Symptoms
The most common initial symptoms are headaches, nausea and vomiting, which are caused by the increased pressure in the skull (intracranial) and the disturbance of the cerebral fluid flow (cerebrospinal fluid circulation). In addition, the obstruction of the cerebrospinal fluid flow leads on both sides to swelling (edema) of the exit point of the optic nerve (congestion papilla) and thus to a considerable deterioration of vision up to 6 or 7 diopters. Since the child’s skull can still expand at this age, the symptoms of general cranial pressure appear relatively late.
When persistent headaches set in, the tumor has usually already reached a large extent. Among the initial symptoms are gait disorders (ataxia), which children try to compensate for by supporting themselves with their hands and carefully standing and walking with their legs apart. They often hold their head in a slightly forward inclined forced position. Other typical symptoms are dizziness, double vision, signs of paralysis, a feeling of numbness in the face and paralysis of the mimic muscles (facial paresis) due to a functional disorder of the facial nerve (nervus facialis). At the time of the onset of symptoms (clinical manifestation), 50% of patients already have metastases.
Diagnosis
In the diagnosis of medulloblastoma, as with all brain tumors, imaging techniques are particularly important in addition to the medical examination. In computed tomography (CT), medulloblastomas present themselves as masses with an increased optical density (hyperdens), which are visible in the IV. Ventricles.
The optical density can be further increased by the administration of contrast agent, a substance that increases the image contrast, so that the tumor can be detected even better. Medulloblastomas consist of solid tumor tissue with occasional necroses. In magnetic resonance imaging (MRI) the medulloblastoma can be visualized even better: In the longitudinal view (T1-image) the medulloblastoma has a reduced optical density (hypotens), in the transverse view an increased optical density (hypodens).
It can be easily distinguished from the cerebellum. The clear contrast image is typical for medulloblastomas and shows the extension of the tumor in the brain stem better than in the CT. MRI also allows the detection of metastases in the cerebrospinal fluid or ventricles. High-resolution, contrast-enhanced MRI images are required to show metastases in the spinal canal (spinal metastases).
In addition, the patient’s cerebrospinal fluid is examined for tumor cells (CSF cytology). The cerebrospinal fluid is obtained by means of a cerebrospinal fluid puncture in which cerebrospinal fluid is removed from a cerebrospinal fluid space. The most common form of cerebrospinal fluid collection is lumbar puncture, in which the fluid is collected from the lower spinal canal. The detection of tumor cells is associated with an unfavorable prognosis, but says nothing about the extent of metastasis of the spinal canal. CSF cytology is important in the differential diagnosis of embryonic tumors, such as medulloblastomas, ependymomas or pinealomas, when imaging techniques do not yet allow a reliable diagnosis of the type of tumor.
