MENINGIOMA Clinical features:
Approximately a quarter of patients with meningioma present with epilepsy - often with a focal component. In the remainder, the onset is insidious with pressure effects (headache, vomiting, papilledema) often developing before focal neurological signs become evident.
Notable characteristic features occur, dependent on the tumour site - PARASAGITTAL/ PARAFALCINE tumours lying near the vertex affect the 'foot' and 'leg' area of the motor or sensory strip. Partial seizures or a 'pyramidal' weakness may develop in the leg (i.e. primarily affecting foot dorsiflexion, then knee and hip flexion). Extension of the lesion through the falx can produce bilateral leg weakness. Posteriorly situated parasagittal tumours may present with a homonymous hemianopia. Tumours arising anteriorly may grow to extensive proportions before causing focal signs; eventually minor impairment of memory, intellect and personality may progress to a profound dementia.
INNER SPHENOIDAL WING tumours may compress the optic nerve and produce visual impairment. Examination may reveal a central scotoma or other field defect with optic atrophy.
N.B. The FOSTER KENNEDY syndrome denotes a tumour causing optic atrophy in one fundus from direct pressure and papilledema in the other due to increased intracranial pressure.
Involvement of the cavernous sinus or the superior orbital fissure may produce ptosis and impaired eye movements (III, IV and VI nerve palsies) or facial pain and anaesthesia (V| nerve damage) - see diagram on page 149. Proptosis occasionally results from venous obstruction from tumour extension into the orbit.
OLFACTORY GROOVE tumours destroy the olfactory bulb or tract causing unilateral followed by bilateral anosmia. Often unilateral loss passes unnoticed by the patient; with tumour expansion, dementia may gradually ensue. SUPRASELLAR tumours - see pages 326-336. Investigations: SKULL X-RAY - note: Associated signs of longstanding increased ICP, i.e. posterior clinoid erosion.
Bony hyperostosis - radiating spicules occasionally seen ('sunray' effect).
15% show calcification.
Before i.v. contrast
Dilated middle meningeal groove. After i.v. contrast
Meningioma - well circumscibed lesions of a density usually greater than, or equal to brain with a surrounding area of low attenuation (oedema). Calcification may be evident.
A dense, usually homogeneous enhancement occurs after contrast injection. n.b. CT is more sensitive than MRI in meningioma detection.
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