Final answer:
Tongue fasciculation and absent DTRs in an infant typically indicate LMN disease, which can manifest as flaccid paralysis or hypotonicity. These symptoms may accompany serious neurological conditions that warrant immediate medical attention and thorough evaluation by healthcare professionals.
Step-by-step explanation:
Tongue fasciculation and absent deep tendon reflexes (DTRs) in an infant are associated with lower motor neuron (LMN) involvement. Fasciculations are small, involuntary muscle twitches resulting from spontaneous LMN discharge. The extrinsic muscles of the tongue, which are connected to other structures such as the hyoid bone or the mandible, control the position of the tongue. When these muscles or their LMN supply is affected, it may result in tongue fasciculations, which are sometimes visible on the surface of the tongue. Absent DTRs further suggest LMN disease, which can lead to hypotonicity or flaccid paralysis. This presentation can be a sign of serious neurological conditions in infants, which may manifest early on with additional symptoms such as temperature instability, feeding difficulties, and general limpness, or in late stages, symptoms like seizures or bulging fontanel.
In such cases, it is crucial to conduct a comprehensive neurological exam to evaluate overall muscle tone, the presence of any muscle weakness (hemiparesis), and to observe for any signs that might suggest a central nervous system disorder, like changes in gait or coordination, if the child is of walking age. Initial appearance of flaccidity and the presence of tongue fasciculations can be concerning and warrant further investigation by medical professionals to determine the underlying cause and appropriate interventions.