Mrcpch Guide Neonate

MRCPCH GUIDE NEONATE Medical treatment of seizures Seizure Type

Generalised

1st Line

Sodium Valproate

2nd Line

Lamotrogine/ carbamazepine

Lamotrogine

Gabapentin/ Topiramate/ Clonazepam Phenytoin

Topiramate

3rd Line 4th Line

Partial Symptomatic Carbamazepine

Partial- Benign

Infantile spasms

Nothing

Vigabatrin ACTH

Carbemezepine

The airways begin as an outpouching from the primitive gut at 24 days and by 26 days two primary branches, which will go to form the major bronchi, can be discerned. For the next 3 months growth consists of branching of the endodermal tube into the surrounding mesenchyme. By 10 weeks cartilage is deposited in the bronchi and by 16 weeks formation of new bronchi is almost complete. The terminal air sacs or alveoli appear as outpouchings of the bronchioles after 28 weeks and increase in number to form multiple pouches of a common chamber called the alveolar duct. After birth alveolar stability is dependent upon the release of pulmonary surfactant into the lumen. Synthesis and release of surfactant rely more on humoral control mechanisms than mechanical factors. Alveolar type II cells, which synthesize surfactant, have microvilli on the luminal surface and contain lamellar bodies. The lamellar bodies (storage sites for surfactant) are first recognized at about 22 weeks. The terminal air sacs are shallow and wide mouthed in the newborn baby; several months later they assume a cup shape. Growth of the lung occurs by increasing the number of bronchiolar divisions, alveoli, alveolar diameters and surface area for gas exchange. Alveoli may continue to form as long as body length increases.

Hydrops Fetalis The importance of infection with B19V is increasingly recognised. Use of diagnostic tests has demonstrated that perhaps 20% of fetal hydrops is associated with this maternal/fetal infection. Other infectious causes include Cytomegalovirus (CMV), Syphilis, herpes simplex, Toxoplasmosis, hepatitis B, Adenovirus, Ureaplasma urealyticum, Coxsackievirus type B, Listeria monocytogenes. The pH of a healthy newborn is between 7.35 and 7.4. The systolic blood pressure at term is normally 60mmHg rising to 90mmHg by 1 year. The survival of infants at 23 weeks is in the order of 30% and rises to around 85% by 28 weeks. The average OFC at term is about 35cm while the PNMR is 7-8/1000 of all births (i.e. live births & still births). ROP is a disease of premature infants. All babies less than 1500 g birth weight or younger than 32 weeks' GA at birt h are at risk of developing ROP. However, higher oxygen saturation levels were not found to worsen the disease in prethreshold babies. Laser surgery (xenon, argon, diode) has been shown to be as effective as cryotherapy for ROP and is used in more advanced cases. Complications include: Loss of vision, amblyopia due to high refractive errors, Strabismus, Glaucoma, Retinal detachment.

IUGR has a prevalence of 10% among all pregnancies. However, the figure varies in different patient populations, with rates of 3-5% among healthy mothers, and rates of 25% or higher in some high risk groups, such as, hypertensive mothers. The cause is often not known. Growth-restricted pregnancies are often complicated by a high rate of antepartum and intrapartum fetal distress and the need for caesarean delivery. Infants born who are small for their gestational dates are predisposed to higher rates of low APGAR scores, low cord pH, intraventricular haemorrhage, necrotising enterocolitis, hypoglycaemia, hypocalcaemia, and polycythaemia. The sonographic criteria for IUGR include (1) an elevated ratio of femoral length to abdominal circumference (AC), (2) an elevated ratio of head circumference (HC) to AC, and (3) unexplained oligohydramnios . In most cases of IUGR, especially those due to primary placental insufficiency (the most common cause), the fetal abdomen is small, while the head and extremities are normal or near normal. This finding is known as the head-sparing effect. In cases of severe, early-onset IUGR (those due to chromosomal anomalies), the fetus tends to be more symmetrically small.

Many syndromes representing problems in the morphogenesis of branchial arches [5], [8] have been reported including Goldenhaar syndrome, Pierre Robin and Treacher Collins syndrome. Ectopic thyroid tissue may be present anywhere along the path of descent of the thyroid gland. A pilonidal sinus is in the natal cleft.

In the first week of life in utero (1/40), the embryo derives its nutrients and discards its waste by a simple process of diffusion. Development of the uteroplacental circulation commences at 9 days and is fully established within the third week after fertilisation (3/40). The cytotrophoblast proliferates, and processes form the primary stem villi. Further differentiation of the mesoderm forms the blood vessels, which subsequently connect with the vessels forming in the embryo. These differentiated structures are called the tertiary stem villi. Gases, nutrients and wastes diffuse between maternal and fetal blood between four established layers: (1) the endothelium of the villus capillaries; (2) the villus connective tissue; (3) a layer of cytotrophoblast; and (4) a layer of syncytiotrophoblast. The placenta contains 150 ml of maternal blood and is replaced 3–4 times per minute. Carbon dioxide, urea and uric acid pass from the fetal to the maternal blood as waste. Trophoblastic lacunae develop within the syncytiotrophoblast. Maternal capillaries within this area expand to form maternal sinusoids. Extra-embryonic mesoderm grows and extends into the primary stem villi to become secondary villi. The placenta produces steroid hormones and prostaglandins.

The pharyngeal pouches consist of bars of mesenchymal tissue separated from each other by pharyngeal pouches and clefts. The endoderm of the pouches gives rise to, in order, the structures indicated in the table below.

Pouch

Structure formed

1st pouch

Pharyngotympanic cavity, Auditory tube, Eustachian tube

2nd pouch

Tongue, Palatine tonsils

3rd pouch

Thymus, Inferior parathyroid gland

4th pouch

Superior parathyroid gland (C cells)

4th–5th pouch Ultimobranchial bodies (parafollicular cells) The thyroid gland originates from epithelial proliferation in the floor of the primitive pharynx and not from the larynx or branchial arches. It is connected by the thyroglossal duct to the foramen caecum at the junction of the anterior two-thirds and posterior third of the tongue. Ectopic thyroid tissue occasionally causes cysts along the path of the duct. The thyroid migrates to its final position in front of the tracheal rings. The parafollicular (C) cells come from the ultimobranchial body, a derivative of the 4th pharyngeal pouch.

Impaired fetal lung development is seen in Potter syndrome, Jeune syndrome and dystrophia myotonica. It is not found in the infants of insulin-dependent diabetic mothers or in Duchenne muscular dystrophy. Impaired fetal lung development is not found in bronchiolitis, facioscapulohumeral dystrophy, Pickwickian syndrome or Kartagener syndrome.

Cocaine, carbimazole and warfarin readily cross the placenta and affect the fetus.

FAS was first reported as a syndrome in 1973 and is now thought to be one of the major causes of mental retardation, having an incidence of 0.2–3 per 1000 live births. It has been estimated that between 10 and 20% of mild mental retardation cases are caused by maternal alcohol use. Severity and timing of alcohol consumption, bingeing, polydrug use (including smoking) during pregnancy, genetic variation and low socioeconomic status are all aetiological factors. Alcohol inhibits N-methyl-d-aspartate (NMDA) receptors, which mediate the postsynaptic excitatory effects of glutamate, and this is thought to have an effect on cell proliferation. Affected newborns are often irritable, hypotonic, experience severe tremors and show other signs of alcohol withdrawal. The cardinal signs are facial features, growth deficit and central nervous system impairment. Facial features include epicanthic folds, microcephaly, short palpebral fissure, underdeveloped philtrum and a thin upper lip. There are often associated behavioural difficulties including hyperactivity and sleep disturbance. Optic nerve hypoplasia with poor visual acuity, hearing loss and receptive and expressive language deficits can also be seen. Cardiac and renal abnormalities include atrial and ventricular septal defects, renal hypoplasia and bladder diverticula.

Prognosis depends on grade of bleed: grades 1 and 2 have a good prognosis with no longterm effects. In grade 3 there may be possible impairment on the contralateral side, depending on the degree of progression of dilatation, and in grade 4 there is likely to be motor impairment on contralateral side.