Spinal Muscular Atrophy

• Type 1: severe infantile form (Werdnig-Hoffman)
• Type 2: late infantile form w/slow progression
• Type 3: juvenile form w/ mildest symptoms

Type1

• usually present before 6 mos
• severe hypotonia, absent DTR’s, generalized weakness
• tongue fasciculations, sparing of extra-ocular muscles (look alert)
• most die by 2 y.o.

Type 2

• onset usually 6-24 mos
• proximal weakness noted first
• expected survival to adulthood

Type 3

• onset >18 mos
• progressive proximal weakness; most attain ambulation
• survival to mid-adult years

CHLA Board Review 2005