MSK Session 10 - Nerve injuries of the Lower Limb & Cancer and The Skeleton Flashcards
Understand the arrangements and structures in a peripheral nerve as well as the structure of a nerve cell.
What are the consequences of nerve injuries?
- Loss of function –motor, sensory and proprioception
- Neuroma formation leading to pain
Have an understanding of the Seddon classification of nerve injuries:
Class I - Neurapraxia
- This is the mildest type of nerve injury and is a temporary physiological block of conduction in the affected axons without loss of axonal continuity.
- The endoneurium, perineurium and epineurium are also intact and there is no Wallerian degeneration.
- Conduction is intact in the distal segment and proximal segment of the nerve but no conduction occurs across the area of injury.
- Hence, there is sensory and motor dysfunction distal to the site of injury.
- Full recovery of the nerve conduction will occur over a period of days to weeks.
Have an understanding of the Seddon classification of nerve injuries:
Class II - Axonotmesis
- This involves loss of continuity of the axons and their myelin sheath, but the endoneurium, perineurium and epineurium are preserved.
- Wallerian degeneration occurs within 3-4 days distal to the site of injury.
- However, axonal regeneration then occurs and recovery is usually possible without surgical intervention.
- Axonal regeneration proceeds at a rate of 1-4 mm/day; hence the time to recovery depends on the distance from the site of injury to the target organ
Have an understanding of the Seddon classification of nerve injuries:
Class III - Neurotmesis
- This is either a partial or complete division of the axons, endoneurium, perineurium and epineurium of a nerve fibre.
- Wallerian degeneration occurs distal to the site of injury within 3-4 days and the sensory, motor and autonomic defects are severe.
- Surgical intervention is always necessary as, even in an incomplete division, the deposition of scar tissue between the divided fascicles precludes regeneration.
Identify the nerve supply to the lower limbs.
- Femoral nerve and branches
- Sciatic nerve and branches
- Obturator nerve, superior gluteal nerve
What are the causes of neuropathy?
- Injury-stretch of nerve, complete division
- Extrinsic pressures: tumour, abscess, etc.
- Medical conditions
I. Diabetes
II. Alcohol excess
III. Drugs
- Other rarer causes: nerve tumours, etc.
Have an understanding of the specific regions each nerve of the lower limb innervates.
Understand the consequences of prolapsed intervertebral disc
Outline Piriformis Syndrome
- Sciatica symptoms not originating from spinal roots and/or spinal disc compression, but involving the overlying piriformis muscle
- Overuse of muscle leads to spasm
- Diagnosis of exclusion and treatment is mostly about activity modificatio
Outline Meralgia paraesthetica
- Compression of the lateral cutaneous nerve of the thigh as it passes through the inguinal ligament or as it pierces the fascia lata
- Causes include obesity (compression by abdominal fat), pregnancy, tight clothing, wearing a tool belt
- Burning or stinging sensation in the distribution of the nerve over the anterolateral aspect of the thigh
I. This is aggravated by walking or standing
II. This is relieved by lying down with the hip flexed
- Tenderness on palpation, reduced sensation; possibly a positive Tinel’s sign
- Diagnosis is confirmed by the absence of motor signs and by excluding pelvic and intra-abdominal causes of irritation such as a tumour
- Corsets and tight belts should be avoided
- Local nerve blocks may be beneficial
- Surgical interventions should be restricted to freeing the nerve; division may aggravate the original symptoms.
Outline femoral nerve injury
Outline the motor effects of the injury of the femoral nerve
Outline tibial nerve injury
Outline common peroneal nerve injury
Outline superficial peroneal nerve injury
Outline saphenous nerve injury
Outline sural nerve injury
