Background: Management of the disproportionately large communicating fourth ventricle is still problematic.
Case presentation: Two cases of disproportionately large communicating fourth ventricle were treated successfully. One was a case of a 51-year-old Han Chinese woman with a complaint of headache and dizziness of 1 year's duration. Magnetic resonance imaging (MRI) demonstrated hydrocephalus with a disproportionately large fourth ventricle. She underwent a ventriculo-peritoneal shunt of the right lateral ventricle. Her symptoms were relieved totally. Five years later, magnetic resonance imaging showed she had a normal ventricular system. The other case was a 24-year-old Han Chinese man with a 2-month history of headache and dizziness accompanied by progressive loss of bilateral vision. Magnetic resonance imaging revealed hydrocephalus with a disproportionately large fourth ventricle, crowded posterior cranial fossa, and syringomyelia extending from C1 to C5. He underwent suboccipital and C1 decompression and duraplasty. Shortly after the surgery, his symptoms were relieved completely, the syringomyelia completely disappeared, and the fourth ventricle became significantly smaller.
Conclusions: The management of the disproportionately large communicating fourth ventricle should be individualized. If it coexists with crowded posterior cranial fossa or syringomyelia, posterior fossa decompression could be an option for initial management. If there is no sign of crowded posterior cranial fossa or syringomyelia, shunt of the lateral ventricles might be the first choice.
Keywords: Fourth ventricle; Fourth ventriculomegaly; Hydrocephalus; Syringomyelia.