II. Signs: Perform complete physical examination
- Infant with decreased Muscle tone
- Exam distinguishes site of disorder
III. Differential Diagnosis: Upper Motor Neuron Causes
- Chromosomal
- Turner's Syndrome
- Down's Syndrome
- Prader-Willi Syndrome
- Infection
- Metabolic
- Toxin
- Drug Intoxication (e.g. Alcohol, Narcotic)
- Heavy Metal Poisoning
- Organophosphate Poisoning
- Anticholinergic exposure
- Perinatal Trauma
- Perinatal asphyxia (HIE)
- Hemorrhage
IV. Differential Diagnosis: Lower Motor Neuron Causes
-
Brainstem or spine
- Spinal muscular atrophy (Anterior Horn Cell Disorder)
- Acute Flaccid Paralysis
- Infection
- Poliomyelitis
- Coxsackie Virus
- Neuromuscular Junction
-
Muscle
- Muscular Dystrophy
- Congenital Myopathy
- Inflammatory Myopathy
- Other
- Tick Paralysis
- Benign Congenital Hypotonia
VI. Diagnostic Studies
VII. Labs: Initial
- Serum Glucose (obtain immediately on presentation)
- Serum Electrolytes
- Serum Calcium
- Creatine Phosphokinase (CPK)
- Blood Culture
- Lumbar Puncture with Cerebrospinal Fluid Examination
- Thyroid Function Tests
VIII. Labs: Test as indicated
- Toxicology screen
-
Serum Ammonia and Venous pH
- Serum Amino Acids
- Urine Amino Acids and organic acid
- Karyotype
- TORCH Virus Screening