Neuromuscular diseases Flashcards Preview

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Flashcards in Neuromuscular diseases Deck (43):
1

What symptoms do UMN diseases produce?

• Spastic tone,
• hyperactive tendon reflexes,
• pathological reflexes (babinski)
• Emotional lability (inappropriate laughing and crying)

2

What symptoms do the damage of sensory and autonomic nerves produce?

• Numbness,
• abnormal painful sensations
• Bowel and bladder disturbance
• Alterations in sensation, sweating, heart rate and blood pressure
• (think of all the ANS tissue targets and what might happen if they were not innervated with proper tone)

3

What symptoms do LMN diseases produce?

• Muscle atrophy, fasciculations, diminished tone and reduced or absent reflexes

4

If there are no sensory problems associated with weakness found by exam, what does that suggest?

• NMJ problem
• Motor neuron problem
• Muscle disease
• (if there are sensory problems as well that suggests an entire nerve problem)

5

What goes on your differential if there is a rapid progression of symptoms? (hours to days)

• NMJ disorders like MG, botulism and organophosphate poisoning
• Acute demyelination in Guillan Barre syndrome
• Electrolyte disturbance
• Toxic myopathies

6

What are the three distribution patterns of weakness?

• Proximal, distal and cranial
• Proximal is weakness in posture and walking (climbing stairs, getting out of a chair)
• Distal weakness, indicative of neuropathy, is in the hands and feet (foot drop, trouble holding things or turnig a key)
• Cranial is seen in MG, droopy eyelids (ptosis), double vision and speaking/swallowing abnormalities

7

The symptom "stiffness" can reflect what problem?

• Myotonia, delayed relaxation of muscle following voluntary contraction
• A problem either with excitation machinery being overactive OR the membrane can't regain the hyperpolarized potential

8

What enzyme studies can you request for NMJ disorders?

• Muscle necrosis results in elevated levels of serum creatinine kinase (CK)
• Highest levels of CK occur with myoglobinuria
• Muscular dystrophies and inflammatory myopathies have moderate elevations

9

What are some signs to look for in infants with NMJ disorders?

• Decreased tone (floppy baby)
• Delay in motor milestones

10

What are some electrodiagnostic studies you can request if you are suspecting a neuromuscular disease?

• Want to distinguish neuropathic from myopathic
• NCS - nerve conduction studies
○ Give you a baseline and numbers to follow for the course of the disease
○ Broadly differentiate between primary demyelinating (super slow conduction) and axonal neuropathies
• Needle EMG
○ Often complement to NCS and helps differentiate myopathic from neuropathic
○ If a nerve problem, the whole motor unit fails
○ If muscle problem, individual fibers of the motor unit fail
• Repetitive nerve stimulation
○ Allows you to look at a muscle in the context of extreme work, and in MG you see depletion take its toll

11

What should go on your differential of "myopathies"?

• Muscular dystrophies
○ Duchenn/becker, limb girdle, FSH
• Myotonic disorders
○ Myotonia congenital, myotonic dystrophy
• Inflammatory myopathies
○ Polymyositis, dermatomyositis, inclusion body myositis
• Endocrine myopathies
• Metabolic myopathies
○ Glycogen storage, lipid myopathy, mitochondrial myopathy
• Toxic myopathies
• Periodic paralysis

12

What does ALS stand for?

• Amyotrophic lateral sclerosis
• Characterized by progressive weakness and wasting from degeneration of brainstem and spinal cord lower motor neurons
• Coexisting spasticity and hyperreflexia b/c of UMN syndrome
• Most cases are sporatdic, though less than 10% are familial
• Initial clinical symptoms may be limited to asymmetric limb weakness in the presence of fasciculations
• Foot drop or marked hand deformity resulting from interosseus wasting may be seen
• Pathological reflexes can be seen
• Sensory exam is normal, but speech may develop a slurred or spastic quality

13

What initial signs and symptoms point to ALS?

• Initial clinical symptoms may be limited to asymmetric limb weakness in the presence of fasciculations
• Foot drop or marked hand deformity resulting from interosseus wasting may be seen
• Pathological reflexes can be seen
• Sensory exam is normal, but speech may develop a slurred or spastic quality

14

What is the average survival of ALS after ddx?

• 3-4 years, but 10% survive 10 years or longer
• Fatal aspiration pneumonia is common from defects in swallowing
• Also diaphragm weakness is a problem

15

What is the average survival of ALS after ddx?


• 3-4 years, but 10% survive 10 years or longer
• Fatal aspiration pneumonia is common from defects in swallowing
• Also diaphragm weakness is a problem

16

What are the treatments for ALS?

• Primarily symptomatic
• Medications for cramps, spasticity, excess saliva and inappropriate laughing or crying
• Riluzole has been shown to slow progression slightly (extend life 3 mo)
• Braces and durable medical equipment for mobility
• Alternative communication devices
• Feeding tube and ventilation

17

Many different inherited neuropathies are often lumped into what disease name?



• CMT - Charcot Marie Tooth
• Autosomal dominant forms are CMT1 and CMT2
• CMT1 is slow nerve conduction and hypertrophic demyelinating neuropathy
• CMT2 is normal nerve conduction velocities and axonal degeneration
• There are many new genes being liked to the disease, and the only one we talked about in detail is CMT1A

18

What do most patients with CMT present with?

• One of three phenotypes based on the age at symptom onset
• Most common - distal hand and foot weakness and sensory loss develops slowly in the first two decades of life
○ Patients don't need much more than walking aides
• Second phenotype - already impaired as infants and experience delayed walking
○ Many are later confined to wheelchair
• Third phenotype - adult onset that appears at 40ish years

19

If the same gene that CMT1A has duplicated is instead deleted, what's the result?

• Gene is PMP22
• If this gene is deleted, it results in HNPP, hereditary neuropathy with liability to pressure palsies

20

What's up with CMT1A?

• Duplication of the DNA containing the peripheral myeling protein gene PMP22
• If this gene is deleted, it results in HNPP, hereditary neuropathy with liability to pressure palsies

21

What electricity test is used most in diferentiating CMT disease?


• NCVs - nerve conduction velocities
• Cutoff for demyelinating and axonal forms are 38m/sec
• There are some intermediate forms though 35-45m/sec
• This test and family history guides you in asking for certain genetic tests

22

What is the treatment regime for CMT?

• PT to maintain muscle strength and ROM
• OT to improve hand function and provide tools to aid activities of daily living
• Orthotics for ambulation aid and reduce falls
• Treat neuropathic pain

23

What is the most common type of diabetic neuropathy?


• Distal sensory or sensorimotor polyneuropathy
• Initially complain of numbness and burning dysesthesias in their feet
• Spreads to legs and eventually hands
• Weakness of foot dorsiflexor muscles results in a slapping foot drop gait
• Grip strength and fine hand dexterity may be diminished as well

24

What ANS problems can happen in diabetic neuropathy

• These can occur with or without other evidence of neuropathy
• Postural hypotension
• Diarrhea
• Impotence
• Urinary retention
• Increased sweating

25

On examination what does one see in diabetic neuropathy?

• Pin sensasion loss in a stocking glove distribution but the distribution is often somewhat asymmetric
• Loss of position, vibration, light touch
• Decreased reflexes in a large fiber pattern
• Great loss of pain and temperature sensation - indicates predominantly small fiber injury
• Pain may have a dull aching quality in the limbs and also a distal, burning discomfort most prominent at night

26

What's up with lumbosacral plexopathy?

• A complication in diabetic neuropathy
• Characterized by acute onset of asymmetrical proximal weakness and pain of the legs
• Frequently occurs at the onset of diabetes and may be associated with weight loss
• Mononeuropathies can affect almost any peripheral nerve as wella s cranial nerves, particularly the extraocular muscles
○ 3rd and 6th nerve palsies

27

What's up with 3rd and 6th nerve palsies?

• Mononeuropathies can affect almost any peripheral nerve as wella s cranial nerves, particularly the extraocular muscles

28

What are the treatments for diabetic neuropathy?

• Metabolic control is likely helpful
• Medications for pain like anticonvulsants, antidepressants and narcotic analgesics
• Foot hygiene is imperitive to avoid trophic ulcers of the feet
• Codeine and diphenoxylate for diarrhea
• Support stockings and fluorocortisone or midodrine for postural hypotension

29

What drugs make you think diabetic neuropathy treatment?

• fluorocortisone or midodrine for postural hypotension
• Codeine and diphenoxylate for diarrhea
• Medications for pain like anticonvulsants, antidepressants and narcotic analgesics

30

Patients with MG often have what other (gland) signs?

• 85% have thymic enlargement
• 10% have a thymoma

31

How do you confirm dx of MG?

• Presence of achr antibodies in serum
• Some have MUSK antibody which binds portion of the postsynaptic membrane
• Intravenous injection of edrophonium, an ache inhibitor, temporarily improves strength and corrects the depletion after repetitive nerve stimulation

32

What are the signs and symptoms of MG?

• Often family history of autoimmune disorders
• Thymic enlargement is common
• Fluctuating weakness and fatigue in cranial, limb or trunk musculature are characteristic
• Ocular symptoms lik eptosis, diplopia and blurred vision
• Facial muscles are weak and speech may become slurred, nasal and hoarse
• Progressive trouble chewing and swallowing and eventual choking and aspiration of food and saliva
• Neck muscle weakness
• Respirator muscle weakness
• Limb muscle weakness is usually not AS big of an issue

33

What is the treatment for MG?


*great management can lead to a great quality of life, which I found surprising
• Symptomatic relief with oral ache inhibitors like pyridostigmine
• Corticosteroids (prednisone) and other immunosuppressive agents (azathioprine, mycophenolate mofitil) are used
• Temporary (2-3 weeks) dramatic improvemtn is seen following plasma exchange or IV IG infusion
• Thymectomy is recommended for all patients with generalized MG except super young and old

34

Why is thymectomy recommended inmost MG patients?

• Thymectomized patients need less immunosuppressive medications and experience fewer medication side-effects

35

What kind of inherited disorders are duchenne and becker dystropy?

• X-linked recessive disorders
• Variety of deletions, duplications and point mutations in the area of the X chromosome coding for dystrophin

36

What are the molecular genetic ideas for treatment?

• Upreguatin utrophin, a shorter isoform of dystrophin
• Admin gentamycin that helps read through stop codons
• Gene therapy by introduction of healthy gene in stem cells

37

Are there drug treatmetns for DUD/BD?

• Controversial
• Immunosuppressive medications slow progression slightly
• Use can have complications with growth, weight gain and behavioral problems

38

How can you determine a carrier status or test the fetus for muscular dystrophy?

• Amniocentesis
• Chorionic villi biopsy
• Peripheral blood of the mother

39

How can you confirm DUD/BD diagnosis?

• Elevated CK (20-100 fold increase)
• Muscle biopsy shoes characteristic features but aren't so used b/c less invasiv DNA tests

40

DUD kills people by what final pathway?

• Weakness of respiratory muscles and heart failure in late teens or early 20s

41

What do you worry about in boys with DUD that are wheelchair confined?

• Kyphoscoliosis, contractures of all joints, equinovarus deformities of the feet

42

What does DUD look like?

• Boys have a clumsy waddling gait from the time they first walk
• Proteuberant abdomen results from an accentuation of the lumbar lordosis
• Enlargement of the calves (pseudohypertrophy)
• Tight heel cords with a tendency to toe walk
• Difficulty in rising from the floor (Gower's maneuver)
• Subnormal intelligence is common
• Eye movements, swallowing and sensation are unaffected
• 9-12 years old, walking is probably unsafe

43

How does BD differ from DUD?

• Duchenne = DUD
• BD = becker
○ Onset is usually later and course is more benign
○ Shorter protein, not fully absent
○ Less mental impairment

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