Chiari II malformation is a complex hindbrain anomaly almost constantly associated with open spinal dysraphism and hydrocephalus [1]-[4]. It is generally considered a consequence of abnormal neurulation and cerebrospinal fluid leakage leading to posterior fossa hypoplasia and hindbrain herniation [2][3].

Beyond the classic hindbrain abnormalities, supratentorial anomalies including corpus callosum dysgenesis and cortical malformations may coexist [5][6]. These findings suggest that Chiari II malformation may represent a broader neurodevelopmental disorder rather than an isolated neural tube defect [7].

Neuronal migration disorders such as periventricular nodular heterotopia occur later during fetal development and are strongly associated with epilepsy and neurocognitive impairment [8]-[11]. Their identification is therefore essential for prognostic assessment in children with repaired myelomeningocele.

We report a case illustrating an extensive polymalformative spectrum demonstrated by MRI.

A 10-year-old child with antenatally diagnosed myelomeningocele surgically repaired at birth was referred for routine MRI follow-up. The patient presented chronic motor neurological impairment requiring wheelchair use and epilepsy.

The myelomeningocele was located at the lumbosacral level and was surgically repaired during the neonatal period. Hydrocephalus developed early in life and was treated by ventriculoperitoneal shunting. No documented shunt revisions were reported. The patient developed permanent motor impairment of the lower limbs leading to wheelchair dependence. Epileptic seizures appeared during childhood and are currently managed with antiseizure medication. Neurodevelopmental follow-up revealed cognitive difficulties requiring adapted schooling.

Chiari II malformation is traditionally explained by early neurulation failure leading to cerebrospinal fluid leakage and posterior fossa hypoplasia [1]-[4]. However, the abnormalities observed in this patient extend far beyond the hindbrain and involve multiple stages of central nervous system development.

The hindbrain herniation and associated spinal dysraphism reflect an early defect of neural tube closure. Chiari II malformation is almost invariably associated with myelomeningocele and is considered a consequence of altered embryonic cerebrospinal fluid dynamics [2][3][12]. The presence of extensive dysraphism supports a global neurulation disturbance rather than an isolated posterior fossa malformation.

Septum pellucidum agenesis and posterior corpus callosum dysgenesis indicate abnormal midline patterning occurring after neural tube closure. These abnormalities are frequently described in Chiari II and reflect disturbance of commissural formation during early brain organization [5][6].

Periventricular nodular heterotopia and stenogyria correspond to abnormal neuronal migration occurring between the 8th and 16th gestational weeks [8]-[10].

Periventricular nodular heterotopia was diagnosed based on nodular lesions lining the lateral ventricles that were isointense to cortical gray matter on all MRI sequences. The cortical abnormality characterized by simplified gyral pattern and abnormal sulcation was consistent with stenogyria, which has been previously described in association with Chiari II malformation [13].

These anomalies are strongly associated with epilepsy and neurodevelopmental impairment [9]-[11], explaining the clinical presentation of epilepsy and severe motor disability in this patient.

Hydrocephalus is classically related to CSF circulation impairment in Chiari II. However, long-term neurological outcome correlates poorly with tonsillar descent and more closely with cortical malformations and callosal abnormalities [6][11]. MRI therefore plays a key role in identifying prognostic factors beyond posterior fossa anatomy [14].

From a clinical perspective, the identification of extensive supratentorial malformations has implications for patient management. These findings support the need for multidisciplinary follow-up including epilepsy management, neuropsychological assessment, and long-term neurological monitoring.

This case illustrates an extensive polymalformative syndrome combining Chiari II malformation, neuronal migration disorders, cortical dysplasia, and closed spinal dysraphism.

This case suggests that supratentorial developmental abnormalities may substantially contribute to neurological impairment in Chiari II malformation, although this observation should be interpreted cautiously given the single-case design.

Comprehensive MRI evaluation is therefore essential for accurate prognostic assessment and clinical management.

Information was collected in accordance with confidentiality requirements and after obtaining the mother’s consent.

All authors contributed to the development of this study and declare that they have read and approved this manuscript.