|
Brain tumours
Tiny terrors and sleeping giants
BY Paul Kongkham, MD and Mark Bernstein,
MD
|
|
Mr. R. is a 57-year-old store owner.
He was brought to his general practitioner's office because of family
concerns regarding changes in his cognitive function and behaviour
for the past six months. He's had progressive difficulty managing
his business and has become withdrawn. His family is worried about
Alzheimer's disease.
Presentation
Physical examination
- alert and oriented to person, place
and time
- flattened affect, "dull" mentally,
mildly dishevelled appearance
- otherwise, no focal motor or sensory
deficits
Investigations
- blood work: normal
- non-contrast computed tomography
(CT) scan: basal frontal mass
- magnetic resonance imaging (MRI)
with gadolinium enhancement: discrete, diffusely-enhancing,
frontal extra-axial tumour, with associated mass effect
and bifrontal edema
Diagnosis
Mr. R. was diagnosed with an anterior
skull base meningioma and referred for neurosurgical consultation.
|
Making the case
Intracranial tumours affect patients of all ages and have an annual
incidence of 20 per 100,000 population. Primary tumours make up
less than 50% of all cases, the rest being metastatic disease. Up
to 85% of brain tumours are found supratentorially. Most pediatric
cases occur below the tentorium.
Few risk factors have been identified. These would include genetic
syndromes, e.g. neurofibromatosis, prior cranial irradiation, immunosuppression
and known extracranial malignancy. In the majority of instances,
however, no underlying cause can be found.
The approach to categorizing brain tumours is based on etiology
(whether primary or secondary), location (intra- or extra-axial),
and aggressiveness (benign vs malignant). Histologically benign
lesions may behave in a malignant fashion due to continued growth
in proximity to critical structures.
Over half of all primary brain tumours are glial, mainly anaplastic
gliomas and glioblastoma multiforme (GBM). Meningiomas account for
another 15-20%. Vestibular schwannomas and pituitary adenomas constitute
5-10%.
Between 20-40% of cancer patients — most commonly lung, breast,
melanoma, colon, and renal — will develop cerebral metastases,
with multiple tumours seen in 70%.
Symptoms and signs
Brain tumours may present insidiously, e.g. slowly growing meningioma.
They may be subacute, e.g. rapidly progressive GBM, or acute, with
symptoms due to seizure, hemorrhage or acute hydrocephalus. Few
findings are pathognomonic for any particular tumour type. The clinical
presentation typically relates to the regional neuroanatomy within
which the tumour arises, and may include features such as the following:
- increased intracranial pressure
- altered mental status
- focal neurologic deficit
- seizures
- endocrine dysfunction
In up to 70% of the cases, intracranial tumours present with progressive
neurologic deficits. Headache can also herald brain tumours, in
50% of instances, and seizures, 25%.
|
