Clinical manifestations of NCM occur most frequently in the first two years of life. They usually result from increased intracranial pressure secondary to obstruction of the ventricular system foramen, subarachnoid cistern or arachnoid granulations secondary to melanocytic proliferations. There may also be bleeding or, as suggested by the definition of the syndrome, cancerization of melanocytic cells. The neurological signs and symptoms include headache, lethargy, vomiting, irritability, increased head circumference, seizures, papilledema and occasionally cranial nerve palsies. Disease progression can lead to ataxia, or cause bladder and / or intestinal dysfunction. Severe and chronic psychosis is also described, especially when the disease manifests itself later.The hypothesis that there could be asymptomatic cases of NCM was confirmed after the development of MRI. Based on the analysis of resonances of patients at risk for developing NCM but without neurological signs or symptoms, it is estimated that at least 4.8% to 26% of these individuals may show characteristic alterations compatible with this syndrome during the exam.