Disorders of the Anterior Horn Cells (SMA, Postpolio Syndrome) Flashcards
SMA Type I course:
- Rapid
- Severe hypotonia
- Death within 3 yr
- 32% survive 2nd yr
- 8% survive 10 yrs
Functional recovery from acute poliomyelitis:
- neuromuscular learning: practice
- use of muscle at a high level
What is the age of onset of SMA Type II?
before 18 months
etiology/pathology of post-polio syndrome; theories:
-
Unknown, but several theories:
- remaining MN can no longer maintain new sprouts; denervation exceeds reinnervation
- motor cortex with dereased capacity to control locomotor activity
- Genetic viral material deregulates immune responses
- stress of aging
- previously affected neuron did not fully recover
- metabolic exhaustion of giant motor units
- NMJ trasnmition deficits
- Scarring within motor units
- Increased weakness due to weight gain
what gene is defective in 99% of all cases of SMA?
SMN 1 Survival Motor Neuron
how many cases of pot-polio syndrome in 1987?
1.6 million in US
How many of the previous acute polio pt develop post-polio syndrome
20-40%
Course of SMA type III:
- Slowly progressive
- can ambulate at some point
- usually wheelchair dependent in adulthood
- shortened lifespan
- some may have normal lifespan
What is survival motor neuron SMN1?
naturally occuring protein
AHC degeneration leads to
progressive muscle weakness & atrophy
What is the course SMA type II?
- Can survivie up to 10 yrs
- Progressive but stabilizes
- Can sit, but standing or walking usually not possible
What is poliomyelitis?
- Poliovirus spreads to CNS & attacks motor neurons in spinal cord & brain
- Results in assymmetric flaccid muscle paresis or paralysis
- LE’s more affected than UE’s
A 1 y/o child has been diagnosed with SMA. What is the prognosis?
will lose ambulatory ability at around age 12
Gene deletion of chromosome 5
SMA
Clinical course of postpolio syndrome
- Normal
- Paralysis
- Recovery
- 10-15 yrs of stability
- Post-polio syndrome
prognosis of SMA
- best prognosis types III and IV
- type III:
- Onset > 2 yrs old; remain ambulatory during adulthood
- Onset before 2 yrs: lose ambulatory ability at age 12 on
average
SMA P.T. Intervention may include:
– Strengthening exercises
– Aerobic exercise
– Developmental skill training
– Aquatic therapy
– Standing program
– Management of respiratory complications
– Management of contractures
– Management of scoliosis/skeletal deformities
– Prescription of/training with assistive devices
Medical treatment of SMA:
- Symptomatic and preventive, no cure
- Respiratory care
- prevent MSK complications
- Maintenance of head control
- feeding assitance
- scoliosis tx
What are the clinical features of SMA type III?
- Prox LE weakness
- Good UE strenght
- Slow, continued developmental progression
- Can sit inddependently
- Gait and postural deviations
What is post-polio syndrome?
- In 70’s and 80’s polio survivors developed new weakness
- Late effects of polimyelitis
- primary, secondary, MSK and psychosocial impairments
Psychological considerations of PPS:
- Coping Styles
- Response to new diagnosis
- Compliance
percentage of people infected with polio virus that do not develop illness or only mild case:
95-99%
How are the EMG/NVC in PPS?
- Sensory NCV: normal
- Motor NCV: normal but may be slowed
- EMG: abnormalities of chronic denervation
- Muscle biopsy
When does the onset of SMA occur?
- varies from early onset to late in life
- majority occur during infancy
- adult forms are very rare
Clinical features of SMA type IV:
- mild to moderate gradual proximal muscle weakness
- may show tremor and twitching, mild respiratory difficulty
- usually remain ambulatory, may need wheelchair
- normal lifespan
What is the adopted posture in children with SMA type I?
- LE: flexed, abbducted, externally rotated
- UE: abducted externally rotated, unable to move to midline against gravity
PPS clinical manifestations:
- Fatigue: most common symptom
- New muscle weakness: asymmetric. prox. and/or distal.
- Due to disuse, overuse, chronic, weight gain
- Muscle atrophy
- Muscle pain: high intensity, associated with mechanical stress
- Swallowing dysfunction
- Gait and difficulty with ADL’s
- Respiratory dysfunction
- Cold intolerance
- Sleep disorders
A group of inherited disorders characterized by degeneration and loss of anterior horn cells (AHC)
SPINAL MUSCULAR ATROPHY (SMA)
Neurological recovery from acute poliomyelitis affected by:
- Motor neurons that recover & resume normal fucntion
- Collateral sprouting to reinnervate orphaned muscle fibers: giant motor units
- Innervated muscle fibers can be hypertrophied by intensive exercise: denervation hypertrophy
Onset of post-polio syndrome
35 yrs after acute polio
What is the adopted posture in children with SMA type II?
LE flexed, abb, ER
onset of SMA type IV
after age 30
in the eraly polio epimic, patient were told to…
- Use “heroic” compensatory methods
- used ligaments for stability (resulted in hypermobility)
How is the weakness presented in SMA?
- Bilateral
- Symetrical
- More proximal
- Facial muscles may be involved
- Relative sparing of eye muscles and anal sphincter
onset of SMA type I
0-3 months
What is the inicidence of SMA type I, II, III?
- Type I: 1 in 15,000 - 25,000 live births
- Type II: 1 in 15,000 - 25,000 live births
- Type III: 6 in 100,000 live births
Diferential diagnosis of PPS need to rule out:
- ALS
- MS
- Hypothyroid myopathy
- Other conditions:
- Anemia
- Chronic infection
- Infectious myopathy
- Myasthenia gravis
- Weakness due to aging
- Weight gain
A 3 y/o child has been diagnosed with SMA. What is the prognosis?
remain ambulatory during adulthood
diagnosis of SMA
- Clinical pictures
- muscle biopsy
- decreased motor AP in EMG
- NCV: slower later in the course
- Genetic testing
What is the long term effect of substitutions and overcompesations?
- Microtrauma of ligaments and joint structures
- Exhaustion of neuromuscular units
(Poliomyelitis)
Second most common fatal autosomal recessive disorder after cystic fibrosis
SMA, mother and father has to have it
What do lab tests in PPS show?
elevated creatine kinase
Clinically, creatine kinase is assayed in blood tests as a marker of damage of CK-rich tissue such as in myocardial infarction (heart attack), rhabdomyolysis (severe muscle breakdown), muscular dystrophy, the autoimmune myositides and inacute renal failure.
Common SMA deformities include:
- Scoliosis
- Kyphosis
- Lordosis
- Contractures
- Joint dislocation
Incidence of SMA type I
1 in 15,000 - 25,000 live births
General picture of SMA:
- Bilateral, symmetric, proximal weakness
- Skeletal deformities
- Progressive atrophy: flaccidity
- Dimished DTR’s
- Normal sensory
- Normal intellectual
- Restrictive lung disease
Severity of signs and symptoms in SMA related to what?
- how many copies of SMN2 are present
- More copies of SMN2 = more SMN protein produced = less severe forms of SMA
Diagnosis of PPS:
- Hx of polio
- 15 yrs of stability
- At least two new symptoms from the following:
- Excessive fatigue
- Muscle or joint pain
- Muscle atrophy
- Cold intolerance
- Rule out: ALS, MS, hypothyroid myopathy, MG, weight gain, wekaness due to aging
Rehab considarations for muscle and joint pain in PPS:
- Heat
- Electrical stimulation
- Stretching exercises/ROM
- Muscle relaxation exercise
- Biofeedback
- Lifestyle changes
Types of SMA?
- SMA I
- SMA II
- SMA III
- Adult SMA (IV)
What is the age of onset of SMA type III?
18 months
SMA prevalence:
- 1 in 20,000 live births
- 1 in 50 carry the genetic defect
SMA goals for PT
- Achieve highest levels of indepence and mobility
- improve/maintain muscle strenght and aerobic capacity
- prevent or delay development of complications
SMA Pathogenesis
- AHC degenration occurs due to decreased level of SMN1
- SMN2 can compensate, but is not as effective.
Which is the most severe form of SMA?
SMA Type I
