Peripheral diseases Flashcards
Distal Axonal Degeneration
Aka “dying-back neuropathy”
● Neuronal cell bodies and proximal axons intact
● Axon regeneration = nerve function return
Neuronopathy
● Little potential for recovery
death of neuronal cell body
Wallerian Degeneration
● Axonal degeneration that occurs in a nerve distal to transection or crush
may regnerate if not too proximal
Segmental Demyelination
Loss of myelin form 1 or more internodes (dysfunctioned schwann cells)
Primary demyelination
Secondary demyelination
what is remyelination step for segmental demyelination
Schwann cells can proliferate → remylinated internodes have shortened internodal length
○ Remyelination of demyelinated segments
○ Recovery of function
Chronic Demyelinating Neuropathies
Repeated episodes of segmental demyelination and remyelination of peripheral nerves
Onion bulb = segmental demyelination followed by remyelination of peripheral nerves
○ Leads to hypertrophic neuropathy (enlargement)
Peripheral Neuropathies etiologies
DM = most common cause of generalized peripheral neuropathy in US
● Etiology
Alcohol
Drugs
Diabetes
Heavy metal poisoning
Guillain - Barre Syndrome
Acquired
○ Campylobacter jejuni
○ Cytomegalovirus
○ Epstein-Barr virus
○ Mycoplasma pneumoniae
● Immune mediated
○ Causes lymphocytes to attack axons
● Acute inflammatory demyelinating polyradiculoneuropathy
● Neuromuscular paralysis
○ Symmetric
○ Begins distally and ascends proximally
● Symptoms
○ Cardiac arrhythmias
○ hyper/hypotension
● CSF
○ High protein
○ Low WBC’s
symptoms of guillain barre syndrome
Acquired
○ Campylobacter jejuni
○ Cytomegalovirus
○ Epstein-Barr virus
○ Mycoplasma pneumoniae
● Immune mediated
○ Causes lymphocytes to attack axons
● Acute inflammatory demyelinating polyradiculoneuropathy
● Neuromuscular paralysis
○ Symmetric
○ Begins distally and ascends proximally
ascending paralysis
● Symptoms
○ Cardiac arrhythmias
○ hyper/hypotension
● CSF
○ High protein
○ Low WBC’s
guillain bare syndrome and CSF
● CSF
○ High protein
○ Low WBC’s
• Albuminocytologic dissociation
TYPICAL CSF FINDINGS ARE AN ALBUMINOCYTOLOGIC DISSOCIATION WITH INCREASED PROTEIN AND FEWER THAN 5–10 WBCS
Charcot Marie Tooth Disease - CMT
● Chronic inflammatory demyelinating polyneuropathy
axonal demeylination
different types of CMT
CMT1 = most common
○ Multiple genes/loci (PMP22) that lead to this
■ Messed up chromosome 17
● CMT2 = less common
● CMTX
○ X-linked (CMTX)
○ Aka CMT 4 (autosomal recessive)
what gene is mutated in charcot marie tooth disease
PMP22
symptoms of charcot marie tooth disease
Symptoms
○ Muscle dystrophy - high arch, clawing of toes
■ Distal muscle wasting
○ Deep tendon reflexes = gone
○ Steppage gait = foot drop
Dejerine - Sottas Syndrome
AKA “CMT3”, but resembles CMT1
● More severe
○ Onion bulbs
○ Axonal loss
● Early infancy
Amyotrophic Lateral Sclerosis (Ice bucket challenge)
Lou Gehrig disease
● Onset = 55
● Men > women
● Die within 3 years
● “Seek care when weakness begins to affect activities of daily living”
● Exclusive motor involvement and the chronologic course distinguish it
● Painless with discomfort with loss of normal abilities
Amyotrophic Lateral Sclerosis (Ice bucket challenge) symptoms
Progressive weakness and atrophy
○ Dragging gait - foot drop
○ Fine movements lost in hands
○ CN involvement = LMN in ALS
■ Example = deviated tongue; hypoglossal CN 12
○ Weak neck extension/flexion
○ Ventilation problems near end of life
■ Abdomen moves out instead of in during breathing
Mild Cognitive Impairment
Longitudinal follow-up of these patients reveals a substantially increased risk of
cognitive decline and eventual “conversion” to dementia
Alzheimer disease
Confused
● Short-term memory loss, cant recall details
● “Overblown concerns”
● Forgets things easily
Gave up old activities
● MRI = atrophy
● Strokes
● Diabetic more likely to develop
○ Hemoglobin A1C elevated
● Dementia - most commonly caused by AD
● High risk of AD in down syndrome patients
● Older > younger
● MMSE low score
○ Tests cognitive function
what causes alzheimers disease
Beta-amyloid protein build up in brain (from APP - amyloid precursor protein)
○ Alpha-beta peptides form pathogenic aggregates = plaques ■ Tangling of plaques causes AD
● Neurofibrillary tangles
Pathologic hallmark of AD
○ Number and tangles = direct severity of dementia
○ Made up of microtubule-associated protein tau
Helical shape
Neuronal cytoskeleton structure
○ Found during autopsy
what differentiates AD from other dementias
● ABSENCE of motor deficits early in AD differentiates it from most other dementias
what is MALCOPE (AD)
MALCOPE = Memory, Attention, Language, Construction, Orientation, Praxis (skills),
and Executive function
alzheimers and CSF
○ Decreased B amyloid / increased tau/phosphotau protein
what is not a diagnositic of AD
● ApoE genotype IS NOT diagnostic of AD
Lewey Bodies
Confusion
● Depression
● Hallucinations
● Forgetful
● Parkinsons as a prior diagnosis
○ Hallmark is LB presence
● Diagnosis
○ Presence of LB pathology regardless of AD pathology
Frontotemporal Lobar Dementia
related to a degenerative process primarily confined to the frontal and temporal lobes
Change of personality
● Forgetful
● Developed OCD
● Hard to remember names
● Lateral frontal lobe atrophy
○ Or temporal lobes
● Intellectual decline
● AKA Pick disease
● Most ages it can start
● Hereditary
symptoms of frontotemporal lobar dementia
Symptoms
○ Low hygiene
○ Social behavior decline
behavior subtypes of frontotemporal lobar dementia
3 major behavior subtypes
○ Disinhibition
○ Apathy
○ Stereotypic behavior
proteins associated with frontotemporal lobar dementia
TDP43
Vascular Cognitive Impairment
Inactive
● Low motivation
● Gave up previous interests
● Feels off balance when making turns
○ Bad gait
Hypertension, cardiovascular disease (at risk for stroke)
○ Not taking medication
● Not happy
● Bilateral babinksi sign
● Cant think for him/herself
● Most common cause of Acute spinal cord syndrome
metastatic deposits
what are metastatic deposits
Most common cause of Acute spinal cord syndrome
● Old people
● Spinal metastatic lesion
○ Usually presents as a tumor elsewhere before
● Leg weakness
○ Impaired gait
● Urinary retention
Infarctions
Occlusion of anterior spinal artery
● Aortic dissection
● Embolism
● Hypotension
● Paraparesis
○ Sensory loss
● Poop themselves - sphincter control lost
Distractive Flexion
Severe flexion of neck with rotation
● Most common
● Posterior ligaments injured initially
○ Spinous processes distance increases
● Examples: car accident or fall
most common type of spinal trauma
distractive flexion
Compressive Flexion
Axial loading with acute severe flexion of the neck
● Example: Diving into shallow water, thrown out of vehicle
● Burst vertebral body
● Commonly C4-5 & C5-6
Distractive Extension
Hyperextension of the spine
● Whiplash !
○ Most minor form
● Elderly patient falling with cervical spondylosis or stenosis
○ Hit forehead
● No traumatic radiographic abnormality
● SC pinched between anterior ostephytes and in-buckled ligamentum flavum
Compressive Extension
Axial loading with hyperextension
“teardrop fracture”
● Laminar frx = minor
● Teardrop frx = major
○ Anterior longitudinal ligament
○ Avulsion frx - pedicles/lamina messed up
Cervical spine injury: Hospital setting
USUALLY after initial traumatic injury
○ From transport and st00f
● Altered mental status have a risk factor
● 15% of injuries are multiple
● Use cervical collar
how to diagnose peripheral neuropathies
Many neuropathies do not show additional disease-specific histologies beyond axonal loss or demyelination, so clinicopathologic correlation is necessary to establish cause
what are lewy bodies
• They are the hallmark histopathologic lesions of primary PD where these occur within neurons of the substantia nigra and other brainstem nuclei
