1、Neonatal Hypotonia Clinical Approach To Floppy Baby,Osama Naga, M.D., PGY2 7/23/09,Neonatal Hypotonia,Central Causes Cerebral palsy Hypoxic ischemic encephalopathy Intracranial hemorrhage Cerebral malformations Chromosomal abnormalities (e.g.Trisomy 21, Prader-Willi syndrome) Congenital infection TO
2、RCH Acquired infections Peroxisomal disorders Drug effects (e.g. benzodiazepines),Neonatal Hypotonia,Spinal cord Birth trauma (especially Breech delivery) Syringomyelia,Neonatal Hypotonia,Anterior Horn Cell Spinal Muscular Atrophy Traumatic myelopathy,Neonatal Hypotonia,Neuromuscular junction Congen
3、ital myasthenia gravis Transient acquired neonatal myasthenia Infantile botulism,Neonatal Hypotonia,Muscle Muscular dystrophies (congenital myotonic dystrophy) Congenital myopathies (e.g. central core disease),Neonatal Hypotonia,Peripheral nerves Hereditary sensory motor neuropathies Charcot-Marie-T
4、ooth disease,Neonatal Hypotonia,Metabolic myopathies Acid maltase deficiency Carnitine deficiency Cytochrome-c-oxidase deficiency,Neonatal Hypotonia,History Any significant family history Affected parents Siblings Consanguinity Stillbirths Childhood deaths,Neonatal Hypotonia,History Maternal disease
5、 Diabetes Epilepsy Myotonic dystrophy Pregnancy and delivery history Drug or teratogen exposure Decreased fetal movements Abnormal presentation Polyhydramnios/ oligohydramnios,Neonatal Hypotonia,History Apgar scores Resuscitation requirements Cord gases,Neonatal Hypotonia,History History since deliv
6、ery Respiratory effort Ability to feed Level of alertness Level of spontaneous activity Character of cry,Neonatal Hypotonia,Identification of hypotonia Holding the infant under the arms The legs will be extended Decreased tone of the shoulder girdle allows the infant to slip through the examiners ha
7、nds,Neonatal Hypotonia,Identification of hypotonia Holding the infant in horizontal suspension The back hangs over the examiners hand, and the limbs and head hang loosely Passive extension of the legs at the knees no resistance is met Pulling the infant from the supine to sitting position the head l
8、ags and continues to lag when the sitting position is reached,Neonatal Hypotonia,Physical Examination Central Normal strength Normal or increased DTRs May be Seizure May be dysmorphic features,Neonatal Hypotonia,Physical Examination Anterior horn cells Generalized weakness Decreased/ absent DTRs Fas
9、ciculations Often described as alert,Neonatal Hypotonia,Physical Examination Nerve Weakness, distalproximal Decreased/ Absent DTRs +/- fasciculations,Neonatal Hypotonia,Physical Examination Neuromuscular Junction Weakness, face/ eyes/ bulbar Normal DTRs No fasciculations,Neonatal Hypotonia,Physical
10、Examination Muscles Weakness, proximaldistal Decreased DTRs,Neonatal Hypotonia,Physical Examination Clues and Pitfalls Profound central hypotonia may have absent DTR Absent DTR in the first few DOL would not rule out a central cause for the hypotonia,Neonatal Hypotonia,Physical Examination Clues and
11、 Pitfalls Presence of profound weakness and hypotonia suggest: Disorder of the lower motor neuron A sign of this may be a weak cry Weakness is uncommon in central hypotonia except in the acute stages,Neonatal Hypotonia,Physical Examination Clues and Pitfalls Arthrogryposis (the fixation of joints at
12、 birth) Associated with: Neonatal hypotonia More commonly with lower motor neuron unit Multisystem abnormalities,Neonatal Hypotonia,Physical Examination Clues Hepatosplenomegaly Storage disorders Congenital infections Renal cysts High forehead Wide fontanelles Zellwegers syndrome,Neonatal Hypotonia,
13、Physical Examination Clues Abnormal odor Metabolic disorders Hypopigmentation, undesceded testes Prader Willi Hepatomegaly Retinitis pigmentosa Neonatal adrenoleukodystrophy,Neonatal Hypotonia,Physical Examination Clues Examination of the mother Congenital myotonic dystrophy Myasthenia gravis,Neonat
14、al Hypotonia,Investigation History and examination Hypotonia and a degree of strength Central cause is most likely Hypotonic and weak Peripheral cause is possible Early review by the neurology service is warranted,Neonatal Hypotonia,Investigation Central Causes Neuroimaging Ultrasound scan in the fi
15、rst instance MRI for structural abnormality EEG: if seizures suspected,Neonatal Hypotonia,Investigation Central Causes Genetics review if any dysmorphic features present Karyotype (if dysmorphic features) TORCH screen DNA methylation studies or FISH for Prader-Willi syndrome (if clinically indicated
16、 after a genetics review) Metabolic work up,Neonatal Hypotonia,Investigation Peripheral causes Neurology services review Molecular genetics CTG repeats, deletions in SMN gene,Neonatal Hypotonia,Investigation Peripheral causes Creatine kinase: If elevated in an early sample, repeat after a few days.
17、Nerve conduction studies Muscle biopsy Depending on clinical situation, may be delayed until around 6 months of age as neonatal results are difficult to interpret,References,1-Fenichel GM. Neonatal Neurology 3rd edition. Churchill Livingston Inc. 1990 2-Paro-Panjan D, Neubauer D. Congenital hypotonia: is there an algorithm? Journal of Child Neurology; Jun2004, Vol.19 (6): 439-43 3-Prasad AN, Prasad C. The floppy infant: contribution of genetic and metabolic disorders. Brain and Development; Oct 2003, Vol.25(7): 457-76,
