The term 'floppy baby' refers to neonatal hypotonia, which is a reduced resistance to passive movement. These babies can present with head lag, truncal instability, feeding and breathing difficulties, or they may just 'feel' different from other babies when handled.
They can present significant diagnostic and therapeutic challenges.
There are several important manoeuvres which help you assess a baby's tone (illustrated):
Approaching a floppy baby can feel very intimidating, as there are literally thousands of differential diagnoses and potential investigations. However, it is possible to take a straightforward and logical approach. The key is to decide whether the cause is general (systemic), central or peripheral.
Any baby that is generally unwell, for example with sepsis or heart failure, can become hypotonic. Physiological hypotonia is seen in premature babies. General causes should be easily identified from the history. It is the central (neurological) and peripheral (neuromuscular) causes which often lead to confusion. The easiest way to differentiate between these is by asking yourself:
Is the baby weak?
In central causes the baby will not be weak. They have upper motor neuron signs, with truncal hypotonia, but normal strength peripherally, and normal antigravity movements of the limbs. There may be peripheral hypertonia, brisk reflexes, and clonus. There may be other signs of central nervous system dysfunction including seizures, microcephaly and reduced visual interaction.
In peripheral causes the baby will be weak. They will have lower motor neuron signs, be globally hypotonic, with loss of antigravity movements of the limbs. Reflexes are reduced or absent. These babies are often cognitively normal, so tend to appear alert and visually interactive.
Central nervous system problems are the cause of the majority (60-80%) of cases of neonatal hypotonia. Specific diagnoses to be considered include:
Peripheral causes are detailed in the 'neuromuscular disorders' section of the fastbleep paediatric notes.
A summary of the key findings in central and peripheral causes, along with some common examples is given in the table below.
With the above approach in mind, you can now confidently gather information in a directed way.
Progress since delivery
Perform a full examination (as you would for a '1st day check'), particularly looking for:
Focus your investigations according to whether have found signs of a central or peripheral disorder in the history and examination. There is an almost limitless number of tests available, but those with the highest yield are shown in the table. Expert advice should be sought before performing any additional tests.
Specific treatment will vary depending on the underlying cause. Supportive management is usually necessary, and a holistic approach should be taken.
The prognosis is also dependant on the underlying diagnosis. However, many of these conditions have a poor prognosis with no specific therapies available. Genetic counselling is important, to aid parents in planning future pregnancies.
Dubowitz V. The floppy infant. JB Lippincott Company, Philadelphia 1980
Forsyth R, Newton R. Oxford Specialist Handbook in Paediatric Neurology. Oxford University Press, Oxford 2007
Photographs and tables by the author
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