lecture 12 Flashcards
1
Q
Charcot-Marie Tooth Disease
Aka peroneal muscular atrophy
Aka hereditary motor & sensory neuropathy
A
- most common inherited disorder affecting motor & sensory nerves
- initially involves fibular nerve and affects mm in foot and lower leg, then progresses to mm of forearms & hands
- characterized by bilateral, distal limb wasting and weakness, usually with skeletal deformities, distal sensory loss and abnormal DTRs
2
Q
CMT1
A
- caused by DNA duplication mutation within chromosome 17
3
Q
CMT2
A
- has chromosomal abnormalities mapped to chromosomes 1, 8, X
4
Q
CMT Symptoms
A
- -slowly progressive
- -distal symmetric mm weakness, atrophy and diminished DTRs
- -will have pes cavus, Hammer toes
- -weak dorsiflexors and everters
- -will have footdrop (steppage gait)
- -as it progresses it will be seen in distal arms
- -proprioception is lost in feet and ankles
- -as mm atrophy progresses below knee, legs look like inverted champagne bottles because normal mm bulk is maintained above knee
5
Q
Diabetic Neuropathy
A
- Common complication of diabetes mellitus - Long term hyperglycemia impairs vasculature function, leading to nerve damage
- Typical neuropathy occurs in a distal, bilateral and symmetrical pattern
- Mainly affects sensory nerves, but can affect motor nerves (less likely) or autonomic nerves
6
Q
Diabetic Neuropathy Mainly affects
A
- Mainly affects sensory nerves, but can affect motor nerves (less likely) or autonomic nerves
- autonomic involvement can lead to hypotension,
N/V/D, trouble sweating - In rare cases neuropathy can be focal (ie. not distal)
7
Q
Alcoholic neuropathy
A
- peripheral neuropathy in a distal and symmetrical pattern
- can affect both motor and sensory nerves
- lesions affecting the peripheral nerves have been attributed to both the direct toxic effects of alcohol on the nerve and nutritional deficiencies in thiamine and other B vitamins from poor dietary habits
- overall etiology is idiopathic
- minor loss of mm bulk, diminished ankle reflexes,impaired sensation in feet, aching in calves
- distal sensory changes include pain, numbness in a symmetric glove and stocking pattern
- begins insidiously and progresses slowly
- in advanced cases all 4 extremities are involved
- weakness and atrophy of distal mm
- bilateral foot drop and wrist drop
8
Q
Chronic renal failure
PNS
A
- Atrophy & demyelination of sensory and motor nerves of PNS
- Lower extremities more commonly affected than upper
- Peripheral neuropathy is usually symmetrical
9
Q
Chronic renal failure
CNS
A
- Recent memory loss, inability to concentrate, perceptual errors, decreased alertness
10
Q
Anemia
A
- Neuropathy occurs in a distal and symmetric pattern
- Patients have trouble walking when in fact they are experiencing the loss of proprioception
- Loss of motor function is a late manifestation of B12 deficiency
- CNS manifestations may include:
- Headache, drowsiness, dizziness, fainting, slow
thought processes, decreased attention span,
depression , irritability
11
Q
Guillain-Barre Syndrome
A
- Most common cause of rapidly evolving motor and sensory problems
- Symptoms peak within 2-3 weeks, but months to recover
- Most common form is known as acute inflammatory demyelinating polyradiculoneuropathy
- Immune-mediated disorder
- Bacterial and viral infections, surgery and vaccinations have been associated with its development
- Lesions occur throughout the PNS from spinal nerve roots to the distal termination of both motor and sensory fibers
- Evidence exists for antibody-mediated demyelination (myelin of schwann cells is the primary target)
- Also axonal degeneration
12
Q
Guillain-Barre Syndrome Acute
A
- Time of onset to peak impairment is 4 weeks or less
13
Q
Guillain-Barre Syndrome Chronic
A
- Time of onset to peak impairment is months
14
Q
Guillain-Barre Syndrome Symptoms
A
- Rapidly ascending symmetrical motor weakness and distal sensory impairments
- First neurological symptom is often paresthesia in toes
- This is followed within hours or days by weakness distally in legs
- Weakness spreads to arms, trunk and facial muscles
- Flaccid paralysis is accompanied by absence of DTRs
- Palatal and facial muscles become involved in about half of the cases
- 30% of patients require mechanical ventilation
- Because preganglionic neurons are myelinated, they can be affected as well
- Symptoms of this can include tachycardia, abnormalities in cardiac rhythm, BP changes and vasomotor symptoms
15
Q
Guillain-Barre Syndrome
50% of cases
A
progression stops within 2 weeks
16
Q
Guillain-Barre Syndrome
90% of cases
A
progression stops within 4 weeks
Symptoms
-
17
Q
Guillain-Barre Syndrome After progression stops
A
- a static phase begins lasting 2-4 weeks, before recovery occurs in a proximal to distal progression
- Recovery can take months or even years
18
Q
Poliomyelitis
A
- Viral infection that was “eradicated” in the US in the 1950s/60s with the introduction of the polio vaccine and increased focus on personal hygiene
- Enterovirus, so transmitted through the GI tract
- ie. Fecal-oral route
19
Q
Poliomyelitis 3 types
A
- Asymptomatic
- Nonparalytic
- Paralytic
20
Q
Poliomyelitis Paralytic
A
- The paralytic form generally develops within a week after the onset of initial symptoms
- The virus invades and damages motor cell bodies
- Extent of paralysis depends on the degree of anterior horn cell involvement
- Paralysis is asymmetrical
- When cell bodies are killed, motor axons experience Wallerian degeneration
- Some were left with mild paralysis, some moderate to severe and 10% died from respiratory involvement
21
Q
Poliomyelitis Paralytic Recovery
A
- Recovery was attributed to recovery of some anterior horn cells as well as collateral sprouting from intact peripheral nerves to hypertrophy of spared muscle fibers
- Polio is a unique neuropathy that creates only focal and asymmetrical motor impairments
22
Q
Post-Polio syndrome
A
- Previous diagnosis of polio is required for this diagnosis
- New muscular symptoms that occur decades after recovery from paralytic polio
- Symptoms vary, but in general patients experience pain, muscle atrophy and fatigue
- Symptoms can be in new areas of the body (not where the polio virus originally affected)
- Post-polio has been attributed to neuronal fatigue
23
Q
Myasthenia Gravis
A
- Most common disorder of neuromuscular transmission
- Prevalence in Canada: 263 per 1 million
- Characterized by fluctuating weakness and fatigability of skeletal muscles
- Autoimmune disorder
24
Q
Myasthenia Gravis Pathology
A
- Defect is at the NMJ (neuromuscular junction)
- Auto-antibodies antagonistically bind to ACh receptors and also cause destruction of the ACh receptors
- This results in a decreased efficiency of NMJ electrical transmission
25
Q
Botulism
A
- Rare, often fatal infection
- The bacteria Clostridium Botulinum produce a potent neurotoxin called the botulinum toxin
- Botulism is caused by ingestion, inhalation or contact with an open wound
- The bacteria is commonly found in improperly canned foods, or simply in the soil
- Proper food preparation is important
- Boiling the food for 15 minutes kills the endospores containing the neurotoxin
26
Q
Botulism Pathology
A
- When the neurotoxin is ingested, digestive acids and proteolytic enzymes cannot destroy the neurotoxin, so it is easily absorbed in the small intestine
- The toxin makes its way to motor endplates
- The toxin doesn’t allow the presynaptic membrane to release Ach into the synapse, resulting in flaccid paralysis
27
Q
Botulism Symptoms
A
- Onset is 12-36 hours after ingestion of the toxin
- Malaise, weakness, blurred and double vision, dry mouth, nausea and vomiting are all common symptoms
- Can also get dysphagia, dysarthria and photophobia
- Paralysis tends to be symmetrical that can progress quite quickly
- Because the motor endplate is involved, there are no sensory changes
- Motor weakness of the face and neck muscles progresses to involve the diaphragm, accessory muscles of respiration and muscles controlling the
extremities - If untreated, can be fatal within a day
