Medulloblastoma is a malignant tumour of the posterior fossa, occurring mainly during childhood although adult cases have been increasingly reported.1,2
The cerebellum is the usual region of localisation of medulloblastoma; when other foci are found, they are generally considered as multifocal and/or metastatic cerebellar medulloblastoma. There have been historically a few rare cases reporting cerebral medulloblastoma, although authors have questioned the existence of this form of tumour.3
More than 75% of cerebellar cases are vermian. More lateral localisations, eventually hemispheric ones, are more usual when the tumour is found during adolescence or adulthood. Our subject was 21 years old, and the localisation was hemispheric.
The change in localisation (vermian in childhood; lateral or hemispheric in adulthood) is hypothetically related to the migration of non-differentiated cells from the posterior medullar velum toward lateral and posterior directions.4
During the first years of life, these cells are localised next to the median line, and theoretically may cause a tumoral growth following this line—that is, in the cerebellar vermis. Later, these cells migrate laterally and the tumour growth will preferably tend toward a hemispheric localisation.5
The infiltration of the brain stem (truncal structures) is usual; other referred localisations are those of the fourth ventricle, other cerebellar regions, or even the spinal cord.1,6
The clinical history of medulloblastoma as a rule is very short, and reflects the aggressive biological behaviour of the tumour. The majority of these patients have a symptomatology of less then 3 months.7
Headache and vomiting are the usual complaints. Truncal ataxia following the severe damage to the vermis is an objective common sign, and is frequently associated with spasticity. Papilloedema (related to hydrocephaly), nystagmus, and sixth cranial nerve palsy are also found in these patients quite often.
In rare cases the neurological status may aggravate very quickly, and death (even sudden) may follow acute intratumoral haemorrhage. The haemorrhage creates an immediate mass effect on the posterior fossa, with an acute hydrocephaly and cessation of the intracranial circulation. The spinal cord compression due to the diffusion of tumoral cells via cerebrospinal pathways is also a phenomenon described in the literature.8
Other authors have explained the risk of sudden death explicitly in relation to the obstructive hydrocephaly, although doubts on the veracity of the hypothesis are expressed.9
An acute hydrocephaly is mostly cited by authors as the probable death mechanism, in comparison with the probability of a direct compression on the vital brain stem structures.
The World Health Organization classifies medulloblastoma as a fourth grade lesion, distinguishing four subtypes of the tumour: classical, desmoplastic, mainly nodular and with advanced neuronal differentiation, and with large cells.2
In conclusion, intracranial tumours might be accompanied by non-traumatic intracerebral and intracerebellar haemorrhage; in some cases such a haemorrhage might be the first clinical sign. Intracranial tumours that can result in sudden death include multiform glioblastoma,10
oligodendroglioma, medulloblastoma, lymphoma, teratoma, etc.
We report the case of sudden death of a 21-year-old man, due to hemispheric cerebellar medulloblastoma with intratumoral haemorrhage. The cerebral oedema found at the autopsy reflected the immediate cessation of the cerebral circulation, obviously due to the acute obstructive hydrocephalus during the cascade of the pathological events at the peri-aqueductal region.
- Sudden death due to intracranial disorders in adulthood represents a major challenge to forensic experts. Among the causative mechanisms mentioned by authors11 are:
- prompt increase of intracranial pressure, due to haemorrhage in different brain territories
- acute obstructive hydrocephalus
- autonomous and/or neurochemical dysfunction, in rare cases of immediate death; the autonomous hyperactivity is thought to be transmitted through lower cranial nerves, or is thought to be related to high concentrations of epinephrine or norepinephrine secreted in the systemic circulation, probably as a part of the ‘response toward stress’.12
- The most quoted mechanism of death according to different authors is the prompt increase in intracranial pressure, mainly in cases of massive haemorrhage, with the possibility of a total cessation of cerebral circulation. On the other hand, patients suffering a haemorrhage in the vicinity of the ventricular system, and particularly in the posterior fossa, might show an acute obstructive hydrocephalus.
- In our case the mechanism of the acute obstruction following the haemorrhage was plausible, because autopsy showed evidence of blood coagulum and intratumoral bleeding, with immediate blocking of the aqueduct at the level of the fourth ventricle.