hypotoniaclinical approach to floppy baby新生儿肌张力低下的临床方法要软盘婴儿（31）课件

Neonatal Hypotonia Clinical Approach To Floppy Baby Osama Naga, M.D., PGY2 7/23/09 Neonatal Hypotonia nCentral Causes nCerebral palsy nHypoxic ischemic encephalopathy nIntracranial hemorrhage nCerebral malformations nChromosomal abnormalities (e.g.Trisomy 21, Prader-Willi syndrome) nCongenital infection TORCH nAcquired infections nPeroxisomal disorders nDrug effects (e.g. benzodiazepines) Neonatal Hypotonia nSpinal cord nBirth trauma (especially Breech delivery) nSyringomyelia Neonatal Hypotonia nAnterior Horn Cell nSpinal Muscular Atrophy nTraumatic myelopathy Neonatal Hypotonia nNeuromuscular junction nCongenital myasthenia gravis nTransient acquired neonatal myasthenia nInfantile botulism Neonatal Hypotonia nMuscle nMuscular dystrophies (congenital myotonic dystrophy) nCongenital myopathies (e.g. central core disease) Neonatal Hypotonia nPeripheral nerves nHereditary sensory motor neuropathies nCharcot-Marie-Tooth disease Neonatal Hypotonia nMetabolic myopathies nAcid maltase deficiency nCarnitine deficiency nCytochrome-c-oxidase deficiency Neonatal Hypotonia nHistory nAny significant family history nAffected parents nSiblings nConsanguinity nStillbirths nChildhood deaths Neonatal Hypotonia nHistory nMaternal disease nDiabetes nEpilepsy nMyotonic dystrophy nPregnancy and delivery history nDrug or teratogen exposure nDecreased fetal movements nAbnormal presentation nPolyhydramnios/ oligohydramnios Neonatal Hypotonia nHistory nApgar scores nResuscitation requirements nCord gases Neonatal Hypotonia nHistory nHistory since delivery nRespiratory effort nAbility to feed nLevel of alertness nLevel of spontaneous activity nCharacter of cry Neonatal Hypotonia nIdentification of hypotonia nHolding the infant under the arms nThe legs will be extended nDecreased tone of the shoulder girdle allows the infant to slip through the examiners hands Neonatal Hypotonia nIdentification of hypotonia nHolding the infant in horizontal suspension nThe back hangs over the examiners hand, and the limbs and head hang loosely nPassive extension of the legs at the knees no resistance is met nPulling the infant from the supine to sitting position the head lags and continues to lag when the sitting position is reached Neonatal Hypotonia nPhysical Examination nCentral nNormal strength nNormal or increased DTRs nMay be Seizure nMay be dysmorphic features Neonatal Hypotonia nPhysical Examination nAnterior horn cells nGeneralized weakness nDecreased/ absent DTRs nFasciculations nOften described as alert Neonatal Hypotonia nPhysical Examination nNerve nWeakness, distalproximal nDecreased/ Absent DTRs n+/- fasciculations Neonatal Hypotonia nPhysical Examination nNeuromuscular Junction nWeakness, face/ eyes/ bulbar nNormal DTRs nNo fasciculations Neonatal Hypotonia nPhysical Examination nMuscles nWeakness, proximaldistal nDecreased DTRs Neonatal Hypotonia nPhysical Examination nClues and Pitfalls nProfound central hypotonia may have absent DTR nAbsent DTR in the first few DOL would not rule out a central cause for the hypotonia Neonatal Hypotonia nPhysical Examination nClues and Pitfalls nPresence of profound weakness and hypotonia suggest: nDisorder of the lower motor neuron nA sign of this may be a weak cry nWeakness is uncommon in central hypotonia except in the acute stages Neonatal Hypotonia nPhysical Examination nClues and Pitfalls nArthrogryposis (the fixation of joints at birth) nAssociated with: nNeonatal hypotonia nMore commonly with lower motor neuron unit nMultisystem abnormalities Neonatal Hypotonia nPhysical Examination nClues nHepatosplenomegaly nStorage disorders nCongenital infections nRenal cysts nHigh forehead nWide fontanelles nZellwegers syndrome Neonatal Hypotonia nPhysical Examination nClues nAbnormal odor nMetabolic disorders nHypopigmentation, undesceded testes nPrader Willi nHepatomegaly nRetinitis pigmentosa nNeonatal adrenoleukodystrophy Neonatal Hypotonia nPhysical Examination nClues nExamination of the mother nCongenital myotonic dystrophy nMyasthenia gravis Neonatal Hypotonia nInvestigation nHistory and examination nHypotonia and a degree of strength nCentral cause is most likely nHypotonic and weak nPeripheral cause is possible nEarly review by the neurology service is warranted Neonatal Hypotonia nInvestigation nCentral Causes nNeuroimaging nUltrasound scan in the first instance nMRI for structural abnormality nEEG: if seizures suspected Neonatal Hypotonia nInvestigation nCentral Causes nGenetics review if any dysmorphic features present nKaryotype (if dysmorphic features) nTORCH screen nDNA methylation studies or FISH for Prader-Willi syndrome (if clinically indicated after a genetics review) nMetabolic work up Neonatal Hypotonia nInvestigation nPeripheral causes nNeurology services review nMolecular genetics CTG repeats, deletions in SMN gene Neonatal Hypotonia nInvestigation nPeripheral causes nCreatine kinase: If elevated in an early sample, repeat after a few days. nNerve conduction studies nMuscle biopsy nDepending on clinical situation, may be delayed until around 6 months of age as neonatal results are difficult to interpret References n1-Fenichel GM. Neonatal Neurology 3rd edition. Churchill Livingston Inc. 1990