<P> Arachnoid cysts are cerebrospinal fluid covered by arachnoidal cells that may develop on the brain or spinal cord . They are a congenital disorder , and in some cases may not show symptoms . However , if there is a large cyst , symptoms may include headache , seizures , ataxia ( lack of muscle control ) , hemiparesis , and several others . Macrocephaly and ADHD are common among children , while presenile dementia , hydrocephalus ( an abnormality of the dynamics of the cerebrospinal fluid ) , and urinary incontinence are symptoms for elderly patients ( 65 and older ) . </P>
what nervous system disorder occurs when lesions form on the cerebral cortex causing dementia
Arachnoid cysts