Robbins - Peripheral Nerves and Muscles (Ch. 27) Flashcards by Andrew Herrmann

3 common causes (general) of mononeuropathies

Trauma
Entrapment/impingement
Infections/malignancy

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Polyneuropathies - how do they generally present?

Symmetric, start in hands/feet and ascend (“Stocking and glove” distribution)

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Common cause of mononeuritis multiplex

Vasculitis

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Polyradiculoneuropathies also involve the ____, leading to symmetric symptoms in the distal AND ___ body

Nerve roots

Proximal

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Acute motor weakness or paralysis in hands and feet that rapidly progresses to proximal muscles. DTRs are absent. Recently was sick.

What is it?

What PMH questions would you ask?

Worst complication?

Guillain-Barré Syndrome (Acute Inflammatory Demyelinating Polyneuropathy)

Autoimmune-mediated inflammation and demyelination of peripheral nerves and spinal nerve roots

Recent pneumonia? Recent viral illness? Recent GI infection?

Respiratory paralysis

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Guillan-Barré – inciting incident? Which ones?

INFECTION

Mycoplasma pneumonia
C. jejuni enteritis
HIV, CMV, EBV viral illness

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Diagnosing Guillan-Barré (3)

CSF protein elevated
No CSF pleocytosis
Slow nerve conduction

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Treating Guillan-Barre´ (2)

Plasmapheresis

- IVIG

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Relapsing and remitting symmetric sensory and motor deficits in the extremities for the past 2+ months. IgG and IgM are found on the myelin sheaths of peripheral nerves. Responds well to steroids.

Chronic Inflammatory Demyelinating Polyradiculoneuropathy

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Systemic autoimmune diseases that can cause sensorimotor neuropathy (3)

RA, Sjogren, SLE

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Loss of pain and sensation in all distal extremities and face. Segmental demyelination is found. Large ulcers found on extremities.

Lepromatous leprosy (M. leprae)

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Dermal nodules of granulomatous inflammation. Surrounding skin has loss of pain and sensation.

Tuberculoid leprosy (M. leprae – cell-mediated immunity)

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Bilateral bell’s palsy, target-like lesion on skin

Lyme disease

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Immigrant from S. America, fever, gray-white patches in throat, sudden peripheral muscle weakness and difficulty breathing.

Diphtheria

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Painful, vesicular skin lesions within a band-like pattern on the thorax or face

VZV (shingles)

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Most common cause of peripheral neuropathy

What kind of neuropathy is it? What is found on biopsy?

What is the cause?

Diabetes mellitus

Axonal (decreased number of axons)

Abnormal glycosylation of neural tissue, causing destruction

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Patient with DM has distal polyneuropathy with numbness, difficulty w/ balance, paresthesias or dysesthesias. What other findings are common (20-40%)? Examples? (3)

Autonomic dysfunctions

Postural hypotension
Incomplete bladder empty
Sexual dysfunction

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A patient w/ DM develops neuropathies, some of which are unilateral and asymmetric. What is the cause for these ones?

Microvascular disease, causing ischemia to those particular nerves

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Uremia produces what kind of peripheral neuropathy?

Symmetric axonal degeneration

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Hypothyroidism causes what kinds of peripheral neuropathy? (2)

Compression neuropathies or distal symmetric sensory neuropathies

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Most common toxic cause of peripheral neuropathy?

Alcohol abuse

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Most common paraneoplastic form of peripheral neuropathy

What does the damage? To what?

Presentation?

Small cell lung cancer –> sensorimotor neuronopathy

CD8+ T cells on dorsal root ganglion cells

Distal, asymmetric, multifocal neuropathy that progresses

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What are paraproteins? Do what?

Distinctive presentation of this?

Monoclonal Ig fragments from neoplastic B cells that bind to neurons and cause immune-mediated demyelination

POEMS syndrome – polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, skin changes

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Common neuropathies caused by physical forces (trauma or entrapment) (5)

Study These Flashcards

Compression neuropathy
Carpal tunnel syndrome
Ulnar nerve entrapment
Saturday night palsy (Radial)
Peroneal nerve

An adult with a peripheral neuropathy. Do NOT rule out an _____ disease

Inherited - often present in adults

Distal LE muscle atrophy, sensory loss, and foot deformities. Leg has "inverted bottle" appearance. What is it? Genetics? (3)

Charcot-Marie-Tooth disease Group of inherited disorders that cause PERONEAL nerve neuropathy. CMT1 = AD, defective myelin CMTX = X-linked, defective gap junction in schwann cells CMT2 = AD, axonal injury due to defective mitochondrial fusion -- SEVERE, EARLY

Transient motor and sensory mononeuropathies triggered by compression at common sites of entrapment Genetics? Causes what finding?

Hereditary neuropathy w/ pressure palsy PMP22 (same as CMT1) -- myelin defect -- swollen bulbous myelin sheaths at ends of internodes

Painless weakness of a muscle...think what? Most common cause?

NMJ impairment Autoantibodies

Patient experiences progressive muscle weakness over the course of the day, worse with exercise or exertion. Can't keep her eyes open, and sees double. Patient is young or middle age. What else to look for? Relationship between these?

Myasthenia gravis Thymoma or thymic hyperplasia (B-cell follicles in the thymus) Thymic disease promotes formation of autoimmunity against acetylcholine receptors on thymic myoid cells

Myasthenia gravis is caused by what?

Autoantibodies against post-synaptic acetylcholine receptors

Patient has weakness of extremities that improves after a few seconds of activity. Dx? Cause? What else to look for?

Lambert-Eaton Myasthenic Syndrome Autoantibodies against presynaptic calcium channels, preventing acetylcholine release Neuroendocrine (small cell) carcinoma of the lung OR an autoimmune disease (vitiligo, thyroid disease, etc.)

Function of botulinum toxin Function of curare

Block release of acetylcholine from presynaptic neurons Block acetylcholine receptors, causing flaccid paralysis

Slow-onset symmetrical proximal muscle weakness and muscle aches. Has trouble getting up from a chair or walking up stairs. Rash around the upper eyelids with edema, or a red scaly rash over joints. May see what on biopsy of muscle or skin? (2) See what on labs? (2) What are those skin rashes called? (2) May also have what?

Dermatomyositis - Perifascicular atrophy of muscle fibers - Deposition of C5-C9 (MAC) within capillary beds - Elevated CK - Anti-Mi2/Jo1/P155 autoantibodies ``` Heliotrope rash (lilac-colored) Gottron papules ``` Paraneoplastic-producing malignancy

How does polymyositis differ from dermatomyositis? (2)

- No cutaneous features | - No perifascicular atrophy

How does inclusion body myositis differ from polymyositis? (3)

- Late adulthood (65+) - Quads and distal UE muscles - cN1A antibody

How to treat inflammatory myopathies?

Corticosteroids

A patient with obesity and hypercholesterolemia is taking a statin to lower his cholesterol. What is the most common complication of this drug?

MYOPATHY (toxic)

Infant presents with severe hypotonia (floppy infant)...what disease class? Most important genetic? Causes what in infants? (2) Causes what in adults?

Congenital myopathies RYR1 (ryanodine receptor) mutation -- hypotonia and skeletal abnormalities MALIGNANT HYPERTHERMIA

Muscular dystrophies present when?

Childhood to adulthood (NOT INFANCY)

Young child (2-5), delayed walking, weakness and atrophy of pelvic muscles. Must place hands on knees to stand up. Labs show normal CK. Dx? Cause? Will see what else on observation? Why? Will find what else on physical exam? (2) Common causes of death?

Duchenne muscular dystrophy X-linked frameshift mutation, causing absence of DYSTROPHIN gene Fibrosis and fatty infiltration of muscle tissue, causing pseudohypertrophy of calf muscles Cardiomyopathy/arrhythmias and cognitive impairment Respiratory insufficiency, pulmonary infection, or HF

How does Becker muscular dystrophy differ from Duchenne?

- Later in childhood or adult - Full life prognosis - Defective but present dystrophin - Much less severe

CK levels in muscular dystrophy What part(s) of muscle is lost?

Elevated in 1st decade of life, then declines as muscle mass is lost Type 1 AND Type 2 fibers

Sagging face, can't close mouth, sustained grip or involuntary contraction of muscles Genetics? What part(s) of muscle is lost?

Myotonic dystrophy CTG trinucleotide repeats Type 1 Fibers ONLY

Slowly progressive humeroperoneal weakness, cardiomyopathy, and early contractures of tendons EMD1/2 mutation - what proteins?

Emery-Dreifuss Muscualr Dystrophy Nuclear lamina protein mutations

Prominent weakness of facial muscles and muscles of shoulder girdle. DUX4 over-expression.

Fascioscapulohumeral dystrophy

Patient has episodes of severe muscle cramping and pain after exercise or during fasting. Most likely has a disease associated with defective ____ Severe cases may present with ____

Lipid or glycogen metabolism/storage Rhabdomyolysis (necrosis)

Patient presents with chronic muscle weakness and elevate serum CK. On PE, extraocular eye muscles appear weak. Must think what kind of disease? Why?

Mitochondrial myopathies Extraocular muscles have the most mitochondria per mass of any muscle

An infant presents with generalized hypotonia, especially of proximal (thorax) muscles and respiratory muscles. SMN1 mutation is found. Cause?

Spinal muscular atrophy Loss of motor neurons

Mutations in ion channels can cause what major clinical manifestations? (5)

- Epilepsy - Migraine - Cerebellar dysfunction - Peripheral nerve disease - Muscle disease

What is the ryanodine receptor? 2 diseases when dysfunctinal?

Regulator of calcium release from sarcoplasmic reticulum Congenital myopathy Malignant hyperthermia

Tachycardia, tachypnea, muscle spasms, hyperpyrexia Triggered by what? What causes the symptoms?

Malignant hyperthermia Halogenated inhalational agents, succinylcholine Excessive calcium efflux from SR --> tetany and excessive heat production

Well-circumscribed encapsulated mass that abuts a nerve without invading it. Palisading nuclei, Antoni A/B, Verocay bodies. Most common nerves? (3) Genetics?

Schwannoma Vestibular br. of VIII Branches of V Branches of dorsal roots NF2

Mass at the cerebellopontine angle, tinnitus and hearing loss Common name?

Schwannoma Acoustic neuroma

Mass of neoplastic Schwann cells, perineural cells, fibroblasts, mast cells, and CD34+ spindle cells Genetics? 3 types Bad prognosis?

Neurofibroma NF1 - Superficial cutaneous (pedunculated nodules) - Diffuse (large plaque-like) - Plexiform (w/ nerve roots or large nerves) PLEXIFORM --> MPNST

Poorly defined, infiltrative mass in the chest, abdomen, pelvis, neck, or limb girdle. Focal areas of random differentiation (glandular, cartilagenous, osseous). 2 types?

Malignant peripheral nerve sheath tumor - NF1 - from plexiform neurofibroma - Sporadic (de novo)

Poorly defined, infiltrative mass in the chest, abdomen, pelvis, neck, or limb girdle. Focal areas of rhabdomyoblastic morphology.

Triton tumor (MPNST)

NF1 - tumors (5)

- Neurofibromas - MPNSTs - Gliomas of optic nerve - Glial/hamartomatous tumors - Pheochromocytoma

NF1 - non-tumor features (4)

- Lisch nodules (pigmented spots on iris) - Cafe au lait spots - Mental retardation - Seizures

NF2 - tumors (3)

- Bilateral 8th nerve schwannomas - Multiple meningiomas - Ependymomas of spinal cord

Robbins - Peripheral Nerves and Muscles (Ch. 27) Flashcards

(59 cards)