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Case 8

Cerebral embolus from atrial myxoma

A 24 year old with sudden hemiplegia

This 24 year old female collapsed suddenly while playing squash. She was found to be dysarthric with a marked right sided hemiparesis. She had previously been fit and well with no past medical history. She was taking the oral contraceptive pill.

She was referred for an emergency CT scan within 2-3 hours of her collapse, and a sample image is shown.

The CT was thought to be normal, though there was suspicion that the basal ganglia on the left show subtle reduction in attenuation. An MRI scan was performed, (approximately 24 hours later) and sample images are shown (coronal T1 weighted and axial T2 weighted images).

Findings

Subtle reduced density in the left basal ganglia on CT.

Increased T2 signal from the head of the left caudate nucleus, the globus pallidus and the insular cortex. There is some mass effect with effacement of the anterior horn of the lateral ventricle. There is lesser signal change in the adjacent white matter.

Echocardiography demonstrated a mass lesion in the left atrium. The selected image shows the mass about to prolapse down through the mitral valve during diastole, towards the left ventricle below.

Diagnosis

Left cerebral infarct secondary to embolus from an atrial myxoma.

Discussion

The clinical and radiological findings were those of a left middle cerebral artery infarct. In a young person the rarer causes of infarction need to be excluded by further investigation. Traumatic dissection was considered, such as a blow from a squash racquet or ball, but excluded by MR angiography of the carotid arteries (not shown).

The commonest causes of infarction are thrombosis, haemorrhage and embolus due to atherosclerotic disease and hpertension. A more detailed list, including some of the rarer causes to be considered is given below:

Arterial disease

• Atheroma eg. internal carotid artery occlusion due to plaque
• Arteritis, eg. giant cell arteritis, polyarteritis nodosa, sarcoidosis
• Trauma, eg. blow to the neck or penetrating injury
• Dissection eg. Marfan's, trauma, ateriography
• Congenital eg. aneurysms
• Infections eg. tonsilitis, endarteritis obliterans (TB, syphilis, bacterial meningitis)
• Irradiation

Embolus (listed in anatomical sequence)

• Paradoxical emboli eg. ASD, patent foramen ovale, pulmonary AVM (hereditary haemorrhagic telangiectasia)
• Left atrium eg. thrombus (atrial fibrillation), myxoma, sino-atrial disease
• Mitral valve eg. infective or rheumatic endocarditis, prosthetic valves
• Left ventricle eg. mural thrombus after myocardial infarction, left ventricular aneurysm, myxoma
• Aortic valve eg. as for mitral valve, syphilis, bicuspid valve
• Congenital cardiac disorders
• Atheromatous plaques eg. from carotid bulb

Haemorrhage

• Hypertension
• Intracranial aneurysm
• AVM

Haematological disorders (may cause thrombosis or haemorrhage)

• Sickle cell disease
• Polycythaemia rubra vera
• Hyperviscosity syndromes eg. Multiple myeloma

Venous infarction and dural sinus thrombosis

• Local eg. sepsis (inner ear), meningitis, tumour invasion
• Systemic eg. dehydration, septicaemia, contraceptive pill, haematological disorders

References

Oxford Textbook of Medicine. 2nd Ed pp 21.155-170.

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