Table 15. The Floppy Infant

Anatomic Site 

Pathology

Clinical Findings

Cerebrum

Idiopathic mental retardation Atonic diplegia

Hyperreflexia Extensor plantar reflex

Basal ganglia

Choreoathetotic cerebral palsy Kernicterus

Dystonia Choreoathetosis

Cerebellum

Ataxic cerebral palsy

Ataxia Hyporeflexia

Spinal cord

Cervical cord injury at delivery

Hyperreflexia; Sensory level Extensor plantar reflex

Anterior horn cell

Werdnig-Hoffman disease; Polio; Glycogen storage disease Type II

Areflexia; Normal sensation

Nerve

Neuropathy, usually metabolic

Hyporeflexia; Slowed nerve conduction time

Neuromuscular junction

Myasthenia gravis 
Drugs; Infant botulism

Positive edrophonium test

Muscle

Muscular dystrophy, myopathy

Elevated muscle enzymes

Connective tissue

Connective tissue disease

Normal muscle, nerve exam