[Downloaded free from http://www.pediatricneurosciences.com on Sunday, May 6, 2018, IP: 109.252.99.223] Case Report Chiari III malformation with hypertelorism and microcephaly in a neonate: Case report and a review of the literature Kapil Garg, Nitin Malik, Awadhesh K. Jaiswal, Sanjay Behari Department of Neurosurgery, Sanjay Gandhi Postgraduate institute of Medical Sciences, Lucknow - 226 014, India Address for Correspondence: Sanjay Behari, Additional Professor, Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow - 226014, India. E-mail: [email protected] ABSTRACT Chiari III malformation is an extremely rare anomaly characterized by low occipital and high cervical encephalocele with herniation of posterior fossa contents, that is, the cerebellum and/or the brainstem, occipital lobe, and fourth ventricle. We report the case of Chairi III malformation in a neonate with associated hypertelorism and microcephaly, discuss the etipopathogenetic and radiological features, and review the pertinent literature. The neonate, a two-day-old child, with Chairi-III malformation had a large low occipital and cervical osseous defect with nearly a nonexistent posterior fossa due to the herniation of the cerebellum and a part of the occipital lobe into the large encephalocele sac. The patient also had associated microcephaly and hypertelorism without hydrocephalus. The existence of significant, viable neural tissue within the encephalocele sac precluded any surgical intervention. In our patient, it is proposed that during early embryogenesis, incomplete distension of the telencephalic and the rhombencephalic ventricles resulted in Chiari III malformation (based upon unifying theory of embryogenesis of McLone and Knepper) with a large encephalocele containing major portions of cerebellum and occipital lobe, and left the chondrocranium without an adequate inductive force of the underlying neural mass. The skull was, therefore, microcephalic and the posterior fossa virtually nonexistent. Hypertelorism also resulted from failure of eyes to completely rotate forward during fetal life owing to the presence of this large posterior encephalocele and the absence of neural cues for the chondrocranial expansion. To the best of the authors’ knowledge, the association of Chairi-III malformation with microcephaly and hypertelorism has not been previously reported. KKeyey wwords:ords: Chiari III malformation, craniovertebral junction anomalies, hypertelorism, microcephaly Introduction of our knowledge, 30 cases of Chiari III malformations have been reported till date with their age ranging from newborn [2-19] Chiari III malformation is the rarest of the three classes to 16 years. We report the case of Chairi-III malformation of hindbrain anomalies described by Chiari in 1891[1] in a neonate with associated hypertelorism and microcephaly, and is associated with an occipital and/or upper cervical discuss the etipopathogenetic and radiological features, and review the pertinent literature. encephalocele that may contain occipital, cerebellar, brainstem, or upper cervical neural tissue.[2-6] Other associated anomalies may include hydrocephalus, tectal beaking, Case Report medullary kinking, a small posterior fossa, low-lying transverse sinuses, heart-shaped incisura, hypoplastic tentorial cerebelli, This two-day-old male child (weight 2.3 kg) was a full-term fenestrated falx cerebelli, concave clivus and petrous bone, normal delivery, born of nonconsanguineous parents. He had syringomyelia, and corpus callosal dysgenesis.[3,7-10] To the best microcephaly with small, lax and open anterior and posterior fontanelles. The coexisting large occipital and upper cervical encephalocele was 6 X 4 cm in size, fluctuant, nontender, Online full text at nonpulsatile, and only partially transilluminant. The skin http://www.pediatricneurosciences.com over the swelling was normal [Figure 1A and B]. He also had 2008 / Jul-Dec / Volume 3 / J Pediatr Neurosci / 169 [Downloaded free from http://www.pediatricneurosciences.com on Sunday, May 6, 2018, IP: 109.252.99.223] Garg et al.: Chiari III malformation with microcephaly and hypertelorism hypertelorism with the canthal index (i.e. the percentage ratio producing cortical heterotopias, gyral anomalies, and callosal of inner canthal distance to the outer canthal distance which dysgenesis) and the rhombencephalon (influencing cerebellar is normally 38 in male and 38.5 in female patients)[20] of 42 and brainstem development), respectively. The growth and [Figure 1A]. He was, however, taking feeds adequately, had a development of the chondocranium are normally dependent good respiratory effort, and was moving limbs spontaneously upon cues provided by expansion of the underlying neural and symmetrically. The tone in the limbs and reflexes were mass (the developing brain and ventricular system) during normal. There was no nystagmus, retrocollis, or postural early embryogenesis.[21,22] In our patient, the embryological abnormality. There was neither any history of any medicinal dynamics that resulted in Chiari III malformation and the intake (including iron and folic acid supplementation) nor consequent displacement of the contents of the posterior fossa any evidence of any maternal infection during pregnancy. contents into the encephalocele sac, also led to incomplete His magnetic resonance imaging (MRI) revealed an occipital distension of the telencephalic and the rhombencephalic and cervical (the dysraphic defect reaching till lower cervical ventricles and left the chondrocranium without an adequate vertebral bodies) encephalocele with herniation of a major inductive force. The skull was, therefore, microcephalic and portion of the occipital and cerebellar contents into it. There the posterior fossa virtually nonexistent. Due to the wide was no associated hydrocephalus or syringohydromyelia opening of the encephalocele sac, the neural tissue was not [Figure 2A-C]. In view of the grave prognosis, the parents impacted and the CSF flow through the foramen of Luschka refused intervention and have opted to wait until further and Magendi was not impaired. Thus, hydrocephalus did assessment regarding his social and language milestones is not develop.[21] possible. Hypertelorism is a rare abnormality characterized by an Discussion increased interorbital distance.[23] During embryonic development, the eyes initially separate from the diencephalon Our patient represents one of the youngest reported cases, as diverticulae and migrate to the lateral portion of the head. being only two-days old.[2-20] He had several unique features. As the face matures, the eyes rotate forward, reducing the The encephalocele contents included a large part of the orbital angle from 180 degrees to 71 degrees by birth and [20,23,24] occipital lobe and cerebellum and therefore, also the torcular to 68 degrees by maturity. Hypertelorism may result region with confluence of the venous sinuses. The posterior from either failure of the forward migration or from its fossa was virtually nonexistent and the cerebellovermian obstruction by congenital malformation such as an anterior [24] region, the midbrain, and parts of the occipital lobes had encephalocele. In our patient, the herniation of the herniated through an osseous defect of the inferior occipital occipital lobe and the contents of the posterior fossa into the bone and posterior elements of nearly the entire cervical large posterior encephalocele sac probably resulted in a failure spine and were below the basion–opisthion line. The of the forward migration of the eyes to normal position. The consequent microcephaly validates the unifying theory of canthal index[20] was abnormally high in our patient. Normally, embryogenesis for Chiari-II and -III formation.[21,22] According a vertical line from the pupils falls over the outer aspect of to this theory, an open neural placode allows cerebrospinal the lips; and, that from the medial canthus touches the alar fluid (CSF) to escape from the central canal of the caudal base of the nose.[23] In our patient, both these vertical lines neural tube. The interference with adequate enlargement were falling far lateral to the above mentioned anatomical of the telencephalic and rhombencephalic ventricles causes landmarks confirming hypertelorism. less support for the telencephalic hemisphere (resulting in disorganized migration of neurons from the ventricular zone, Chiari III malformation usually has a dismal prognosis with Figure 2: (A) T1; (B) T2 weighted sagittal MRI showing an occipital and cervical (the dysraphic defect reaching till lower cervical vertebral bodies) encephalocele with herniation of a major portion of the occipital and cerebellar contents into it. There was no associated hydrocephalus or Figure 1: (A) Patient’s frontal photograph showing hypertelorism; (B) syringohydromyelia; (C) T1 weighted axial MRI showing the large bony Patient’s lateral photograph showing the large occipital encephalocele with defect with the herniation of the viable occipital and cerebellar tissue into the microcephaly. The skin over the swelling is intact encephalocele sac 170 / J Pediatr Neurosci / Volume 3 / Jul-Dec / 2008 [Downloaded free from http://www.pediatricneurosciences.com on Sunday, May 6, 2018, IP: 109.252.99.223] Garg et al.: Chiari III malformation with microcephaly and hypertelorism most reports stating an early death and severe disability.[6,13] literature. Childs Nerv Syst 2001;17:373-5. Raimondi, however, has stated that