What are leg tremors?
Leg tremors are involuntary shaking or trembling movements in one or both legs. They are a neurological condition caused by muscle contractions and can be constant or intermittent [1].
Causes of leg tremors in newborns
A variety of factors can cause leg tremors in newborns. One of the primary causes is Vitamin D deficiency. In some cases, newborns who present with shudders, shivers, jitteriness, or tremors may be showing the earliest signs of this deficiency [2].
Another cause of leg tremors in newborns is neonatal anoxia, a condition characterised by a lack of oxygen. This can lead to body and chin tremors that are unresponsive to anti-epileptic drugs [3].
Hypocalcaemia and hypoglycaemia are also associated with persistent neonatal tremors. In a study of 102 healthy infants, 18 who continued to exhibit tremors were found to have either of these conditions [4].
Genetics can also play a role in causing leg tremors. A type of shaking called essential tremor may be passed down through families, affecting various body parts, including the legs [5].
In some cases, leg tremors in newborns can be associated with muscle tone impairments, often seen in infants at high risk of developmental disorders [6].
In Neonates (Infants less than four weeks old) having spina bifida aperta, leg movements by myotomes caudal to the meningomyelocele are transiently observed, which could potentially cause tremors [7].
Lastly, intrauterine exposure to illicit drugs during gestation can also lead to multiple patterns of neuromotor abnormalities, including leg tremors [8].
Other complications
Leg tremors in newborns can be associated with other complications; although the tremors do not directly cause these, they are often related to the underlying conditions that cause the tremors.
In some rare cases, tremors can be a symptom of congenital myopathy, a muscle disorder that can cause respiratory distress and other complications [9].
Intravenous (IV) infiltration in neonates, although rare, can lead to orthopaedic complications such as growth arrest, limb length discrepancy, and joint deformities that require surgical intervention [10].
Neonatal tremors can also be associated with periventricular leukomalacia (PVL), a type of brain injury that can lead to cerebral palsy and other neurological disorders [11].
In some cases, tremors can be associated with severe neuromuscular diseases, which can lead to a range of complications, including hypotonia, weakness, and respiratory distress [6].
In rare instances, nontraumatic, acute neonatal paraplegia, a condition characterised by sudden paralysis in the lower limbs, can occur along with vascular phenomena [12].
It's important to note that while these complications can be associated with newborn leg tremors, they are not caused by the tremors themselves. Instead, they are related to the underlying conditions that cause the tremors.
Should you worry?
Newborn leg tremors can be a cause for concern, but not always. However, it's important to note that tremors in newborns can have a variable evolution and rate of resolution. A study found that the percentage of infants with a normal assessment progressively increased at 6, 9, and 12 months (34.5%, 77%, and 93%, respectively) [3].
As we previously discussed, in some cases, tremors in newborns could be related to hypocalcaemia or hypoglycaemia. A study found that out of 102 healthy neonates with tremors, 18 who continued to have tremors had either hypocalcaemia (n = 13) or hypoglycaemia (n = 5) [4]. The aforementioned neonatal anoxia, a condition in which the baby lacks sufficient oxygen, could be fatal if left untreated [13]. Apart from these, there are a variety of underlying conditions, most of which we have already covered, that lead to Leg tremors and shaking in newborns.
In conclusion, while newborn leg tremors can be signs of certain deficiencies or conditions, they can also resolve over time. If your newborn is experiencing leg tremors, it's strongly advised to consult a healthcare professional for a proper diagnosis and treatment plan.