Juvenile spinal muscular atrophy, characterized by
slowly progressive muscular weakness as a result of degeneration of anterior
horn cells (spinal motor neurons). Onset is between the ages of 2 and 17
years. Early symptoms consist of atrophy and weakness of the proximal muscle
of the extremities (mainly legs), followed by thoracic muscles. Should not
be confused with muscular dystrophy syndromes.
Kugelberg-Welander Syndrome; Juvenile type of Muscular
Atrophy Syndrome; Neurogenic Familial Girdle type of Muscular Atrophy, type
K-W; Spinal Muscular Atrophy type III; Juvenile Spinal Muscular Atrophy.
Neurological disorder resulting from degeneration of
anterior horn cells. Kugelberg-Welander Spinal Muscular Atrophy is the least
severe of the three forms of spinal muscular atrophy.
1:15,000 live births; genetic carrier prevalence is
1:80. Both sexes affected, but more severe in males.
Mostly autosomal recessive; some families with
autosomal dominant inheritance; very rarely, X-linked transmission. Gene map
location (usually) is 5q13.
Degeneration of anterior horn cells.
Blood DNA analysis, electromyography, and muscle biopsy.
Onset at the age of 3 to 4 years, with
progressive muscular dystrophy involving, at first, the proximal muscles.
Progressive weakness of the axial muscles, pharyngeal control, and
swallowing. Decreased or absent tendon reflexes and muscular fasciculations.
Progressive respiratory failure as a result of muscular weakness. Cardiac
involvement seems to be significant and includes atrial hyperexcitability,
atrioventricular blocks, and right-sided heart failure as a result of
pulmonary hypertension. Congestive biventricular failure has also been
Check pulmonary functions before
induction. Numerous postoperative pulmonary infections. Need intensive care
unit stay after operation, and may need several days postoperative
ventilation. Check ECG for signs of right cardiac overload; echocardiography
may be useful. Cardiovascular status and intravascular fluid volume should
Very poor vascular access. Maintain
intravascular volume. Perioperative cardiac monitoring is necessary.
Intracardiac stimulation should be available in operating room in case of severe sudden
Avoid succinylcholine. Exaggerated
response to neuromuscular blockers (complete muscular blockade with 20 to 30% of the
usual dose), titration is indicated and the use of neuromuscular monitoring highly recommended.
Avoid drugs that could trigger cardiac dysrhythmias.
Other variants of spinal
muscular atrophy including type 1 (Werdnig-Hoffman disease, the most severe
form); type 2 (chronic spinal muscular atrophy, juvenile spinal muscular
atrophy, or intermediate spinal muscular atrophy); and type 4 (adult spinal
muscular atrophy) need to be considered.
Fehlings DL, Kirsch S, McComas A, et al: Evaluation of therapeutic
electrical stimulation to improve muscle strength and function in children
with types II/III spinal muscular atrophy. Dev Med Child Neurol
Nicole S, Diaz CC, Frugier T, et al: Spinal muscular atrophy: Recent
advances and future prospects. Muscle Nerve
Veen A, Molenbuur B, Richardson FJ: Epidural anaesthesia in a child with
possible spinal muscular ...