Progressive or rapidly growing macrocephaly

Specialty: Pediatrics.

• Accelerated growth of the cranial perimeter
• infantile macrocephaly

Why it occurs

• Benign familial macrocephaly or constitutional megalencephaly (variant of normal with healthy brain parenchyma, similar family history and normal development)
• Obstructive or non-obstructive hydrocephalus (abnormal accumulation of cerebrospinal fluid due to stenosis of the Sylvian aqueduct, Chiari malformation or previous meningitis)
• Chronic subdural hematoma or subdural hygroma (accumulation of blood or serous fluid in the subdural space, suspect accidental trauma or shaken infant/abuse syndrome)
• Neurofibromatosis type 1 or Tuberous Sclerosis Complex (neurocutaneous syndromes that associate macrocephaly and skin lesions)
• Lysosomal storage diseases or leukodystrophies (Canavan disease, Alexander disease, mucopolysaccharidosis with accumulation of metabolites in the brain parenchyma)
• Tumors of the central nervous system (astrocytomas, medulloblastomas or ependymomas that occupy space and induce hydrocephalus)

Initial workup

Rigorous measurement of the head circumference of the infant and both parents. Transfontanellar ultrasound (rapid and safe initial test in infants with open fontanelle to distinguish hydrocephalus from subdural collections or megalencephaly). High-resolution Brain Magnetic Resonance (MRI) (the gold standard to characterize the anatomy of the ventricular system, the brain parenchyma and rule out masses or fluid collections). Ophthalmological examination with fundus to look for papilledema or retinal hemorrhages (highly suggestive of physical abuse or intracranial hypertension).

Standard management

• In case of obstructive hydrocephalus or tumor, the definitive treatment is surgical — ventriculo-peritoneal shunt placement or endoscopic ventriculostomy of the third ventricle). Acetazolamide (carbonic anhydrase inhibitor that reduces CSF production, used temporarily in slowly progressive or presurgical hydrocephalus; dose of 20 to 100 mg/kg/day orally divided every 8 hours
• Furosemide — adjuvant loop diuretic; dose of 1 mg/kg/day orally or IV
• Corticosteroids such as Dexamethasone (indicated to reduce vasogenic edema associated with brain tumors; doses of 0.15 to 0.5 mg/kg/day IV).