Metastases in the brain (secondary tumours of the brain) are more common as compared to the primary tumours of the brain. Metastases in the brain are secondary tumours that have metastasised from primary cancer located in other parts of the body. The most common primary cancers that are known to metastasise to the brain are carcinoma of the lung and carcinoma of the breast. Other primary cancers that often metastasise to the brain include carcinoma of the kidney, carcinoma of the colon, malignant melanoma and most of the sarcomas. Sometimes, there are metastases in the brain with an unknown primary site. Metastases in the brain are usually located in the white matter of cerebellum and cerebral hemispheres. Secondary tumours of the brain have similar signs and symptoms as that of the primary brain tumours. These include headache, seizures, changes in personality, visual disturbances and ataxia. Procedures used in the diagnosis of secondary tumours of the brain include X-rays, CT scan, MRI, EEG, cerebral angiography and pneumoencephalography.
Focal Effects of Intracranial Tumours
- Frontal lobe tumours may lead to a slowing of mental activity, personality changes, progressive intellectual decline and contralateral grasp reflexes. There may be expressive aphasia, anosmia and focal motor seizures.
- Temporal lobe tumours may lead to a variety of disturbances such as seizures with olfactory or gustatory hallucinations, motor phenomena (e.g. licking or smacking of the lips) and some impairment of external awareness without the actual loss of consciousness. There may be depersonalisation and changes in behaviour, personality and emotions. The temporal lobe tumours may also lead to micropsia or macropsia, visual field defects, auditory illusions and hallucinations. The left-sided temporal lobe lesions may lead to dysnomia and aphasia, whereas the right-sided lesions lead to disturbances in perception of musical notes.
- Parietal lobe tumours may lead to contralateral disturbances in sensations, sensory seizures and sensory loss. There may be loss of postural sensibility, loss of touch analysis, contralateral spontaneous pain, hyperpathia, visual field defects, ideational apraxia, constructional apraxia, dressing apraxia and anosognosia.
- Occipital lobe tumours may lead to crossed hemianopia, visual agnosia, visual hallucinations, cortical blindness, loss of colour perception and seizures (usually preceded by an aura of flashing lights). The patient suffering from occipital lobe tumour may not be able to identify a familiar face.
- Cerebellar tumours may lead to marked ataxia of the trunk and hypotonia in the limbs.
- Brain stem tumours may lead to cranial nerve palsies, ataxia, nystagmus, pyramidal and sensory deficit in limbs.
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