Spinal (Bulbospinal) Muscular Atrophy

Wikis > Neurology > Motor Neuron Disease > Spinal (Bulbospinal) Muscular Atrophy

Spinal (Bulbospinal) Muscular Atrophy (SMA)

Group of inherited neurodegenerative disorders that begin in infants or children (most are autosomal recessive – defect(s) on chromosome 5). Characterised by progressive symmetric weakness and wasting of muscle – from degeneration and loss of lower motor neurons. Affects 1/10 000 newborn. Most due to mutation on chromosome 5.

Main types:
Type 1 SMA (Werdnig-Hoffman Disease):
• almost always fatal before age of 18 –27 months due to respiratory failure; 1/20 000 live births; M=F; autosomal recessive
• hypotonic at birth – ‘floppy infant’; lower limbs in ‘frog leg’ position; poor feeding; weak cry

Type 2 SMA (intermediate form):
• symptomatic by 6-12 months; delay of motor milestones are most common presentation; hypotonic and weakness of muscles; absent deep tendon reflexes; tongue fasciculations; can usually sit independently, but unable to stand or walk; contractures develop if weakness untreated
• most survive intro adolescence or early adulthood; usually fatal from respiratory complications
• life expectancy can be increased with spinal fusion to prevent kyphoscoliosis and with good respiratory management

Type 3 SMA (Juvenile spinal muscular atrophy/Kugelberg-Welander Disease):
• onset around 2-3yrs, often later; survive until 20-30’s; variable progression rates – similar to Type 1, but slower progress; autosomal recessive
• onset is with progressive proximal muscle weakness; progression is slow; scoliosis, kyphosis, weakness and wasting in legs, equinovarus feet (mimics limb-girdle muscular dystrophy)
• management – prevention of contractures and scoliosis; respiratory care

Type 4 SMA:
usually autosomal dominant (but is variable); adult onset; slow progression

We have not yet got to this page. We will eventually. Please contact us if you have something to contribute to it or sign up for our newsletter or like us on Facebook and Instagram or follow us on Twitter.

Page last updated: @ 8:34 pm

Comments are closed.