Peripheral Nerve Disorders Flashcards
What does peripheral neuropathy refer to?
Refers to many conditions that involve damage to the peripheral nervous system
How is nerve signaling disrupted in the neuropathy?
Either by loss of signals, inappropriate signaling, or errors that disrupt the messages
What are the symptoms with a motor nerve is damaged?
muscle weakness that can also include painful cramps, fasciculations, muscle atrophy
What are the symptoms when a sensory nerve is damaged?
Various symptom patterns
Loss of vibratory sense
Stocking glove sensation
Loss of reflexes
Loss of position sense
Loss of temperature sensation
Pain
What is autonomic nerve damage associated with
small-fiber neuropathies
What are the symptoms when autonomic nerve is damaged?
Excessive sweating, heat intolerance, inability to expand and contract small blood vessels regulating BP, GI symptoms
Mononeuropathy affects
One nerve
Multiple mononeuropathy or mononeuritis multiplex affects
several discrete nerves
Polyneuropathy affects
Multiple nerves diffusely
Plexopathy affects
a plexus
Radiculopathy affects
a nerve root
What are the two general causes of peripheral neuropathy
Acquired sources (trauma or diabetes) or genetics
Why does diabetes lead to peripheral neuropathy
Excess glucose, nerves are essentially getting drunk off the sugar and lead to nerve damage
What is a common vitamin deficiency that leads to peripheral neuropathy?
Low vitamin B12
HIV can cause what type of neuropathy?
Symptomatic acquired neuropathy
What is a genetic condition that commonly causes inherited peripheral neuropathy?
Charcot-Marie-Tooth
Are hyperreflexia and hypertonia typically associated with peripheral nerve lesions?
No
What is included in the evaluation of peripheral neuropathy?
Medical History
PE with full neurological exam
Labs (CBC, inflammatory markers, CSF)
Genetic tests
Nerve function tests (NCV, EMG)
Neuropathy tests of nerve appearance (nerve biopsy)
Autonomic Testing
Imaging
What is a cause to consider when you see unilateral deficits?
Focal disorders (mononeuropathies, plexopathies)
What is a cause to consider when you see symmetric, diffuse deficits
Diffuse disorders (toxic-metabolic, hereditary, infectious or inflammatory disorders, or immune-mediated disorders)
What diagnostic evaluation is considered the gold standard for diagnosing small fiber neuropathies?
Neurodiagnostic skin biopsy
How are you going to treat peripheral neuropathies?
Address neuropathy causes (glucose control, diet, immunoglobulins)
PT/OT, orthotics, acupuncture, behavioral strategies, TENS unit
How can motor neuron symptoms be treated?
Orthotics, mechanical aids
How can autonomic neuron symptoms be treated?
acupuncture, massage, CBT/psychotherapy, herbal remedies
How can sensory neuron symptoms be treated?
Behavioral strategies
What are some pharmacological treatments for peripheral neuropathy?
TCA’s, SSRI’s, gabapentin, topiramate, duloxetine, topical/local anesthetics (capsaicin), lidocaine
What treatment modality is used as a last resort in peripheral neuropathy?
Surgery (remove compression or cutting the nerve)
What is the best way to treat neuropathies
By preventing
Vaccine against Shingles
Diabetes management
Minimize medication use with neuropathy SE
Unnecessary procedures
When do you consider vascular or ischemic neuropathy?
If there is abnormal pain and temperature sensation and atrophy in proportion to the weakness
When do you consider motor neuron disease?
Chronic progression of muscle weakness, fasciculations, muscle atrophy, and no sensory deficits
What is complex regional pain syndrome?
Chronic (>6 months) pain condition that most often affects one limb usually after an injury
What differentiates CRPS-I and CRPS-II?
CRPS-I doesn’t have a confirmed nerve injury and CRPS-II is with a confirmed nerve injury
Does CRPS typically effect men or women more?
Women, peak age 40 years
What nerves do you typically see CRPS?
Small unmyelinated or thinly myelinated sensory nerve axons carrying pain messages
What is the key symptom in the presentation of CRPS?
Prolonged severe pain, that is consistent (present with all activities including sleep)
What is allodynia?
Increased sensitivity in affected area, normal contact with the skin is very painful (even wind blowing by- think gout pain)
What type of diagnosis is CRPS?
Clinical, no specific test to confirm CRPS
R/o gout, lyme disease, generalized muscle disease
What is the hallmark to diagnosis in CRPS?
Injury in affected area
What is the treatment for CRPS?
PT and rehabilitation, psychotherapy, sympathetic nerve block
What are some of the pharmacological treatments of CRPS?
Bisphosphonates, NSAIDs, steroids, neuropathic pain meds (gabapentin)
What is the premiss behind the lidocaine coma?
Turning the computer off (sensory nerves) and turning it back on again (rebooting)
Why is vitamin B12 important?
Important in cellular metabolism and maintenance of the integrity of the nervous system
What is the most common etiology of vitamin B12 deficiency?
Lack of intrinsic factor (pernicious anemia)
Where is excess B12 stored?
The liver, strict vegans will deplete their stores after 3 years
What patient cohort is vitamin B12 more common?
Elderly (regardless of cause)
What should your history and physical focus on when vitamin B12 deficiency is suspected?
GI and neuro findings
What are common symptoms in vitamin B12 deficiency?
Pallor, fatigue, glossitis (swollen tongue), GI disturbances, HA, peripheral neuropathy, neuropsychiatric disturbances
What labs would you order to work-up a vitamin B12 deficiency?
CBC with peripheral smear, serum B12 and folate
Can also order methylmalonic acid (MMA), homocysteine, anti-intrinsic factor antibodies
What is the treatment for Vitamin B12 deficiency?
Replace missing B12 (oral in vegans, or IV once monthly in intrinsic factor deficiency)
What diseases would you chronically screen for vitamin B12 deficiency?
Crohn’s, Celiac
What are some complications of undiagnosed vitamin B12 deficiency?
Heart Failure
Severe disabling neurological deficits
Increased risk for gastric cancer
Increased risk for autoimmune disease
What are some other conditions that present similarly to vitamin B12 deficiency?
Lead toxicity
Syphilis
Multiple Sclerosis
What is Guillain-Barre Syndrome?
Rare neurological disorder in which the body’s immune system mistakenly attacks peripheral nervous system
What is a devastating effect of Guillain-Barre?
Respiratory compromise in which the patient can’t breath, can also potentially interfere with BP and heart rate
When do most cases of Guillain-Barre start?
few days to weeks following a respiratory or GI viral infection
What is the molecular mimicry/innocent bystander theory?
A virus makes the immune system less discriminating and no longer able to recognize own nerves- T lymphocytes and B lymphocytes produce antibodies against myelin (perceived as foreign)
Is GBS symmetric or unilateral weakness?
Symmetric weakness
When does pain worsen with GBS?
Pain can be severe at night
What are they typical findings in GBS?
Symmetry and speed of onset of symptoms (days to weeks)
What is the most common type of GBS seen in the US?
Acute inflammatory demyelinating polyneuropathy (AIDP)
What is the acute treatment of GBS?
Admit and treat in ICU
Plasma exchange or IV IgG (both are equally effective, treat with one or the other)
What are the rehabilitation treatments for GBS?
PT, OT, and vocational therapy
