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Spinal Muscular Atrophy SMA
Terms in this set (33)
What is Spinal Muscular Atrophy?
-A genetic disease affecting the anterior horn cells found in the spinal cord
-Muscular The muscles are unable to receive signals from the nerve cells
-Atrophy when muscles are not active they lose size and girth and waste away.
What causes Spinal Muscular Atrophy SMA?
-A defect; usually on chromosome 5
-Deficiency of a motor neuron protein called SMN, for "survival of motor neuron."
-Other forms of SMA
-Mutation in UBE1 gene on X-chromosome
-Mutation of the DYNC1H1 gene on chromosome 14
What is the Inheritance for SMA?
-Chromosome 5 SMA is an autosomal recessive disease
-2nd most common fatal recessive disease
-X-linked SMA is inherited in an X-linked manner that causes the mutation of UBE1
-Females require 2 affected X's to express the disease
-Males require only 1 affected X to express the disease
-SMA from DYNC1H1 gene mutation on chromosome -14 is dominantly inherited
-Only 1 gene from one parent is required to express the disease
What are some of the Diagnosis criteria for SMA?
Creatine Kinase, CK
Muscle biopsy and nerve conduction velocity tests can also be performed but are less frequently required
How can Genetic Testing be done?
Simple blood test
What is Creatine Kinase, CK?
-An enzyme that leaks out of muscles that are deteriorating
-Nonspecific test b/c CK levels are elevated in many neuromuscular diseases
What are some Symptoms of SMA?
-Range of symptoms from mild to severe
-Primary symptom is weakness of the voluntary muscles.
-Impacts respiration, posture, and overall mobility
-Typically; intelligence, social development, sensation, and sphincter control are preserved
What is type 1 SMA?
Acute Childhood SMA / Infantile onset
What are some of the implications for Acute Childhood SMA / Infantile onset (Type 1 SMA)?
-Also known as Werdnig-Hoffmann Disease
-Weakness present at birth or prior to 4 months of age
-Cranial nerve involvement may or may not be seen
-Respiratory problems often with accessory muscles present for breathing
-Do not transition away from belly breathing due to impaired diaphragm strength
-Swallowing and feeding difficulties
-May require G-tube for feeding
-Muscle fasciculations - inc tongue
-Tremor may be present
-In general, alert and responsive
What is type 1 SMA known as?
What are some Secondary Impairments of Type 1 Acute Childhood SMA / Infantile onset?
-Alignment issues ; talipes equinovarus due to decreased uterine movement (mother typically reports dec movement in last trimester).
What are some clinical characteristics for type 1 SMA?
-Weakness most prominent in the neck, trunk, shoulders, and pelvic girdle and specifically antigravity muscles
-Typically assume a frog legged position
-Head/trunk control is significantly limited
-Typically unable to clear airway in prone
-Usually do not meet the milestone of unassisted sitting
-Death from PNA or other respiratory complication common within the first few months to a few years of life
-Mean age of death for type 1 is 6 months
-Have been cases that live up to 42 months
What is the mean age of death for type 1 SMA?
What is the main focus of type 1 SMA?
Respiratory health is the main focus (Chest PT required)
What are some of the implications for Positioning in patients with type 1 SMA?
-Supine with supports
-Sidelying is a good position for these children
-Promotes respiratory health and un-weights one side completely
-Can be very functional due to antigravity positioning, allows midline play
-Prone - Typically avoided
What position is typically avoided in patients with type 1 SMA?
What types of chest PT should you do in patients with type 1 SMA?
-Postural drainage positions
-Respiratory support devices, ie; vibration vests
What support should you give to a patient with type 1 SMA?
-May use abdominal binder
-Will need to monitor for spinal alignment
-Assist in providing appropriate positioning
-Hammocks are great for allowing independent but supported movement
-Range of motion for contracture management
-Family training and counseling required
What is SMA Type 2 "Chronic Childhood SMA"?
-Also known as "intermediate SMA"
-Weakness typically seen in the first year of life. Typically between 7 and 14 months of age.
-Course extremely variable
-95% of children showed signs of weakness before age 3
-Weakness in proximal >distal as in type 1 but to a lesser degree
-Greatest in hip and knee extensors and trunk
-Distal muscle involvement occurs as disease progresses
-½ demonstrate tongue fasciculation
-Contractures less severe but still present
-46% never walked
-38% walked unaided at some stage
-Median age of death >10 years
-Pulmonary health plays a factor in life span
What are the 3 sub groupings within type 2 SMA?
What is severe type 2 SMA?
children resemble type 1 with inability to sit and significantly impaired respiratory system
What is intermediate type 2 SMA?
Children can sit alone but do not achieve ambulation
What is mild type 2 SMA?
Children ambulate I but lost ability by the end of the first decade
What are some of the Type 2 treatments in Infancy in patients with SMA?
-Program for the baby with chronic SMA should look similar to that of Type 1
-Focus on trunk control in antigravity positions
-Promote developmental activities and gross motor skills
-Understand that some children will not continue to achieve milestones; work to maintain function
-Aquatic therapy - maintaining strength and function
-Use of adapted equipment
-Standers - supine stander especially if not standing by 16 months
-May use TLSO for assistance with trunk alignment in upright positions
-Assists in slowing the deforming effects of gravity on the spine
-Family training for positioning and maintenance techniques
What are some of the Type 2 Treatment considerations for the Preschool/School Age in SMA?
-Orthotics may be used to support standing and ambulation in toddlers
-Usually lightweight KAFO's
-Assisted walking programs may begin
-Safety is crucial 2* increased fracture risk and falls due to weakness
-Supported walking can decrease
-Progression of scoliotic curve
-For those who cannot achieve ambulation, power mobility should be promoted
-Power wheelchairs vs scooters
-Monitor closely for alignment
-Contracture development 2* prolonged sitting
-Progression of scoliosis - High incidence
-Surgery for spinal stabilization
What are the implications for SMA Type 2 and their Transition to Adulthood?
-Survival into adulthood is variable
-Requires assistance for all mobility and most ADL's
-Aide and or family member is required around the clock
-Aggressive pulmonary care program
-Aggressive ROM program
-Vocational services will be required
What are the implications for SMA Type 3 (Juvenile-Onset)?
-Also known as Kugelberg-Welander Disease
-Onset of weakness after 18 months, typically late into the first decade
-Children can typically stand and walk independently, although they may require aids
-Proximal LE weakness primary finding
What is SMA Type 3 also called?
What are some secondary impairments for patients with type 3 SMA?
-Postural compensations, Trendelenburg, increased lumbar lordosis
-Contractures; usually in the PF's if any less common than in DMD
-Scoliosis - Degree depends on ambulation status
What are the implications for SMA Type 3 in the school aged child?
-Presentation similar to DMD with difficulty rising from floor
-Keeping up with peers
-Proximal UE strength preserved
-Ambulation typically preserved life long as primary mode of locomotion
-For those with more severe cases scooter may be required
-Management similar to other types.
-Teach use of adaptive equipment as needed
What are the implications for SMA Type 3 in the transition to adulthood?
-Generalized weakness may be present
-Lifespan is not shortened therefore; vocational counseling is required.
What is type 4 SMA?
-Onset in adulthood
-People are able to walk during their adult years
What is the overall clinical picture of SMA?
-Proximal to distal, symmetric weakness, contractures, and respiratory health concerns to varying degrees are hallmarks in all forms of spinal muscular atrophy.
-PT's can play a major role in the care and management of this population from infancy through transition to adulthood.
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