Hydrocephalus with Spontaneous Regression in a 14-year-old Girl

We report on a 14-year-old girl with hydrocephalus that underwent spontaneous regression without any specific treatment, such as ventriculoperitoneal shunt surgery. A 14-year-old girl was referred to our hospital with severe headache, dizziness, nausea, and vomiting. Computed tomography and FLAIR-MRI findings on admission showed markedly dilated lateral, third and fourth ventricles with periventricular hyperintensity and downward displacement of the tonsils induced by dilatation of the fourth ventricle. We diagnosed hydrocephalus of unknown etiology. Although no specific treatment for hydrocephalus was performed, the symptoms gradually improved. One year after onset, the patient was completely free of neurological symptoms, and findings of physical examination and magnetic resonance imaging of the brain had returned to normal. The etiology of the spontaneous regression is unclear, but the following mechanisms are discussed: 1) rupture of ventricular diverticulum, 2) head injury causing skull-base fracture with leakage of cerebrospinal fluid, 3) extremely radiosensitive neoplasms diminished by X-p exploration, and 4) cerebrospinal fluid leakage due to lumbar puncture.