Spinal Muscular Atrophy "SMA" Flashcards
SMA
Defined:
Genetic disease affecting anterior horn cells in SC
Spinal Muscular Atrophy
Muscular:
Mm’s unable to receive signals from nerve cells
Spinal Muscular Atrophy
Atrophy
When mm’s not active→ lose size+girth and waste away
SMA
Causes → MAIN
-
Defect→ Chromosome 5
- Motor PRO deficiency→ SMN→ “survival of motor neuron”
- 4 types
- Motor PRO deficiency→ SMN→ “survival of motor neuron”
SMA
other causes
- Mutations in UBE1 on X-chromosome
- Mutation of DYNC1H1 gene on chromosome 14
SMA
Diagnosis
-
Creatine Kinase, CK
- leaks out of mm’s when deteriorating
- nonspecific test
-
Genetic Testing
- blood test
-
MM biopsy and NCVT
- less freq.
Symptoms of SMA:
Range: Mild→Severe
-
Primary sx’s→ Weakness of voluntary mm’s
- Prox weak>Dist weak
- Typ symmetrical
- respiration, posture, overall mobility
-
PRESERVED→
- intelligence, social dev, sensation*, sphincter control
SMA Prognosis
Depends on type and severity
MOST SEVERE SMA
Type 1
Type 1 SMA:
aka
Acute Childhood/Infantile SMA
Type 1 SMA; Acute Childhood/Infantile SMA
*MOST severe
- Werdnig-Hoffman Disease
- Weakness→ @ birth or <4mos
- CN involve.
- Resp. probs and accessory mm use to breathe
- continue to belly breathe due to impaired diaphragm strength
- swallow/feeding diffs
- MM fasciculations→ also tongue
- Tremor
IN GENERAL→ alert and responsive
SMA Type 1:
Clinical Characteristics/Facts
- Weakness→ neck, trunk, shoulders, pelvic girdle, antigrav mm’s
- Frog legged pos.→ gravity pulls them into this
-
Limtd head/trunk control
- cannot clear airway in prone
- no unassisted sitting milestone
- scoliosis prominently seen→ early in type 1
SMA Type 1: Childhood SMA/Infantile Onset
MSK issues
- MM contractures & alignment issues→ 2* weakness and not taking mm’s thru full ROM
SMA Type 1: Childhood SMA
Life span
- Death from PNA or resp comps common w/in first few mos to few yrs
-
Mean age of death= 6mos
- some cases up to 42mos
SMA Type 1: Tx
MAIN FOCUS
-
Respiratory health
- Chest PT reqd***
- Assist cough
- Postural drainage pos’s
- Support devices; ex. vibration vests
- Chest PT reqd***
SMA Type 1: Tx
besides resp health
- Positioning
- Supine w/ suppors
-
S/L GOOD position
- +resp health and un-wts one side
- very functional due to antigravity pos.== midline play
- Prone avoided
SMA Type 1: Tx cont’d
Supported Sitting
- Supported sitting
- Abdom binder,
- spinal alignment
- hammocks→ great for allowing IND but supported mvmt
- ROM for contracture mgmt
- LIGHT strengthening in certain pos’s
SMA Type 1 videos
Acute childhood SMA
see slide 12******
SMA Type 2
aka
Chronic Childhood SMA aka “Intermediate SMA”
SMA Type 2: Chronic Childhood SMA
Clinical presentation:
- Weakness→ typ first year of life→ typ bw 7-14mos
- Variable course
-
Pearn and colleagues:
- 95%→ weakness <3yo
- 46% never walked
- 38% ambulate unaided @ some stage
- Median age of death >10yrs
- Pulm health plays factor in life span
SMA Type 2: Chronic Childhood SMA
Eng reports 3 subgroupings w/in Type 2
-
Severe
- resembles Type 1→ inability to sit, sig. impaired resp system
-
Intermediate
- sit alone but do NOT achieve amb.
-
Mild
- children amb. IND but lost ability by end of first decade
Type 2 SMA
Weakness
- Prox weak> dist weak as in type 1, to a lesser degree
- hip, knee exts, trunk
- less severe but present contractures
Type 2 SMA Tx: Infancy
- Baby program w/ chronic SMA similar to type 1
- Trunk control in antigravity pos’s
- Dev. activities and gross motor skills
- maintain function if not achieving milestones
- Aquatic tx
- Adapted equip.
- Standers→ esp if not standing by 16mos
-
TLSO→ assist w/ trunk alignment in upright pos.
- slows gravity deforms
Type 2 SMA Tx: Preschool/School Age
- Orthotics→ lt. wt. KAFOs
- Assisted walking programs
- SAFETY! 2* incd fx risk and falls bc weakness
- Supported walking DECs:
- contracture, hip disloc’s, scoliosis curve progression
- power mobility if not ambulating
- contractures 2* prolonged sitting
- progression of scoliosis high incidence
- sx for spinal stab.
Scoliosis and TLSO
see pics
THKAFO and power chair
SMA Type 2: Transition into Adulthood
- Adulthood survival variable
- Weakness progresses
- All mobility and ADLs assistance needed
- aide and/or family mbr around the clock
- Aggressive pulm hygiene program
- Continued ROM
- Vocational services
SMA type 2 videos
slide 20****
SMA Type 3 aka
Juvenile Onset
*Kugelber-Welander Disease
SMA Type 3: Juvenile Onset
Clinical Presentation
- Weakness→ after 18mos @ least, OR late into first decade
- typ stand/walk IND, may req. aids
-
Prox. LE weakness====PRIMARY FINDING***
-
2* Impairs:
- postural compensations, trendelenburg gait, INC lumbar lordosis, contractures, scoliosis
-
2* Impairs:
Type 3 SMA: School-Age
-
Difficulties:
- rise from floor, stairs, keeping up w/ peers
-
Characteristics:
- waddling gait, balance defs, tremors, prox UE strength preserved
Type 3 SMA: Juvenile Onset
School-Age
Ambulation?
Ambulation typ preserved as primary mode of loco.
more severe→ scooter
Type 3 SMA: Juvenile Onset
School-Aged
PT mgmt
*similar to other types
- Maint. ROM
- Maint. strength
- teach adaptive equip. use
Type 3 SMA: Transition to Adulthood
- Gen weakness
- Lifespan NOT shortened→ episodic PT and HEP preserves function
- Vocational counseling absolutely req’d
Type 4 SMA: Adult Onset
- Onset in adulthood
- Function fairly typical prior to onset**
- Amb preserved t/o adulthood w/ weak. developing gradually over time
Severity of SMA vs Types of SMA
Severity DECs as types INCs
Types I-III== PEDS
Hallmarks in ALL FORMS of SMA
Prox>Distal, symmetric weakness
Contractures
Resp. health concerns***
PTs play a major role in care/mgmt of SMA from infancy→ adulthood ***
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