ankle only reduced Bowel/bladder Late Early Sexual function Impaired – less severe Impaired – more severe Causes • Compressive: • Disc herniation, epidural abscess, spinal epidural haematoma, diskitis, tumour, spinal fracture • Non-compressive: • Spinal cord infarction, spinal arteriovenous malformation • Inflammatory conditions • Eg Multiple sclerosis, Chronic Inflammatory Demyelinating Polyradiculopathy, Sarcoidosis • Infection • Eg HIV, VZV, CMV, HSV, EBV, Lyme, TB L5/S1 disc herniation compressin g cauda equina Nerve Root Entrapment – ‘sciatica’ CompressionDisc- 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) Lower Limb Root Lesions - reflex and sensory loss Lower limb dermatomes more variable than upper limb 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 Knee jerk L4 Ankle jerk S1 Lower Limb Innervation Action Muscle Nerve Root Hip flexion Iliopsoas Femoral nerve L1/2 + nerve roots Hip extension Gluteus maximum Inferior gluteal L5/S1 Knee extension Quadriceps Femoral L3/4 Knee flexion Hamstrings Sciatic S1 Ankle dorsiflexion Tibialis anterior Deep peroneal L4/5 (fibular) Ankle plantar flexion Gastrocnemi us/soleus Tibial nerve S1/2 Ankle inversion Tibialis posterior Tibial nerve L4/5 Ankle eversion Peroneus longus and brevis Superficial peroneal (fibular) L5/S1 Hallux Extensor Deep peroneal L5 Lumbar plexus Sacral plexus Lumbosacral Plexus Lesions • Direct trauma • Eg posterior hip disolation, sacral fracture • Pregnancy related • Post-operative • Eg haematoma • Metabolic/inflammatory • Eg Diabetic and non-diabetic LS radiculoplexopathy; sarcoid • Infection • Eg HIV, Lyme disease, TB, psoas abscess • Malignancy • Vascular lesion • Eg femoral vessel catheterisation; aortic dissection 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 Femoral / Lateral Cutaneous Nerves 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) Difficulty standing from seated Up stairs, knee buckling Sensory loss Femoral N. Saphenous (sensory branch of femoral n.) Femoral N. damage Surgery Gynae procedures, esp hysterectomy, femoral a. bypass/ puncture) Sciatica Pain in distribution of the sciatic nerve Common term that often more accurately describes nerve root entrapment (usually L5 / S1) Sciatic nerve or its branches supply all muscle groups other than those innervating hip flexion, knee extension and hip adduction Sciatic N. 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) Sciatic nerve injuries AEITIOLOGY: Trauma Hip dislocation Acetabular fracture Iatrogenic causes Direct surgical trauma Positioning during anaesthesia Injection injuries Radiation Tourniquets 2 compartments of sciatic N. Beware Partial sciatic n. damage can look like Common peroneal or Tibial n. damage Sciatic Nerve Major Divisions Tibial Nerve- Behind knee 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. In the popliteal fossa the nerve gives off branches to gastrocnemius , popliteus, soleus and plantaris, and the sural nerve. Sural nerve Sural Nerve – superficial, sensory Nerve biopsy Common Peroneal Nerve May be damaged by tight plaster casts, leg crossing, prolonged squatting Multiple colloquial names eg Strawberry picker’s palsy, slimmer’s palsy Sensory loss -dorsum of foot and outer aspect lower leg Weakness of -dorsiflexion and eversion of foot Neurogenic Foot drop • Upper motor neuron (brain/ spinal cord) • Conus • L4/L5 • Cauda equina • Sacral plexus • Sciatic n. • Common peroneal n. Lower Limb Innervation Action Muscle Nerve Root Hip flexion Iliopsoas Femoral nerve L1/2 + nerve roots Hip extension Gluteus maximum Inferior gluteal L5/S1 Knee extension Quadriceps Femoral L3/4 Knee flexion Hamstrings Sciatic S1 Ankle dorsiflexion Tibialis anterior Deep peroneal L4/5 (fibular) Ankle plantar flexion Gastrocnemi us/soleus Tibial nerve S1/2 Ankle inversion Tibialis posterior Tibial nerve L4/5 Ankle eversion Peroneus longus and brevis Superficial peroneal (fibular) L5/S1 Hallux Extensor Deep peroneal L5 Polyneuropathy • Polyneuropathy – generalised relatively homogeneous process affecting many peripheral nerves with the distal nerves affected most prominently. • Peripheral neuropathy – refers to any disorder of the peripheral nervous system including radiculopathies and mononeuropathies Length dependent polyneuropathy • Common causes (Toxic/metabolic) • • • • • Diabetes Alcohol B12 deficiency Chemotherapy Idiopathic • Also – genetic; inflammatory • Clinical symptoms • Numbness, paraesthesia, weakness • Pain Non-length dependent polyneuropathy Guillain Barre syndrome • Named after French Neurologists in 1916 • 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 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 Neuronopathy Site of damage to cause sensory neuronopathy Site of damage to cause motor neuronopathy Polyradiculopathy • Affects multiple nerve roots. • Causes: • Spinal stenosis: Cervical, lumbar • Cancer: Leptomeningeal metastases • Infection: Lyme, HIV, Types of peripheral neuropathies Compartments of the leg What is compartment syndrome? Increase in pressure within a myofascial compartment which has limited ability to expand, leading to compromised circulation and function of tissues within that space May be acute or chronic Acute compartment syndrome is a surgical emergency Where does CS occur? Commonest sites: Leg Forearm But also Hand Foot Thigh Gluteal region Why leg in particular ? Causes of Acute Compartment Syndrome Traumatic injuries: Fractures, especially long bones (1-10% tibial fractures) Burns, crush injury, penetrating trauma, animal bites/stings, vascular injury, rhabdomyolysis from extreme exercise Non-traumatic injuries: Rhabdomyolysis from extreme exercise Anticoagulation/Haemophilia Nephrotic syndrome Ischaemia-reperfusion injury – eg revascularisation surgery; prolonged limb compression Myositis – infective (eg GpA Strep), inflammatory IV drug use Consequence of CS 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 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 Acute posterior CS 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 ?  Pain! (out of proportion to the original injury)  Pain +++ on passive stretching  Tense limb  Distal neurologic compromise  Reduced senation  Muscle weakness paralysis  Pallor/Reduced distal pulses Investigations Clinical suspicion is all important - serial assessments in ‘at risk’ patients Measuring of intra-compartmental pressures can be useful Creatine kinase (CK) of 1000-5000 U/mL Myoglobinuria Raised lactate 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 Treatment of compartment synd. Complications of mismanagement 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 Delayed Fasciotomy Learning Objectives • Nerve roots, cauda equina, lumbar and sacral plexus • Common patterns of lower limb nerve injury • Differential diagnosis of foot drop • Common causes of peripheral neuropathy • Diagnosis and management of compartment syndrome The End