Neuropathy Flashcards
Refers to lesions affecting the peripheral nervous system
Peripheral neuropathy
Depends on whether myelin or axons are affected, which axons, and where they are affected
Symptoms of Neuropathy
Symptoms may include weakness and muscle atrophy, loss of reflexes, and loss of sensation
Neuropathy
Peripheral nerve neuropathy affecting all fibers would cause
Sensory, motor, and autonomic symptoms
Peripheral nerve neuropathy affecting only small fibers would cause
Pain, temperature, and autonomic loss
Peripheral nerve neuropathy affecting myelin (large fibers) would cause
Vibration and position sense loss, with motor loss
Peripheral nerve neuropathy affecting only sensory ganglia would cause only
Sensory symptoms
Tissue may be damaged, but nerves and nervous system are intact with
Nociceptive pain
Arises from lesions in the peripheral and central nervous system
Neuropathic pain
May include burning, shooting, stinging pain mixed with areas of numbness
Neuropathic pain
A common feature of chronic pain is
Depression
What are the primary drugs used to treat neuropathic pain?
Antidepressants and anti-epileptic drugs
When symptoms follow a nerve root pattern, it is referred to as
Radiculopathy
Often caused by compression of nerve roots from protruding discs
Radiculopathy
When symptoms follow a peripheral nerve, it is referred to as
-Often caused by injuries
Mononeuropathy
Involves nerve roots and the pattern of loss is along a dermatome or myotome
Radiculopathies
In contrast to radiculopathies, are lesions or specific nerves or plexuses
Mononeuropathies and plexopathies
A herpes zoster infection arising in the sensory neurons of the dorsal root ganglion of T1 spinal nerves
-May produce just sensory symptoms at the T1 dermatome (usually unilateral)
Radiculopathy
A carpal tunnel syndrome may affect all sensory, motor, and autonomic components of the median nerve, distal to the wrist. This is an example of a
Mononeuropathy
Caused by a generalized process affecting peripheral nerves
Polyneuropathy
May show a distal and symetrical sensorimotor (and possibly autonomic) distribution
Polyneuropathy
Polyneuropathy is sometimes called a
Glove and sock pattern
The most common causes of polyneuropathy are
Diabetes, alcohol, hypothyroidism, and Vitamin B12 deficiency
May result from damage or injury to cell bodies, axons, or myelin sheaths
Peripheral neuropathy
Axonal damage produces
Wallerian Degeneration (Or dying forward)
Distal axonal degeneration, chromatolysius, and recruitment of macrophages
Wallerian degeneration
The proximal stump after a neuron lesion can recover at a rate of
1-2 mm/day
Conditions that affect the health of the neuron such as metabolic diseases causes the
Dying of back axons
Longer axons are affected first, resulting in the
Distal extremities being affected first
Occurs when myelin sheaths are damaged by trauma or disease
Segmental demyelination
May be affected secondarily to axonal death
Myelin
Symptoms of demyelination are detected by nerve conduction tests which detect
Conduction block and slowed CV
Myelin and conduction can return in
Days to weeks
Trauma affecting myelin can be thought of as a
Nerve “concussion”
Note that it is only when the axon is interrupted that you will see
Muscle atrophy
What are two causative disorders/agents that result in nutritional/metabolic causes of peripheral neuropathy
Diabetes Mellitus and Vitamin B12 deficiency
An autoimmune disease that can result in non-traumatic peripheral neuropathy
Guillain-Barre Syndrome
What is an inherited disorder that causes non-traumatic peripheral neuropathy?
Charcot-Marie-Tooth Neuropathy
Affects 1.9% of the population
-most common complication in this population
Diabetic Neuropathy
The greatest source of morbidity and mortality in diabetes patients
Diabetic neuropathy
Accounts for greater than 80% of patients with diabetic neuropathy
Length-dependent diabetic neuropathy
Length dependent polyneuropathy gives a
-Produced by most nutritional, metabolic, and toxic diseases
Glove and stocking pattern of sensory loss
Symptoms include parethesias, dyesthesias, numbness, tingling, and burning
-Motor weakness of the distal limbs is also present
Length dependent polyneuropathy
Length dependent polyneuropathy can lead to trophic changes like
Calluses and plantar ulcers
More affects in ALL distal neuropathies
Sensory neurons
The most common metabolic neuropathy
-May affect peripheral nerves, optic nerves, spinal cord, and brain
B12 deficiency
Symptoms of neuropathy from B12 deficiency include the distal limbs, beginning more commonly in the
Upper Limb
The most common feature of peripheral neuropathy from B12 deficiency is
Loss of vibration sense
Vitamin B12 neuropathy may primarily or secondarily affect lateral and dorsal columns of the spinal cord. This is called
Subacute combined degeneration
Therefore, ataxia and spasticity can occur together with the symptoms of
Peripheral neuropathy
Can see in vegetarians or people with gluten sensitivity or malabsorption syndromes
B12 deficiency
Without B12, is abnormal
-NCV will decrease
Myelin production
Needs to be differentiated from MS
B12 deficiency
The most common cause of acute paralysis seen in clinical practice
-Also called Acute Inflammatory Demyelinating polyneuropathy (AIDP)
Guillain Barre
The most rapidly progressing and potentially fatal form of neuropathy
Guillain Barre
Primarily motor with ascending symmetric paralysis
Guillain Barre
May begin with paresthesias in toes and fingers and aching in the thighs and back
Guillain Barre
What are two major features of Guillain Barre?
Nerve conduciton velocity is decreased and there is increased protein in CSF w/ normal cell count
60% of the time, Guillain Barre begins how long after an infection or vaccination?
1-3 weeks
Widespread inflammatory process that affects myelin sheaths
Guillain Barre
The 2 most important diagnostic tests for Guillain Barre are
CSF analysis and Nerve Conduction Tests
The results of these tests are
Increased protein in CSF and decreased NCV
Classified s hereditary motor and sensory neuropathy
Charcot-Marie-Tooth Disease
Which form of Charcot-Marie-Tooth (CMT) disease affects
- ) Myelin
- ) Axons
- ) CMT1
2. ) CMT2
The most common form of CMT: produces a combined motor sensory neuropathy
CMT1
CMT1 primarily affects distal muscle, particularly affecting the
Peroneal nerve
Because of the demyelination, are not affected by CMT1
Small fiber types carrying pain and temperature
The typical onset of CMT1 is in
Late childhood
Identifiable by the slowly progressive nature and by the reduced conduction velocity in all nerves
CMT1,
