CC1: Peripheral Neuropathies Flashcards
What classification of nerve injury is neuropraxia?
Class 1
What is the cause of neuropraxia?
Compression or acute ischemia
What does neuropraxia do to the nerve?
Conduction block, no axon changes (MILD)
What classification of nerve injury is axonotmesis?
Class II
What is the cause of axonotmesis?
A crash injury to a limb causing axonal disruption
What does axonotmesis do to the nerve?
- Axonal damage results in loss of continuity
- Wallerian degeneration distally
How long is axonotmesis recovery?
Depends on nerve regeneration 1-3 mm/d (slow)
What classification of nervy injury is neuronotmesis?
Class III
What causes neuronotmesis?
Connective tissue elements severance, injuries that separate entire nerve
What does neuronotmesis do to the nerve?
Separates entire nerve from tissue - endoneuro and schwann cell tube
Can axonal regeneration occur in neuronotmesis?
Is very limited, little hope of functional recovery without surgery
What can ocurr in neuronotmesis malformation?
Neuroma formation and aberrant regeneration
Peripheral neuropathies can be subdivided into two major categories:
Primary axonopathies
Primary myelinopathies
What are neuropathic disorders?
Diseases of the neuron cell body and their peripheral processes
Large myelinated axons project:
Motor and sensory axons responsible for proprioception, vibration, and light touch
Thinly myelinated axons project:
Sensory fibers responsible for light touch, pain, temperature, and preganglionic autonomic functions
Small unmyelinated fibers project:
Pain, temperature, and postganglionic autonomic functions.
What type of spacial distribution does a mononeuropathy have?
Ex. Entrapment neuropathies as in carpal tunnel or local trauma
Focal spatial distribution - one nerve affected
What type of spacial distribution does a multiple mononeuropathy have?
Ex. Vasculitis
Multifocal - usually asymmetric
What type of spacial distribution does a polyradiculopathy have?
Ex. Sensory/motor diabetic neuropathy
Diffuse - symmetric
Which fiber is involved with :
LMN weakness
Muscle loss atrophy
Loss of tendon reflex
Impaired proprioception
Abnormal Romberg test
Large fiber type neuropathy
Which fiber is involved with :
Contact hyperalgesia
Burning, aching, stabbing pain
(non specific)
Mild distal disturbance in sharp- dull discrimination
Normal DTR’s
Orthostatic hypotension
Small fiber neuropathies
Which type of neuropathy involves axonal atrophy, impaired transport, chromatolysis, dying back?
Axonal neuropathy
Which type of neuropathy has a gradual insidious of tingling and prickling onset found in lower extremities?
Axonal neuropathy
Which type of neuropathy has a normal CSF protein level?
Axonal neuropathy
Which type of neuropathy has a decreased ankle reflex?
Axonal neuropathy
Which type of neuropathy has toxins, B vitamins, diabetes, hypothyroid, HIV?
Peripheral Sensory Motor Axonal Polyneuropathy
Which type of neuropathy has autoimmune diseases?
Demyelinating neuropathies
Where does destruction of myelin sheath often begin at in demyelination?
Nodes of Ranvier
Which type of neuropathy has elevated CSF protein?
Demyelinating neuropathy
Which type of neuropathy has fast progressive weakness?
Demyelinating neuropathy
Which type of neuropathy has cranial nerve involvement?
Demyelinating neuropathy
Which type of neuropathy has mild sensory loss?
Demyelinating neuropathy
Which type of neuropathy has multifocal hereditary adquision?
Demyelinating neuropathy
Which type of neuropathy has absent Deep tendon Reflexes?
Demyelinating neuropathy
What type of studies are done in laboratories for peripheral neuropathies?
EMG and nerve conduction studies
The most common cause of neuropathy worldwide:
Clinical Diabetic Neuropathy
What type of neuropathy is Clinical Diabetic?
Distal axonopathy, focal and multifocal, sensory snd autonomic manifestations
Unilateral oculomotor nerve palsies occur in what type of neuropathy? CN III
Cranial neuropathy
Burning type of pain in
thigh and pain with sensory loss with unilateral proximal muscle weakness and atrophy occurs in what type of neuropathy?
Proximal Diabetic Neuropathy of the Lower Limbs
What accumulates in the nerve creating a hypertonic condition and water accumulation?
Sorbitol
Chronic hyperglycemia increases ______ of proteins producing accumulation in tissues and endothelial cell membranes (causing microvascular disease)
glycosylation
Alteration in polyol metabolism
Glucose → Sorbitol → Fructose
Vascular pathogenesis of diabetics involves:
- hypoxia or ischemia of microvasculature of the nerve
- mitochondria in DRG
- oxidative stress
Guillain Barre syndrome is what type of neuropathy?
Acute Inflammatory Demyelinating Polyneuropathy
2/3 of the patients have a predisposing factor such as respiratory infection or gastroenteritis:
Guillain Barre
In Guillain Barre CSF protein is _____
Elevated
Pathogenesis is immune mediated: “molecular mimicry”
Guillain Barre
What are the 2 groups of vessels involved in vaculitic neuropathies?
- nerve large arteriole vasculitis
- nerve microvasculitis
A diverse group of disorders characterized by the acute-to-subacute onset of painful sensory and motor deficits that result from inflammatory destruction of nerve blood vessels and subsequent ischemic injury:
Vaculitic neuropathies
The two main pathways that lead to ischemic vasculitic nerve damage are:
- Immune complex deposition
- Cell-mediated immunity
Ooccurs when antigen-presenting cells present relevant antigens to circulating T cells producing proinflammatory cytokines and other inflammatory mediators that cause
Cell mediated immunity
What type of ischemic pathways is within the vessel walls with complement deposition and release of proinflammatory cytokines.
Immune mediated complex deposition
The most common is the median nerve entrapment in the wrist
Carpal tunnel syndrome
Weakness in ankle dorsiflex and eversion - compression in the knee is what type of neuropathy?
Peroneal
Tibial nerve compression in the region of the ankles as the nerve passes under the transverse tarsal (laciniate) ligament
Tarsal tunnel syndrome
Impingement of the Lateral Femoral Cutaneous Nerve under the inguinal ligament
Meralgia paresthetica
