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ABNORMALITIES OF HEAD SIZE

ABNORMALITIES OF HEAD SIZE. (MACROCEPHALY & MICROCEPHALY). MICROCEPHALY. Literarily means “Small Head” Defined as occipito-frontal circumference less than the 5 th centile for age OR more than 2SD below the mean for the age.

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ABNORMALITIES OF HEAD SIZE

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  1. ABNORMALITIES OF HEAD SIZE (MACROCEPHALY & MICROCEPHALY) TA OGUNLESI (FWACP)

  2. MICROCEPHALY • Literarily means “Small Head” • Defined as occipito-frontal circumference less than the 5th centile for age OR more than 2SD below the mean for the age. • Microcephaly may be subdivided into two main groups: primary (genetic) microcephaly and secondary (nongenetic) microcephaly. TA OGUNLESI (FWACP)

  3. Primary microcephaly refers to a group of conditions that usually have no other malformations and follow a mendelian pattern of inheritance or are associated with a specific genetic syndrome. • The more common types include familial and autosomal dominant microcephaly and a series of chromosomal syndromes. TA OGUNLESI (FWACP)

  4. Secondary microcephaly results from a large number of noxious agents that may affect a fetus in - utero or an infant during periods of rapid brain growth, particularly the first 2yr of life. • These are common in this environment than the primary types. TA OGUNLESI (FWACP)

  5. SECONDARY MICROCEPHALY • Izuora (Enugu, 1987) • Asphyxia neonatorum (with ICH) • Severe neonatal jaundice • Repeated early neonatal convulsions • Prematurity • TORCHES infection • Neonatal tetanus with recurrent apnea • Others include: • Meningitis/encephalitis • Maternal phenylketonuria • Drugs (alcohol, phenytoin) • Irradiation TA OGUNLESI (FWACP)

  6. SYNDROMES ASSOCIATED WITH PRIMARY MICROCEPHALY • Down (21-trisomy) • Edward (18-trisomy) • Cri-du-chat (5 p-) • Cornelia de Lange TA OGUNLESI (FWACP)

  7. DIAGNOSIS • Skull radiograph, CT scan/MRI to detect calcifications and cerebral atrophy. • Serology: To screen for the TORCHES infection using antibody titres. • Maternal serum phenylalanine. • Karyotype for chromosomal analysis. • Fasting plasma/ urine amino acid analysis. TA OGUNLESI (FWACP)

  8. CRANIOSYNOSTOSIS (CRANIOSTENOSIS) • Craniosynostosis is defined as premature closure of the cranial sutures due to abnormalities of skull development. • The cause is unknown. • Genetic syndromes account for 10–20% of cases. • The most prevalent genetic disorders associated with craniosynostosis include (1) Crouzon (2) Apert (3) Carpenter syndromes. TA OGUNLESI (FWACP)

  9. FONTANELLES & SUTURES • FONTANELLE • Anterior • Posterior • SUTURES • Sagittal • Coronal • Lambdoid • Metopic TA OGUNLESI (FWACP)

  10. FORMS OF CRANIOSYNOSTOSIS • Scaphocephaly (boat-shaped) corresponding to sagittal synostosis. • Plagiocephaly (oblique or sloping) corresponding to unilateral coronal synostosis. • Trigonocephaly (triangular-shaped) corresponding to metopic synostosis. • Brachycephaly (short head; both coronal sutures) TA OGUNLESI (FWACP)

  11. CLINICAL MANIFESTATION • Most cases of craniosynostosis are evident at birth. • Characterized by a skull deformity that is a direct result of premature suture fusion. • Palpation of the suture reveals a prominent bony ridge. • Fusion of the suture may be confirmed by plain skull roentgenograms or bone scan in ambiguous cases. TA OGUNLESI (FWACP)

  12. CLINICAL MANIFESTATIONS • Syndromic types are also associated with airway problems from maxillary hypoplasia. • Difficulty with nose-breathing may occur, hence, mouth-breathing is common. • Sleep apnea affects not only their growth pattern, but also their behavior and speech. TA OGUNLESI (FWACP)

  13. CLINICAL MANIFESTATIONS • Children with raised intracranial pressure (ICP) can complain of chronic headaches, declining school performance, and gradual visual failure. • As children grow, abnormal facial appearance has a negative effect on their social integration, with a corresponding effect on personality development. TA OGUNLESI (FWACP)

  14. CLINICAL MANIFESTATIONS • Progressive facial and cranial deformity, intracranial hypertension, and progressive exophthalmos threatening the eyes. • Increased ICP, papilledema, optic atrophy due to abnormalities of the optic foramina, respiratory problems secondary to a deviated nasal septum or choanal atresia, and disorders of speech and deafness. TA OGUNLESI (FWACP)

  15. MANAGEMENT • Plain radiographs (abnormal sutural ridging) • CT scan/MRI (to exclude cortical atrophy) • Craniectomy TA OGUNLESI (FWACP)

  16. MACROCEPHALY • Literarily means “Big Head” • Defined as occipito-frontal circumference more than the 95th centile for age OR more than 2SD above the mean for the age. • It may be a variant of the normal (constitutional or familial) or abnormal (due to enlarged skull, enlarged brain or accumulated fluid within the cranium). TA OGUNLESI (FWACP)

  17. CAUSES OF MACROCEPHALY • Enlarged skull • Rickets • Haemoglobinopathies (SCA, Thalassaemia) • Achondroplasia • Accumulated fluid • Intraventricular (Hydrocephalus) • Subdural effusions/ haematoma/ empyema TA OGUNLESI (FWACP)

  18. CAUSES OF MACROCEPHALY • Enlarged brain tissues • Neurofibromatosis • Cerebral gigantism • Maple syrup urine disease • Degenerative diseases like glycogen storage diseases • Brain tumors TA OGUNLESI (FWACP)

  19. HYDROCEPHALUS • Abnormal enlargement of the head as a result of CSF accumulation and ventricular dilatation. • The CSF is formed primarily in the ventricular system by the choroid plexus, which is situated in the lateral, third, and fourth ventricles. Stimulation of the adrenergic system diminishes CSF production, whereas excitation of the cholinergic nerves may double the normal CSF production rate. • In a normal child, approximately 20 mL of CSF is produced per hour. The total volume of CSF approximates 50 mL in an infant and 150 mL in an adult. Most of the CSF is extraventricular i.e in the subarachnoid space. TA OGUNLESI (FWACP)

  20. PATHOPHYSIOLOGY • Normally, CSF flows from the lateral ventricles through the foramina of Monro into the third ventricle. It then traverses the narrow aqueduct of Sylvius to enter the fourth ventricle. The CSF exits the fourth ventricle through the paired lateral foramina of Luschka and the midline foramen of Magendie into the cisterns at the base of the brain. TA OGUNLESI (FWACP)

  21. PATHOPHYSIOLOGY • Hydrocephalus resulting from obstruction within the ventricular system is called obstructive or noncommunicating hydrocephalus. • Hydrocephalus resulting from the obliteration of the subarachnoid cisterns or malfuncion of the arachnoid villi is called nonobstructive or communicating hydrocephalus. TA OGUNLESI (FWACP)

  22. AETIOLOGY • Congenital • Aqueductal stenosis • Vein of Galen malformation (obstructing CSF flow) • Posterior fossa malformations (Dandy-Walker, Chiari) • Acquired • Meningitis (pyogenic & tuberculous) • Intracranial (intraventricular) haemorrhage • TORCHES infection • Leukaemic infiltrates TA OGUNLESI (FWACP)

  23. CLINICAL MANIFESTATIONS • In an infant, an accelerated rate of enlargement of the head is the most prominent sign. • The anterior fontanel is wide open and bulging. • The scalp veins are dilated and prominent. • Cranio-facial disproportion (broad forehead dwarfing the face) TA OGUNLESI (FWACP)

  24. CLINICAL MANIFESTATIONS • Setting-sun eye appearance (from impingement of the dilated suprapineal recess on the tectum) • Sutural diastasis (widely separated sutures) • “Cracked pot” note on percussion of the skull (Macewen sign). • A foreshortened occiput suggests Chiari malformation, and a prominent occiput suggests the Dandy-Walker malformation. TA OGUNLESI (FWACP)

  25. CLINICAL FEATURES • In an older child, the cranial sutures are partially closed so the signs may be more subtle (Irritability, lethargy, poor appetite, and vomiting) • Papilledema, CN VI palsy, and pyramidal tract signs, which are most evident in the lower extremities, are apparent in most cases. • Brisk tendon reflexes, spasticity, clonus and Babinski sign occur owing to stretching and disruption of the corticospinal fibers • Spinal bifida may occur in Dandy Walker malformation. TA OGUNLESI (FWACP)

  26. DIAGNOSIS • Clinical features. • Transillumination. • Skull radiography to verify chronically raised intracranial pressure. • Transfontanelle ultrasound/ CT scan/MRI which show ventricular enlargement with fluid accumulation. TA OGUNLESI (FWACP)

  27. MANAGEMENT • MEDICAL Use of drugs like Acetazolamide (5mg/kg/dose q 8 hourly) and Frusemide (1-2mg/kg/dose q 12 hourly) which reduces CSF production • SURGICAL • Extra-cranial shunts (Ventriculo-atrial shunts and ventriculo-peritoneal shunts) • Major problems of the shunt procedures are recurrent infections (meningitis), kinking and need to review the length with increasing age and growth. TA OGUNLESI (FWACP)

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