The early “flu-like” signs of this tumor — lethargy, irritability and loss of appetite — are often so nonspecific that the disease first goes unnoticed. In infants, increased head size and irritability may be the first symptoms. Older children and adults may
experience headaches and vomiting upon awakening. Typically, the person feels better after vomiting and as the day goes on. As the pressure in the brain increases due to a growing tumor or blocked fluid passages, the headaches, vomiting and drowsiness may increase. Other symptoms depend on the nerves and brain structures affected by the tumor. Since medulloblastomas appear in the cerebellum, the center of balance and movement, problems with dizziness and coordination are common. Tumors growing close to the brain’s fourth ventricle may expand into that cavity, blocking the normal flow of cerebrospinal fluid. This can result in hydrocephalus — the buildup of cerebrospinal fluid within one of the cavities of the brain. The pressure of this buildup triggers the tumor’s characteristic symptoms: Morning headaches, nausea, vomiting and lethargy.
Children with this tumor may exhibit a clumsy, staggered walking pattern. They may also complain of visual problems. For instance, if the tumor involves the sixth cranial nerve which controls outward muscle movement of the eye, diplopia (double vision) can occur. Nystagmus (involuntary jerking of the eye) may also be a problem. While seizures are not common with medulloblastoma, other symptoms such as mild neck stiffness and a tilt of the head may occur. As many as 2 out of every 10 children with medulloblastomas may be less than 2 years of age at the time of diagnosis. In infants, symptoms can be more subtle and include intermittent vomiting, failure to thrive, weight loss, an enlarging head with or without a bulging of the soft spot of the head (fontanelle), and inability to raise the eyes upward (the so-called “sun-setting” sign).