Neuropathy, Myopathy, and Motor Neuron Disease Flashcards
(49 cards)
Mononeuropathy refers to involvement of a single, major, named nerve, usually by what two general etiologies?
Trauma; compression
Methods to localize mononeuropathy?
Beside neurological exam; EMG
Polyneuropathy (aka peripheral neuropathy) is a disorder of multiple nerves, but major and small, unnamed nerves, or branches. Describe the presentation of common polyneuropathies.
Symptoms and signs are symmetrical.
Sensory impairment occurs early and often remains prominent
Numbness and tingling begins distally, progresses to fingers and hands.
“Stocking and glove” pattern
May report paresthesia or dyesthesia
Early loss or decrease or reflexes
If autonomic involvement -> orthostatic hypotension, incontinence, impotence, sweating abnormalities
What are the two basic pathological processes at work in neuropathy?
- Demyelination
- Axonal degeneration
One or the other tends to predominate or occur initially
Demyelination is characteristic of what type of neuropathy
Mononeuropathy due to focal compression, such as carpal tunnel syndrome
Demyelination is also the primary process in what syndrome?
Guillain-Barre (acute type of polyneuropathy)
What happens in a severe crush or penetrating focal nerve injury?
Axonal loss via Wallerian degeneration, in which axons and myelin degenerate distal to the point of injury
Axonal degeneration is the primary pathology in what types of neuropathy?
Most polyneuropathies from toximetabolic causes
Most mononeuropathies are due to ___.
Trauma
Most mononeuropathies are due to trauma and occur at typical sites of nerve compression or entrapment, such as the ___ nerve at the wrist, ___ nerve at the elbow, and the ___ nerve at the fibular head.
Median; ulnar; common peroneal
List several general causes of multiple mononeuropathy syndromes.
Autoimmune (lupus)
Infiltrative (sarcoid)
Infectious (leprosy)
List some causes of non-acute polyneuropathy.
- Current or recent medications (eg, chemo)
- Toxic neuropathies (eg, neurotoxins in the workplace, alcohol, etc.)
- Malnutrition and vitamin deficiencies
- Hereditary neuropathy (+ family history, begins early in life)
If limb weakness occurs early during growth and development, what three physical exam findings may occur?
Pes cavus (high-arched feet)
Hammertoes
Scoliosis
When the clinical picture or EMG suggests a chronic polyneuropathy is due to inflammatory, immune-mediated, or vasculitic causes, what helps confirm the diagnosis?
Sural (sensory nerve) biopsy
If a non-acute polyneuropathy has no helpful historical clues as to its etiology, and the EMG test is non-specific, “screening” for a cause, particularly a treatable one, is done with what tests?
Blood tests for DM, liver or renal dysfunction, vitamin B12 deficiency, hypothyroidism, CBC to screen for anemia or other blood disorders
Rx significant median mononeuropathy at the rest?
May benefit from surgical decompression
Effective topical medications for neuropathic pain?
Topical capsaicin (substance P deplete) or lidocaine patches
Effective oral medications for neuropathic pain?
Anticonvulsants (gabapentin, pregabalin, carbamazepine)
Antidepressants (duloxetine, amitriptyline)
Presentation of GBS?
Rapidly progressive polyneuropathy
Any age
Follows a recent viral illness; may occur after surgery or trauma
Ascending, areflexic paralysis; progression plateus after 3-4 weeks
Signs of sensory impairment are minimal (patients may report tingling or numbness)
Pathogenesis of GBS?
Immune system targets peripheral nerve myelin, which was possibly modified by or antigenically resembles the virus encountered weeks earlier
Work-up of GBS?
Observation in an ICU, since MV may be needed
EMG shows evidence of asymmetrical demyelination in proximal and distal segments of various nerves
CSF: elevated protein with few if any WBCs and no signs of infection
Management of GBS?
Most patients recover fully; recovery may be hastened with plasmapheresis or infusion of IVIG
DM is a frequent etiology of polyneuropathy - what types of neuropathy may be seen?
Isolated or multiple mononeuropathies Autonomic neuropathies (gastroparesis or orthostatic hypotension) Cranial neuropathies (3rd nerve palsy)
In addition to DM, what are some other etiologies of polyneuropathy?
Metabolic/endocrine (uremia, hypothyroidism) Rheumatologic (RA, SLE) Cancer or myeloma Infection (AIDS, leprosy) Nutritional deficiencies (B vitamins) Toxins (alcohol, lead, solvents, drugs)
