Week 4 - B - Peripheral Neuropathy (includes GBS and Charcot Marie Tooth disease)

Question 1

Approach to peripheral nerve problems Which nerves are damaged? Where are they damaged? How are the nerves damaged? Why are the nerves damaged? Can we stop the nerves from being damaged? What does the peripheral nervous system encompass?

Answer 1

Encompasses the nerves and ganglia outside of the brain and spinal cord

Question 2

Which cranial nerves are not considered part of the peripheral nervous system?

Answer 2

Cranial nerve II is considered part of the CNS instead of PNS

Question 3

What is the difference between a peripheral neuropathy and a radiculopathy?

Answer 3

Radiculopathy - a condition in which one or more spinal nerve roots are affected Peripheral neuropathy is when a peripheral nerve is affected

Question 4

What is the most common cause of a radiculopathy?

Answer 4

Most common cause of a radiculopahy is due to a bulging/herniated disc compressing a spinal nerve root

Question 5

Peripheral neuropathy also includes the autonomic nervous system Give an example of an immune condition that causes automic neuropathy?

Answer 5

Diabetic autonomic neuropathy - this affects the autonomic nervous system

Question 6

What is the function of the autonomic nervous system and describe how symptoms here may present?

Answer 6

ANS keeps the heart pumping and the body digesting Diabetic autonomic neruopaty can cause easy fatigue, irregular heartbeat, gastroparesis (can cause a neausea and sickness)

Question 7

The majority of motor and sensory nerves have myelin and as they get smaller and smaller tend to become unmyelinated If the very large myeinated motor fibres are affected, what symptoms are present? If the large sensory fibres are affeted by neuropathy, what symptoms?

Answer 7

Large myelinated motor fibres affected by peripheral neuropathy - weakness, unsteadiness, wasting Large sensory fibres - numbness, parasthesia (pins and needles), unsteadiness

Question 8

What are the types of nerve fibre that regulate pain and temperature? IS their conduction velocity fast? DO these fibres have a thick or thin diameter? WHat tract regulates pain and temperature? which other sensory modality does it regulate?

Answer 8

C - fibres are unmeylinated nerve fibres regulating pain and temperature sensation * As they are un-myelinated they have a low conduction velocity (ie hand in a fire, takes a second before pain is realised) & they have a thin diameter * Type Adelta fibres - also mediate pain&temp - are thin and thinly myelinated SPinothalamic tract regulates pain and temperature (also crude touch and pressure) - Anterior spinothalamic - crude touch and pressure, lateral - pain and temperaturre

Question 9

What is the type of gait seen in people with peripheral neuropathy?

Answer 9

High stepping gait - Bilateral foot drop

Question 10

WHy is there a foot drop in people with peripheral neuropathy? Is it usually unilateral or bilateral?

Answer 10

In people with peripheral neuropathy there is a problem with the peripheral nerves that supply the dorsiflexors of the foot therefore the foot plantarflexes when walking hence the drop The foot drop seen is normally bilateral

Question 11

What is the nerve root that supplies the dorsiflexors of the ankle?

Answer 11

The L5 nerve root supplies the dorsiflexors of the ankle - therefore tis nerve is usually affected

Question 12

What is the main muscles that brings about dorsiflexion of the ankle? What nerve supplies the anterior compartment of the leg? What would be the likely cause of a unilateral foot drop?

Answer 12

Tibialis anterior - anterior compartment of leg - supplied by the deep fibular nerve Likely cause of a unilateral foot drop would be a radiculopathy at L5 level

Question 13

Radiculopathy occurs in the nerve roots Which root is for sensory information and which for motor information? Where do the roots join to form the spinal nerve?

Answer 13

The anterior rootlets and roots carry motor informatioon The posterior rootlets and roots relay sensory information to the spinal cord The anterior and posterior roots join at the intervertebral foramen to form the spinal nerve

Question 14

What are the three different types of peripheral neuropathy?

Answer 14

Mononeuropathy Mononeuritis multiplex Length dependent peripheral neuropathy

Question 15

Mononeuropathy describes a condition in which only a single nerve or nerve group is damaged. This condition negatively affects the part of the body associated with that nerve or nerve group, causing a loss of sensation, movement, or function in that part of the body. Mononeuropathy can affect any part of the body. What is one of the more common forms of mononeuropathy?

Answer 15

Carpal tunnel syndrome - this is when the median nerve is compressed in the carpal tunnel of the hand

Question 16

What can carpal tunnel syndrome cause? When is carpal tunnel syndrome sometimes seen not so much as a result of pathology?

Answer 16

Can cause numbeness, weakness and paraesthesia to where the median nerve supplies distal to the carpal tunnel Seen in pregnant women bilaterally sometimes

Question 17

What is the usual cause of mononeuritis multiplex?

Answer 17

People who have a vasculitic disease (can also occur in people with diabetes and connective tissue diseases)

Question 18

What are the are small arteries that provide blood supply to peripheral nerves. These vessels supply blood to interior parts of nerves and their coverings.? These are the arteries that help causes mononeuritis multiplex in people

Answer 18

These arteries are referred to as the vasa nervorum

Question 19

What is the most common cause of length dependent mononeuropathy? Does it usually present asymmetrically or symmetrically?

Answer 19

Mot common cause is diabetes Length dependent mononeuropathy usually presents symmetrically

Question 20

When two or more (typically just a few, but sometimes many) separate nerves in disparate areas of the body are affected it is called - A - Length dependent peripheral neuropathy (polyneuropathy) B - Mononeuritis multiplex

Answer 20

B - mononeuritis multiplex

Question 21

Length dependent mononeuropathy is generally described as being a glove and stocking distribution WHat does this mean?

Answer 21

This means that first the sensation from the knee downwards is lost - stocking as these are the longest length of nerves in the body By the time the loss of sensation reaches the knee, the length of nerves in the arm are the same as the ones reaching the knee and therefore sensation in the upper limb extremeties begins - gloves

Question 22

Does the sensory loss come before the motor loss in glove and peripheral neuropathy or not? IS lenght dependent peripheral neuropathy symmetrical or not?

Answer 22

Usually the snrsory loss (numbness, paraesthesia (pins and needles)) come first before the weakness arises This is a symmetrical distribution in this type of peripheral neuropathy

Question 23

In the events of a plyneuropathy or moneoneuropathy, what is a sinister diagnosis?

Answer 23

This would be motor neuron disease

Question 24

What is seen in this picture? Which dermatome is affected? What could be the potential causes of this?

Answer 24

Can see wasting of the thenar eminence here - supplied by median nerve C6 dermatome is affected - Long standing carpal tunnel syndrome Radiculopathy ie a cervical rib More sinister is MND

Question 25

What would preferential wasting of the thenar eminence compared to the wasting of the hypotenar eminence as seen in motor neurone disease be known as?

Answer 25

The split hand sign, which is because of dissociated muscle weakness in the hands (thenar muscles disproportionately wasted as compared to the hypothenar muscles) is a useful clinical sign for bed side diagnosis of ALS.

Question 26

What type of peripheral neuropathy would this be? IF presented with wrist drop or foot drop which nerves woul be affected?

Answer 26

This is mononeuritis multiplex Wrist drop - this would be the radial nerve Foot drop - common peroneal nerve

Question 27

What are the nerve roots of the radial nerve?

Answer 27

C5 - T1

Question 28

What is the most important demylinating neuropathy?

Answer 28

Guillain Barre Syndrome

Question 29

Does guillain Barre syndrome muscle weakness ascend or descend? Does myasthenia muscle weakness begin cranially or caudally? Does lambert eaton begin cranially or cadually? (just thrown these two in here)

Answer 29

Guillainn Barre synrome muscle weakness is ascending MG is a descending muscle grups affected - post synpatic ACh receptors are attacked LEMS - Ascending muscles groups affected - presynaptic voltage gated Ca2+ channels affected

Question 30

Guillain Barre Syndrome is an acute inflammatory demyleinating polyneuropathy causing disease What is the typical presentation of Guillain Barre Syndrome?

Answer 30

A few weeks after an infection a symmetrical ascending muscle weakness starts There is a progressive weakness of all 4 limbs accompanied by areflexia

Question 31

What are typical infection triggers to Guillain barre sydrome? (name 2)

Answer 31

Camplobacter jejuni is the most common cause of GBS Mycoplasma pneumoniae can also trigger it

Question 32

In GBS, how long does the progressive paraplegia occur over before recovery?

Answer 32

Progressive paraplegia occurs over days to 4 weeks - peaks is usually around the 2 week period

Question 33

10% of patients with guillain barre sydrome die form autonomic failure, is it from cardiac or respiratory failure that is more common cause?

Answer 33

Cardiac arrythmia is usually reason patients with GBS die

Question 34

What two investigations are usually carried out to aid in the diagnosis of GBS?

Answer 34

Lumbar puncture - looking for an increased protein content (greater than 550mg/L) and Nerve conduction studies

Question 35

What is the treatment options for GBS?

Answer 35

Treatment is IV immunoglobulin and/or Plasma exhange

Question 36

Demylinating neuropathies Acute (days to weeks) - GBS (Guillaine Barre syndrome or AIDP) Chronic (Months to years) - CIDP (chronic inflammatory demyelinating polyradiculopathy). - Hereditary sensory motor neuropathy( formerly known as Charcot-Marie-Tooth disease) How does CIDP differ from Guillain Barrer sydrome?

Answer 36

CIDP is characteried by a slower onset and recovery than GBS

Question 37

What is the hereditary demyleinating neuropathy known as?

Answer 37

Charcot-Marie-Tooth disease (CMT) is a group of inherited conditions that damage the peripheral nerves.

Question 38

Charcot–Marie–Tooth disease is caused by mutations that cause defects in neuronal proteins. Nerve signals are conducted by an axon with a myelin sheath wrapped around it. Most mutations in CMT affect the myelin sheath, but some affect the axon. What is the most common form of CMT disease?

Answer 38

Charcot Marie Tooth disease Type 1a (CMT1a) is the most common presentation of CMT (70-80% of cases)

Question 39

What is the mutation in charcot marie tooth disease type1a?

Answer 39

There is a mutation on the PMP22 myelin gene on the short arm of chromosome 17 (Peripheral myelin protein 17 - lies on chromosme 22) and this causes peripheral nerve demylination

Question 40

What mode of inheritance is CMT1a?

Answer 40

It is autosomal dominant inheritance

Question 41

Where is the mutation in charcot marie tooth disease type 1a? (remember CMT has axonal and demylinating variants - CMT1a is a demylinating type) What are the presenting features of the disease?

Answer 41

Atrophy of the peroneal muscles of the leg High arching foot- pes cavus, clawed toes

Question 42

HMSN type 1 - Hereditary motor sensory neuropathy tpe 1 - just means CMT type 1 How are the legs usually described?

Answer 42

The legs are usually described as the inverted champagne bottle appearance

Question 43

Charcot–Marie–Tooth disease (CMT)is characterised by progressive loss of muscle tissue across the body, not only the peroneal muscle, high arch foot and clawed toes ie the hands are also affected by muscle loss IS there any sensory loss in CMT?

Answer 43

Yes there is sensory loss in CMT

Question 44

Name two conditions that can cause autonomic neuropathy?

Answer 44

Amyloidosis Diabetes

Question 45

Say somebody has an axonal neuropathy Eg if they have polyarteritis nodosa Polyarteritis nodosa can often be caused by something else and therefore it is important to treat the cause to clear the symptoms What conition is polyerarteritis nodosa assocaited with?

Answer 45

This would be hepatitis C

Question 46

In the treatment of vasculitis causes of axonal neuropathy eg mononeuritis multiplex due to vasculitis What is the treatment?

Answer 46

IV steroids + IV cyclophosphamide

Question 47

62 year old retired journalist Painful paraesthesia and “burning” sensation in lower limbs for 4/52. Grip strength reduced in right hand. O/E left 4/5 abductor pollicis, Dorsiflexion on left leg 4/5 reduced sensation to pinprick over L5. absent L ankle reflex. What nerves are damaged here?

Answer 47

Reduced grip strength = median nerve - median also supplies abductor pollicis Dorsiflxeion and reduced sensation over L5 - common peroneal nerve damage Also absent ankle reflex on left leg suggests an S1,2 - nerve is the tibial nerve that supplies the ankle reflex muscles

Question 48

62 year old retired journalist Painful paraesthesia and “burning” sensation in lower limbs for 4/52. Grip strength reduced in right hand. O/E left 4/5 abductor pollicis, Dorsiflexion on left leg 4/5 reduced sensation to pinprick over L5. absent L ankle reflex. WHat type of neuropathy does thi sounds like? What is usually the cause?

Answer 48

Sounds like a mononeuritis multiplex Usuaully caused by vasculitic disease

Question 49

62 year old retired journalist Painful paraesthesia and “burning” sensation in lower limbs for 4/52. Grip strength reduced in right hand. O/E left 4/5 abductor pollicis, Dorsiflexion on left leg 4/5 reduced sensation to pinprick over L5. absent L ankle reflex. Person was tested and came back ANCA+, treatment?

Answer 49

Give IV steroids + IV cyclophosphamide

Question 50

How does Guillain Barre Syndrome present? What is it also known as? What are its triggers? What is used in its diagnosis? WHat is the prognosis?

Answer 50

It is also known as acute inflammatory demylinating polyneuropathy Usuaully occurs a few weeks after an infection with symmetrical ascending muscle weakness Camplobacter jejuni (most common trigger) and mycoplasma pneumonia are known triggers (also linked with HIV, EBV) Lumbar puncutre (protein >550mg/L with no raised WCC) and neerve conduction studies Prognosis is vey good - 86% recovery

Question 51

What is the treatment of GBS? What condition is alike GBS but presents with a slower onset and recovery? Name a heridatry sensory motor polyneuropathy causing condiiton? Name the most common type and the mutation? NAme the features of the condition?

Answer 51

IV immunoglobulin and/or plasma exhange in GBS Chronic inflammatory demyinating polyradiculopathy - slower onset and recovery Charcot-Marie-Tooth disease - CMTType1 - mutation in the PMP22 gene on short arm of chromsome17(peripheral myelin protein 22)-AD inheritance Presents with muscle weakness and sensory loss all over body - especially peroneal muscle atrophy, pes cavus, clawed toes