Rationale

Hypotonia in an infant can be an indication of severe systemic disease requiring urgent intervention, or it can be an indication of neurologic disease potentially requiring long-term multidisciplinary care.

Causal Conditions

(list not exhaustive)

1. Neurologic (e.g., perinatal asphyxia, spinal muscular atrophy, infantile botulism)

2. Disorders of skeletal muscle (e.g., myotonic dystrophy, congenital myopathies)

3. Genetic and metabolic causes (e.g., Prader-Willi syndrome, hypothyroidism)

4. Systemic illness (e.g., sepsis, meningitis, dehydration, hypoglycemia)

Key Objectives

The candidate will recognize hypotonia in an infant as a finding requiring urgent attention. Considering the presence or absence of other clinical findings, the candidate will formulate an appropriate differential diagnosis, assess the severity of the condition, and initiate an appropriate management plan.

Enabling Objectives

Given a hypotonic infant, the candidate will

1. list and interpret critical clinical findings, including those based on

   1. an assessment of physiologic stability (e.g., oxygenation, cardiorespiratory function),

   2. a thorough history, including gestational, perinatal, developmental, and family history, and

   3. a complete physical examination, including a detailed neurologic examination;

2. list and interpret critical investigations appropriate to the clinical condition, which may include

   1. urgent investigations relevant to an acutely ill infant (e.g., arterial blood gas, electrolytes, serum glucose level), and

   2. diagnostic investigations (e.g., magnetic resonance imaging, serum creatine kinase level, electromyography, genetic studies, lumbar puncture);

3. construct an effective initial management plan, including

   1. immediate support of airway, breathing, and circulation when required,

   2. supportive communication with family,

   3. referral for specialized care if necessary, and

   4. urgent correction of metabolic abnormalities if present.