Case Report

The ‘‘Heart Appearance’’ Sign in Bilateral Pontine Infarction Debraj Sen, MD,* Vijinder Arora, MD,† Saurabh Adlakha, MRCGP,‡ Yoginder S. Gulati, MD,x Anil Doppaladudi, MD,jj and Shreyash Tiwary, MBBS{

Background: Although rarely seen, bilateral anteromedial infarction of the pons demonstrates the characteristic ‘‘heart appearance’’ sign on magnetic resonance imaging (MRI). This sign has hitherto been described in only 2 patients before this article. This typical pattern can be attributed to atherosclerotic or thrombotic involvement of bilateral paramedian and short circumferential pontine arteries supplying the anteromedial pons. Methods and Results: A 60-year-old man, a known patient of primary hypertension and diabetes mellitus, presented with a posterior circulation stroke. Urgent computerized tomography and MRI revealed a ‘‘heartshaped’’ area of acute infarction in the anteromedian mid-pons. A few scattered infarcts were also noted in the posterior and inferior part of the right cerebellar hemisphere. The basilar artery appeared normal with preserved flow void on MRI, and there were no signs of hemorrhage. These findings were consistent with acute nonhemorrhagic infarcts involving bilateral paramedian and short circumferential pontine arteries and the right posterior inferior cerebellar artery. A repeat MRI performed after a week disclosed hemorrhagic transformation and enhancement of the pontine infarction. The basilar artery appeared normal on magnetic resonance angiography. Conclusions: Recognizing the ‘‘heart appearance’’ sign in a strokelike episode may be helpful in differentiating bilateral anteromedial pontine infarction from other pathologic processes involving the pons. Key Words: Heart appearance’ sign—infarction—pons—bilateral. Ó 2015 by National Stroke Association

Introduction Appearance of a ‘‘medullary heart’’ in patients of bilateral medial medullary infarction on magnetic resonance imaging (MRI) although uncommon has been reported From the *Department of Radiodiagnosis, Military Hospital Amritsar; †Department of Radiodiagnosis, Sri Guru Ramdas Institute of Medical Sciences and Research, Amritsar, India; ‡Lead GP, Harness Harlesden Practice, London, United Kingdom; xDepartment of Radiodiagnosis, Military Hospital Jalandhar, Jalandhar, India; jjKedzie Medical Associates, Chicago, Illinois; and {301 Field Hospital, India. Received July 22, 2014; accepted August 3, 2014. Address correspondence to Debraj Sen, MD, Department of Radiodiagnosis, Military Hospital Amritsar, Amritsar Cantonment, Amritsar-143001, India. E-mail: [email protected]. 1052-3057/$ - see front matter Ó 2015 by National Stroke Association http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2014.08.009

in literature.1-3 A similar ventral ‘‘heart appearance’’ in bilateral anteromedial pontine infarction although rare is characteristic and has hitherto been described in only 2 patients before this article.4,5 The aim of this article is to highlight this unique sign and to briefly discuss the etiopathogenesis and differential diagnosis of similar appearances on imaging.

Case Report A 60-year-old man, a known patient of primary hypertension and diabetes mellitus, on regular medication for the last 19 years was brought to hospital with a history of sudden onset dizziness and unsteadiness of gait, rapidly followed by progressive weakness of all 4 limbs. There was no loss of consciousness. He had been a smoker (6-7 cigarettes/day) for the last 35 years and occasionally consumed alcohol.

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Figure 1. The axial contrast-enhanced computerized tomography section of the brain through the pons shows a relatively well-defined hypodense ‘‘heart-shaped’’ area in the anteromedial pons (thick white arrow). Also seen is a hypodense area in the right cerebellar hemisphere (thin white arrow). The basilar artery is well opacified with contrast.

His general physical examination revealed a regular pulse of 86 per minute, blood pressure of 160/94 mm Hg, and respiratory rate of 18 per minute. On neurologic examination, the patient was drowsy with a Glasgow Coma Scale of E3M3V2. He had quadriparesis (muscle power around the shoulders was grade 3 and the power around the elbows was grade 3-4 with 40% power on hand grip; the lower limbs revealed grade 3 power). The deep tendon jerks were exaggerated and the plantars were extensor. Tactile and proprioceptive senses could not be assessed; however, pain sensation appeared preserved. There was bilateral internuclear ophthalmoplegia and pseudobulbar palsy. Examination of the cardiovascular system did not reveal any other abnormality. Laboratory investigations revealed microcytic hypochromic anemia (hemoglobin 10 g/dL). Serum electrolytes and the rest of the biochemical tests were normal.

An urgent contrast-enhanced computerized tomography of the patient’s brain was performed that revealed diffuse swelling of the pons and a relatively welldefined ‘‘heart-shaped’’ nonenhancing hypodense area in the anteromedian mid-pons (Fig 1). A hypodense area was also noted in the right cerebellar hemisphere. A subsequent MRI corroborated the computerized tomography findings and showed a well-defined lesion in the midpons with a ‘‘heart-appearance’’ on both T2-weighted and fluid-attenuation inversion recovery images with restriction on diffusion-weighted imaging. The lateral and dorsal parts of the pons were spared (Fig 2). A few scattered areas of restricted diffusion were also noted in the posterior and inferior part of the right cerebellar hemisphere. The basilar artery appeared normal with preserved flow void. These findings were consistent with acute nonhemorrhagic infarcts involving bilateral paramedian and short circumferential pontine arteries and the right posterior inferior cerebellar artery. The patient was started on conservative supportive therapy. He became quadriplegic over the next few days with worsening of sensorium and had to be put on ventilatory support. A repeat MRI was performed on the seventh day and susceptibility-weighted imaging revealed hemorrhagic transformation of the infarcts. As expected, a heartshaped area of enhancement was noted at the site of the pontine infarct. The basilar artery appeared normal on magnetic resonance angiography (Fig 3). The patient’s condition progressively deteriorated and he died of cardiorespiratory complications on the 10th day of his admission.

Discussion Appearance of a ‘‘medullary heart’’ in patients of bilateral medial medullary infarction on MRI although uncommon has been reported in literature.1-3 A similar ventral ‘‘heart appearance’’ in bilateral anteromedial pontine infarction although rare is characteristic and has hitherto been described in only 2 patients before this article.4,5 In their seminal paper on 150 pontine infarctions, Kumral el al6 schematically depicted 7 cases of bilateral anteromedial pontine infarcts bearing the shape of a ‘‘heart’’; however, no particular reference was

Figure 2. The panel of axial Flair, T2-weighted, and diffusion-weighted images shows the ‘‘heart shaped’’ area of hyperintensity in the pons (thick white arrows).

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Figure 3. (A) The axial susceptibilityweighted image reveals multiple hypointense foci within the infarct, consistent with hemorrhage (thin white arrow). (B) The axial postcontrast T1-weighted image shows marked enhancement in the heart-shaped area of infarct (thin white arrow). (C) Sagittal maximum intensity projection image showing the patent basilar artery (thick white arrow).

as such made to this most unusual appearance. They also theorized that infarcts reaching up to the pontine surface in the absence of atheromatous involvement of the basilar artery or cardiac embolism were because of microatheromas in basilar artery branches. The pons and the cerebellum are supplied by the basilar artery by branches that fall into 3 groups: (1) 7-10 paramedian branches that supply a wedge of tissue on either side of the midline (anteromedial pons); (2) 5-7 short circumferential branches that that supply the lateral two thirds of the pons (anterolateral pons) and the middle and superior cerebellar peduncles; and (3) paired long circumferential (superior cerebellar and anterior inferior cerebellar arteries).7 For a pontine infarct to assume the shape of a heart as demonstrated in our case, arteries supplying bilateral anteromedial and anterolateral territories need to be involved. Figure 4 shows a simplified diagram of the arterial supply of the pons and the important structures in the mid-pons that may be affected because of such an infarction. Although a very rare appearance, in the appropriate clinical setting the ‘‘heart appearance’’ sign is characteristic of ischemic pontine infarction involving the anteromedial and anterolateral vascular territories. However, it would be prudent to keep in mind other entities like osmotic myelinolysis and neoplastic lesions of the pons. Osmotic myelinolysis may present a similar appearance on fluid-

attenuation inversion recovery, T2-and T1-weighted images with restriction of diffusion on diffusion-weighted imaging. However, the periphery is characteristically spared as are the descending corticospinal tracts. There is often concomitant involvement of other extrapontine sites (putamen, caudate, midbrain, thalamus, subcortical white matter) and a history of rapid correction of hyponatremia. Diffuse pontine gliomas may also mimic the ‘‘heart appearance’’ but they commonly occur in children, often distort the shape of the pons, reveal no or mild

Figure 4. This schematic diagram of the pons depicts its arterial supply and some of the important structures within it. Abbreviations: BA, basilar artery; CST, corticospinal tract; CTB, central tegmental bundle; ML, medial lemniscus; MLF, medial longitudinal fasciculus.

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restriction of diffusion, and minimal contrast enhancement (and no ‘‘luxury perfusion’’ like an infarct on an interval scan) before radiotherapy. Acute disseminated encephalomyelitis may involve the pons, but a history of antecedent viral infection/vaccination, asymmetric involvement of the cerebral hemispheres, no restriction of diffusion in the center of the lesion, and arc-like peripheral enhancement can distinguish it from a pontine infarct. ‘‘Radiological neurodegeneration’’ in Langerhans cell histiocytosis may present a similar appearance; however, lesions are often hyperintense on both T1- and T2-weighted images and may be accompanied by other lesions in the basal ganglia and cerebellum and associated with other pituitary, hypothalamic, or skeletal signs of the disease. In the immune-compromised patients, rhombencephalitis may present a similar picture; however, clinical features of infection, diffuse involvement of the brain stem, and cerebellum are distinguishing features.

Conclusion In the appropriate clinical setting, the ‘‘heart appearance’’ sign in the pons is a unique and characteristic sign of bilateral anteromedial pontine infarction.

References 1. Tokuoka K, Yuasa N, Ishikawa T, et al. A case of bilateral medial medullary infarction presenting with ‘‘heart appearance’’ sign. Tokai J Exp Clin Med 2007;32:99-102. 2. Maeda M, Shimono T, Tsukahara H, et al. Acute bilateral medial medullary infarction: a unique ‘heart appearance’ sign by diffusion-weighted imaging. Eur Neurol 2004;51: 236-237. 3. Thijs RD, Wijman CAC, van Dijk GW, et al. A case of bilateral medial medullary infarction demonstrated by magnetic resonance imaging with diffusion-weighted imaging. J Neurol 2001;248:339-340. 4. Kumral E, Bay€ ulkem G, Evyapan D. Clinical spectrum of pontine infarction. Clinical-MRI correlations. J Neurol 2002;249:1659-1670. 5. Venkatesan P, Balakrishnan R, Ramadoss K, et al. Heart appearance sign in pontine stroke: a result of bilateral infarction due to small vessel disease. Neurol India 2014; 62:115-116. 6. Ishizawa K, Ninomiya M, Nakazato Y, et al. ‘‘Heart appearance’’ infarction of the pons: a case report. Case Rep Radiol 2012;2012:690903. 7. Smith WS, English JD, Johnston SC. Cerebrovascular diseases. In: Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson JL, Loscalzo J, eds. Harrison’s principles of internal medicine. 18th edn. New York: McGraw Hill 2012: 3288-3292.

The "heart appearance" sign in bilateral pontine infarction.

Although rarely seen, bilateral anteromedial infarction of the pons demonstrates the characteristic "heart appearance" sign on magnetic resonance imag...
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