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.
What are the two types of plexopathy?
Brachial plexopathy
Lumbosacral plexopathy
What does Brachial plexopathy cause?
Weakness, sensory loss, and loss of tendon reflexes in body regions innervated by nerves in the C5-T1 distribution.
What does lumbar plexopathy cause?
Weakness, sensory loss and reflex changes in the distribution of spinal segments L1-L4.
- hence weakness in obturator and femoral innervated territories
What is sacral plexopathy?
Causes same abnormalities in segments L5-S3
- weakness and sensory loss in gluteal (motor only). peroneal and tibial nerve territories.
What are some causes of brachial plexus?
Direct injury to the nerve.
Stretching injuries (birth trama)
Pressure from tumors in area.
Damage resulting from radiation therapy.
What is brachial neuritis?
Common cause of brachial plexopathy.
aka neuralgic amyotrophy or Parsonage-Turner syndrome.
- one form inherited, one form idiopathic
What is atrophy?
When muscles are weak, muscle tissue can be lost.
What is radiculopathy?
‘pinched nerve in spin’
set of conditions in which one or more nerves are affected and do not work properly.
- can result in pain (radicular pain), weakness, numbness or difficulty controlling specific muscles
What are the different types of radiculopathy?
- Cervical
- when nerve in neck or upper back compressed - Thoracic
- nerve compression in mid back - Lumbar
- nerve compression in lower part of back
What are some generalised symptoms of radiculopathy?
Sharp pain in back extending to foot.
Sharp pain with sitting or coughing.
Numbness / weakness in left and foot.
Sensation or reflex changes.
State some examples of genetic polyneuropathy?
- Charcot-Marie-Tooth Disease
- Distal hereditary motor neuropathy
- Familial amyloid polyneuropathy
What is Charcot-Marie Tooth disease and state some symptoms?
Group of inherited conditions that damage the peripheral nerves.
- muscle weakness in feet, ankles, legs and hands
- awkward gait
- highly arched or flat feet
- numbness in feet, arms and hands
What is the name given to the foot abnormality of having a high arch?
Pes Cavus
What is Distal hereditary motor neuropathy (type V) ?
Progressive disorder affecting nerve cells in spinal cord.
Results in muscle weakness, affects movement of hands and feet.
- atrophy of muscles of hand
- pes cavus
- gait disturbance
What is familial amyloid polyneuropathy?
Rare, inherited and progressive.
Caused by abnormal deposits of proteins (amyloid) around peripheral nerves and other tissues.
What are the causes of FAP? TEEHEE
- Mutations in TTR gene.
- TTR - instructions for protein important for transproting vit A and thyroxine.
- Mutatant TTR protein forms amyloid deposits in tssues (heart, nerves, kidneys, eyes)
- These build up and lead to damage of affected organs.
Describe aquired axonal polyneuropathy?
Typical onset >70s
Usually painful
- nocturnal burning feet
Define radicular neuropathy?
Associated with acute onset of severe back pain that radiates to leg and arms
Describe Guillain-Barre syndrome?
In affected patients:
- cross reactive auto-antibodies attack host’s own axonal antigens
- results in inflammatory and demyelinating polyneuropathy.
What is chronic demyelinating polyneuropathy?
Caused by inflammation of nerves and nerve roots.
Swelling can destroy myelin.
Causing weakness, pain, fatigue and numbness
Compare and contrast CIDP with GBS?
Both - nerve problems - cause weakness, numbness GBS - comes on days or weeks after person has illness (stomach bug) - patients usually recover when treated CIDP - not linked with illness - longer term problem
Describe small fiber neuropathy?
Occurs when small fibers of peripheral nervous system are damaged.
- small fibers in skin relay info about pain and temp.
- in these organs small fibers regulate automatic functions such as heart rate and breathing
What symptoms does small fiber neuropathy cause?
Sensory symptoms
- pain, burning, tingling or prickling (paresthesia)
Often start in feet and progress up body.
In some cases, small fiber neuropathy disrupts autonomic functions. Give examples of symptoms?
Constipation Difficulty sweating Dizziness Dry eyes Dry mouth Incontinence Sexual dysfunction Skin discoloration
Describe paraproteinaemic neuropathy?
Presence of excessive amounts of abnormal immunoglobulin or monoclonal proteins in blood produced by a single clone of plasma cells.
What are paraproteins?
Immunoglobulins produced in excess by an abnormal clonal proliferation of B-lymphocytes or plasma cells.
- Relevant paraproteins associated with IgM more than IgG or IgA.
What is amyloidosis?
Name for a group of rare, serious conditions caused by a build up of abnormal protein (amyloids) in organs and tissues.
What does paraneoplastic mean?
Syndrome (set of signs and symptoms) that is a consequence of cancer in body.
Group of uncommon disorders that develop in some people who have cancer.
