Spasmophilia in children

In pediatrics, the pathological tendency to involuntary muscle spasms and spontaneous convulsions – tetany (from the Greek tetanos – convulsion), caused by increased neuromuscular excitability due to a disruption of calcium metabolism in the body, is often defined as spasmophilia in children.

Epidemiology

According to statistics, the development of rickets in children in developed countries is 1-2 cases per 100 thousand infants in the first year of life; in Ukraine, pediatricians note signs of rickets in 3% of children under 6 months. [ 1 ]

According to some data, spasmophilia develops in 3.5-4% of cases in children suffering from rickets.

Causes spasmophilia in a child

The causes of convulsive syndrome or spasmophilia in children under two years of age may be due to:

• low calcium levels in the baby at birth – neonatal hypocalcemia, which leads to ionic imbalance in the blood;
• vitamin D (calciferol) deficiency - rickets, which usually occurs in infants aged 3 to 6 months;
• a disorder of the formation of 1,25-dihydroxyvitamin D (dihydroxycholecalciferol) in the kidneys, which is called hypocalcemic rickets or hereditary phosphate diabetes type III or IV; [ 2 ]
• dysfunction of the parathyroid glands - neonatal hypoparathyroidism, which results in a deficiency of circulating parathyroid hormone (parathyroid hormone or PTH) and, in turn, a decrease in calcium levels.
• Cases of development of spasmophilia with hypokalemia in the absence of alkalosis have been described. [ 3 ], [ 4 ]

Risk factors

Experts attribute the following risk factors to spasmophilia in children:

• prematurity of infants and low birth weight of full-term infants;
• maternal toxicosis during pregnancy;
• vitamin D deficiency in pregnant women, as well as a history of preeclampsia, severe osteomalacia (softening of bone tissue with low mineralization), and gluten intolerance;
• asphyxia of newborns; [ 5 ]
• immaturity of the child's parathyroid glands at birth;
• artificial feeding of a child;
• insufficient insolation (exposure to UV rays);
• malabsorption of vitamin D in the intestine;
• excess phosphates (hyperphosphatemia);
• low magnesium levels – autosomal dominant primary hypomagnesemia. [ 6 ], [ 7 ]

Pathogenesis

The pathogenesis of the state of increased excitability of the central and peripheral nervous system lies in disturbances of perinatal metabolism and abnormal concentrations of electrolytes in the blood serum, which leads to an increase in the frequency of the action potential of muscle cells or nerve fibers innervating the muscles.

In rickets, either the metabolism of vitamin D (which is involved in mineral metabolism – the absorption of calcium in the intestine – and bone growth) or the phosphorus-calcium metabolism, which ensures the formation of bone tissue and its mineralization, is disrupted.

Spasmophilia accompanied by generalized seizures and tremors in children under one year of age may have a genetically determined mechanism:

• in vitamin D-dependent rickets type I, associated with abnormalities in the gene that encodes the renal enzyme 25-hydroxy-D-1α-hydroxylase (CYP27B1), which is necessary for the activation of this vitamin with transformation (in the liver, kidneys and intestines) into 1,25-dihydroxyvitamin D;
• in vitamin D-dependent rickets type II – hereditary 1,25-dihydroxyvitamin D-resistant rickets (also called hypophosphatemic rickets), which occurs due to a defective VDR gene (on chromosome 12q13), which codes for vitamin D receptors in body tissues and is involved in maintaining normal calcium levels; [ 8 ]
• in hereditary hypoparathyroidism with impaired secretion of parathyroid hormone (PTH), which maintains serum calcium levels within certain limits;
• in primary hypomagnesemia, which not only leads to hypocalcemia but also prevents the release of parathyroid hormone. In particular, magnesium deficiency in young children is possible due to mutations in the FXYD2 gene (which encodes the gamma subunit of the electrogenic transmembrane ATPase expressed in the distal tubules of the kidneys) or in the HNF1B gene (which encodes a transcription factor of the renal epithelium). These genetic abnormalities (inherited or sporadic) are diagnosed as Gitelman syndrome or Bartter syndrome, and, in fact, belong to hereditary tubulopathies. [ 9 ]

What happens when total and ionized calcium levels in the blood and interstitial fluid are insufficient? The positive charge in the extracellular space decreases, and the membrane potential shifts toward depolarization – causing hyperexcitability of peripheral neurons and increasing the possibility of action potentials. And spontaneously occurring action potentials provoke involuntary contraction of peripheral skeletal muscles.

Read also – Hypocalcemic crisis in children

Symptoms spasmophilia in a child

The first signs of spasmophilia – clonic and tonic convulsions (convulsive syndrome) in children – with neonatal calcium deficiency can appear literally from the first days of birth or within two weeks after the child’s birth. [ 10 ]

Quite often, the symptoms can be mild: in the form of focal muscle spasms and paresthesia. However, there are also painful tonic contractions of skeletal muscles - spasms in children with spasmophilia or generalized cramps.

Also, the semiotics of spasmophilia in children includes laryngospasm - an involuntary contraction of the muscles of the larynx and vocal cords, leading to a narrowing of the airways or their obstruction. With mild laryngospasm, the child's skin turns pale with the appearance of cold sweat, stridor (breathing with wheezing) is observed. In this case, an accelerated heartbeat and rapid intermittent breathing can be observed. The duration of such an attack does not exceed one and a half to two minutes, but during the day it can be repeated several times.

Also noted are spasms of the muscles of the hand (in the wrist area) with extension of the interphalangeal joints, adduction and flexion of the metacarpophalangeal joints; spasms of the muscles of the feet near the ankles. These are the so-called carpopedal myospasms, which can be either short-term or longer-lasting - strong and quite painful. [ 11 ]

The most severe form is eclampsia in children with spasmophilia (from the Greek eklampsis – outburst) or an attack of tonic-clonic seizures, which occurs in two stages. The first begins with twitching (fasciculations) of the facial muscles and lasts 15-20 seconds; the second includes the spread of seizures to the limbs and muscles of the body, muscle spasms can last from 5 to 25 minutes. Laryngospasm, respiratory failure, general cyanosis, loss of consciousness, involuntary urination and defecation are also observed. [ 12 ]

In addition to the clinically expressed form of spasmophilia, specialists note hidden spasmophilia in children - latent tetany with a practically normal level of calcium, which is determined quite often in rickets. When a child is frightened, after vomiting, or due to an increase in temperature during an infectious disease, this form can transform into a symptomatic one. How hidden spasmophilia is detected, read further - in the Diagnostics section.

Complications and consequences

The main complications and consequences of spasmophilia in children are:

• general hypokinetic disorder;
• severe respiratory distress syndrome or respiratory arrest following laryngospasm or an attack of eclampsia;
• prolongation of the QT interval (detected by electrocardiography) with dilation of the ventricle - hypocalcemic dilated cardiomyopathy, leading to heart failure.

Prolonged attacks of tetany can lead to damage to the central nervous system, delayed mental development of the child in the future, and in severe cases, can be fatal. [ 13 ]

Diagnostics spasmophilia in a child

Diagnosis begins with anamnesis and examination of the child. A positive Chvostek sign allows one to suspect hypocalcemia before receiving laboratory test results: twitching of the muscles of the nose or lips when tapping the facial nerve between the earlobe and the corner of the mouth. [ 14 ]

And latent spasmophilia is usually determined by the so-called Trousseau sign, when cramps of the fingers, forced adduction of the thumb, flexion of the metacarpophalangeal joints and wrists appear with occlusion of the brachial vascular-nerve bundle by compression.

In addition, the diagnostic criteria for spasmophilia in children include a decrease in the level of total calcium in the blood <1.75 mmol/l (in newborns <1.5 mmol/l) or iCa (ionized calcium) <0.65-0.75 mmol/l.

Blood tests for calcium, phosphate, plasma electrolytes, alkaline phosphatase and 1,25-dihydroxyvitamin D, PTH, blood urea nitrogen, and creatinine are required; urine tests for the amount of calcium and phosphate excreted.

Instrumental diagnostics are performed using muscle electromyography (which allows determining the level of neuromuscular conductivity), as well as EEG – electroencephalography, which reveals the electrical activity of the brain. An ECG (electrocardiography) and an MRI examination of the brain may be required.

Differential diagnosis

Based on the fact that seizures in children without excessive excitability of muscle fibers are not spasmophilia (tetany), differential diagnosis should exclude: birth trauma to the brain and ischemic encephalopathy; seizures provoked by increased intracranial pressure, dysgenesis/hypotrophy of the brain or cerebral vascular anomalies; epilepsy and epileptic encephalopathy (including mitochondrial and toxic); paroxysmal dyskinesia and dystonic hyperkinesia; dehydration (caused by vomiting and/or diarrhea), as well as the manifestation of muscle spasms in congenital syndromes (West, Menkes, Lennox-Gastaut, Schwartz-Jampel, etc.).

Rickets, spasmophilia and hypervitaminosis D in children are also differentiated. Intoxication with this vitamin is characterized by hypercalcemia, decreased appetite, frequent vomiting, sleep disorders, increased sweating, dehydration, and may also cause convulsions.

Treatment spasmophilia in a child

Clinical recommendations concern vitamin D deficiency: there is a Protocol for the treatment and prevention of rickets, approved by the Ministry of Health of Ukraine.

In case of laryngeal muscle spasm, emergency assistance is required, read more - First aid for laryngospasm: algorithm of actions

Treatment of spasmophilia in children is aimed at normalizing the level of calcium in the blood and stopping seizures, for which such basic drugs as calcium gluconate (10% solution) and magnesium sulfate (25% solution) are used, which are administered parenterally. [ 15 ]

The next step in the treatment of this condition is the administration of oral vitamin D3 preparations: Calciferol, Aquadetrim, Vigantol.

See also - Treatment of Rickets

Prevention

Prevention of spasmophilia is timely diagnosis and appropriate treatment of rickets.

Rickets prevention in children should also be carried out: monitoring the level of vitamin D during pregnancy and, if there is a deficiency, taking it orally from the 28th to 32nd week of gestation. Vitamin D3 preparations (5 mcg per day) are given to children. In addition, breastfeeding of the child and adequate nutrition of women during the lactation period are important. For more information, see - How to prevent rickets?

Forecast

If latent tetany is detected and eliminated, hypocalcemia is adequately corrected, and timely assistance is provided for laryngospasm and/or eclampsia in children with spasmophilia, the prognosis is favorable.

In severe cases of eclampsia, which most often affects children in the first year of life, respiratory and cardiac arrest are possible.