Hypotonia

Abnormally decreased skeletal muscle tone, characterized by diminished resistance to passive movement, often resulting from disorders affecting the central nervous system, peripheral nerves, neuromuscular junction, or muscle.

Causes

• Genetic and congenital causes

  • Down syndrome

  • Prader–Willi syndrome

  • Marfan syndrome

• Perinatal causes

  • Anoxic or hypoxic brain injury during birth

  • Birth trauma

  • Cerebral palsy (early hypotonic phase)

• Neuromuscular causes

  • Spinal muscular atrophy

  • Muscular dystrophy

  • Myasthenia gravis

  • Congenital myopathies

  • Peripheral neuropathies

• Central nervous system causes

  • Brain injury

  • Stroke

  • Cerebellar disorders

  • Spinal cord disorders

• Endocrine and metabolic causes

  • Vitamin B12 deficiency

  • Hypothyroidism

  • Electrolyte disturbances

  • Inherited metabolic disorders

• Toxic and medications causing neuromuscular depression

  • Exposure to toxins

  • Alcohol intoxication

  • Sedatives

• Severe systemic illness

• Malnutrition

• Critical illness neuropathy or myopathy

• Idiopathic hypotonia