L10 - Diseases of Peripheral nerves Flashcards
- Understand the clinical syndromes that localise to the peripheral nervous system - mononeuropathy, multiple mononeuropathy, polyneuropathy, plexopathy and radiculopathy with examples - Understand the subtypes of polyneuropathy - acute or chronic, demyelinating or axonal, large fibre or small fibre, sensory, motor or autonomic. - Learn about the range of pathological processes that affect the peripheral nerves - genetic, inflammatory, toxic, metabolic (eg diabetes).
What is mononeuropathy?
Damage to a single nerve, which results in loss of movement, sensation etc.
- often nerve outside brain and spinal cord (peripheral neuropathy)
Describe how pressure on a nerve may result in mononeuropathy?
- Longterm pressure on nerve due to swelling / injury.
- Myelin sheath or axon damaged.
- Damage slows / prevents signals from traveling through the damaged nerves.
State some common forms of mononeuropathy?
- Axillary nerve dysfunction (loss of movement or sensation in shoulder)
- Common peroneal nerve dysfunction
(m/s loss in foot and leg) - Carpal tunnel syndrome (median nerve dysfunction)
What may a femoral nerve dysfunction involve?
mononeuropathy
Femoral nerve
- Hip flexion and knee extension
- gives rise to saphenous nerve
Loss of movement or sensation in part of leg
What may a radial nerve dysfunction involve?
mononeuropathy
Problems with movement in arm and wrist and with sensation in the back of the arm or hand.
What may sciatic nerve dysfunction involve?
mononeurpathy
Sciatic
- Hip extension and knee flexion
Problems with the muscles of the back of the knee and lower leg.
Sensation to back of thigh, part of lower leg and sole of foot.
What is cubital tunnel syndrome?
Ulnar nerve dysfunction.
- numbness, tingling, weakness of outer and underside of arm, palm, ring and little fingers.
Describe multiple mononeuropathy?
Simultaneous malfunction of two or more peripheral nerves in separate areas of the body.
Describe polyneuropathy?
Affects many nerves, usually in about the same areas on both sides of the body.
- acute
- chronic
What are some common causes of multiple mononeuropathy?
- Diabetes.
- BV diseases
- Vasculitis, Polyarteritis nodosa - Connective tissue diseases
- Rheumatoid arthritis.
What is sarcoidosis?
less common cause of multiple mononeuropathy
Disease in which inflammation occurs in the lymph nodes, lungs, liver, eyes, skin.
Granulomas (clusters of immune cells) form in certain organs.
What is Sjogren syndrome?
less common cause of multiple mononeuropathy
Disorder in which glands producing tears and saliva are destroyed
Describe some causes of acute polyneuropathy? (3)
- infections involving a toxin produced by bacteria (diphtheria)
- autoimmune reaction (Guillain-Barre syndrome)
- organophosphate insecticides
Describe examples of causes for chronic polyneuropathy?
- Diabetes
- Excessive use of alcohol
- b12 deficency
- underactive thyroid
- kidney failure
How may b12 deficiency cause chronic polyneuropahty?
B12 deficiency causes
- subacute combined degeneration of the spinal cord.
B12 needed for formation and maintenance of myelin sheath.
Describe diabetic neuropathy?
refers to some forms of polyneuropathy that diabetes can cause. (can also cause mononeuropathy or multiple mononeuropathy)
- leads to weakness, typically of eye or thigh muscles.
Sciatic nerve gives rise to what two nerves?
- Common peroneal nerve
- ankle dorsiflexion and eversion - Tibial nerve
- ankle plantarflexion and inversion
What is plexopathy?
Disorder affecting a network of nerves, BV or lymph vessels.
Affects nerves at bracial or lumbosacral plexus.