Peripheral Nerve Lesions Flashcards
Obturator nerve lesion presentation and risk factors
-History of obstetric/gynaecological procedure/ anterior hip dislocation
-Pain, numbness, and weakness in distribution of obturator nerve
-Weakness of hip/thigh adduction and internal rotation
-Preservation of other L2-L4-innervated muscles (e.g., quadriceps)
-Numbness over proximal medial thigh, groin, or pubic bone
RISK FACTORS: patient positioning during total hip replacement, childbirth, pelvic trauma, exercise
Obturator nerve lesion investigation and management
-Investigation: EMG (neurogenic changes in thigh adductors), nerve conduction velocity (normal), MRI (atrophy in adductors)
-Management: neuropathic pain relief, physical therapy, surgical decompression
Femoral nerve lesion presentation and risk factors
-Pain and weakness in leg when walking
-Buckling of the knee resulting in falls
-Numbness and paraesthesia may involve anterior thigh and/or medial calf (L2-L4)
-History of diabetes mellitus
-Weakness and wasting of quadriceps muscle and absence of knee-jerk reflex (knee extension, thigh flexion)
-Possible atrophy
-Normal hip adduction
-Numbness in distribution of saphenous nerve
-Risk factors: trauma, traction during operation, spontaneous haematoma. Hip and pelvic fractures, stab/gunshot wounds
Investigation of femoral nerve lesion
-EMG (neurogenic changes in affected myotomes)
-Nerve conduction velocity (reduced saphenous sensory amplitude)
-MRI of pelvis/ inguinal region (positive if compressive lesion)
-CT scan to exclude retroperitoneal haematoma
Management of femoral nerve lesion
-Pain relief (neuropathic)
-Exercises
-Avoidance of excessive external rotation and abduction of the hip with knee bracing
-Treat underlying cause
-Improves slowly in absence of aggravation.
Overview of musculocutaneous nerve
-C5-C7
-Motor: elbow flexion (supplies biceps brachii) and supination
-Sensory: lateral part of forearm
-Mechanism: isolated injury rare- usually injured as part of brachial plexus injury
Presentation of axillary nerve lesion
-C5, C6
-Flattened deltoid usually due to humerus neck fracture/ dislocation
-Loss of function of deltoid (inability to initiate abduction of arm): shoulder abduction
-Loss of sensation over small area of skin on lateral aspect of upper arm (inferior region of deltoid)
Diagnosis and management of axillary nerve lesion
-Diagnosis: X-ray of broken bones, MRI of damage to nerve and surrounding soft tissues
-Management: physical therapy to maintain flexibility across the shoulder joint, splint in abduction of the shoulder
Presentation of radial nerve lesion
-SATURDAY NIGHT PALSY
-C5-8
-Wrist drop due to humeral midshaft fracture.
-Often precipitated by sleeping in abnormal posture, e.g. arm over back of chair.
-Weakness in extension (forearm, wrist, fingers, thumb)
-Sensory loss over dorsum of thumb/ 1st and 2nd metacarpals
Diagnosis and management of radial nerve lesion
-Diagnosis: EMG and nerve conduction studies: isolated radial neuropathy and localised site of lesion to spiral groove
-Management: splint or pain medicine, physical therapy, nerve block, surgical decompression
Presentation of ulnar nerve lesion
-C8, T1
-Claw hand due to medial epicondyle fracture.
-Paraesthesia on medial border of hand
-Wasting and weakness of hand muscles (all small hand muscles excluding abductor pollicis brevis), weakness of wrist flexion
-Sensory loss medial palm and little finger, medial half of 4th finger.
Diagnosis and management of ulnar nerve lesion
-Diagnosis: EMG and nerve conduction studies- slow and conduction block
-Management: occupational therapy to strengthen ligaments and tendons in hands and elbows, NSAIDs, splints
Presentation of median nerve lesion
-C6, C8, T1
-Carpal tunnel syndrome (if wrist)
-Pain and paraesthesia on palmar aspect of hands, fingers, waking patient from sleep, may extend to arm and shoulder.
-Abductor pollicis brevis and Opponens pollicis weakness (ape hand deformity)
-Wrist= paralysis of thenar muscles Opponens pollicis/ elbow= loss of pronation of forearm and weak wrist flexion
-Sensory loss lateral palm and thumb, index, middle and lateral half of 4th finger.
Diagnosis and management of median nerve lesion
-Diagnosis: Electrophysiology: motor and sensory: prolongation of action potential
-Management: 6-week trial of conservative treatments (symptoms mild to moderate) of corticosteroid injection, wrist splints at night. If severe, surgical decompression (flexor retinaculum division)
Overview of long thoracic nerve
-C5-C7
-Often during sport- following blow to ribs
-Possible complication of mastectomy
-Winged scapula
