Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 51, Num. 1, 2003, pp. 73-74

Neurology India, Vol. 51, No. 1, Jan-Mar, 2003, pp. 73-74

Case Report

Paradoxical embolism through patent foramen ovale causing cerebellar infarction in a young boy

Devidayal, B. R. Srinivas, A. Trehan, R. K. Marwaha

Advanced Pediatric Centre, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Dr. R. K. Marwaha, Department of Pediatrics, Advanced Pediatric Centre, Postgraduate Institute of Medical Education and Research, Chandigarh-160012, India.

Accepted on 01.05.2001.

Code Number: ni03018

A previously healthy young boy who suffered an acute stroke involving superior cerebellar artery circulation is presented here. Echocardiography revealed a patent foramen ovale through which paradoxical embolism had probably occurred. Low dose aspirin was started and surgical closure was planned to prevent further recurrences.

Key Words: Cerebellar infarction, Patent foramen ovale, Paradoxical embolism.

Cerebellar infarction occurs very rarely in children. Embolism from a cardiac source is implicated in about one-third of all patients younger than 40 years.¹ With the advent of newer methods of echocardiography, paradoxical embolism through a patent foramen ovale (PFO) is increasingly recognized in association with embolic strokes^2-4 especially involving the superior cerebellar artery circulation.¹ The communication describes a young child who suffered an embolic stroke. He had a PFO which probably allowed the embolus to reach the systemic circulation.

Case Report

A 9-year-old boy was admitted with a history of weakness of left side of the body and unsteadiness of gait. A month prior to admission, after vigorous outdoor activity, he experienced sudden severe headache and giddiness followed by several bouts of vomiting which relieved his headache. The vomiting and headache continued intermittently. After 2 days, he was observed to be veering on either side whilst walking and had difficulty holding objects in his left hand. The unsteady gait and the weakness in the left hand started improving after 4-5 days. There was no seizure, unconsciousness, memory loss, dysarthria or bowel and bladder disturbance. He had hypertension for which amlodipine had been started by the primary care physician. His development had been normal. There was no family history of cerebrovascular accidents but his paternal grandparents and his father were hypertensive.

Physical examination revealed a well-nourished child. The peripheral pulses were well palpable. The blood pressure ranged between 120-130/60-70 mm Hg in all four limbs. There was mild decrease in muscle tone and grade IV/V power in left upper and lower limbs. There were cerebellar signs such as dysdiodokokinesia, positive finger-nose and knee-heel tests and mild gait ataxia. Cranial nerves and optic fundus examination were normal. Examination of the other systems was unremarkable.

Complete blood count, serum electrolytes, renal and liver function tests, cholestrol and lipid profile were within normal limits. HBsAg and VDRL tests were negative. Screening tests for coagulation were normal. The urine examination showed no sediment and no proteinuria. Tests done to exclude a collagen-related disease or a vasculitis syndrome, namely lupus anticoagulant, rheumatoid factor, anticardiolipin antibodies, antineutrophilic cytoplasmic antibodies, LE cell and antinuclear factor were all negative. An ultrasonogram of kidneys and suprarenal structures, doppler studies of renal vessels, micturating cystourethrogram and dimercaptosuccinic acid renal scan showed no abnormality.

Magnetic resonance imaging of the brain, done in the initial days of illness, had shown an area of abnormal hyperintensity on T2-weighted and fast FLAIR (fluid attenuated inversion recovery) images involving the left cerebellar hemisphere which was hypointense on T1-weighted images. The rest of the brain parenchyma including the brainstem was normal. These findings were consistent with a fresh infarction involving the left cerebellar hemisphere in the vascular territory of the superior cerebellar artery (SCA). Magnetic resonance angiography done after 4 weeks, showed no abnormality of vessels.

An echocardiogram, using colour doppler flow, revealed a small PFO with a left to right shunt. Thus, paradoxical embolism from a subclinical venous thrombosis was presumed to have occurred causing cerebellar infarct in the area supplied by SCA. Non-surgical transcatheter closure of PFO was initially planned but cost constraints compelled the parents to opt for a surgical closure at a subsequent date. He was started on low dose acetyl salicylate. At a 6 months follow-up he had no apparent neurological deficit.

Discussion

Cerebellar infarctions are known to occur in approximately 1.5% of elderly patients with stroke.⁵ The incidence in the pediatric population is unknown. In one study, only 4.4% of 45 infants and children with cerebrovascular disorders, were found to have cerebellar infarction.⁶ The presumed causes include migraine, fibromuscular dysplasia, vertebral dissection with or without trauma, atlanto-axial subluxation, vigorous exercise and dehydration, embolism from the heart and unknown origin.^1,7-9 As was seen in the present case, infarcts in the SCA territory are usually cardioembolic in origin.¹⁰ At least 42% of cerebellar infarctions occurring in the SCA circulation were attributable to cardiac source of embolism primarily from PFO and rheumatic heart disease.¹ Patent foramen ovale is now increasingly recognized as an important source of paradoxical embolism in patients less than 55 years of age with cryptogenic strokes.^2-4 The risk increases if PFO is associated with atrial septal aneurysm.³ It has also been suggested that PFO may be responsible for stroke more often than is usually suspected.²

Although PFO could be detected easily by conventional echocardiography in this child, the detection may be difficult at times. Transesophageal and contrast echocardiography can detect this abnormality in the majority of those in whom routine echocardiography is negative. ^2-4 Even then, repeated trials are necessary if the first one is negative.¹⁰ The evidence of PFO in cryptogenic stroke should prompt a search for a subclinical venous thrombosis as the embolic source.^2-4 In our patient, a diligent search for conditions associated with thrombosis, proved futile. It was, therefore, presumed that hard physical activity and dehydration were the predisposing factors to latent thrombosis. Closure of PFO is necessary to prevent further recurrences and avoid life-long anticoagulation.¹¹ Although non-surgical closure by transcatheter technique seems ideal,¹² the cost of the double umbrella device precludes the use of this option in a country with limited resources. Surgical closure can also be achieved with minimal morbidity.^11,13 The medical treatment depends on the perceived cause of infarction. As aspirin may provide sufficient prophylaxis after initial ischemia,³ this was started in our patient.

The long-term prognosis is favorable and the majority of patients survive their illness, although recurrences and rare deaths have been reported.^1,14,15 Recurrences after surgery need further evaluation to identify causes other than paradoxical embolism.¹¹

The propositus serves to highlight the need for extensive investigation of young children presenting with stroke. The identification of an underlying cause could lead to prompt institution of remedial measures to avoid further morbidity.

References

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