Table 2. Probability of respiratory decompensation in inherited neuromuscular disorders
DiagnosisProbability of respiratory failureProgressionSecretion clearance problemsComments
Type 1 SMAInevitable by age 2 yearsMarkedSevereFull time ventilatory support required
Type 2 SMA∼40% in childhoodGradualModerateNocturnal ventilatory support required
Type 3 SMARare in childhoodGradualRare in childhoodOccasional ventilatory support
SMARDHigh in first 6 monthsMarkedSevereFull time ventilatory support
Duchenne MDHigh
After loss of ambulation
GradualAfter loss of ambulationCardiomyopathy may determine prognosis
Ullrich congenital MD70% in adolescence or beforeGradual, may stabiliseOccasionalMarked contractures
Rigid spine syndromeModerateGradualOccasionalCan develop respiratory failure with preserved VC before loss of ambulation
Nemaline myopathyHigh risk in neonatal variant, may be late onsetVariableIn severe formHighly heterogeneous disorder
Myotubular myopathyHigh in severe X-linked formMarkedIn severe formCan be complicated by opthalmoplegia and hepatic haemorrhage
Congenital myastheniaFluctuating may occur in neonatal periodVariableUncommonGenotype links
DOK-7 variant associated with stridor
Mitochondrial myopathyCommonVariableVariable
  • SMA: spinal muscular atrophy; SMARD: SMA with respiratory distress; MD: muscular dystrophy; VC: vital capacity. Reproduced from [1] with permission from the publisher.