Table 2.
Typical clinical, imaging, and genetic characteristics of cerebellar malformations without known genetic cause.
| Disorder | Clinical features | Imaging features | Causes/testing | Inheritance |
|---|---|---|---|---|
| OCCS | Orbital cysts, micro/anophthalmia, focal skin defects and appendages | Severely hypoplastic vermis, normal or hypoplastic cerebellar hemispheres, enlarged dysplastic tectum, thick, vertical SCPs, CC agenesis, frontal PMG | Unknown | Sporadic |
| PCH type 7 | Ambiguous or female external genitalia with 46,XY karyotype, hypergonadotrophic hypogonadism, hypotonia, seizures. Severe NDV impairment |
Small pons and cerebellum, enlarged ventricles, thin corpus callosum | Unknown | AR |
| PHACE syndrome | Segmental hemangioma (usually head and neck), intracranial and great vessel abnormalities. Variable NDV impairment in <50% (usually mild). |
Unilateral cerebellar hypoplasia with or without vermis involvement, DWM. Dysmorphic or absent major vessels. Occasional heterotopia, PMG. |
Unknown | Sporadic |
| PTCD | Hearing loss, trigeminal anesthesia/corneal scarring, dysphagia, variable cardiac and vertebral/rib defects, substantial ataxia. Moderate to severe NDV impairment. |
Hypoplastic pons, mildly hypoplastic cerebellum, “cap” of white matter on dorsum of pons, markedly hypoplastic middle and inferior cerebellar peduncles | No specific testing | Sporadic |
| RES all types | Alopecia, trigeminal anesthesia (GLH syndrome), head shaking (usually “figure 8” pattern), hyperactivity/impulsivity, VACTERL features (<50%), variable ataxia. Full range of NDV outcome. |
Absent septum pellucidum, aqueductal stenosis, fused colliculi, posterior holoprosencephaly (rare), absent olfactory bulbs (<50%) | Unknown | Sporadic (one recurrence reported) |
OCCS, oculocerebrocutaneous syndrome; SCP, superior cerebellar peduncles; CC, corpus callosum; PMG, polymicrogyria; PCH, pontocerebellarhyplasia; NDV, neurodevelopmental; AR, autosomal recessive; PHACE, Posterior fossa malformations, Hemangioma, Arterial anomalies, Cardiac defects, and Eye anomalies; DWM, Dandy–Walker malformation; PTCD, pontine tegmental cap dysplasia; RES, rhombencephalosynapsis; GLH, Gómez–López–Hernández; VACTERL, Vertebral defects, Anal atresia, Cardiac defects, Tracheo-Esophageal fistula, Renal defects, and Limb defects.