Hypoglycaemia is difficult to define in neonates but generally considered as serum blood glucose concentrations – less than 45 mg/dl. Neonatal hypoglycemia is a common complication among preterm infants, small-for-gestational-age infants, and infants of diabetic mothers.
Neonatal hypoglycaemic encephalopathy is a permanent brain injury caused by neonatal hypoglycaemia – which is not uncontrolled or not treated properly. Prolonged or severe hypoglycaemia is risky for a child. The extent of Neonatal Hypoglycaemic brain injury depends on the duration of hypoglycaemia and the prevalence of other comorbidities.
Severe hypoglycaemia is a metabolic event that causes irreversibly altered levels of consciousness, cognitive abnormalities or decline and death. Recurrent or persistent hypoglycaemia can cause permanent brain injury which may lead to hearing impairment, visual disturbance, secondary epilepsy, tachycardia and other disorders of the central nervous system.
The neonatal brain develops rapidly. The severities of such injuries can exceed hypoxic-ischemic injury. Permanent brain injury may lead to cognitive decline, vision disturbance, cerebral palsy, occipital lobe epilepsy and other disorders.
Neonatal hypoglycaemic encephalopathy or Neonatal Hypoglycaemic Brain Injury (NHBI) is either symptomatic or has non-specific symptoms. The symptoms associated with NHBI are non-specific and include the following:
- Feeding problems
- Not interested in feeding
- Hypothermia (low body temperature)
- Apnea (breathing trouble)
- Becomes less active
- irregular or fast heartbeat
- Lack of energy and movement (lethargy)
- Pale skin
- Blue tint to skin and lips (cyanosis)
- Poor muscle tone (floppy muscles)
- Altered conscious state
- Lack of consciousness
- Develops convulsions and Seizures
The other pathological conditions may include severe infection or birth asphyxia.
- Gestational Diabetes
- Congenital metabolic disorders, lack of enzymes for gluconeogenesis, glycogenolysis and fatty acid β oxidation
- Infants born to diabetic mothers
- Birth-weight less than small-for-gestational-age infants
- Babies born under significant stress
- Babies who are large for their gestational age
- Gestational age less than 36 weeks
- Infants with Rh haemolytic disease
- Infants with Beckwith-Wiedemann syndrome
- Effect of Beta-blockers used by mother
- Perinatal asphyxia
- Islet cell dysregulation syndrome
A paediatric neurologist diagnoses hypoglycaemic encephalopathy by examining the infant, evaluating the risk factors, reviewing the symptoms, and checking the blood glucose levels. The doctor initially evaluates the infant to rule out other conditions such as sepsis, asphyxia or hypocalcaemia as the majority of the signs and symptoms are non-specific. Infants who are at increased risk and without the signs and symptoms require immediate blood glucose check. Abnormally low blood glucose levels confirm the diagnosis.
The most sensitive and specific screening method for diagnosing hypoglycaemic encephalopathy (Neonatal Hypoglycaemic brain injury) is MRI – which is far better than ultrasound and CT. This neuro-imaging test is useful for early diagnosis and follow-ups. It is also useful for demonstrating the extent of brain injury and predicting clinical outcome.
Hypoglycaemia is a medical emergency and therefore, if you notice any signs and symptoms of extremely low blood glucose levels in your infant, ask for medical help immediately – it could lead to life-threatening complications – convulsions, cognitive abnormalities, seizures and even death.