Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content ++ Bulbospinal muscular atrophyHereditary neuronopathyProgressive muscular atrophy1Werdnig-Hoffman disease ++ 335.0 Werdnig-Hoffman disease335.1 Spinal muscular atrophy335.10 Spinal muscular atrophy, unspecified335.19 Other spinal muscular atrophy ++ G12.0 Infantile spinal muscular atrophy, type I [Werdnig-Hoffman]G12.8 Other spinal muscular atrophies and related syndromesG12.9 Spinal muscular atrophy, unspecified ++ Pattern 5E: Impaired motor function and sensory integrity associated with progressive disorders of the central nervous system +++ Description ++ Group of four subtypes of degeneration of anterior horn cells that results in progressive muscle atrophySpinal muscular atrophy (SMA I), Werdnig-Hoffman (acute)Spinal muscular atrophy (SMA II), Werdnig-Hoffman (chronic)Spinal muscular atrophy (SMA III), Kugelberg-WelanderSpinal muscular atrophy (SMA IV) +++ Essentials of Diagnosis ++ Autosomal recessive genetic disorder that results in a lack of survival motor neuron gene1 on chromosome 5q11.2-132 +++ General Considerations ++ SMA type I: weakness between birth and 3 months of ageSMA type II: signs and symptoms by 3 years of ageSMA type III: signs and symptoms between 2 to 9 years of ageSMA type IV: adult onset +++ Demographics2 ++ Type I: 27% of all SMA casesTypes II and III: 46% of all SMA casesType IV: 8% of all SMA casesWerdnig-Hoffman 1:10,000 birthsKugelberg-Welander 6:100,000 births +++ Signs and Symptoms ++ Fasciculations (especially of tongue)Muscle weaknessHypotoniaMuscle atrophyDecreased or absent deep tendon reflexesDifficulty feeding (infant)Lack of extension during Landau reflexContractures (type 1)ScoliosisTrendelenburg sign during gait +++ Functional Implications ++ Inability to sit independentlyInability to ambulateRequire assistance with ADLs +++ Possible Contributing Causes ++ Autosomal recessive genetic disorder on chromosome 5q11.2-132 +++ Differential Diagnosis ++ Muscular dystrophyGuillain-BarréBrachial plexus birth injuryOther genetic syndromes +++ Laboratory Tests ++ Genetic testing +++ Imaging ++ Plain radiograph for scoliosis +++ Diagnostic Procedures ++ Electromyography (EMG)Muscle biopsy +++ Medication ++ HydroxyureaValproic acid ++ GeneticistOccupational therapist ++ Head lag when infant pulled into a sitting position from supinePoor head controlInability to sitInability to pull to standInability to walkContractures of biceps and wrist flexors ++ Hammersmith functional motor scale for children2Dynamometer2-minute walk testManual muscle testForced vital capacity ++ Important to avoid fatigue during intervention with patients who have SMAStrengtheningStretching to prevent contractures, especially of wrist flexorsDevelopmental activitiesProne on elbows with assistanceSupported sittingSupported standingFacilitating pulling up from sitting ... Your Access profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free a profile for additional features.