Neuropathy Flashcards
notes
mononeuropathy
multiplex - isolated , but more than one.
connective tissue disease - e.g sacrodosis
polyneuropathy - disease of mu;tiple periphearal nerves
tend t be bilateral , symmetrical , motor and sensory impact.
distal part loses function first - proximal part spared in early times , as progress damage spreads t proximal part
aeitolgy - is it linked to cancer etc , cause
radiculopathy - compression of nerve root
pain along nerve - weakness , sensory lost , dysfuntion of what the nerve innervates.
doral plus vebtral roye form spinal nerv.
motor neurone d - with cns - cortex to
amytrophic musclar atropy - upper , lower , brainstem motr neurones impacted — whole thing affected
PLS - Primary laterl SCLEROSIS - damage to brainstem neurones
Muscular dystrophy - motor neurones in spinal cord damage.
nerve damage
compression
damage to myelin - central & peripheral mylein are the same.
central neurones - less myelin vs peripheral
peripheral - whole series of shwann cells wrapping around peripheral nerve - thick covering - the outer layer has a cytoplasm which contains nuclues
central - oligodenendrocyte - many branches - single layer - cover given by OLigodendrocytes are sparse vs cshwann cells - so in the case of muscular sytropy - so impacts on central nervous system vs peripheral
classification
- Transient block - damage to myelin sheath ,
- Axonotmesis - damage to axon
- Neurootmesis - damage to axon , endoneurtum , perineuritum , epineuritum
( can be entire axon )
progressively it gets worse.
segemental demyeination - segments of myelin gone.
axonal demyelination - myelin sheath in tact , but problem with the axon itself
Wallerian degeneration -
axoplasmic flow - directly connected to cell body.
Nerve vs Neurone ?
Nerve - collection of neurones
Neurone - single neurone.
What is a Spinal nerve made out of ?
Structure
Ventral & Dorsal route join together to form spinal nerve.
Spinal nerve - part of peripheral NS.
Structure -
epineurium - sheath surrounding spinal nerve
Contains :
0 BV - Veins , Arteries
0 fascicle - clusters of bundles of neurone.
o each
fascicle
surrounded
by
perineurium
0 Neurones - contained in fascicle - either myelinated / unmyelinated
( endoneurium - surrounds this )
Parts of the neurone ?
0 Axon
0 Cell body - ( Soma) -( if this is damage - neurone cannot regenerate )
0 Dendrites
0 Terminal bulbs - (if this is damaged regeneration can occur. )
neurotransmitter released from here.
Why don’t most CNS fibres regenerate while PNS fibres can ?
0 Oligodendocytes which surround CNS fibres - inhibit regeneration ( shwann cells cover PNS fibres - so dont have this problem. Shwann cells actually assist in regeneration.)
0 Clean up is slow ( faster in PNS by macrophages)
0 environment not very optimal
Time is important - need to clean up damage - to allow the fibres that can regenerate to regenerate.
Classification of Nerve injury ?
Neuropraxia - myelin sheath damage - demyelination ( reversible conduction block )
0 can happen as a result of compression - axon ,endoneurium ( surrounds neurone intact ) but myelin sheath compressed .
e.g radial nerve compression. (wrist drop )
Axonotmesis - Demyelination + Axon loss
Axon and corresponding segment of myelin sheath loss - but endoneurium still intact so it can grow back.
( However , distal end - terminal bulb will undergo Wallerian degeneration )- commoly seen in crash inhries - fractures.
Neurotmesis - Demyelination , Axon loss + ( one or all of following - endoneurium , perineurium , epineurium damage )
IF DAMAGED
o endoneurium - can grow back / fair growth.
o perineurium - poor regrowth o epineurium - no growth
What is Wallerian degeneration ?
Damage to neurone interrupts connection to cell body - or damages cell body itself.
Part of axon is disconnected from the soma of neuron.
Disconnected portion degenerates & debris is cleared aided by glial cells.
CNS - causes
0 Tumour
0 Haemorrhage
0 head injury with shearing of fibres.
Types of Neuropathies ?
- Mononeuropathy
Mononeuropathy mutiplex
WHAT IS IT ?
CAUSES?
EXAMPLES
Mononeuropathies - damage to single peripheral nerve - sensory disturbances ( paranthesia , numbness , pain ) & weakness in one isolated area - supplied by the peripheral nerve.
CAUSES -
TRAUMA
- compression
- violent muscular activity / overextension of joint.
0 Compression —–>1. entrapment neuropathy - narrows passageways , nerve compressed e.g carpal tunnel syndrome.
- Compression - by tumour , cast , crutches , prolonged cramped postures —–> nerve compression syndrome - can cause paralysis.
- compression - by hemorrhage.
Compression can be : o transient (eg, caused by an activity) o fixed (eg, caused by a mass or anatomic abnormality).
Mononeuropathy multiplex / Mononeuritis Multiplex - damage to more than two isolated peripheral nerve .
o Sensory
disturbance
& weakness
in more than
2 isolated
areas -
corresponding
to peripheral
nerves.
CAUSES -
0 Connective tissue disorders
o polyarteritis nodosa,
o systemic lupus
erythematosus [SLE],
o other types of
vasculitis,
o Sjögren syndrome,
o rheumatoid arthritis
0 Sarcoidosis
0 Metabolic disorders
o diabetes,
o amyloidosis)
0 Infectious disorders (eg, Lyme disease, HIV infection, leprosy)
neuropathy - can either be sensry , motor or mixed.
o sensory - sensory disturbance - no weakness
o motor - weakness , no sensory D.
EX. of mononeuropathy
- Carpal tunnel syndrome - compression of median nerve.
Peroneal nerve palsy - compression of peroneal / fibular nerve against fibular neck.
(FOOTDROP)
Radial nerve palsy - compression of radial nerve against humerus.
(WRIST DROP - weakness of wrist & finger extensors ) - C7 radiculopathy - compression of C7 nerve root can cause similar symptoms
Ulnar nerve Palsy - compressed under medial condyle - cubital tunnel syndrome . ( SENSORY DEFICIT IN 5TH , 4TH DIGIT - WEAKEND / ATROPHIEDINTEROSSEUS MUSCLE OF HAND - found by metatarsal bones - help control fingers )
POLYNEUROPAHTY - extensive involvement of many nerves.
RADICULOPATHY - damage due to compression of spina nerve root. -radiating pain , weakness , sensory disturbance down dermatome.
Types of Neuropathies ?
0 Polyneuropathy
- Pattern of presentation
- causes
- things to consider
Extensive involvement of many nerves
Bilateral , symmetrical
CAUSES
0 damage to myelin sheath - demyelination - infectious causes
0 Damage to BV supplying nerve - causes nerve infarction
(Chronic arteriosclerotic ischemia, vasculitis, infections, hypercoagulable states )
0 Axon damage - can be symmetric or asymmetric
CAUSES
0 Nutritonal deficiences - B12 , B6 , E
0 Alcohol
0 Infection
Common
causes of symmetric
o Diabetes mellitus
o Chronic renal insufficiency
o Adverse effects of chemotherapy drugs (eg, vinca alkaloids)
THINGS TO CONSIDER
- can affect;
- sensory vs motor vs autonomic
- distribution of nerve injury - stocking glove syndrome
- nerve compartment affected - BV , Myelin or Axon]
- Pattern of inheritance - acquired vs congenital
- Cause
What is the Stocking glove syndrome ?
- Peripheral neuropathy.
Early stages of peripheral neuropathy -
sensory disturbances , muscle weakness - present distally at first ———————–> as disease progresses it moves proximally.
Types of Motor neurone disease ?
ALS - Amyotrophic Lateral Sclerosis
A - No
myo - muscle
Trophic - nourishment
( NO MUSCLE NOURISHMENT)
Neurogenerative disorder - damage to neurones - upper , lower & brainstem motorneurones ( ALL THREE )
- upper motor neurone - from brain to spinal cord
- lower motor - spinal cord / brainstem to sketetal m. - cause movement
DAMAGE HERE - IS MORE DISABLING WEAKNESS VS UPPER
Motor neurone stop working —-> neurone & muscle atrophies
progressive weakening of muscles
( start to lose hand and arm fuction ————-> difficulty walking, speaking —————–> difficulty breathing )
0 respiratory failure often cause of death - death usually 3 -5 yrs after diagnosis.
CAUSES
O Accumulation of dysfunctional proteins in neurones ( cell body )————————-> degeneration of neurone —— muscles die / atrophy due to no activation ——> impair function.
SYMPTOMS
Early
- asymmetricc hand weakness - dropping objects
- cramping of upper extremities
- dysarthria , dysphagia , dysphonia
Intermediate
- Atrophy ——————-> can’t ambulate ( walk without any assistance ) ————> wheelchair use.
Late
- respiratory weakness —–> dyspnea ——> respiratory infection
- recurrent cough , fever , chill , pneumonia
-
What is Progressive muscular atrophy ?
Subtype of Motor neurone disease
- only affects mainly Lower motor neurones - Slow , progressive damage .
no UMN signs (but most people will progress to showing these ) - prognosis better than ALS
SYMPTOMS
0 Weakness in hands ——————-> spreads into the lower body- can be severe.
0 muscle wasting (shrinking),
0 clumsy hand movements, twitches, and muscle cramps.
0 Torso muscles and breathing may be affected.
*Exposure to cold can worsen symptoms.
What is Primary Lateral Sclerosis ?
Affects only upper motor neurone ( supply hands , legs , face )
- neurodegenerative disease - progressive stiffness & weakness
SYMPTOMS
PAINLESS
- slow & difficult movement in hands , legs ,face
caused by spasticity - spasm
Legs first —————–> torso ————–> arms & hands ——-> muscles used for swallowing , speaking , chewing in face (less common).
difficult to walk , speak , fine hand coordination.
( distal to proximal )
Progresses more slowly than ALS.
if they develop LMN symptoms - diagnosis change to ALS.
What is Spinal musclar atrophy (SMA) ?
Affects LMN only.
most common cause of genetic infant mortalilty .
alpha LMN (responsible for innervation of voluntary skeletal muscle ) from spinal cord (anterior horn ) die prematurely - ( LMN can die or the whole LM nerve )
————> motor unit ( neurone / nerve + muscle fibre ) - stops working———————–>
IF ENOUGH MUSCLE FIBRES STOP WORKING
muscles weakness & flaccid -low tone paralysis ———————> Muscle atrophies ( lack of innervation ).
0 Fasciculations (Spontaneous involuntary muscle contraction ) — If a lot of muscle fibres affected
0 Diminished reflexes - deep tendon reflexes
CHRONIC SYMPTOMS
0 Scoliosis - poor support of spine
0 extremely thin limbs - muscle wasting.
