Neuropathy, myopathy, and motor neuron disease Flashcards
what is a neuropathy
any syndrome where one or more nerves are affected by any of several mechanisms
what is mononeuropathy
involvement of a single, major, named nerve (i.e. median nerve, peroneal nerve)
sensory or motor defects related to its anatomical distribution
what is a polyneuropathy or peripheral neuropathy
a disorder of multiple, major and small nerves
what usually causes a mononeuropathy
trauma or compression
what is more common poly neuropathy or mononeuropathy
poly/peripheral neuropathy
what are characteristics of a poly neuropathy
symmetrical signs and symptoms
early sensory loss or impairment in distal limbs (feet, with longest sensory fibers in body, then hands: “stocking & glove;”
paresthesia and dysesthesia;
distal limb weakness and atrophy
early loss or decrease of muscle stretch reflexes
How is the pattern of poly neuropathy described?
stocking and glove pattern
parasthesia
a spontaneous tingling. “pins and needles” sensation
dysesthesia
unpleasant sensation from a non-noxious stimulus
what symptoms indicated autonomic nerve involvement in a poly neuropathy
orthostatic hypotension, incontinence, impotence, or sweating abnormalities
how do you diagnosis a mononeuropathy
usually clinical findings, sometimes use nerve conduction/ EMG testing to help localize and assess the severity of the nerve lesion
what is the most common mononeuropathy
median mononeuropathy - carpal tunnel syndrome
what are common characteristics of a myopathy
proximal weakness or fatigue
normal sensation
late loss of reflexes only after significant atrophy
what are the 2 process of neuropathy
demyelination and axonal degeneration
what is the main mechanism of carpal tunnel syndrome
demyelination
what has a better chance of recover demyelination or axonal degeneration
demyelination
axon damage tends to be permanent
how does carpal tunnel sydnrom occure
flexor tendons passing through the carpal tunnel get inflamed or swollen, compressing the median nerve
fluid retention during pregnancy may also compress the median nerve here, in addition to rarer diseases depositing material in the carpal tunnel
what are the symptoms of carpal tunnel
tingling numbness of the hand may waken the patient, while thenar weakness and atrophy occur in more severe cases;
how do you treat carpal tunnel
treatment of carpal tunnel syndrome (and other compressive mononeuropathies) ranges from local rest, anti-inflammatory medication, splinting, to surgical decompression of the nerve;
where does Wallerian degeneration occur
at the site of severe nerve injury, involving myelin and axons distal to that point
what helps re-innervation to occur
if the perineurium and epineurium (connective tissue) remain providing a framework/scaffolding
shorter distances to reach the muscle
what is Wallerian degeneration
loss of axons due to a severe crush or penetrating injury. axons and myelin degenerated distal to the injury
what happens if there is not connective tissue to guide regeneration
re-sprouting axons pile up in a bulbous neuroma (often painful)
what is the primary pathology of polyneuropathies from toximetabolic causes
axonal degeneration (demyelination is a secondary or additional process)
what causes must be considered in a patient with multiple mononeuropathies
systemic illness which is inflammatory or autoimmune (SLE), infiltrative (sarcoidosis) or infectious (leprosy)
true or false: a cause is usually identified for non-acute polyneuropathies
false - 50-60% of patients may have an unknown etiology
what are some possible causes of a polyneuropathy
- medications (chemotherapy)
- neurotoxins (work place exposures, or alcoholism)
- malnutrition and vitamin deficiencies (B)
- hereditary neuropathy (presents early)
- infections (AIDS, leprosy)
- DM
- metabolic or endocrine disorders
- rheumatological disease
- cancer or myeloma
what does an EMG do
an electromyogram tests the electrical activity and function of nerves and muscles.
what is a sural biopsy
sensory nerve biopsy - can be used to confirm the diagnosis if a poly neuropathy is due to an inflammatory, immune-mediated or vasculitic cause
what is the side effects of a sural biopsy
bc the sural nerve in the foot is removed the patient is left with permanent numbness along the lateral foot
what oral medications are effective for nerve pain
anticonvulsants and antidepressants
what does a slowing of nerve conduction velocity seen in EMG testing suggest
demyelination problem
what does a decreased amplitude in EMG testing suggest
axonal loss
when is needle EMG testing used
the electrical activity of muscles within individual motor units is assessed for evidence of denervation, reinnervation, or muscle disease.
treatment options for polyneuropathy
Treatment of its primary, underlying cause (e.g., control of diabetes, abstinence from alcohol);
Orthotic devices to allow for safe ambulation;
Physical therapy to maintain joint range of motion;
Medications to relieve painful sensory disturbances (paresthesia, dysesthesia)
(topical creams or ointments,
oral anticonvulsants or antidepressants)
how does Guillain-Barre progress
very acute
weakness progresses over hours to days
at its worst by 4 weeks
what kind of paralysis does guillain-barre cause
an ascending (legs first), areflexic paralysis
(generalized (including respiratory) paralysis may occur;
some paresthesia, little objective sensory loss)
what is Guillain-barre associated with
recent viral respiratory infection (50% of the time)
what is the etiology of Guillain-Barre
misdirection of the immune system to attack normal peripheral nerve myelin (? antigen modification by the recent virus)
what is the pathology of Guillain-Barre
inflammation and demyelination of peripheral nerves or roots (if severe, secondary axonal loss)
how do you diagnose Guillain-Barre
evidence of demyelination by EMG testing of nerves;
elevated protein in CSF, with few if any WBCs;
what is the prognosis of Guillain-Barre
good with medical care
what treatments are available for Guillain-Barre
Plasmapheresis or immunoglobulin infusions (IVIG) may shorten the illness and hasten recovery;
what are symptoms of hereditary neuropathies
onset in childhood - may be subtle
distal sensorimotor deficits, little to no paresthesia or dysesthesia
what orthopedic deformities may be present with hereditary neuropathies
scoliosis, hammertoes, pes cavus
due to neuropathy in a growing child
treatment of hereditary neuropathies
no curative treatment
give assistive devices or orthotics as needed
what is a myopathy
primary disease of the muscle
what are symptoms of a myopathy
- Symptoms of weakness, fatigue, sometimes cramps
- Proximal limb weakness and atrophy (shoulders, hips)
- Late loss of reflexes (after significant atrophy present)
- normal sensation
how is a myopathy diagnosed
- review of family history (muscular dystrophy)
- serum muscle enzymes (CK) are often elevated
- EMG demonstrates a disorder of muscle
- muscle biopsy
what is Polymyositis
Inflammation and weakness of multiple muscles may occur from viral infections or drug reactions;
what is the most common cause of polymyositis in the US
Autoimmune
what are common symptoms of polymyositis
- proximal weakness over weeks to months;
- a rash around the eyes or fingers may occur (dermatomyositis)
- rarely related to underlying cancer;
how is a diagnosis of polymyositis confirmed
EMG testing, and presence of inflammation and muscle fiber necrosis on biopsy;
what are treatment options for polymyositis
corticosteroids or other immunosuppressive drugs
how is Duchenne’s muscular dystrophy inherited
X-linked
what is the etiology of Duchenne’s muscular distrophy
virtual absence of dystrophin, critical structural protein, in muscle; involves respiratory and cardiac muscles also
what symptoms are commonly seen in Duchennes muscular dystrophy
- proximal weakness begins in boys of childhood age;
- calf pseudohypertrophy from muscle replaced by fat, connective tissue;
- cardiorespiratory death by third decade
- in order to stand from laying the child must “crawl” up
what are motor neuron diseases (MND)
Disorders, occasionally hereditary, where degeneration of upper (UMN) or lower (LMN) motor neurons, or both, occurs with varying severity and rate of progression;
spinal muscular atrophy involves what part of the spinal cord
anterior horn cell involvement
what are symptoms of spinal muscular atrophy
LMN signs (weakness, atrophy, areflexia, fasciculations.
range from fatal to milder types (later onset)
what is Werdnig-Hoffman
infantile onset of spinal muscular atrophy. A terminal condition due to rapid development of diffuse weakness with no current treatment
what signs might be noticed in an infant with Werdnig-Hoffman
weak cry, not sucking well, lack of movement, breathing difficulties (usually die in first year)
bell-shaped thorax, frog leg posture
what is Amyotrophic lateral sclerosis (ALS)
progressive degeneration of all motor neuron subgroups:
• UMN (corticobulbar and corticospinal tracts) and LMN (anterior horn cells, brain stem motor nuclei);
what is the prognosis of ALS
worse prognosis of all MNDs
50% die within 3 years- with respiratory failure or complications of profound weakness
what are clinical manifestations of ALS
- drooling - impaired swallowing and poor facial muscle tone
- difficulty chewing and swallowing
- asymmetric atrophy, weakness, and fasiculations of the tongue w/ deviation
- variable speech impairment
how is ALS diagnosed
clinical picture and EMG testing
how does ALS initaially present
Frequently begins with regional weakness and atrophy of a limb (e.g., shoulder), which spreads and becomes bilateral; or initial weakness of swallowing or speech;
signs of ALS on exam
Diffuse fasciculations may be prominent;
Hyper-reflexia, spasticity or Babinski signs are noted;
treatment for ALS
riluzole prolongs survival by months
what are some possible causes of myopathy
- influenza
- medications (statins)
- Endocrin disorders (cushings, hypothyroidism)
- hereditary
what do you expect to see on muscle biopsy in someone with polymyositis
inflammatory infiltrate, necrotic and regenerating muscle fibers
what is Grower’s maneuver
seen in boys with Duchenne’s muscular dystrophy. Seen when the boy uses his upper limbs to compensate for weak trunk and pelvis muscles when getting up from the floor
what disease to you commonly see pseudohypertrophy of the calves
Duchenne’s Muscular dystrophy
